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Re: NEutron QF
Sunil C Nair wrote:
> In the energy range 2MeV to 20MeV, (where the QF is less than the 100KeV
> to 2MeV range) N(n,p), H(n,gamma) and elastic collisions with Hydrogen
> still dominate the contribution to the dose. Thus we are essentially
> dealing with the same protons (either recoil or reaction product) with
> more energy, and gamma photons. Now, QF depends on the LET of the
> secondary particles that deposit energy in the tissue. Does the LET
> changes so drastically in such short span of energy?
> If as absorption cross section does come down, as suggested by Scott
> Schwan and Neal Zapp, how is the dose per neutron an increasing function
> all the way ? I have found tables and figures in literature to show that
> dose increase as neutron energy. (1). Accelerator Health Physics,
> Patterson & Thomas, page 70, fig 2.12. (2). is "A guide to radiation and
> radioactivity levels near high energy particle accelerators by A.H.
> Sullivan, page 27, Fig 1.17).
I misplaced my Sullivan book, but referring to the Patterson & Thomas, that
refers to dose equivalent, not dose. I provide below a table that gives dose,
dose equivalent, and QF from a bit older source, ICRP-21. ICRP-60 roughly
doubles the Wr and broadens the energy categories. I hope this also helps.
Please note that this table will line up only using a fixed width font.
ICRP-21 ICRP-21
Energy Flux to Flux to dose
Max(MeV) dose equivalent QF
4.14000E-07 5.26E-10 1.15E-09 2.2
6.82600E-07 6.09E-10 1.23E-09 2.0
1.44500E-06 6.18E-10 1.25E-09 2.0
3.05900E-06 6.14E-10 1.24E-09 2.0
6.47600E-06 6.07E-10 1.23E-09 2.0
1.37100E-05 6.01E-10 1.21E-09 2.0
2.90200E-05 5.97E-10 1.20E-09 2.0
6.14400E-05 5.94E-10 1.18E-09 2.0
1.30100E-04 5.89E-10 1.16E-09 2.0
2.75400E-04 5.70E-10 1.12E-09 2.0
5.92900E-04 5.47E-10 1.08E-09 2.0
1.23400E-03 5.25E-10 1.04E-09 2.0
2.61300E-03 5.15E-10 1.02E-09 2.0
5.53100E-03 5.08E-10 1.01E-09 2.0
1.17100E-02 5.04E-10 1.01E-09 2.0
2.47900E-02 5.63E-10 1.51E-09 2.7
5.24700E-02 6.64E-10 2.69E-09 4.0
1.11100E-01 7.85E-10 4.78E-09 6.1
2.23700E-01 1.04E-09 8.30E-09 8.0
4.50800E-01 1.45E-09 1.42E-08 9.7
9.07200E-01 2.24E-09 2.39E-08 10.7
1.87200E+00 3.41E-09 3.51E-08 10.3
3.67900E+00 4.22E-09 4.00E-08 9.5
7.40800E+00 5.78E-09 4.07E-08 7.0
1.49200E+01 6.62E-09 4.11E-08 6.2
2.58100E+01 9.10E-09 4.36E-08 4.8
4.46500E+01 9.61E-09 4.43E-08 4.6
7.72500E+01 1.01E-08 4.71E-08 4.7
1.33600E+02 1.14E-08 5.03E-08 4.4
2.31200E+02 1.49E-08 5.54E-08 3.7
4.00000E+02 1.79E-08 6.36E-08 3.5
Regards,
Scott
--
Scott O. Schwahn, CHP
Thomas Jefferson National Accelerator Facility
schwahn@jlab.org
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