NEA-1552 SINBAD ACCELERATOR-. (Abstract last modified 15-SEP-2006)
1.
NAME - SINBAD ACCELERATOR, Shielding Benchmark Experiments. 2.
COMPUTER FOR WHICH PROGRAM IS DESIGNED AND OTHER MACHINE VERSION PACKAGES AVAILABLE -
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Machines used:
Package-ID Orig.Computer Test Computer
NEA-1552/01 Many Computers Many Computers
NEA-1552/03 Many Computers Many Computers
NEA-1552/07 Many Computers Many Computers
NEA-1552/08 Many Computers Many Computers
NEA-1552/10 Many Computers Many Computers
NEA-1552/12 Many Computers Many Computers
NEA-1552/13 Many Computers Many Computers
NEA-1552/14 Many Computers Many Computers
NEA-1552/15 Many Computers Many Computers
NEA-1552/17 Many Computers Many Computers
NEA-1552/18 Many Computers Many Computers
NEA-1552/19 Many Computers Many Computers
NEA-1552/21 Many Computers Many Computers
NEA-1552/22 Many Computers Many Computers
NEA-1552/23 Many Computers Many Computers
NEA-1552/24 Many Computers Many Computers
3.
DESCRIPTION - 4.
METHODS -
NEA-1552/03:
NAME OF EXPERIMENT - SINBAD-TIARA. Transmission of Quasi-Monoenergetic Neutrons Generated by 43 MeV and 68 MeV Protons Through Iron, Concrete(1996) and Polyethylene(1997) Shields.
NEA-1552/07:
NAME OF EXPERIMENT - SINBAD-52P. Transmission Through Shielding Materials of Neutrons and Photons Generated by 52 MeV Protons (1981).
NEA-1552/08:
NAME OF EXPERIMENT - SINBAD-65P. Transmission Through Shielding Materials of Neutrons and Photons Generated by 65 MeV Protons (1991).
NEA-1552/10:
NAME OF EXPERIMENT - SINBAD-ROESTI I, II and III. Hadron and low-energy neutron fluences and absorbed doses in the cascades induced in iron and lead dumps irradiated by high-energy hadron beams.
NEA-1552/12:
NAME OF EXPERIMENT - SINBAD-BEVALAC. BEVALAC experiment stopping 272 and 435 MeV/nucleon Nb ions on Nb and Al targets.
NEA-1552/13:
NAME OF EXPERIMENT - SINBAD-MSU/155 HE-C. MSU experiment stopping 155 Mev/nucleon He and C ions on aluminum target (1993).
NEA-1552/14:
NAME OF EXPERIMENT - SINBAD-RIKEN. RIKEN Development of a Quasi-monoenergetic Neutron Field from the Li-7(p,n)Be-7 Reaction in the 70-210 MeV Energy Range.
NEA-1552/15:
NAME OF EXPERIMENT - SINBAD-PSI-P590MEV. High Energy Neutron Spectra Generated by 590-MeV Protons on a Thick Lead Target (1979).
NEA-1552/17:
NAME OF EXPERIMENT - SINBAD-HIMAC800-FE. Measurements of high energy neutrons (up to 800 MeV) penetrated through iron shields (HIMAC/NIRS) (2002).
NEA-1552/18:
NAME OF EXPERIMENT - SINBAD-HIMAC800-CONC. Measurements of high energy neutrons (up to 800 MeV) penetrated through concrete shields (HIMAC/NIRS) (2001).
NEA-1552/19:
NAME OF EXPERIMENT - SINBAD-TEPC-FLUKA. Simulation of the lineal energy distribution of the energy deposition in biological cells, TEPC-FLUKA Comparison.
NEA-1552/21:
Name of Experiment - SINBAD-ISIS800. ISIS Benchmark Experiment on Deep-Penetration Neutrons through Concrete and Iron Shields (1998)
NEA-1552/22:
NAME OF EXPERIMENT - SINBAD-HIMAC. HIMAC experiments stopping He, C, Ne, Ar, Xe, Fe & Si ions on Al, C, Cu & Pb targets.
NEA-1552/23:
Name of Experiment - SINBAD-KENS-P500MeV. Shielding Experiment using 4m Concrete at KEK Spallation Neutron Source Facility (KENS) (2002-2004)
NEA-1552/24:
Name of Experiment - SINBAD-CERF-BSS. Response of a Bonner Sphere Spectrometer to charged hadrons measured at CERF facility (2003).
Program-name Package-ID Status
SINBAD ACCELERATOR-- NEA-1552/01 Tested
SINBAD-65P NEA-1552/02 Obsolete
SINBAD-TIARA NEA-1552/03 Tested
SINBAD-52P NEA-1552/04 Obsolete
SINBAD-52P NEA-1552/05 Obsolete
SINBAD-65P NEA-1552/06 Obsolete
SINBAD-52P NEA-1552/07 Tested
SINBAD-65P NEA-1552/08 Tested
SINBAD-52P NEA-1552/09 Obsolete
SINBAD-ROESTI NEA-1552/10 Tested
SINBAD-HIMAC NEA-1552/11 Obsolete
SINBAD-BEVALAC NEA-1552/12 Tested
SINBAD-MSU/155 HE-C NEA-1552/13 Tested
SINBAD-RIKEN NEA-1552/14 Tested
SINBAD-PSI-P590MEV NEA-1552/15 Tested
SINBAD-HIMAC800-FE NEA-1552/17 Tested
SINBAD-HIMAC800-CONC NEA-1552/18 Tested
SINBAD-TEPC-FLUKA NEA-1552/19 Tested
SINBAD-ISIS800 NEA-1552/20 Obsolete
SINBAD-ISIS800 NEA-1552/21 Tested
SINBAD-HIMAC NEA-1552/22 Tested
SINBAD-KENS-P500MeV NEA-1552/23 Tested
SINBAD-CERF-BSS NEA-1552/24 Tested
SINBAD is a new electronic database developed to store a variety of radiation shielding benchmark data so that users can easily retrieve and incorporate the data into their calculations. SINBAD is an excellent data source for users who require the quality assurance necessary in developing cross-section libraries or radiation trans- port codes. The future needs of the scientific community are best served by the electronic database format of SINBAD and its user- friendly interface, combined with its data accuracy and integrity. It has been designed to be able to include data from nuclear reactor shielding, fusion blankets and accelerator shielding experiments.
The guidelines developed by the Benchmark Problems Group of the American Nuclear Society Standards Committee (ANS-6) on formats for benchmark problem description have been followed by SINBAD. SINBAD data include benchmark information on (1) the experimental facility and the source; (2) the benchmark geometry and composition; and (3) the detection system, measured data, and an error analysis. A full reference section is included with the data. Relevant graphical information, such as experimental geometry or spectral data, is included. All information that is compiled for inclusion with SINBAD has been verified for accuracy and reviewed by two scientists.
NEA-1552/03:
SINBAD-TIARA
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Purpose and Phenomena Tested:
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Intermediate-energy neutron spectra and reaction rates behind and inside up to 130 cm thick iron shield, up to 200 cm thick concrete shield, and up to 180 cm thick polyethylene were measured for 43 and 68 MeV p-Li7 quasi-monoenergetic neutron source at the 90-MV AVF cyclotron of the TIARA facility in JAERI.
The energy between 1E-10(MeV) and the peak energy of the neutrons generated by the Li7(p,n) reaction was measured.
Description of Source and Experimental Configuration:
----------------------------------------------------
Figure 1 shows a cross sectional view of the Takasaki Ion Accelerator for Advanced Radiation Application (TIARA) facility with the experimental arrangement.
Quasi-monoenergetic source neutrons were generated by 43- and 68-MeV protons bombarding 3.6 mm and 5.2 mm thick 99.9 % enriched Li-7 targets, respectively. The protons penetrating the target with a 2-MeV energy loss were bent down toward the beam dump by a clearing magnet. The neutrons produced in the forward angle reached the experimental room through a 10.9 cm diameter and 225 cm long iron collimator embedded in the concrete wall. The intensity of source neutrons was monitored with a proton beam Faraday cup and two fission counters placed near the Li-7-target and the collimator. An iron test shield of 10 to 130 cm thickness was assembled [1, 2, 5] with 10 cm thick iron slabs of 120 cm x 120 cm rectangular surface on a movable stand. A concrete test shield of 25 to 200 cm thickness was also assembled [3, 6] with 120 x 120 x 25 cm3 slabs on the movable stand. A polyethylene test shield of 30.5 to 183.0 cm thickness was also assembled [4, 7] with 118.5 x 118.0 x 30.5 cm3 slabs on the movable stand. An additional iron collimator was used for measurements of thinner test shields and off axis measurements in order to depress the neutron leakage through the collimator wall and rotary shutter. The additional collimator of 40 to 80 cm thickness was assembled with 120 x 120 x 10 cm3 slabs with a 10.9 cm diameter cylindrical hole on the movable stand. Thicknesses of the test shields and the additional collimator, peak flux of source neutrons per proton beam charge (microcoulombs-microC) are given. Atom densities of the iron, concrete and polyethylene test shields and the additional collimator are given.
Absolute fluxes of source neutrons in the monoenergetic peak per proton beam charge (microcoulombs), shown in Table 1, have been measured with a proton-recoil-counter-telescope (PRT) set at the position of 5.54 m from the Li target. The spectra of quasi-monoenergetic source neutrons were measured by the time of flight (TOF) method with the BC501A liquid scintillation detector placed about 14 m away from the target. Normalized measured source neutron energy spectra are given in Tables 3 and 4, presented as flux per proton beam charge.
NEA-1552/07:
SINBAD-52P
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Purpose and Phenomena Tested:
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Attenuation of secondary neutrons and photons generated by 52 MeV protons through shielding materials. Graphite, iron, water and ordinary concrete assemblies were studied to obtain information on the secondary neutron effects, needed for the design of high energy accelerator shielding.
