RE: conversion electrons and recoil nuclei

["Broseus, Roger" <rbroseus@exchange.nih.gov>]

Paul: I-125 produces a lot of counts in the H-3 and C-14 channel of liquid
scintillation counters.  There are several low E Auger and conversion electrons
associate with decay of I-125.  An un-knowledgeable person could mistake I-125
for these radionuclides or not perform necessary corrections to count rates for
'dual isotope' counting if I-125 contamination were to be present.  On the other
hand, the emission of low E electrons by many gamma emitters is an advantage
when one is performing contamination control surveys: even for 'pure gamma'
emitters like I-125 and Tc-99m, one can detect these radionuclides readily with
a liquid scintillation counter.

Hope this is helpful.


-- Roger
   301-496-2253
   Email: RogerB@nih.gov


	----------
	From: 	FRAMEP@ORAU.GOV[SMTP:FRAMEP@ORAU.GOV]
	Reply To: 	radsafe@romulus.ehs.uiuc.edu
	Sent: 	Wednesday, February 18, 1998 10:34 AM
	To: 	Multiple recipients of list
	Subject: 	conversion electrons and recoil nuclei

	Good day

	I am looking for information (especially references) about  situations
	where conversion electrons appeared to be betas or contributed to beta
	counts. 

	I could imagine situations where pure alpha contamination appeared to
	have a beta component (aside from proportional counter cross talk) and
	situations where the activity of CE producing beta contamination was
	overestimated.

	Are there any good examples where this was a significant real world
	problem? I understand that there are ways that this phenomenon can be
	used to advantage but I am interested in the problems that arise.

	In addition, does anyone have references that give ballpark estimates of
	the contribution to alpha counts from recoil nuclei in windowless
	detectors.

	Thanks a bunch

	Paul Frame
	Professional Training Programs
	ORISE
	framep@orau.gov