BLOCKING MEASUREMENTS OF NUCLEAR DECAY TIMES.

Determination of transition matrix elements for decay of excited nuclear states provides an important test of the validity or scope of nuclear models. This can be done by measurement of the energy width, GAMMA , or through use of the uncertainty relationship GAMMA equals h/ tau , by measurement of the decay time, tau , of the state. A new technique that extends the accessible time range from the limit of similar 10** minus **1**2 sec obtainable by coincidence and similar 10**1**4 sec by Doppler shift attenuation methods to a new limit of similar 10** minus **1**8 sec and called the Blocking Technique for Nuclear Lifetime Measurement, or, the Blocking Lifetime Technique (BLT) is discussed.