Description of the Source and Experimental Configuration:
--------------------------------------------------------
The experiments were performed at the FM cyclotron of Institute for Nuclear Study of University of Tokyo. The 52 MeV proton beam was extracted into the air through a 0.15-mm-thick stainless-steel window of the beam transporting duct and injected to the center of a 2.145-cm-thick graphite target placed 5 cm from the window. A thickness of the graphite target was sufficient to stop the 52 MeV protons which have a range of 1.6 cm. Most neutrons were generated by C-12(p,n)N-12 reaction (Q=-18.14 MeV). The diameter of proton beam was about 5 mm at the injecting point. The beam intensity was 1 to 2 nA.
NEA-1552/08:
SINBAD-65P
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Purpose and Phenomena Tested:
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Transmission of secondary neutrons and photons generated by 65 MeV protons through shielding materials. Graphite, iron, lead and concrete assemblies were studied to obtain information on the secondary neutron effects, needed for the design of high energy accelerator shielding.
Description of the Source and Experimental Configuration:
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The experiments were performed at the AVF cyclotron of Research Center of Nuclear Physics, Osaka University. A copper target of 65 MeV proton stopping range was used. The secondary neutrons and photons were collimated by a 7.5-cm diam., 50-cm long iron-lined concrete hole. The test shields of concrete, iron, lead and graphite were placed very close to the collimator exit. The shields were slabs about 40 x 40 cm in cross section and 10 to 100 cm thick.
NEA-1552/10:
SINBAD-ROESTI
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Purpose and Phenomena Tested:
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Space distribution of hadron and low-energy neutron fluences and absorbed doses in the cascades induced in iron and lead dumps irradiated by high-energy hadron beams.
Description of Source and Experimental Configuration:
----------------------------------------------------
The experiments Roesti I (Ref. [1]) and III (Ref. [3]) were performed at the H6 secondary beam in the North Experimental Area of the CERN SPS (Super Proton Synchrotron). The beam consisted of positive hadrons (2/3 protons and 1/3 positive pions) with a momentum of 200 GeV/c. The beam had a gaussian profile with standard deviations of the projected horizontal and vertical beam profile distributions equal to 1.2 and 0.9 cm respectively.
Experiment Roesti II (Ref. [2]) took place at an extracted beam of the CERN PS (Proton Synchrotron). The beam consisted of protons of 24 GeV/c momentum, with a Gaussian profile of standard deviation 0.13 cm in both the horizontal and the vertical direction.
In Roesti I and II the target was a dump made of twenty 5 cm thick, 30x30 cm square iron plates. The density of the iron was 7.86 +/- 0.02 g/cm3. The plates were welded to an iron framework with gaps of 0.7 cm between the plates. Extra detector slots were provided in front of the first plate (slot 0) and behind the last plate (slot 20). The beams were incident on the centre of the first absorber slab. Aluminium plates, 0.4 cm thick, 24 cm wide and 30 cm high, were inserted into each slot excepted slot 9, which was left empty. Aluminium disks of varying sizes were punched out of the plates at different radial distances from the center and several of them were used as activation detectors. Other detectors (RPL glasses inside polyethylene capsules of 0.8 cm internal diameter, sulphur and indium disks) were placed in the remaining holes.
In Roesti III the target was a dump made of twenty 5 cm thick, 50x50 cm square lead plates. The density of the lead was not measured. The lead composition was known to include a small amount of antimony (about 4%).
The lead plates were bolted together with 0.8 cm gaps and placed on an iron support structure. The beam was incident on the first absorber slab 10 cm off-centre in the horizontal mid-plane. Activation detectors, mounted on aluminium plates 0.05 cm thick and with 50x50 cm lateral dimensions, included aluminium, indium, sulphur and polyethylene disks. A slight azimuthal asymmetry around the nominal beam axis was found for the detectors with the highest activation threshold (but not for the others). The data reported for each radial distance are the aritmetic mean of different azimuthal detector positions.
NEA-1552/12:
SINBAD-BEVALAC
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Purpose and Phenomena Tested:
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The stopping of high energy Nb ions in Niobium and Aluminum targets has been investigated in the BEVALAC facility of Lawrence Berkeley Laboratory during July 1991. The neutron spectra were measured by the time-of-flight method.
Description of source and Experimental Configuration
----------------------------------------------------
The energy of the projectile was 272 and 435 MeV/nucleon for Nb ions stopping in Niobium target and 272 MeV/nucleon for Nb ions stopping in Aluminum target. They were delivered in spills of 1 second every 6 seconds with approximately 3E+05 particles per spill reaching the target.
A set of two thin detectors were located in the beam trajectory upstrem of the target. They were used to define valid particles from a coincidence logic.
The Niobium target was a 5.08 x 5.08 cm2 square plate 1 cm thick for the higher energy and 0.51 cm thick for the lower energy. The Aluminum target was a 5.08 x 5.08 cm2 square plate 1.27 cm thick. The targets were oriented perpendicular to the beam. All the targets were thick enough to stop the beam. Mass thickness of targets is 8.57 g/cm2 for Niobium with 435 MeV/ nucleon, 4.37 g/cm2 for Niobium with 272 MeV/nucleon and 3.43 g/cm2 for Aluminum.
The target was housed inside a rectangular steel scattering chamber with a thin Mylar window 0.25 mm thick in the face of the scattering chamber, directly between the target position and the neutron detectors. The longer dimension of the chamber was perpendicular to the beam axis and big enough to allow neutrons leaving the target to reach the detectors though the Mylar window. Chamber walls were 0.32 cm thick. Pressure inside scattering chamber was at most 1.E-05 Torr.
NEA-1552/13:
SINBAD-MSU/155 HE-C
===================
Purpose and Phenomena Tested:
----------------------------
An aluminum target was bombarded with He and C ions of 155 MeV/nucleon at the National Superconducting Cyclotron Laboratory (NCSL) facility in the Michigan State University (MSU) during September 1993. Neutron yields were measured by the time-of-flight method.
Description of Source and Experimental Configuration:
----------------------------------------------------
The energy of the projectile is 155 MeV/nucleon for both He and C ions. They are delivered in bursts of 1 to 3 nanoseconds width with a period of 41.6 ns.
The target is an aluminum cylinder, 13.34 cm long with a diameter of 1.78 cm. It is coaxial with the beam. At the entrance side there is a cylindrical hole 5.08 cm long and 1.59 cm diameter also coaxial with the beam in order to minimize the loss of backscattered delta electrons, since the number of beam particles is calculated from the total amount of charge collected in the target.
The target is suspended inside a spherical scattering chamber of diameter 91.44 cm with 3.2 mm thick steel wall. Pressure inside chamber is 1.E-06 Torr.
NEA-1552/14:
SINBAD-RINKEN
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Purpose and Phenomena Tested:
----------------------------
A quasi-monoenergetic neutron field was developed using the Li-7(p,n)Be-7 reaction in the energy range from 70 to 210 MeV in the ring cyclotron facility at RIKEN [1]. Neutrons were generated from a 10-mm-thick Li-7 target injected by protons accelerated to 70, 80, 90, 100, 110, 120, 135, 150 and 210 MeV.
Description of Source and Experimental Configuration:
----------------------------------------------------
A quasi-monoenergeric neutron field was developed at the E4 experimental room of the RIKEN ring cyclotron facility. This room has a big charged-particle spectrometer, named SMART (Swinger and Magnetic Analyzer with a Rotator and a Twister), for nuclear-physics research; a part of it is used as a neutron beam line. Ions are accelerated in two steps with an AVF-cyclotron and a ring-cyclotron, and are transported to E4-room. The beam swinger permits to bombard the accelerated particles onto a target in a scattering chamber at any angle up to 110 deg.
Quasi-monoenergetic neutrons were produced from a 10-mm-thick Li-7 metal target (99.98 atm% enriched, 0.54 g/cm3) injected by 70, 80, 90, 100, 110, 120, 135, 150, 210 MeV protons. Proton beam was focused on the center of the Li target within ~2-mm-diameter. The beam intensity used is up to 100 nA in order to suppress the activities induced in other experimental instruments.
The protons that penetrated the Li-7 target were focused by the PQ1 and PQ2 quadruple-magnets, and were bent towards the beam dump by a PD1-dipole-magnet. A beam dump of lead is set in the beam duct through the PD1, and the whole PD1 is insulated so as to be used as a Faraday cup.
The neutrons produced at 0° from the target pass through a 3-cm-thick acrylic vacuum window and a 120-cm-thick ironcollimator having 22-cm-wide x 22-cm-high hole, and reach the neutron measurement area. Concrete and iron shields are additionally equipped in order to shield the spurious neutrons produced at the PD1 beam dump.
The neutron energy spectra were measured with an NE213 organic liquid scintillator using the time-of-flight (TOF) method. The absolute peak neutron yields were obtained by measurement of 0.478 MeV gamma-rays from Be-7 nuclei produced in the Li-7 target.
NEA-1552/15:
SINBAD-PSI-P590MEV
==================
As part of a feasibility study for a German spallation source, a series of experiments [2] were performed in 1979 at the Swiss Institute for Nuclear Research (SIN) to determine high energy particle spectra from spallation targets. The experiment presented here used a time-of-flight (TOF) technique to measure angular neutron spectra resulting from 590-MeV protons on a thick lead target.
Description of the Source and Experimental Configuration:
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A 590-MeV proton beam obtained from the SIN cyclotron was focused to a 2-cm diameter onto a cylindrical lead target. The target was composed of twelve cylindrical blocks, each 5-cm long and 10-cm diameter, giving an overall length of 60 cm. The proton current was monitored during the experiment using a carbon scatterer placed in the incident proton beam. A pair of thin plastic scintillators operated in coincidence was used to detect the scattered protons. The monitor was calibrated with respect to the absolute proton flux by counting individual protons in the direct beam with a third thin plastic scintillator at sufficiently reduced current. Measurements of the neutrons emitted from the target were performed at 30-deg., 90-deg. and 150-deg. via an iron collimator (about 1 m thick).
