Personnel neutron dosimetry using electrochemically etched CR-39 foils Page: 4 of 43
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NEUTRON ENERGY RESPONSE
Low-frequency electrochemical etching at elevated temperatures produces a
different energy dependence than that obtained with high frequency or chemical
etching of CR-39 foils. Figure 1 shows the energy response we obtained in two
separate studies. The upper curve was obtained using monoenergetic neutrons
from the Tandem Van de Graaff accelerator at the Los Alamos National
Laboratory, and the lower curve was obtained using an accelerator at the
Battelle Northwest Laboratory. The slight difference in these curves is
caused in part by a change In the etching procedures that occurred between
these studies. The upper curve was obtained using our present etching
techniques and is the curve that should be used. It indicates that neutrons
with energies between about 80 keV and 3.5 MeV are detected with a relative
flat energy dependence.
We are presently investigating the effect that changes in the etching
high voltage and etching time have on the energy dependence. A flat energy
dependence over the largest possible range of energies is desired. If our
studies show that a different etching high voltage or etching time would give
a better energy response curve, we will recommend changes in the etching
parameters in a later report.
CR-39 does not respond to thermal neutrons. Using our etching
parameters, there is also no response to neutron between 0.01 and about
0.05 MeV, and a lower than desired response to neutrons with energies in the
1316 MeV region (see Fig 1). We are now studying the effect of changes in
the etching parameters on the high-energy response. It may be that changes in
the etching voltage can also be used to improve that response.
Thi energy dependence of CR-39 foils using our etching procedures is
superior to that obtainable with albedo neutron dosimeters or from chemical
etching of CR-39. In Table 2, we show the results obtained using a z52Cf
source moderated in the polyethylene, water, D20, and aluminum spheres that
are used for studies in our calibration facility. The results indicate that
the energy dependence of CR-39 using our etching techniques is sufficiently
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Hankins, D.E.; Homann, S. & Westermark, J. Personnel neutron dosimetry using electrochemically etched CR-39 foils, article, September 17, 1986; California. (digital.library.unt.edu/ark:/67531/metadc1054939/m1/4/: accessed January 21, 2019), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.