Puzzler: How Does Humidity Affect Counting Efficiency?

["Bradt, Clayton" <Clayton.Bradt@Labor.State.Ny.Us>]

My suspicions would turn to looking for ways that a change in stray

capacitance could affect the counting efficiency.  It's probably not the

change in air conductance, per se, but a change in capacitive coupling

between components.   Now, would higher humidity increase or decrease stray

capacitance?  I'd say decrease.   Decreasing capacitance increases

capacitive reactance ( X =1/(2pifC) ).  So with higher humidity you're

bleeding off less of the high frequency counting signal and therefore your

apparent efficiency increases (?).   Sounds plausible, but then why isn't

you're beta efficiency affected? Hmm.



Clayton J. Bradt, CHP

Principal Radiophysicist

NYS Dept. of Labor

Radiological Health Unit

voice: (518) 457-1202

fax:    (518) 485-7406

e-mail: Clayton.Bradt@labor.state.ny.us



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