Re: BREMSSTRAHLUNG

[baumbaug@nosc.mil (Joel T. Baumbaugh)]

     Mr./Ms. J.James


1. What should the bremsstrahlung spectrum look like?

     In/with  my experience, I've found that, as with the  beta's
involved,  there  will be an e-max x-ray with most of the  x-rays
being  produced about 1/3 of the e-max.  So instead of  gamma-ray
photon  spikes,  you'll get a "curve" like response (it  sort  of
looks like a liquid scintillation (LSC) spectrum).

2.   Is   there   any  relationship  between  the   beta   energy
(E-max,average) and the spectrum on the scintillation detector?

     Yes, tenuous, but yes.

3.  Is  there  a reference that might give  information  on  this
subject?

     I've looked for info. (electronic data searches) without any
results.

4. Does anyone use this method to identify beta isotopes?

     I've  had  EXACTLY the same problem that you have  had  with
trying  to  I.D. unknown encapsulated beta sources.   I've  tried
different thickness' of absorbers to find the beta e-max (you can
buy  some  nifty kits), and used the MCA method to try  and  help
"quantify"  my  absorber results.  If only you could  "cram"  the
suckers into a LSC with a spectrum analyzer you'd be set...

     While  the  e-max bremstrahlung gives you a "rough" idea  of
what  the e-max beta energy may be, I've found that the  material
used  (type/thickness etc.) for encapsulation does make a  slight
difference on what you see on your MCA.  "IF" you have some known
beta  sources  and look at their x-ray spectra  under  conditions
similar  to  what  you already have (lets say a  stainless  steel
absorber/attenuator  [30 mill thickness]) it may help give you  a
"feeling" for what your system "sees".


     I hope this helps a little,


     Joel Baumbaugh  (baumbaug@nosc.mil)
     NRaD
     San Diego, CA

Std  Disclaimer.   These are my own opinions,  not  (necessarily)
those of my supervisor, the Federal Government, or the Navy.