G Value

[John R Laferriere <John.R.Laferriere@dupontpharma.com>]

Greetings, Radsafers- 

I am trying to estimate the amount of pressurization due to radiolysis inside a sealed quartz ampoule containing Ni-63 in an aqueous solution.  I know enough to know I am looking for a G-value, which is the production rate of a gas per unit of ionizing energy deposited.  

I have an old calculation done for H-3 which gives a G-value for H2 evolution via radiolysis of 0.53 molecules per 100 eV of energy deposited in water.  I will use this for the Ni-63 problem unless I can get hold of a better value.  I would guess that, due to its higher beta energy, Ni-63 would have a lower LET than H-3, and therefore might have a lower G-value.  I would also guess that if you can calculate a H2 production rate, you can estimate the O2 production rate as being one half the H2 rate based on the H2O atom ratio (barring any competing reactions like H2O2 production).  

If anyone has either specific values they can offer or a reference to point me to, that would be great.  I've done a little web searching but can't find any web-resident data tables yet, although I did get a hit for "G-men and FBI collectibles- values".  Also, if I'm off base on any of the above information, enlightment would be appreciated.  Thanks in advance for your time if you are able to respond!

Sincerely,

John Laferriere
DuPont Pharmaceuticals Co.
Medical Imaging Division
(978) 671-8316
(978) 671-8149 (fax)