request info: GM energy response

[Keith Welch <welch@CEBAF.GOV>]

Can anyone point me to a reference for photon response curves specific to
the "pancake" gm tube commonly used in contamination monitoring.  Also would
like to compare this response to typical SWGMs and to the beta response.
I'm assuming there is an over-response to low energy photons when calibrated
with Cs-137. What I'm after is a quantitative comparison of typical beta
efficiency against the gamma efficiency for a range of gamma energies.

Thanks much in advance.

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