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SINBAD ABSTRACT NEA-1552/19

TEPC-FLUKA Comparison



 1. Name of Experiment:
    ------------------
    TEPC-FLUKA Comparison

 2. Purpose and Phenomena Tested:
    ----------------------------
    Measurements and simulation of the lineal energy distribution of the energy deposition
    in biological cells of 2m diameter. This is first done in  well characterized 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.

 3. Description of the Source and Experimental Configuration:
    --------------------------------------------------------
    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.


 4. 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 2m. The wall of
    the sphere is made of a tissue equivalent plastic (A150). The TEPC sphere is contained
    in an aluminum 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].
    The geometry of TEPC is shown on tepc-geo.jpg, and the corresponding material
    composition in the file tepc-mat.xls.


 5. 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 have 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. 


 6. Special Features:
    ----------------
     None

 7. Author/Organizer
    ----------------
    Experiment and analysis:
    M. Autischer(1), P. Beck(1), A. Ferrari(2), M. Latocha(1), M. Pelliccioni(3),
    S. Rollet(1) and R. Villari(3)

    (1) Austrian Research Centre Seibersdorf, A-2444 Seibersdorf, Austria
    (2) CERN, 1211 Geneva 23, Switzerland
    (3) INFN, Laboratori Nazionali di Frascati, 00044 Frascati, Italy


    Compiler of data for Sinbad:
    S. Rollet
    Austrian Research Centre Seibersdorf, A-2444 Seibersdorf, Austria
 
    Reviewer of compiled data:
    I. Kodeli
    OECD/NEA, 12 bd des Iles, 92130 Issy les Moulineaux, France


 8. Availability:
    ------------
    Restricted

 9. References:
    ----------
    [1] Mitaroff, A. and Silari, M., The CERN-EU High-Energy Reference Field
        (CERF) Facility for Dosimetry at Commercial Flight Altitudes and in
        Space, Rad. Prot. Dosim. Vol.102, No. 1. pp.7-22, (2002). 
    [2] Far West Techn. Inc., Environmental radiation monitor with 5 inches 
        tissue equivalent proportional counter, Operations and repair manual, 
        December, (2000).
    [3] Fasso, A., Ferrari, A., Ranft, J., Sala, P.R., FLUKA: Status and Prospective 
        for Hadronic Applications  Proc. of the MonteCarlo 2000 Conference, Lisbon, 
        October 2326 2000, Springer-Verlag Berlin, p. 955-960, (2001).
    [4] S. Rollet, P. Beck, A. Ferrari, M. Pelliccioni, M. Autischer, Dosimetric 
        Considerations on TEPC FLUKA-Simulation and Measurements, Rad. Prot. Dosim.,
        Vol. 110, Nos 1-4, pp. 833-837 (2004)
    [5] P. Beck, A. Ferrari, M.Pelliccioni, S. Rollet and R. Villari,
        FLUKA Simulation of TEPC Response to Cosmic Radiation


10. Data and Format:
    ---------------

        Filename     Size[bytes]   Content
    ---------------- ----------- -------------
  1 tepc-fluka.htm    10,044  This information file 
  2 tepc-fluka.pdf   184,156  Detailed description and reference paper for comparison with
                              standard sources.
  3 cosmic-fluka.pdf 116,218  Detailed description and reference paper for comparison
                              onboard of aircraft.
  4 fig1.pdf          84,775  Sketch of the geometry layout of a HAWK simulated with FLUKA. 
  5 fig2.pdf         191,551  Simulated Microdosimetric spectra y d(y) for photon sources at
                              different energies.
  6 fig3.pdf         150,085  Microdosimetric spectra y d(y) for a 60Co source.
                              Comparison between simulation and measurements. 
  7 fig4.pdf         145,315  Microdosimetric spectra y d(y) for a 0.5 MeV neutron source.
                              Comparison between simulation and measurements. 
  8 fig5.pdf         197,820  Microdosimetric spectra y d(y) for an 241AmBe source. 
                              Comparison between simulation and measurements.
  9 fig6.pdf         212,922  Microdosimetric spectra y d(y) for the reference source at CERF.
                              Comparison between simulation and measurements. 
 10 tepc-geo.jpg      47,128  TEPC geometry 
 11 tepc-mat.xls      15,872  TEPC material composition
 12 meas_raw.xls      83,456  Raw data of TEPC measurements at CERF (position CT10)
 13 CERF-comp.xls    152,576  Comparison between measurements and simulations data at CERF
                              (plot and data)
 14 phospc.dat         4,285  Photon energy spectrum at CT10 (data) 
 15 phospc.pdf        12,890  Photon energy spectrum at CT10 (plot)
 16 neuspc.dat         4,565  Neutron energy spectrum at CT10 (data)
 17 neuspc.pdf        14,466  Neutron energy spectrum at CT10 (plot). 
                              Data and plots at commercial flight altitude.
 18 prispc.pdf        18,128  Plot of the primary energy spectra at the top of the atmosphere
                              (particles with Z up to 26)
 19 fig1a.pdf          9,331  Simulated spectral neutron fluence
 20 fig1b.pdf          8,083  Simulated microdosimetric neutron spectra yd(y) as seen by TEPC
 21 fig2a.pdf          7,412  Simulated spectral proton fluence
 22 fig2b.pdf          8,059  Simulated microdosimetric proton spectra yd(y) as seen by TEPC
 23 fig3a.pdf          8,186  Simulated spectral photon fluence
 24 fig3b.pdf          8,058  Simulated microdosimetric photon spectra yd(y) as seen by TEPC
 25 fig4a.pdf          9,330  Simulated spectral electron+positron fluence
 26 fig4b.pdf          8,056  Simulated microdosimetric electron+positron spectra yd(y) as seen by TEPC
 27 cosm.pdf          13,453  Simulated microdosimetric spectra yd(y) for all particles + total
 28 flight-comp.pdf    9,092  Microdosimetric spectra yh(y) comparison between simulation
                              (in free atmosphere) and measurements (inside the aircraft)


SINBAD Benchmark Generation Date: 7/2005
SINBAD Benchmark Last Update: 7/2005