Re monitoring

[R.Ryder@dl.ac.uk]

Keith,
I think your accelerator is a CW device. The original question was 
specifically related to pulsed radiation with a 1microsec pulse every few 
secs. Will your area monitor counters, particularly the BF3 handle this?
Roy Ryder
Daresbury Laboratory
 ----------
From: Keith Welch <welch@CEBAF.GOV>
To:  Multiple recipients of list <; DL/MAINOFFICE/HA
Subject: Re:
Date: 02 October 1996 21:15



>>What I am looking for, is an active method to measure such radiation 
fields.

>I see this as two questions.  Measuring the prompt field is quite different
>than doing area radiation monitoring.

>For the prompt field, we employ ( in our machine protection system) PMTs
>(with no scintilator) which respond via cherenkov.  I'm told that the key 
to
>getting the best performance from a system like this is to synchronize the
>analysis of teh signal to the pulse.  Our tubes are set up something like
>this:  Output current goes to an I/V converter, voltage goes to an ADC, and
>the ADC should be synchronized to the beam pulse (presently it is not which
>makes for lots of slop in the system).  All this beam sync stuff needs to 
be
>done with adequate attention given to the signal rise and processing times..

>The main thing about any system used in these conditions is that if you 
want
>to get anything other than qualitative information, you have to do some 
kind
>of calibration or reference exposure as has been mentioned.

>>How area radiation monitoring is acheived in such accelerators elsewhere?

>We do our area monitoring with Nuc Research Corp ADM-610.  They use sealed
>proportional tubes with energy compensation.  The tube also operates in a
>variable HV mode, which gives it a very wide dose rate range - from
>background readings in micro-R/hr up to about 10 R/hr (I may be wrong on 
the
>max dose rate).  We also have a  neutron channel on these instruments with
>BF-3.

>Keith Welch
>Thomas Jefferson National Accelerator Facility
>Newport News VA
>welch@cebaf.gov