APPLICATION OF A SEALED TUBE NEUTRON GENERATOR TO THE CHARACTERIZATION OF VERY SHORT HALF-LIFE ISOMERIC STATES

A SODERN sealed tube neutron generator producing 14 MeV neutrons has b een used for detecting radionuclides with a half-life from about 20 mu s to 1 s. An interesting feature of this kind of sealed tube neutron generator is the pulsed operation at adjustable pulse width from 5 mu s to 10 ms or more, and at frequencies from continuous mode to 10 kHz. This capability allows the study of very short-lived isotopes down to a few microseconds with the cyclic activation method. A semiconductor gamma ray detector Ge(HP) and ORTEC electronics were used for spectro metric measurements. The half-life measure:ment of short-lived activat ion products is performed with a fast multiscaler. Seven isomeric stat es have been successfully studied, characterized and their activation cross sections evaluated by the cyclic activation method: In-141, Ta- 181, W-181*, Pb-205*, (206)pb*, (207)pb*, and Bi-208*.