NEA-1552/17:
SINBAD-HIMAC800-FE
==================
Purpose and Phenomena Tested:
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The neutron energy spectra penetrated through iron shields were measured using the Self-TOF detector and a NE213 organic scintillator at HIMAC (Heavy-Ion Medical Accelerator) of NIRS (National Institute of Radiological Sciences), Japan [1]. Neutrons were generated by bombarding 400 MeV/nucleon C-12 ion on a thick copper target. The neutron spectra were measured in the energy range from 20 MeV to 800 MeV. The neutron fluence and fluence attenuation length were obtained from the experimental results and the calculation.
Description of the Source and Experimental Configuration:
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The shielding experiment was performed at HIMAC PH-2 beam line. The neutrons are produced by bombarding copper target with 400 MeV/nucleon C-12 ions beams on thick (stopping length). The target size was 10 cm x 10 cm and 5 cm thick. A transmission-type ionization chamber was placed behind the end window of a beam line as a beam monitor. An NE102A plastic scintillator (100mm x100mm and 3mm thick) placed just in front of the shields, was also used as a relative monitor. The Self-TOF detector was placed 509 cm downstream of the target front face on the beam axis. An iron collimator of 60 cm x 60 cm and 40 cm thickness with a hole of 10 cm x 10 cm was set in front of the Self-TOF detector to decrease the accidental signals which were induced by the incidence of fragment charged particles on the stop counters, and also to inject neutrons almost normally into the detector. A veto counter (150 mm x 150 mm and 5 mm thick NE102A plastic scintillator), was placed in front of the radiator to remove fragment charged particles from neutrons.
The Self-TOF detector was fixed at the same position, in opposition of the NE213 detector which was placed in contact with the shielding surface, (Measuring point (A)) and distant from the shielding surface (Measuring point (B)), 503 cm downstream of the copper target on the beam axis. The measuring point (B) is selected for comparison with the Self-TOF results.
The assembly of iron shields is 100 cm x 100 cm in size and 10 cm thickness was put onto the steel platform to fix the center of the shield on the beam axis. The thickness of the shield assembly was changed to be 20, 40, 60, 80 and 100 cm. The mass density of iron shield is 7.8 g/cm3.
NEA-1552/18:
SINBAD-HIMAC800-CONC
====================
Purpose and Phenomena Tested:
----------------------------
The neutron energy spectra penetrated through concrete shields were measured using the Self-TOF detector, an NE213 organic liquid scintillator and the Bi and C activation detectors at HIMAC (Heavy-Ion Medical Accelerator) of NIRS (National Institute of Radiological Sciences), Japan [1]. Neutrons were generated by bombarding 400 MeV/nucleon C-12 ion on a thick copper target. The neutron spectra were measured in the energy range from 20 MeV to 800 MeV. The neutron fluence attenuation length were obtained from the experimental results and the calculation.
Description of the Source and Experimental Configuration:
--------------------------------------------------------
The shielding experiment was performed at HIMAC PH-2 beam line. The experimental arrangements using the Self-TOF detector, NE213 detector and the (Bi and C) activation detector are shown. The neutrons are produced by bombarding copper target with 400 MeV/nucleon C-12 ions beams on thick (stopping length). The target size was 10 cm x 10 cm and 5 cm thick. A transmission-type ionization chamber was placed behind the end window of a beam line as a beam monitor. An NE102A plastic scintillator (100mm x100mm and 3mm thick) placed just in front of the shields, was also used as a relative monitor. The Self-TOF detector was placed 506 cm downstream from the target front face on the beam axis. An iron collimator of 60 cm x 60 cm and 40 cm thickness with a hole of 10 cm x 10 cm was set in front of the Self-TOF detector to decrease the accidental signals which were induced by the incidence of fragment charged particles on the stop counters, and also to inject neutrons almost normally into the detector. A veto counter (150 mm x 150 mm and 5 mm thick NE102A plastic scintillator), was placed in front of the radiator to remove fragment charged particles from neutrons.
The Self-TOF detector was fixed at the same position, in opposition of the NE213 detector which was placed in contact with the shielding surface, (Measuring point (A)) and distant from the shielding surface (Measuring point (B)), 500 cm downstream of the copper target on the beam axis. The measuring point (B) is selected for comparison with the Self-TOF results. Five pairs of Bi and C activation detectors were insert between each concrete shield of 50 cm thickness (50, 100, 150 and 200 cm thickness) and behind the most downstream shield of 250 cm thickness on the beam line, simultaneously. After 10 hours irradiation, the measurements of the gamma-rays from the activation detectors were carried out with two high-purity Germanium (HPGe) detectors (GC-1818 and GC-2020, Canberra Industries, Inc.).
The assembly of concrete shields is 100 cm x 100 cm in size was put onto the steel platform to fix the center of the shield on the beam axis. The Self-TOF detector and the NE213 detector were used to measure neutron energy spectra penetrating through shields up to 200 cm thickness, Bi and C
activation detectors were used to measure them up to 250 cm thickness.
NEA-1552/19:
SINBAD-TEPC-FLUKA
=================
Purpose and Phenomena Tested:
----------------------------
Measurements and simulation of the lineal energy distribution of the energy deposition in biological cells of 2 micrometer diameter. This is first done in well characterised mixed radiation field in order to evaluate the response of the instrument. The comparison is then repeated in the complex cosmic ray environment on board of an aircraft.
Description of the Source and Experimental Configuration:
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Sources:
Pure photon: Co60
Pure Neutron: 0.5 MeV at PTB
Mixed Field: AmBe without lead cap
High energy field: CERN-EU High Energy Reference Field (CERF) facility [1] (Positively charged hadron beam (mixture of protons and pions) with 120 GeV/c momentum on copper target producing secondaries passing through 80 cm concrete shielding. The resulting neutron spectrum has two maximum at about 1 Mev and 70 MeV) similar to the high-energy component of the radiation field created by cosmic rays at commercial flight altitudes.)
Radiation field at commercial flight altitude.
NEA-1552/21:
SINBAD-ISIS800
==============
Purpose and Phenomena Tested:
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The purpose of this experiment was to measure the deep-penetration neutrons through a thick bulk shield at an intense spallation neutron source facility, ISIS, of the Rutherford Appleton Laboratory (RAL), United Kingdom [1].
Description of the Source and Experimental Configuration:
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The source is a thick tantalum target (total length of 296.5 mm) impinged by 800 MeV - 200 micro-A protons, producing neutrons. This target, placed at the center of the target station, is shielded with approximately 3-m-thick steel and 1-m-thick ordinary concrete in the upward direction, through which the neutrons are transmitted. On top of the shield of the target station, the neutron flux attenuations through concrete and iron shields, which were additionally placed up to 1.2-m and 0.6-m thicknesses respectively, were measured using activation detectors of graphite, bismuth, aluminum and a multi-moderator spectrometer using indium-oxide activation detector. The attenuation lengths for concrete and iron of high-energy neutrons above 20 MeV at 90 degrees to the proton beam axis were obtained from the 12C(n, 2n)11C reaction rates. The neutron energy spectra in the energy range from thermal to 400 MeV behind concrete and iron were also obtained by an unfolding analysis using the reaction rates of 12C(n, 2n)11C, 27Al(n, a)24Na, 209Bi(n, xn)210-xBi (x=4~10), and 115In(n, g)116mIn.
NEA-1552/22:
SINBAD-HIMAC
============
Purpose and Phenomena Tested:
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Carbon, Aluminum, Copper and Lead targets were bombarded with He, C, Ne, Ar, Fe, Xe and Si ions of energies ranging from 100 to 800 MeV/nucleon.
They were performed at the Heavy Ion Medical Accelerator of Chiba (HIMAC) depending of the National Institute of Radiological Sciences (NIRS) of Japan in different experimental sets from 1997 to 1999.
Description of Source and Experimental Configuration:
----------------------------------------------------
The energy of the projectile is 100 and 180 MeV/nucleon for He ions, 100, 180 and 400 MeV/nucleon for C and Ne ions, 400 MeV/nucleon for Ar, Fe and Xe ions and 800 MeV/nucleon for Si ions. The Si ions are only stopped on C and Cu targets.
The beam is extracted from the synchrotron with a time pulse of 0.5 seconds every 3.3 seconds. The microtime structure corresponds to 5 MHz.
The target is a 10x10 cm2 plate of carbon, aluminum, copper and lead. Its thickness is calculated to stop completely the incident particles.
NEA-1552/23:
SINBAD-KENS-P500MeV
===================
Purpose and Phenomena Tested:
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Penetration of up to 500 MeV neutrons, generated on a thick tungsten target bombarded by 500 MeV protons, through an ordinary concrete shieldof 4-m-thickness was studied to check the accuracies of the transmission and activation calculation codes.
Description of Source and Experimental Configuration:
----------------------------------------------------
A high-energy neutron source produced in the forward direction from a thick tungsten target bombarded by 500 MeV - 5 microA protons was arranged at the KENS spallation neutron source facility. Using a 0-degree beam course downstream of the target, high-energy neutron source produced in the forward direction is available from the beam exit. An ordinary concrete shield of 4-m thickness was assembled in contact with the beam exit of the neutron irradiation room, and 7 slots reaching the beam axis inside the concrete shield were equipped in every 40-80 cm thickness for irradiation sample insertion. The angular and energy distributions of neutrons produced from the target assembly was calculated using the MARS14 code. The MARS14 source calculation is described in [2].
