Tritium Control

["Bruce A. Busby" <bbusby@umich.edu>]

Hi All, 

So, finals are almost over, and you will get my two cents worth on 
tritium.  

First, the radiation reading from the end of a neutron generator I would 
guess would be from induced activity of the structual componants, iron 
and Mn probably. tritium in targets can be several curies per cm^2, with 
targets running 5-18 curies often used, depending on machine. Target 
thickness effects yeild, thicker the target, more nuetrons produced, but 
thicker targets have more energy spread. Neutron fluxs can be upwards of 
10^11 n/sec.  Tritium targets are made by "putting" a metal, like 
titanium, on a backing metal, like copper, then placing the metals into a 
tritum gas chamber, the tritum migrates into the titanium, forming a hydride.
                                                              
Tritium will evolve off the target as tritium gass (T-T), which needs 
another reaction to become an oxide but will also evolve as water 
vapor (H-T-O). The T-T is of not much consequence, but the H-T-O will 
contaminate items, be absorbed in the body, etc. 

Because of the 12.3 year half life, a target or exit sign will have a lot 
of atoms of tritum in it, something like 2E19 tritium atoms per curie of 
tritium. 

The x rays should not have a higher energy than about 13.6 eV max, iwth 
an average near 4 eV. These could be detected with a Si(Li) detector, but 
I doubt with a GM.

The Beta particles, Max energy of 18.6 keV would be detectable in a open 
window Ion Chamber, but not make it through the windows of most other 
detectors (Average 5.6 keV). If anyone hase time, what is the range of a 
18.6 keV and what is the thickness of the entrance window of GM detectors?

-Bruce