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Transmission Through Shielding Materials of Neutrons and Photons Generated by 52 MeV Protons

 1. Name of Experiment:
    Transmission Through Shielding Materials of Neutrons and Photons Generated by
    52 MeV Protons (1981)

 2. Purpose and Phenomena Tested:
    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.

 3. 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.

 4. 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-see Figure 2
      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%)

 5. 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]).

 6. Special Features:

 7. Author/Organizer
    Experiment and analysis:
    Uwamino Y.(*), Nakamura T.(**) and Shin K.(***):
    (*) Institute for Physical and Chemical Research,
        Hirosawa 2-1, Wako 351-01, 188, Japan
    (**) Cyclotron and Radioisotope Center, Tohoku University,                  
         Aramaki, Aoba, Sendai, 980, Japan
    (***) Dep. of Nuclear Engineering, Kyoto University                      
          Sankyo, Kyoto, 606, Japan
    Compiler of data for Sinbad:
    I. Kodeli, OECD/NEA, 12 bd des Iles, 92130 Issy les Moulineaux, France

    Reviewer of compiled data:
    Hamilton Hunter, Radiation Shielding Information Center, Oak Ridge National
    Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6362, fax 423-574-6182, 
    e-mail: h3o@ornl.gov.

 8. Availability:

 9. References:
   [1] Shin K., Uwamino Y., Yoshida M., Hyodo T. and Nakamura T.: 
      "Penetration of Secondary Neutrons and Photons from a Graphite 
       Assembly Exposed to 52-MeV Protons," 
       Nucl. Sci. Eng., 71, 294-300 (1979).
   [2] Uwamino Y., Nakamura T. and Shin K.: "Penetration Through Shielding 
       Materials of Secondary Neutrons and Photons Generated by 52-MeV 
       Protons," Nucl. Sci. Eng., 80, 360-369 (1982).
   [3] K. Shin et al., Nucl. Technol., 53, 78 (1981).
   [4] K. Hayashi, et al.: "Accelerator Shielding Benchmark Analysis and 
       Future Items to be Solved", SATIF Proceedings of the Specialists 
       Meeting, Arlington, USA, 28-29 April 1994, OECD 1995
   [5] H. Nakashima, et al.: "Accelerator Shielding Benchmark Experiment 
       Analyses", SATIF-2 Proceedings of the Specialists' Meeting, CERN, 
       Geneva, Switzerland, 12-13 Oct. 1995, OECD 1996
   [6] T. Nakamura and T. Kosako, Nucl. Sci. Eng., 77, 168 (1981)
   [7] Personal Contact w/ Katsumi Hayashi, Aug. 1997.
   [8] H. Nakashima et al., Benchmark Problems for Intermediate and High
       Energy Accelerator Shielding, JAERI 94-012 (Sept.1994).

10. Data and Format:


        Filename     Size[bytes]   Content
    ---------------- ----------- -------------
  1 p52-abs.htm          10.960  This information file.
  2 p52-exp.htm          24.911  Description of Experiment.
  3 P52-fig1.gif          8.668  Figure 1: Experimental arrangement. (preview) 
  4 P52-fig2.gif         11.479  Figure 2: Neutron spectra in graphite.(preview) 
  5 P52-fig3.gif         12.480  Figure 3: Neutron spectra in iron. (preview) 
  6 P52-fig4.gif         11.249  Figure 4: Neutron spectra in water. (preview) 
  7 P52-fig5.gif         11.389  Figure 5: Neutron spectra in ordinary concrete. (preview) 
  8 P52-fig6.gif         14.953  Figure 6: Photon spectra in graphite. (preview) 
  9 P52-fig7.gif         13.739  Figure 7: Photon spectra in iron. (preview) 
 10 P52-fig8.gif         12.853  Figure 8: Photon spectra in water. (preview) 
 11 P52-fig9.gif         13.523  Figure 9: Photon spectra in ordinary concrete. (preview) 
 12 P52-FIG1.TIF         19.741  Figure 1: Experimental arrangement. (high quality) 
 13 P52-FIG2.TIF         37.540  Figure 2: Neutron spectra in graphite. (high quality) 
 14 P52-FIG3.TIF         41.836  Figure 3: Neutron spectra in iron. (high quality) 
 15 P52-FIG4.TIF         25.386  Figure 4: Neutron spectra in water. (high quality) 
 16 P52-FIG5.TIF         30.323  Figure 5: Neutron spectra in ordinary concrete. (high quality) 
 17 P52-FIG6.TIF         40.544  Figure 6: Photon spectra in graphite. (high quality) 
 18 P52-FIG7.TIF         39.701  Figure 7: Photon spectra in iron. (high quality) 
 19 P52-FIG8.TIF         26.257  Figure 8: Photon spectra in water. (high quality) 
 20 P52-FIG9.TIF         31.531  Figure 9: Photon spectra in ordinary concrete. 
 21 J94_012.PDF       3.233.504  Reference 
 22 52P_1.PDF           630.515  Reference 
 23 52P_2.PDF           972.531  Reference 

    File P52-EXP.htm contains the following tables:
    (1)   Dimensions and compositions of materials,
    (2, 3)  Neutron and Photon source spectra,
    (4, 5, 6, 7, 8, 9, 10, 11) Neutron and photon spectra transmitted through graphite, iron, water and
    concrete assemblies.

    Figures are included in TIFF format using LZW compression and GIF format (preview).
    Neutron and photon spectra are shown on figures with the measurement uncertainties.