[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: Energy response of cylindrical 1x1" NaI(Tl)
You may find this of interest...
The following is from measurements that were done using a Ludlum Model 44-2
1-inch x 1-inch NaI detector and a Ludlum Model 44-33 2-inch x 0.5-inch NaI
detector (stabilizer off) with a Ludlum Model 2218 dual analyzer:
The operating voltage range for the 1-inch NaI detector was determined to
be from 375 V to 725 V. The HV potentiometer DCA is calibrated to be 250 V
per turn. Upon evaluating the detector at several different voltages, the
relative peak shift was approximately 2 V per channel. Increasing the
voltage shifted the peak right. At 362.5 V, the instrument was operating at
approximately 20 keV/CH (2000 keV max), and at 400 V, 9 keV/CH (900 keV
max). The peak locations using the 1-inch detector were matched with those
of the 2-inch x 0.5-inch detector when the operating voltages were set at
400 V and 850 V, respectively. The detectors were compared using a Ba-133
standard and a mixed gamma standard (Am-241, Cs-137, Co-60).
It is not hard to see what happens to the spectrum when the operating
voltage is set at 900 V for the 1-inch detector (typical operating voltage
for a Ludlum Model 19 uR meter). Glen Knolls text Radiation Detection and
Measurement may be a place to start-in the 2nd edition, page 342, is a
graph(Figure 10-20) of the intrinsic total efficiency of various
thicknesses of NaI for gamma rays perpendicular to its surface.
"Clement, Christopher" <clementc@aecl.ca>@romulus.ehs.uiuc.edu on
01/04/2000 09:51:34 AM
Please respond to radsafe@romulus.ehs.uiuc.edu
Sent by: radsafe@romulus.ehs.uiuc.edu
To: Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
cc:
Subject: Energy response of cylindrical 1x1" NaI(Tl)
Radsafers:
I've had a look through my references, but I couldn't find any good data on
the energy response of a cylindrical 1x1" NaI(Tl) detector. (i.e.. graph of
relative detector response vs. incident photon energy). I'm particularly
interested in data from a real instrument, which will include the primarily
low-energy effects of shielding from the housing. We happen to use
Eberline
SPA-8 instruments, but I assume that most industry-standard instruments
will
have a similar response. Can anyone point me in the direction of such
information?
Thanks.
--------------------
Christopher H. Clement, M.Sc., CHP
Scientific Specialist / Radiation Protection Program Manager
Low-Level Radioactive Waste Management Office
Atomic Energy of Canada Limited
clementc@aecl.ca
Telephone (613) 998-4525
Facsimile (613) 952-0760
************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html
************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html