Ni-63 portable detector -Reply

[FRAMEP@ORAU.GOV]

Wes has identified what I think would be your best option i.e a thin
windowed gas flow proportional. Going to something that would also
pick up tritium would mean a windowless detector and that can lead to
unnecessary trouble.

A pancake GM would have a substantially lower efficiency for Ni-63,
say 1% or so, because of the thicker window. In addition, you're limited
to a small window area.

One other possibility might be a plastic scintillator of the sort made by
Bicron. The windows are quite thin so Ni-63 detection should be
possible. But the very limited experience I've had with beta scintillators
suggested that the efficiency was highly susceptible to small voltage
fluctuations. That might  represent an anomalous bad experience
however. I'd sure be interested in hearing from those who have used
plastic scintillators  and whether or not they think that they might be a
reasonable alternative to the proportional detector for low energy betas.

Paul Frame
Professional Training Programs
ORISE
framep@orau.gov