RE: x-ray fluoroscence from NaI(Tl) 33keV ??

["Fulmer, Philip" <FulmerP@ttnus.com>]

What you're seeing are the characteristic x-rays from barium.  After
beta decay of Cs-137 to Ba-137m, the 662 keV gamma is emitted about 85%
of the time.  However, internal conversion occurs roughly 6% of the
time; so you would get the characteristic x-rays of barium (since the
cesium has already been transformed to barium by this time) following
the internal conversion.

The barium x-rays have the following energies
K_alpha1=32.2 keV
K_alpha2=31.8 keV
K_beta1=36.7 keV

Cs-137 is a great all-around spectroscopy calibration source.  You get
the 662-kev gammas for gamma spectroscopy, you get the barium x-rays for
x-ray spectroscopy, and you can use the conversion electrons as a
monoenergetic source of electrons for calibrating beta spectroscopy
systems.

Regards,

Philip



________________________
Philip C. Fulmer, PhD, CHP
TetraTech NUS
900 Trail Ridge Road
Aiken, SC 29803
(803) 649-7963
fulmerp@ttnus.com


-----Original Message-----
From: John Lam [mailto:lamhc@hkusua.hku.hk]
Sent: Thursday, April 29, 1999 10:53 AM
To: Multiple recipients of list
Subject: x-ray fluoroscence from NaI(Tl) 33keV ??



tell me where does the 33keV come from ?

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