MEASUREMENT OF THE EFFICIENCY OF A BF3 COUNTER

A final year undergraduate nuclear experiment is described in which th e efficiency of a boron trifluoride (BF3) counter is determined. This involves attaching neutron sensitive activation foils to the surface o f the counter, exposing the foils to the neutron flux from an Am-Be ne utron source for a given time, and measuring the total number of neutr ons entering the sensitive volume of the counter. Several basic princi ples of nuclear physics are incorporated into one single experiment wh ich has proved instructive and challenging to final year undergraduate students. The student is expected to understand and apply topics such as radioactive half-life, absorption of nuclear radiation, nuclear de tection, neutron activation and nuclear decay schemes in a single expe riment. The experiment can also be converted into an open ended projec t where, in addition, the student can study several other aspects of t he subject including the kinetics of (alpha,n) reactions. (C) 1996 Ame rican Association of Physics Teachers.