Re: Energy response of cylindrical 1x1" NaI(Tl)

[sbrightwell@shepmill.com (Shane Brightwell)]

What Mr. Whitfill described sounds analogous to a "Single Channel Analysis"
operating mode.  We drive Ludlum 44-10 NaIs with Ludlum 2350-1 data loggers
in this mode in the field.  This instrument has no "gain adjust", but the
keV/channel calibration can be performed by adjusting HV, then set
operating windows for isolating the photopeaks of desired gamma-emitting
isotopes.  This "SCA" operating voltage is always lower than the plateau
voltage that is typically used in instruments calibrated to measure
exposure rate.  Not all gamma detecting instruments allow this type of
calibration without considerable effort.

What I think Mr. Clement was interested in was the energy response of such
a detector operated at plateau high voltage.  There is a graph in the back
of the Ludlum Model 19 Instruction Manual that depicts how the NaI (when
calibrated/normalized to Cs-137) overresponds/underresponds at lower/higher
gamma energies, respectively.



Reg's,

Shane Brightwell, M.S., CHP
Senior Staff Engineer
Shepherd Miller, Inc.
3801 Automation Way
Suite 100
Fort Collins, CO 80525
Ph: (970)223-9600 (main)
    (970)206-4315 (office)
    (970)481-3036 (cell)
FAX:(970)223-7171
mailto:sbrightwell@shepmill.com
http://www.shepmill.com

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