RE: Discrpancies among different dosimeters

["Edwards, Richard W" <Richard.Edwards@PSS.Boeing.com>]

With regards to the x-ray source:

How consistent is the source? Do multiple measurements taken with the same unit and the same dosimetric device in the same geometry give you consistent results? If there is some element of non-uniformity of the beam...spacial irregularities in the x-ray flux density, variations in the energy or total x-ray production, these could account for much of the difference between measurements taken with similar measuring devices. If the variation is in the spacial distribution of the flux, I would expect the effect to be greater for a small measuring device such as a TLD as opposed to a relatively large one such as a pocket ion chamber.

You might try NIST. They should have some insight into the variability of x-ray producing devices for measurements such as yours.

Rick Edwards, Analyst
The Boeing Company
richard.w.edwards@boeing.com

> ----------
> From: 	Mr Jo[SMTP:mjo@scs.unr.edu]
> Reply To: 	radsafe@romulus.ehs.uiuc.edu
> Sent: 	Thursday, May 20, 1999 10:25 AM
> To: 	Multiple recipients of list
> Subject: 	Re: Discrpancies among different dosimeters
> 
> Thank you for those who provided me with additional information regarding my
> question in this topic from yesterday.
> 
> Here are some additional information about dosimeters. The TLDs contain two LiF
> powder capsules. The Al Oxide contain (an?) Al Oxide strip. The TLDs and Al oxide
> responses are independent of incoming beam direction (forward or backward)
> according to the vendors. The TLD correction factors are being adjusted after
> discussion of x-ray energies with the company but I do not expect drastic
> difference from the current values (may go up to about 25%). Distance between the
> x-ray source and the dosimeters were about one foot and I feel that distance is
> fairly uniform among all dosimeters.
> 
> I will be collecting more data within 1-2 weeks and expect to know more. I welcome
> any suggestions.  M. Jo
> 
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