NEA-1552/24:
SINBAD-CERF-BSS
===============
Purpose and Phenomena Tested:
----------------------------
Bonner Sphere Spectrometers (BSS) are employed in neutron spectrometry and dosimetry since many years. A real 'calibration' of the BSS response to charged hadrons would require the availability of broad beams of protons and charged pions of several defined energies up to tens of GeV, which is not really feasible. Thus an experimental verification of the response of the BSS to a monoenergetic beam of high-energy hadrons was performed at the CERF facility at CERN as described here.
Description of Source and Experimental Configuration:
----------------------------------------------------
Source: 120 GeV/c positive hadron beam (composed of 1/3 protons and 2/3 pions) of Gaussian profile with FWHM (full width at half maximum) of 30.5 mm and 31.7 mm in the horizontal and vertical planes, respectively (determined with a multi-wire proportional chamber), at the CERF facility at CERN [1].
NEA-1552/03:
SINBAD-TIARA
============
Measurement System:
------------------
Five kinds of detectors were used: the BC501A organic liquid scintillation detector, the Bonner ball counter, 238U and 232Th fission counters, Li7F and Li(nat)F thermoluminescent dosimeters (TLD) and solid state nuclear track detectors (SSNTD).
To measure the neutron energy spectra, a 12.7 cm diameter x 12.7 cm long BC501A liquid scintillation detector was placed behind the test shields. The pulse height distributions of the detector were converted to neutron energy spectra by the FERDOU unfolding code [8] and a measured response matrix [9].
A Bonner sphere spectrometer with four polyethylene moderators of thicknesses 1.5, 3.0, 5.0, 9.0 cm, and without moderator was placed behind the test shields for measurements of energy dependent neutrons. The central part is a 5.08 cm diameter spherical proportional counter filled with 10 atm (at 22 degree) He-3 gas. Reaction rates above gamma-ray discrimination level were measured for five different moderator thicknesses. These five reaction rates were unfolded with the SAND-2 code [10] and the response functions given by Uwamino et al [11].
U-238 and Th-232 fission counters (Centronic FC480/1000) with a 10.1 cm long x 3.81 cm diameter active volume were used to measure fission rates behind the test shields. Absolute efficiencies of U-238 and Th-232 fission counters were (1.05 +- 0.04) x 1.E+3 and (9.86 +- 0.34) x 1.E+2 barn/cm^2/counts, respectively, which were measured with a Cf-252 neutron source.
Neutron reaction rates were measured on the beam axis in the test shield using Li7F and Li(nat)F thermoluminescent dosimeters (TLD) (Harshaw Co. Ltd.) of 1 x 1 x 6 mm3. Thermoluminescence was converted to the absolute dose in TLD using a calibration factor determined with a Co60 gamma-ray source within the uncertainty less than 3 %.
The neutron reaction rates in the test shield were also measured using a solid state nuclear track detectors. The composition of the detector is Allyl diglycol carbonate which is the same as that of CR-39. The detector is a rectangular solid of 10 mm x 5 mm and 1 mm thick attached with a 1 mm thick polyethylene radiator. The exposed detectors were etched chemically, the etch pits on the detectors were counted through an optical microscope of 400 times magnifications.
Description of Results and Analysis:
-----------------------------------
The main source of information were references [1, 2, 3, 4].
Transmitted neutron energy spectra behind the iron test shields measured with the BC501A scintillation detector are given. The spectra on the beam axis behind the iron test shields are presented. The spectra at the off beam positions are shown. The error bars consist of errors of spectrum unfolding and counting statistics. Other errors in the source neutron flux are estimated to be less than 6.6% (errors of PRT (3-5%), conversion factor of fluence monitor to total charges of proton beam (3%), neutron penetration factor through objects on the beam line (3%) and the fluence monitor counting statistics (less than 1%)).
Transmitted neutron energy spectra behind the concrete and polyethylene test shields measured with the BC501A scintillation detector are given.
The reaction rates of the Bonner sphere spectrometer behind the iron, concrete and polyethylene test shields are given. Neutron spectra behind the iron, concrete and polyethylene test shields obtained from the reaction rates using the SAND-2 unfolding code and the response functions are given. The experimental errors of the Bonner sphere spectrometer could not be estimated by the SAND-2 unfolding code.
The fission rates measured behind the iron, concrete and polyethylene test shields using fission counters are given. The uncertainties of the measured data given in the tables include the counting statistics of the fission counters and neutron fluence monitors. The U-238 and Th-232 fission counters measure the neutron flux above the threshold energy of about 1 MeV.
The differences between neutron reaction rates of Li7F and Li(nat)F TLDs measured inside the iron and concrete shields are given. As the Li7F and Li(nat)F response functions differ significantly only below about 1 MeV, these differences are the measure of the neutron flux up to 1 MeV. The uncertainties of the measured data given in the tables include the counting statistics of each detector and neutron fluence monitor.
The neutron reaction rates of SSNTD measured inside the iron, concrete and polyethylene shields are given. The detector is sensitive to neutrons below 10 MeV. The uncertainties of the measurements include the counting statistics of etch pits and neutron fluence monitor.
Model for Calculation:
The calculations of the 43- and 68-MeV p-Li neutron energy spectra using Monte Carlo and deterministic transport codes are described in [4, 5, 6] (using MORSE-CG, DOT3.5 and HETC-KFA2 codes), [14, 17] (DORT, MCNP4B), [15] (LAHET) and [16, 18] (MCNPX). The input data used for the LAHET and HMCNP4A calculations are given in [15].
The authors of the experiment propose [1] to use a three-dimensional (X,Y,Z) or two-dimensional (R-Z) calculational models. Calculational geometry used for the MORSE and HETC Monte Carlo codes is shown. In the figureTc is a thickness of additional collimator which are given. The 43- and 68-MeV p-Li neutron beams impinge on the shielding assembly at its center. The neutron beam spreading is 5.94 x 1.E-4 sr. Cylindrical flux estimators were placed behind the shield surface on and off beam axes. The measured source energy spectra for 43- and 68-MeV p-Li neutrons are given. Atom densities of the test shields and the additional collimator are also given.
To calculate the fission rate, the U-238 and Th-232 fission cross sections given in Table 45 can be used. They include the data from JENDL-3 [12] in the neutron energy up to 20 MeV, and those measured by Lisowski et al. [13] in the energy region between 20 and 400 MeV.
Normalization Between Calculation and Measurement:
Calculated values of the transmitted spectra and count rates should be normalized by proton beam charge (microcoulombs). Total source neutrons per proton beam charge can be calculated with the peak flux and the energy spectrum given.
NEA-1552/07:
SINBAD-52P
==========
Measurement System and Uncertainties:
------------------------------------
The transmitted neutron and photon spectra were measured in the forward direction along the proton beam axis with a 51-mm-diam and 51-mm-long NE-213 scintillation detector placed in contact with the rear face of the slabs. Exception were three measurements of graphite, performed in 1979, where the detector was placed on the extended axis at 3.45 m from the front target surface (not reported here). The number of protons incident on the target was monitored by a current integrator connected to the target.
Angle-dependent source neutron from the graphite target were measured with the NE-213 system at 0, 15, 30, 45 and 75 degrees, and the photon spectra at 0 degrees. Only neutrons with energies higher than about 2 MeV were measured. An estimation of low energy neutrons may be needed for gamma calculations to take into account neutron induced gamma rays. The following are experimental uncertainties derived from [7].
Item Uncertainty
Detector Placement < 1-cm
Material Thickness Error < 1%
Material Density Error < 1%
Source Measurement Error like 21.4 cm Graphite
Neutron Penetration Spectra As Shown with Figures of Data Results
Gamma-ray Penetration Spectra As Shown
Background Contributions at 3 m Neutron (3-10%) Gammas (40-70%)
Description of Results and Analysis:
-----------------------------------
The neutrons and photons produced at the target were transmitted through slabs of graphite (21.4, 42.8 and 64.5 cm thick), iron (19.3, 38.6 and 57.9 cm), water (60 and 101 cm), and ordinary concrete (46, 69 and 115 cm).
The pulse height distributions were converted to neutron and photon energy spectra by using the revised FERDO unfolding code [3] and the calculated response matrix.
In the experimental geometries with the detector in contact with the shield, the background was considered to be negligible. In the case of 1979 graphite experiments (data are not included here) background room scattering was estimated with the detector at 3 m from the graphite assembly and a shadow bar between the assembly and the detector. Background radiation contributed between 3 and 10 % to the observed transmitted neutrons and between 40 and 70% to the transmitted photons.
NE-213 spectral data are reported in tables lacking statistical errors. Data plots contained 1-sigma error bars and computational comparisons using ANISN and MMCR-U transport codes. Data for Neutron transmission are tabulated from 2.5 MeV and continue in 1 MeV steps to 35.5 MeV. Photon flux was measured from 0.25 MeV and are tabulated in steps of 0.25 MeV through 10 MeV.
Calculations were performed by MORSE, ANISN, MCNP-4A, and MMCR-U codes using DLC58/HELLO, DLC119/HILO86, DLC87/HILO and ENDF/B-VI high energy cross-section libraries ([2], [4], [5]).
NEA-1552/08:
SINBAD-65P
==========
Measurement System and Uncertainties:
------------------------------------
A 76-mm-diam. x 76-mm-long NE-213 scintillation detector was placed just behind the shield system. The pulse height distributions were converted to neutron and photon energy spectra by using the revised FERDO-U unfolding code [2]. The background data were obtained in the same geometrical condition except that the collimator was closed by an iron plug.
The collimated 0 deg. neutron source spectrum measurement was made without the shield at a location 538 cm down from the copper target using the same detection system. Neutron source below 4.5 MeV was not measured. Use of the evaporation spectrum was suggested in this energy range. Gamma ray source spectrum is also given for energies above 1.8 MeV. Information on the uncertainties is available only in graphical form.
