LIFETIME OF THE 937-KEV AND 885-KEV RESONANCES IN THE AL-27(P,ALPHA) REACTION

We have used the crystal blocking technique to measure the lifetimes of Si28 compound states excited by the Al27 (p,±) reaction at Ep=937 and 885 keV. Axial blocking on the 110 axis of thick Al crystals and Kodak LR 115 plastic detectors are used. Measurements have been made at a 0.2 m depth. A study is made of the yields of some (p,±) resonances on Al and of the depth dependence of blocking dips. The data are analyzed by comparison with a realistic Monte Carlo model. The resulting lifetime,937<17 as (as = 10-18 s) and 885=38-9+10 as are compared with previous work. NUCLEAR REACTIONS Al27(p,±)Mg24, E=0.731-1.183 MeV; measured yields in thin targets. LR 115 cellulose nitrate detectors. E=0.885, 0.937 MeV; measured blocking effect. Si28 deduced mean lifetime. Single crystal thick Al targets. © 1979 The American Physical Society.