Thanks for: Activation Products

[welch@CEBAF.GOV (welch)]

Thanks for the responses on the Br-82 question.  Several of you pointed to
the Bromine used for fire retardants in the pc boards.  My assumption now is
that this is in fact the source of the Br-82 that we are seeing.  Thermal
neutron capture would account for the activity.  Some of my confusion was
due to the fact that the location of these devices is not directly on beam
line or even line of site to the beam line (it is inside an experimental
hall) so the thermalized neutron scenario makes good sense. There is a
'stew' of neutrons in the hall, so there are plenty of low energy neuts
around this area even though it is shadowed by shielding.  The boards are in
large HV power supplies and are fairly massive - so they must contain a
considerable amount of the bromine soup. Typical board measures about 24
inches square and reads 20-40 microrem/hr above bkg shortly after beam run.
Keith Welch
Continuous Electron Beam Accelerator Facility
Newport News VA
welch@cebaf.gov