Discrpancies among different dosimeters

[Mr Jo <mjo@scs.unr.edu>]

I am trying to characterize radiation field from 100 ns x-ray pulse. The
expected x-ray energy is between 0-2.8 MeV. X-rays below ~60 keV do not
escape the chamber based on my calculation. I used pocket dosimeters (0-200
mR and 0-5 R range), TLD, and Aluminum Oxide dosimeter in a group and placed
them in four directions about one foot from the x-ray chamber (anode).

Here are the readings and the numbers represent locations (TLD (1), Pocket
dosimeter (1), and Al Oxide (1) are from the same location).
    Pocket dosimeters: (1) 0.7 R (2) 0.8 R (3) 0.7 R (4) 0.8
    TLD: (1) 600 mrem (2) 400 mrem (3) 180 mrem (4) 780 mrem
    Al Oxide: (1) 1804 mrem (2) 2098 mrem (3) 2210 mrem (4) 1060 mrem

The TLDs and Al Oxide dosimeters were provided and processed by NVLAP
accredited vendors.

I did not pay attention to whether the dosimeters were facing the beam or
facing away from the beam. Variances in distance should not be significant
as they were placed in a zip lock bag and the bag was taped to the chamber.

I am confused about the results. I welcome any suggestions to explain what
could have happened. Thank you. M. Jo
========================================================
Myung Chul Jo, MS, CHP
EH&S, Mail Stop 328
University of Nevada, Reno
Reno, Nevada 89557
(702)784-4540
(702)784-4553 fax
mjo@scs.unr.edu


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