Description of Results and Analysis:
-----------------------------------
Absolute neutron penetration spectral measurements were reported at 20, 40, and 60-cm-thick-iron; 10, 20, and 30-cm-thick lead; 30, 60, and 90-cm-thick graphite; and 20, 50, and 100-cm-thick concrete. The photon spectral measurements are reported for the 20-cm-thick iron, 10-cm-thick lead, 30-cm-thick graphite, and the 20 and 50-cm-thick concrete. Neutron spectral measurements were reported for 5 MeV to 61 MeV and Photon spectral measurements for 1.9 MeV to 9.4 MeV. Data are plotted with 1-sigma error bars and with computational results using MORSE/DLC-87.
Calculations were performed by MORSE, ANISN and MCNP-4A codes using DLC58/HELLO, DLC119/HILO86, DLC87/HILO and ENDF/B-VI high energy ross-sections [3], [4].
NEA-1552/10:
SINBAD-ROESTI
=============
Measurement System and Uncertainties:
-------------------------------------
Activation detectors:
--------------------
In115(n,n')In115m: indium disks of 1.0 cm diameter, 0.36 cm thick. 336 keV gammas measured with a GeLi detector (absolute emission probability assumed = 46.7%)
S32(n,p)P32: sulphur pellets of 2.3 cm diameter, 0.6 cm thick (thickness larger than max. range of emitted beta particles). Betas were measured with a thin-window GM tube calibrated with a thick sulphur sample irradiated by neutrons from a PuBe source of known yield. Note that the original calibration, on which the results reported in Ref. [1], [2] and [3] were based, was later found incorrect. The numerical data available here are based on the new correct calibration.
Al27(n,a)Na24: aluminium disk thickness 0.4 cm (Roesti I) or 0.05 cm (Roesti II and III). Diameter: 1.0 to 3.0 cm (Roesti I & II), 1.0 to 4.0 cm (Roesti III) (increasing with radial distance). 2.754 MeV gammas were measured with a 3"x3" NaI detector covered by a perspex cap.
Al27(h,spall)F18: same disks and measuring apparatus as for the previous detector. Annihilation photons of 0.511 MeV energy were measured by placing the disks between two sheets of perspex to ensure annihilation close to the source.
C12(x,xn)C11: polyethylene disks 0.04 cm thick, with a 1.5 to 3.5 cm diameter (increasing with radial distance). These detectors were used only in the Roesti III experiment. The experimental data are not available.
The measured activities were corrected for decay during and after the irradiation and during counting. A correction for non uniformity of the beam intensity was also made, based on several monitors. `
The presence of the detectors was not considered in the calculational models described in chapter 5. The aluminium detectors were cut out of the aluminium support plates, so only the plates must be considered. The other detectors were generally too smallor of too small density to affect the development of the shower.
Dosimeters:
----------
Schott-Jenner DOS2 Radiophotoluminescent dosimeters (RPL): glass rods 0.6 cm long and with a 0.1 cm diameter, read with a Toshiba FGD-6 reader. The composition is the following (in weight %): O-53.7%, P-33.4%, Al-4.6%, AG-3.7%, Li-3.7%, B-0.9% (A_eff ~ 19, Z_eff ~ 10). These detectors were used only in the Roesti I and Roesti II experiments.
A photo of a bare RPL and an irradiated one (braun) in the tube is given. (An RPL becomes brown when it is irradiated to very high doses, which was never the case in these experiments. So, only the bare RPL in the picture corresponds to those used).
In the simulations, the RPL geometry was not reproduced in detail (they were too small to get enough scoring statistics and to affect particle transport) but in a first phase dose was scored at their position, assuming a composition of 54% Oxygen and 46% "Aluminium equivalent". After some tests, it was found that scoring simply dose in aluminium was giving the same results (in the mixed fields of hadronic cascades, dose depends only very weakly on atomic number).
Uncertainties:
--------------
The authors estimate that the results should have typical uncertainties of few percents, maximum 10%. Detectors were positioned by taping them with adhesive tape at positions known with the normal accuracy available with a measurement tape (typically about 1 mm, to be compared with detector diameters of the order of 1 cm).
Description of Results and Analysis:
-----------------------------------
The measured results are given in files rosti1.exp, rosti2.exp, rosti3.exp. In the tables the standard deviations represent the spread of several measurements from different azimuthal detector positions.
Calculations have been performed with FLUKA92 (Ref. [4], [5]) and with HETC88 (Ref.[6]).
The following FLUKA92 input files prepared by J. Zazula are included here as a guide for the computational model development:
- fl24fe1.inp: FLUKA92 input for iron dump, 24 GeV/p (act. detectors)
- fl24fe2.inp: FLUKA92 input for iron dump, 24 GeV/p (absorbed dose)
- fl200fe1.inp: FLUKA92 input for iron dump, 200 GeV/h (act. detectors)
- fl200fe2.inp: FLUKA92 input for iron dump, 200 GeV/h (absorbed dose)
- fl-24pb.inp: FLUKA92 input for lead dump, 24 GeV/p (act. detectors)
- fl-200pb.inp: FLUKA92 input for lead dump, 200 GeV/h (act. detectors)
The input files are sufficient for a description of the geometry of the experiment, but the complete analysis included also several user routines which are not included here.
Unfortunately input files are not all consistent with each other. For instance some of the inputs for the Pb dump use a symmetrical geometry, while others describe more accurately the actual geometry, with the beam hitting the dump off-center. Also the material composition may appear to be with or without a small amount of antimony.
Note also that these files refer to a very old version of the code and are made available mainly to help in the geometry and material description. Many defaults have now changed, and most settings should be revised, in particular those concerning the neutron cross sections (the 37-group library has been replaced by one with 72 groups).
NEA-1552/12:
SINBAD-BEVALAC
==============
Measurement System:
-------------------
Neutron detectors were located outside the scattering chamber at laboratory angles from 3 to 80 deg. The detectors consist in 10.16 cm thick big rectangular slabs of plastic scintillator NE-102 covered with a very thin reflective cover and about 0.1 cm of black adhesive tape. These cover completely the detectors except for the top and bottom faces, where the coupling with the bundle of light guides takes place. These guides couple to their respective photomultipliers.
There were 16 detectors, all of them with a height of 101.6 cm and different width, between 2.5 and 50.8 cm and hence different solid angle relative to the target. The centers of the detectors were located at the same height that the center of the target. The values of angular position of each detector, their width and flight path are given.
In front of each main detector another thin NE-102 detector was located with height and width slightly larger than main detectors and thickness 0.64 cm. The purpose was to reject any charged particle incident on the neutron detector.
The detectors efficiency was calculated by using the M.C. code by Cecil, Anderson and Madey (Ref. 2).
Background neutrons were not measured, instead they were estimated from the analysis of two regions of the time-to-digital converter spectra.
Description of Results and Analysis:
------------------------------------
The results are presented as double differential neutron yield (energy and angle) in terms of neutron per MeV, per milisteradian and per incident ion. There are only results for 14 detectors since the results from detectors at 40 and 64 deg. are not available.
The results for 272 MeV/nucleon Nb ions on Nb target are presented for angles 3 to 24 deg. and for angles 28 to 80 deg.
For Nb ions of 435 MeV/nucleon also on Nb target the results are presented for angles 3 to 24 deg. and for angles 28 to 80 deg.
Finally the results for 272 MeV/nucleon Nb ions on Al target are presented for angles 3 to 24 deg. and for angles 28 to 80 deg.
Integrated yields of neutrons above 20 MeV are presented. These numbers represent yields of neutrons over 20 MeV per incident ion and are given for the forward space beyond the target (0-90 deg.) and also for the first 45 deg. and the first 10 deg.
NEA-1552/13:
SINBAD-MSU/155 HE-C
===================
Measurement System:
------------------
Neutron detectors in groups of 1, 3 or 7 detectors per position are located outside the scattering chamber at laboratory angles of 10, 30, 45, 60, 90, 125 and 160 deg. at the left side of the incident beam and at angles of -30, -45 and -60 deg. at the right side of the incident beam. The origin of the angle is taken at the extension of the incident beam (passed the target) and the positive angle as counterclock.
Absolute position, flight path and solid angle for each individual detector are presented.
The 3 detectors at angle 90 deg. are grouped in a triangle with 2 in the base and 1 at the top. The bundles of detectors at 10, 30, 45 and 60 deg. are formed by 7 detectors, one in the center and other 6 detectors surrounding the central ones at angular pitch of 60 deg. The detectors at angles 125, 160, -30, -45 and -60 deg. are individual detectors.
The dimensions of the detectors are 12.7 cm in diameter and the most 7.62 cm thick but there are also 5.08 cm thick detectors. There is one 5.08 cm thick detector in each bundle of 3 or 7, except at angle 30 deg. Where there are two of them. The individual detectors are all 7.62 cm thick.
Each individual neutron detector consists of a liquid scintillator (BC-501 or NE-213) encased in a cylindrical cell constructed of either glass or aluminum.
Other plastic scintillator detectors were placed between the target and the neutron detectors to detect any charged particle reaching the main neutron detectors. They are referred as veto detectors. They are 12.7 cm in diameter and 6.35 mm thick.
The detectors efficiency has been calculated by using the M.C. code by Cecil, Anderson and Madey (Ref. 2).
Background neutrons were measured by interposing cylindrical iron or brass bars.
Description of Results and Analysis:
-----------------------------------
The numerical results of the experiment are presented. They are expressed as double differential values in neutrons per angle unit(msr), per energy(MeV) and per incident ion.
Table 4 presents the results for He ions at angles 10 to 60 deg.
Table 5 presents the results for He ions at angles 90 to 160 deg.
Table 6 presents the results for C ions at angles 10 to 60 deg.
Table 7 presents the results for C ions at angles 90 to 160 deg.
