Re: Response of Pocket dosimeters

["Mike Malaxos" <rss@arach.net.au>]

Depending upon the actual dose rate GM detector instruments may under read
because of saturation and the resulting non-linear response as well as the
inherent photon energy dependence.

It would be interesting to try using an ion chamber personal dosimeter
which can resolve 0.1 mSv( 1 mrad)  such as the Riken 7 produce by Riken
Keiki of ??Tokyo Japan). This unit has a chamber volume of about 15 cc. and
can handle dose rates exceeding 6000 rad/h.

Best Regards
M.Malaxos
Radiation Safety Services
69-71 Robinson Avenue Belmont
Western Australia.  6104 
Fax 61 89 475 0165
P 61 89 475 0099  a/h 089 255 1214
email rss@arach.net.au
 

----------
> From: Sunil C Nair <sunil@tifr.res.in>
> To: Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
> Subject: Response of Pocket dosimeters
> Date: Wednesday, 29 July 1998 11:57
> 
> 
> Hi all
> 
> I am trying locate response of pocket dosimeters( Direct Reading
> Dosimeters) to 60 KeV X rays. (lead charecteristic X-rays). 
> 
> The x-rays originate from a superconducting linac cavity using
> lead-copper technology, excited by a RF power of 10W( the present testing
> power), repeated at a frequency of 150MHz, followed by 2-3 seconds delay.
> I was trying to measure the resulting radiation field by a 'MINI'(Mini
> Instruments UK) Gamma survey meter. The meter faithfully shows one kick
> in 3 seconds(about 10microSv, after some lead and concrete shield). It
> probably averages the 150MHz and read as one kick. I am not expecting it
> to respond to 150MHz, but I worry it may be underestimating the actual
> dose rate, in case it averages or gets saturated. So I am planning to use
> those pocket dosimeters and see the integrated dose after  every hour. 
> 
> It is here I would like to know the response of such a dosimeter.
> 
> Does someone have a better idea to do this job in an active(readings
> should be available as and when required) manner ?
> 
> Thanks in advance to all.
> 
> Sunil Nair
> Pelletron accelerator, 
> TIFR, Bombay.
> mailto:sunil@tifr.res.in
> 
> 
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