[ RadSafe ] Gamma emissions of Co-60 ?

[Bob Cherry]

Frank,

Having done my thesis on directional correlation of gamma rays, I can assure
that you have been misinformed. 

The gamma cascade in cobalt-60, as virtually all quantum events, occurs
randomly. For a cascade from a single decay, you cannot predict the angle
between the two. But for a large number of them, statistically you will see
a pattern. This pattern has to do with the spins and parities of the nuclear
levels in the excited nucleus that is decaying. If you know the spins and
parities you can predict the pattern. Of course, usually you are looking at
the pattern to get the spins and parities. Experimental uncertainties
usually obfuscate the predicted spins and parities for most cascades, but it
is a useful technique for some nuclides and allowed me to get my degree.

Dr. Bernard Cohen is an expert in this area and he may have more to add.
(Much more can be added to the above.)

It turns out that the cobalt-60 cascade directional correlation is so well
known, that it is used for calibration in directional correlation
measurements.

Bob

-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On Behalf
Of Frank Helk
Sent: Thursday, June 02, 2005 5:25 AM
To: radsafe at radlab.nl
Subject: [ RadSafe ] Gamma emissions of Co-60 ?

Hi folks,

I've read or heard somewhere, that the main gamma rays emitted from Co-60
(1173 keV and 1333 keV) thru the decay process are always emitted in 
opposite directions. I'm somewhat puzzled about that, and I can't find any
source about that behaviour.

Does anybody out there have a hint ("true", "false", literature source if
true ?)

Best regards

	Frank


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