The previous results have been integrated with the angle for obtaining the total yields for both ions. Also the calculated interaction fraction and number of neutrons per interaction are presented.
The uncertainty due to the procedure used to discriminate neutrons coming from different bursts is estimated in 10 to 15%. Other systematic uncertainty due to the detector efficiency calculation is estimated in 10%. The total systematic uncertainty is estimated in 20 to 25%. The statistical uncertainty was of the order of 5% for the spectra at 30 deg.
The MCNPX model for MSU experiment used by P. Ortego is given in mcnpxmsu3.i, and the corresponding results are included in the EXCEL file MSU_MCNPX.xls. The results seem acceptable for this type of experiments with very good estimation for the evaporation part at 90 deg. and more uncertain results in the small angle detectors.
NEA-1552/14:
SINBAD-RINKEN
=============
Measurement System:
------------------
The neutron energy spectra were measured by the time-of-flight (TOF) method using a 12.7-cm-diameter x 12.7-cm-long NE213 organic liquid scintillator. The neutron detector was placed both 12 and 20 m away from the Li-7 target in order to obtain a good time resolution of the TOF measurement for the high-energy neutrons. The detector efficiency was determined by a calculation code from [2].
The peak neutron fluences were measured by two relative neutron fluence monitors in the position of 8.37 and 12.0 m from the Li-7 target along the neutron beam line. An NE213 organic liquid scintillator (5.08-cm-diameter x 5.08-cm-long) near to the PD1 magnet (Monitor 1) and an NE102A plastic scintillator (2-cm-wide x 2-cm-high x 0.5-cm-thick) at the collimator exit (Monitor 2), were also equipped because of an uncertainty in the amount of proton charges through the beam dump in a low-current experimental run. The counts of these neutron fluence monitors were calibrated to the absolute monoenergetic peak neutron fluence on the beam line after an estimation of the number of Be-7 nuclei produced in the Li-7 target. The number of residual Be-7 nuclei equals the number of peak neutrons released in the 4p direction [3]. In order to determine the number of residual Be-7 nuclei in the target, 0.478 MeV gamma-ray emitted from the decay of Be-7 with a half-life of 53.3 day was measured with a high-purity Ge detector. The efficiency of the Ge-detector was determined with 3% accuracy. Correction factors for neutron attenuation through the acrylic window and air and also neutron scattering at the collimator were evaluated by Monte Carlo calculation.
Description of Results and Analysis:
-----------------------------------
The peak neutron fluences at the two measuring positions of 8.37 and 12 m from the target issued from the evaluation of the target activity are listed. In this table are also listed the correction factors applied for the neutron attenuation through the acrylic window and air and also neutron scattering at the collimator. The peak neutron fluences were also estimated by integrating over the peak region of the neutron-energy spectra resulted by the NE213 scintillator measurements.
The fluences obtained by these two methods are listed and compared. The neutron-energy spectra measured with the TOF method are shown.
Error Assessment:
The absolute peak neutron fluence was obtained within 7.5% accuracy with the target activity measurements and within 15.6% with the integrated spectra over the peak region obtained by the NE213 scintillator measurements.
NEA-1552/15:
SINBAD-PSI-P590MEV
==================
Measurement System and Uncertainties:
-------------------------------------
Two detectors were used for measurements. The main detector was a 3-cm thick, 4.5-cm diameter NE213 liquid scintillator employing n-gamma pulse discrimination. The distance between the target axis and the center of the main detector was 117.3 cm (+- 0.3 cm). A secondary detector, a 0.5-cm thick plastic scintillator, was located immediately in front of the liquid scintillator. This secondary detector was used as counter to remove pulses from charged particles also produced in the target. The model of the plastic scintillator is not specified in [1]. Background measurements were performed by removing the target block opposite the collimator entrance. The contents for each time bin were integrated and the results divided by the NE213 detector efficiency. The efficiency was calculated by using the Monte Carlo code of Stanton as modified by Cecil et al. [6]. Then the data were scaled by the solid angle subtended by the detector, the dead time correction factor, the number of incident protons, and the target average surface. In the interpretation of the experimental data, no information is provided about the meaning of or the way to determine the so-called "target's average surface", which is said to be 12.5 cm squared. No errors were given for the experimental spectrum. However, it was specified that during the off-line data processing, there was an error associated to the procedure used to separate the response of the high energy neutrons from the response of the low energy neutrons in the TOF spectra. That error was reported as being small.
Description of Results and Analysis:
-----------------------------------
The spectrum of neutrons emitted from the first block (0 - 5 cm) in the target at 90 deg., as presented in Reference 1, is illustrated. The neutron yield is given as neutrons per MeV per incident proton per steradian per cm squared. This spectrum was compared to a calculation performed at KFA Julich. The calculational method was based on the high energy nucleon meson transport code HETC [7]. The comparison of calculation and experiment is illustrated. It was observed that the calculated spectrum is much softer than the measured spectrum. The measured spectrum was available only as a plot. For comparison purposes the measured data were extracted from the plot and digitized.
More recent benchmark calculation has been performed in ref. [1] by MCNPX code. The new 150-MeV cross section set, LA150, was used in these calculations [5]. The sample input for the MCNPX code is given in file mcnpx.inp. A comparison of the calculated spectrum and the measured spectrum is shown. It can be seen from Figure 5 that the calculation and experiment compare well. The largest difference between the calculated and the measured data is at lower energies (below 3 MeV).
NEA-1552/17:
SINBAD-HIMAC800-FE
==================
Measurement System and Uncertainties:
-------------------------------------
The Self-TOF detector consists of radiator detectors, a start counter and a stop counter of nine segments. The radiator is a stack of 20 thin plastic scintillator (NE102A) of 10 cm x 10 cm with 0.6 cm thickness. Each plastic scintillator is viewed by a 0.95 cm-diameter photo-multiplier (Hamamatsu R1635) through a light guide. The start counter is a plastic scintillator (NE102A) of 10 cm x 10 cm x 0.5 cm viewed by two 5.08 cm-diameter photo-multipliers (Hamamatsu R2083) from both sides through light guides. The stop counter is designed to cover an area 20 cm x 20 cm x 2 cm each of which is viewed by a 12.7 cm-diameter photo-multiplier (Hamamatsu R1259) through a light guide. The distance between the start and stop counters is adjustable, and is chosen to be 1.2 m for a usual measurement.
An in-coming neutron produces charged particles in twenty radiators, and then the charged particles emitted in the forward direction reach any one of nine stop counters through the start counter. The energy of the charged particle is determined by using the TOF method between the start and stop counters. In this detector, we selected only proton events H(n,p) and C(n,p) reactions to obtain the detector response function. The neutron energy spectrum can be obtained from the measured proton energy spectrum using an unfolding method with the response function which has already been measured for neutrons in the energy range of 60 to 800 MeV [2]. Although the Self-TOF detector can measure neutron above 30 MeV in principle, the detection efficiency is very low for neutrons below 100 MeV because low energy charged particles produced in a radiator stop in the following radiators and never reached the start and stop counters.
The NE213 scintillator (12.7 cm diam. by 12.7 cm thick) was coupled with the R4144 photo-multiplier connected to E1458 base (Hamamatsu Photonics. Co. Ltd.), which is designed to expand the dynamic range of output pulses for high-energy neutron measurements [3]. The thin NE102A plastic scintillator (15 cm by 15 cm square and 0.5 cm thick), coupled with the H1949 photo-multiplier and base (Hamamatsu Photonics. Co. Ltd.), were placed in front of the NE213 scintillator as veto counter to discriminate charged particles from non-charged particles, neutrons and photons. The response matrix has already been measured in the energy range up to 800 MeV experimentally at the HIMAC [4].
Description of Results and Analysis:
------------------------------------
The neutron energy spectra measured by the Self-TOF detector are shown. The source neutron spectrum measured at 0 degree on the beam axis by Kurisawa et al. [5] and the calculated results with the MCNPX 2.1.5 Monte-Carlo code [6] combined with the LA150 cross-section library [7] are also shown in figure 3. The spectra have a broad peak around 200 to 300 MeV with the iron thickness up to 80 cm. The softening of the neutron spectra can scarcely be observed with the increasing of the shielding thickness. For the calculated spectra the broad peak and the softening of the spectra are also observed but those are harder than the measured results for all cases.
For the NE213 detector, neutron energy spectra measured for both detector positions (A) and (B) are shown. The measured and the calculated with the MCNPX 2.1.5 code, energy spectra are reported for both detector positions. At position (A) in contact with the rear surface of the shield, calculations overestimate the measurements with increasing the iron thickness in the energy range below 100 MeV. The calculations are fairly in good agreement with the measurements in the energy range between 100 and 400 MeV, especially in good agreement in the whole energy range of 20 to 800 MeV for 20 and 40 cm thick iron shields. At the position (B) continuous neutron energy spectra could be obtained, however, large error bars can be seen at 40 cm and 60 cm thicknesses in the energy range between 20 to 150 MeV.
Since the measured position (B) of the NE213 detector is almost the same position where the Self-TOF was set, the neutron energy spectra measured by these two detectors are compared. The NE213 spectra cannot reproduce the peak due to the large errors and are also much higher in the energy region below 200 MeV for 100 thick iron than the Self-TOF spectra, because the non-collimated NE213 detector detects a lot of neutron components scattered from the shield and the room floor.
In order to obtain the neutron fluence attenuation length, the contribution of the room scattered neutrons must be subtracted from the NE213 results. This components were estimated by MCNPX calculations, Figure 7 shows the calculated energy spectra in both cases (with and without room floor) at two iron thicknesses of 20 cm and 100 cm. The attenuation of neutron fluence could be obtained by integrating the neutron flux over the energy range. The attenuation profiles of neutron fluence integrated from 100 to 600 MeV for Self-TOF and MCNPX results, from 20 to 800 MeV for NE213 and MCNPX results are shown. The neutron fluence attenuation lengths of two different energy ranges are summarized.
