RE: Identification of gamma peak 1576 keV

["Bob Hearn" <rah@AMERICA.NET>]

This is the energy for a double-escape peak from the 2598.5 keV gamma (16.9

%) of Co56, but you would expect to see a lot of the higher intensity gamma

lines (846.7, 1238.2 keV) and positron annihilation peak for this peak to be

discernable.



Bob Hearn

rah@america.net



-----Original Message-----

From: owner-radsafe@list.vanderbilt.edu

[mailto:owner-radsafe@list.vanderbilt.edu]On Behalf Of LAM HOI CHING

Sent: Tuesday, December 18, 2001 11:39 PM

To: RadSafe

Subject: Identification of gamma peak 1576 keV





Dear Radsafers,

Subject :Identification of 1576 keV gamma peak



  Our department recently purchased a 10mCi Co57 flood source for gamma

camera QA purpose. In using  a Ge MCA detector, several gamma peaks have

been recorded other than the usual 122keV and 136 keV for Co57.

  There are peaks for

   Co58  : 810keV , 864

   Co56  (keV) : 846.7, 977.2,

1037.9,1175.1,1238.3,1360.3,1442.5,1771.4,1810.8,

                 1963.6,2015.3,2034.8

   Co57 (keV) : 339.7,352.3,366.6,569.9,692



Question 1:

   An unclassified peak of 1576.7 keV (±0.2keV) has been detected.

   What is that unknown peak ?

Question 2:

    I have used the gamma yield% values from LLNL website ( nuclide search

: Co57) noticed that the yield% values for 569.9 keV and 692 keV have given

resultant Co57 activity 2 times larger in activity value than those

calculated from 339.7,352.3 and 366.6keV.



  Thank you for any possible suggestions or answers.



Best regards



John Lam, Physicist, Eastern Hospital, Hong Kong









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