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Tuesday, September 6, 2011

Why does manufacturers coat inner walls of BF3 counters with activated charcoal?

The charcoal coating is used for tubes filled with BF3 gas and also for He3 filled counters operated in high neutron fluxes. The activated charcoal serves to absorb electronegative gases that build up during nuclear irradiation.

For instance, in a BF3 filled detector three fluorine atoms are released with each neutron capture.The Fluorine atoms will combine with electrons released in subsequent neutron captures. Initially, this process reduces electric pulse amplitude and eventually output pulses are eliminated altogether.