The calculated neutron fluence are in good agreement with the experiment for the Self-TOF and NE213(A) but largely overestimated in the calculation for the NE231 (B) results. For the attenuation length there is a very good agreement within 5% between experiment and calculation.
NEA-1552/18:
SINBAD-HIMAC800-CONC
====================
Measurement System and Uncertainties:
-------------------------------------
The Self-TOF detector consists of radiator detectors, a start counter and a stop counter of nine segments. The schematic drawing of the detector is given. The radiator is a stack of 20 thin plastic scintillators (NE102A) of 10 cm x 10 cm with 0.6 cm thickness. Each plastic scintillator is viewed by a 0.95 cm-diameter photo-multiplier (Hamamatsu R1635) through a light guide. The start counter is a plastic scintillator (NE102A) of 10cm x 10cm x 0.5cm viewed by two 5.08 cm-diameter photo-multiplier (Hamamatsu R2083) from both sides through each light guide. The stop counter is designed to cover an area of 60 cm x 60 cm and is segmented into nine plastic scintillators (NE102A) of 20 cm x 20 cm x 2 cm each of which is viewed by a 12.7 cm-diameter photo-multiplier (Hamamatsu R1259) through a light guide. The distance between the start and stop counters is adjustable, and is chosen to be 1.2 m for a usual measurement.
An in-coming neutron produces charged particles in twenty radiators, and then the charged particles emitted in the forward direction reach any one of nine stop counters through the start counter. The energy of the charged particle is determined by using the TOF method between the start and stop counters. In this detector, only proton events H(n,p) and C(n,p) reactions have been selected to obtain the detector response function. The neutron energy spectrum can be obtained from the measured proton energy spectrum using an unfolding method with the response functions which have already been measured for neutrons in the energy range of 60 to 800 MeV [2]. Although the Self-TOF detector can measure neutron above 30 MeV in principle, the detection efficiency is very low for neutrons below 130 MeV because low energy charged particles produced in a radiator stop in the following radiators and never reach the start and stop counters.
The NE213 scintillator (12.7 cm diam. by 12.7 cm thick) was coupled with the R4144 photo-multiplier connected to E1458 base (Hamamatsu Photonics Co. Ltd.), which is designed to expand the dynamic range of output pulses for high-energy neutron measurements [3]. The thin NE102A plastic scintillator (15 cm by 15 cm square and 0.5 cm thick), coupled with the H1949 photo-multiplier and base (Hamamatsu Photonics. Co. Ltd.), were placed in front of the NE213 scintillator as veto counter to discriminate charged particles from non-charged particles, neutrons and photons. The response matrix have already been measured in the energy range up to 800 MeV experimentally at the HIMAC [4].
The Bismuth detector, 8 cm-diam. x 1.1 cm-thickness, was used through the 209Bi(n,4n)206Bi to 209Bi(n,10n)200Bi reactions. The cross section data have already been measured by Kim et al.[5] in the energy range of 20 to 150 MeV and the measured data are in good agreement with ENDF/V-VI high-energy library data [6] calculated by Fukahori [7]. Their threshold energies monotonously increase from 22 MeV of 209Bi(n,4n) to 70 MeV of 209Bi(n,10n) with the interval of 8 MeV corresponding to binding energy per nucleon. The half lives of Bi-200 to Bi-206 are between 36.4 min. and 15.31 days. The physical properties of 209Bi(n,xn) reaction are shown.
The 12C(n,2n)11C reaction has the threshold energy of about 20 MeV and the reaction cross section has recently been measured up to 150 MeV also by Kim and al.[5] and [8], which has almost constant value of about 20 mb above 20 MeV. The half life of C-11 is about 20 min., which is shortly-activated good neutrons flux monitor of energy above 20 MeV. The detector size is 8 cm-diam. x 1 cm-thickness.
Description of Results and Analysis:
------------------------------------
The neutron energy spectra measured by the Self-TOF detector are shown compared with the results of the LAHET 2.7 Monte Carlo code calculation [9]. The source neutron spectrum measured at 0 degree on the beam axis by Kurosawa et al. [10] is also shown. The spectra have a broad peak around 200 to 300 MeV and the shapes of the spectra do not change so much with the concrete thickness. The softening of the neutron spectra can scarcely be observed with the increasing of the shielding thickness. For the calculated spectra, the LAHET results tend to overestimate with increasing the thickness, especially for neutrons above 300 MeV. At 200 cm thickness, the discrepancy between measurements and calculation is growing up to factor 7 in the energy range of 300 MeV to 400 MeV.
The neutron energy spectra measured by NE213 for both detector positions (A) and (B) are shown. They are compared with the results of MCNPX calculation [11] combined with the LA150 cross section library [12], and also with the source neutron spectrum [10]. MCNPX results underestimate the measurements in the energy range below 100 MeV and above 400 MeV, and overestimate that in the in the energy range between 150 and 400 MeV. With increasing the concrete thickness, the calculated spectra show a good agreement with the experimental results up to 150 cm, but large underestimation can be seen at 200 cm thickness in the energy range below 100 MeV.
Since the measured position (B) of the NE213 detector is almost the same position where the Self-TOF was set, the neutron energy spectra measured by these two detectors are compared. The NE213 spectra cannot reproduce the peak due to the large errors and are also much higher in the energy region below about 100 MeV than the Self-TOF spectra, because the non-collimated NE213 detector detects a lot of neutron components scattered from the shield and the room floor.
Concerning Activation detectors, neutron energy spectra are shown. The calculated results with the MCNPX are also shown on the same figure. The measured spectra give large overestimation of 300% at 50 cm depth of 250 cm shielding thickness compared with the MCNPX results. This large discrepancy becomes smaller with the shield thickness and at 250 cm depth the MCNPX calculation gives very good agreement with the experimental results.
In order to obtain the neutron fluence attenuation length, the contribution of the room scattered neutrons must be subtracted from the NE213 results. This components were estimated by MCNPX calculations, Figure 7 shows the calculated energy spectra in the two cases (with and without room floor) at two concrete thicknesses of 100 cm and 200 cm. The attenuation of neutron fluence could be obtained by integrating the neutron flux over the energy range. Figure 8 shows the attenuation profiles of neutron fluence integrated from 100 to 600 MeV for Self-TOF and LAHET results, from 20 to 800 MeV for NE213 and Bi and C activation detectors and MCNPX results. The calculated neutron fluence are in good agreement with the experiment for the Self-TOF and NE213(A) but the experimental results become smaller than the calculated results with increasing the shielding thickness. For the attenuation length, calculated results indicate a little larger values than the measured ones up to 27% for all measurements.
NEA-1552/19:
SINBAD-TEPC-FLUKA
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Measurement System and Uncertainties:
------------------------------------
The detectors used were:
A Tissue Equivalent Proportional Counter (TEPC) is a standard instrument for measurements in a mixed radiation field. Particularly in aircrew radiation dosimetry the TEPC is of major interest for usage as a reference instrument. It measures the microdosimetric distribution d(y) of absorbed dose as a function of the lineal energy y over up to five orders of magnitude.
Dose equivalent is calculated folding this distribution with the quality factor as a function of linear energy transfer (LET), as defined in ICRP74.
The TEPC instrument used at the Austrian Research Center Seibersdorf (ARCS) is a sphere of 125 mm inner diameter. Since the TEPC is filled with pure propane gas, at low pressure (933.2 Pa) it simulates a tissue volume with a diameter of 2 micrometers. The wall of the sphere is made of a tissue equivalent plastic (A150). The TEPC sphere is contained in an aluminium cylindrical structure together with the required electronics. The complete assembly, cased inside a portable trolley of an aircraft hand-baggage dimension, is called HAWK [2].
Description of Results and Analysis:
-----------------------------------
The response of a Tissue Equivalent Proportional Counter (TEPC) has been simulated with the Monte Carlo transport code FLUKA[3]. Absorbed dose rate and ambient dose equivalent rate distributions as a function of lineal energy have been simulated for several reference sources and mixed radiation fields. The comparison between the simulated and measured microdosimetric spectra in these standard fields show a good agreement.
The Monte Carlo code FLUKA has also been used to calculate the radiation field at aircraft altitudes to simulate the TEPC response to this field. This simulation has been compared with TEPC in-flight measurements done at the same geographical position, altitude and same solar condition. The microdosimetric spectra measured within the aircraft shows a reduction of the high-LET contribution compared with the one simulated in free atmosphere. This reduction can be due to the influence of the aircraft structures.
NEA-1552/21:
SINBAD-ISIS800
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Measurement System and Uncertainties:
------------------------------------
Two types of graphite activation detectors were used: one was a disk type of 8-cm diameter x 3-cm thickness; the other was the Marinelli type, for measuring the spatial neutron flux distribution on the shield top without an additional shield and behind additional concrete and iron shields of various thicknesses. This detector uses the 12C(n, 2n)11C reaction : the half life of 11C is about 20 min., which makes a good rapidly activated neutron flux monitor for an energy above 20 MeV.
Bismuth detectors (8-cm diameter x 1.1-cm thickness), were used to obtain the high-energy neutron spectrum by using 209Bi(n, xn)210-xBi (x=4~12) reactions. Their threshold energies regularly increase from 22 MeV of 209Bi(n, 4n) to 70 MeV of 209Bi(n, 10n) with an interval of 8 MeV corresponding to the binding energy per nucleon. The half lives of 200Bi to 206Bi are between 36.4 min. and 15.31 days.
The aluminum detector was of the Marinelli type with the same size as the graphite detector. The threshold energy of the 27Al(n, a)24Na reaction is 3.25 MeV and the half life of 24Na is 15.02 hr. The cross-section data are from the ENDF/B-VI high-energy library [2] calculated by Fukahori using the ALICE code [3].
