Search for Delayed Neutrons from the Photon Bombardment of Lithium

Abstract

A search has been made for delayed neutrons resulting from the reaction ${\mathrm{Li}}^7(\gamma , 2p){\mathrm{H}}^5$ in an effort to decide whether or not ${\mathrm{H}}^5$ exists. Delayed neutrons were detected in a moderated counter assembly and scaled in nine delay channels which were variable in width and initial delay. A small signal observed after background subtraction showed no decay within statistics over a period of 0.45 sec. The first 0.05-sec counting period has been analyzed for the presence of a decay of 0.01-sec half-life and compared with a predicted yield of the reaction ${\mathrm{Li}}^7(\gamma , 2p)$ obtained by extrapolation of the measured yields of the reactions ${\mathrm{B}}^{11}(\gamma , 2p)$ and ${\mathrm{F}}^{19}(\gamma , 2p)$. The conclusion is that less than one percent of the expected ${\mathrm{Li}}^7(\gamma , 2p)$ yield can result in a particle stable final state.