As for the Indium-oxide loaded multi-moderator activation detector, In2O3 powder (2.875 g) was filled in a spherical cavity of 0.735-cm radius in a cylindrical acryl, and it was placed in a spherical polyethylene moderator (Bonner sphere) [4]. Five kinds of detectors were used, which used four kinds of moderators and no moderator(bare). Using the reaction rates of the detectors, the neutron energy spectrum can be available through an unfolding technique.
A neutron dose meter (Rem Ion Monitor, Harwell, U.K.) and a gamma-ray dose meter (RO2, Eberline, Inc., U.S.A) were used in a current mode for measuring the neutron and gamma-ray dose-equivalent rates, respectively. This REM-counter was a conventional BF3 ion-chamber covered with a polyethylene moderator of cylindrical shape, which had low sensitivity to neutrons of energies higher than 20 MeV.
The errors of the results (reaction rates) of the experiment can be estimated by the equation :
delta(R) = squareroot(delta(Qh)2 + delta(c)2 + delta(p)2)
- delta(Qh) is the error of the beam current which was estimated to be about 1 %,
- delta(c) is the statistical error of the photo peak area,
- delta(p) is the error of the peak efficiency of HPGe detector estimated by the EGS4 Monte Carlo code, which is within a few %.
delta(R) is then dominated by delta(c), which varies from 2 to 50% depending on the total peak counts.
Description of Results and Analysis:
-----------------------------------
The neutron energy spectra were obtained on the floor without an additional shield, behind a 60-cm-thick additional concrete shield and a 30-cm-thick additional iron shield.
The obtained neutron spectrum on the shield top floor has two components: a hadron cascade peak of around 100 MeV in the energy range above 10 MeV and a broad peak including evaporation and slowing down neutrons around 500 keV below 10 MeV. The neutron spectrum through an additional 60-cm-thick concrete shield placed on the shield top shows an evaporation peak around 1 MeV and a rather flattened lethargy spectrum down to thermal energy, especially in the low-energy component below 100 keV. This reflects the slowing-down effect due to the elastic collisions of light elements, like hydrogen in the concrete. This spectrum has a typical 1/E slowing-down spectrum after the concrete.
The neutron spectrum through a 30-cm thick iron shield also has a typical spectrum after the iron, where high-energy neutron components above a few MeV are slowed down to less than 1 MeV by inelastic collisions with iron; also, a broad peak over the region from 10 eV to 500 keV is remarkable due to the low inelastic cross section of iron in this energy region and the increasing neutron capture cross section below 10 keV.
The neutron attenuation length for concrete at 90 degrees to the 800-MeV proton beam axis obtained in this study is compared with other experimental and calculated results: the present value of 125.4 g/cm2 is just between the values of 120 g/cm2 for 25-GeV proton by Stevenson et al. [5] and 143 g/cm2 for 12-GeV proton by Ban et al. [6] For the attenuation length of iron, the present value of 161.1 g/cm2 is slightly larger than that of 148 g/cm2 obtained by Jeffrey et al.using a 800-MeV proton accelerator at Los Alamos National Laboratory [7]. Stevenson and Ban have also given values of 147(+/-)10 g/cm2 for 25-GeV protons and 188(+/-)12 g/cm2 for 12-GeV protons, respectively : the present value is just between them.
NEA-1552/22:
SINBAD-HIMAC
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Measurement System:
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Neutron detectors are located at laboratory angles of 0, 7.5, 15, 30, 60 and 90 deg. The measurements were performed simultaneously at 3 detectors each time.
Each neutron detector consists of a NE-213 liquid scintillator 12.7 cm in diameter and 12.7 cm thick, covered first with glass 1 mm thick and externally with aluminum 1.6 mm thick. These are the E counters.
Other detectors, plastic scintillators NE102A, are 15x15 cm2 plates 0.5 cm thick. These are the delta-E counters to discriminate charged particles.
The detectors efficiency has been calculated by using the M.C. code by Cecil et al. (Ref. 5).
Background neutrons were measured by interposing iron bars 15x15 cm2 square and 60 cm long.
Description of Results and Analysis:
-----------------------------------
The numerical results of the experiments are given in terms of neutrons produced per angle unit(sr), per energy unit(MeV) and per incident particle.
They are presented as follows:
in Tables 2 to 7 for He ions with 100 MeV/nucleon
in Tables 8 to 13 for He ions with 180 MeV/nucleon
in Tables 14 to 19 for C ions with 100 MeV/nucleon
in Tables 20 to 25 for C ions with 180 MeV/nucleon
in Tables 26 to 31 for C ions with 400 MeV/nucleon.
in Tables 32 to 37 for Ne ions with 100 MeV/nucleon
in Tables 38 to 43 for Ne ions with 180 MeV/nucleon
in Tables 44 to 49 for Ne ions with 400 MeV/nucleon.
in Tables 50 to 55 for Ar ions with 400 MeV/nucleon
in Tables 56 to 61 for Fe ions with 400 MeV/nucleon
in Tables 62 to 67 for Xe ions with 400 MeV/nucleon
in Tables 68 to 73 for Si ions with 800 MeV/nucleon
The statistical uncertainties vary from 2 to 5% at low and mid-energy but increases until 30% for the energy threshold. The room scattered background is less than 10%. The total normalization uncertainty is less than 14%.
The transport calculations using MCNPX code were done by P. Ortego and are described in Ref. [8]. Some results are provided in file HIMAC_PO.xls. The two models for HIMAC experiments with alpha particles on C, Al, Cu and Pb are given in files mcnpxhim.015 and mcnpxhim.390. Two models are necessary because of the target is turned 45 deg. for some detectors, so HIM015 is the case for detectors 0 to 15 deg. (no turn of target) and HIM390 is the case for detectors 30 to 90 deg. (target turned 45 deg.).
The different atom densities for other target materials are given in comment lines. The same is done for the alpha particle energy. Default values for high energy models are used.
NEA-1552/23:
SINBAD-KENS-P500MeV
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Measurement System:
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Activation detectors of bismuth, aluminum, indium and gold foils were inserted into 8 slots inside the shield, and attenuations of neutron reaction rates were obtained by measurements of gamma-rays from the activation detectors. Because of large neutron intensity gradients, a variety of detector sizes and thicknesses were employed. From analyses of the photo peak counts of each gamma-ray, the following activation reaction rates were obtained:
Reaction Threshold[MeV]
209Bi(n,9n)201Bi 61.73
209Bi(n,8n)202Bi 53.98
209Bi(n,7n)203Bi 45.31
209Bi(n,6n)204Bi 37.99
209Bi(n,5n)205Bi 29.63
209Bi(n,4n)206Bi 22.56
27Al(n,alpha)24Na 3.25
27Al(n,X)22Na ~30
27Al(n,X)7Be ~100
115In(n,n')115mIn ~0.5
198Au(n,gamma)197Au Thermal
The reaction rates were estimated using one or a few gamma-rays from the radioactive products, and the reaction rates in the same slot agreed within about 10%, independently of gamma-rays analyzed or detector sizes used.
Description of Results and Analysis:
-----------------------------------
Experiment Analysis:
The experiment was simulated by the authors using the Monte-Carlo MARS14 code.
The MARS14 input data used in this analysis include besides the main input
(mars.inp) also 2 subroutines:
beg1_src.f: source routine
reg1.f: geometry routine
NEA-1552/24:
SINBAD-CERF-BSS
===============
Measurement System and Uncertainties:
------------------------------------
The BSS used in the present experiment employs a spherical Centronics SP9 3He proportional counter (3.2 cm active diameter, filled to a pressure of 202 kPa 3He and 101 kPa Kr, see he3.jpg) at the centre of moderators of different diameters and composition: five polyethylene spheres of outer diameter 81 mm, 108 mm, 133 mm, 178 mm and 233 mm and two spheres made of a composite polyethylene/cadmium/lead moderator to detect high-energy neutrons (called Stanlio and Ollio). The density of the polyethylene (CH2)n is 0.963 g/cm3. Five of the spheres are made of pure polyethylene with different outer diameter. Ollio is a sphere with outer diameter of 255 mm, consisting of moderator shells of (from the central 3He proportional counter outwards) 3 cm polyethylene, 1 mm cadmium, 1 cm lead and 7 cm polyethylene thickness. Stanlio has outer diameter of 118.5 mm and consists of moderator shells of 2 cm polyethylene, 1 mm cadmium and 2 cm lead thickness. The geometry of the seven detectors is also described in the FLUKA input files (see section 5).
Each detector of the BSS was exposed to the 120 GeV/c hadron beam. The beam impinged on each sphere at 25 mm from its centre.
The 10% uncertainty given on the experimental data is an estimate of the total uncertainties, but it is mainly uncertainty on the beam monitoring (which is done with an air-free ionisation chamber placed in the beam, the standard monitor used at CERF). The statistical uncertainty on the number of counts is negligible. The information on the uncertainties due to the size or positioning of the sphere is not available.
Description of Results and Analysis:
-----------------------------------
Monte Carlo simulations with the FLUKA code were performed reproducing the exact experimental conditions. The 14 input files are given (two per each of the seven detectors of the BSS, one for 120 GeV/c proton beam and one for 120 GeV/c positive pion beam). The experimental data (counts per beam particle) are compared with the results of the FLUKA Monte Carlo simulations. The agreement is rather good except for the two smaller spheres where the experimental figure is about of factor 2 higher than the simulation value.
The present results served as experimental confirmation of the complete response matrix of the BSS to charged hadrons calculated with FLUKA [2]. The information on the response of the BSS to charged hadrons was used to correct the results of an experiment performed at CERN aimed at determining the neutron yield and spectral fluence at various angles from unshielded, semi- thick copper, silver and lead targets, bombarded by a mixed proton/pion beam with 40 GeV/c momentum [3].