Detecting Short-lived Isotopes Outside the OMEGA-60 Target Chamber Milliseconds After a High-Yield Shot*

It may be possible to make fundamental nuclear science measurements of low-energy light-ion cross sections by collecting and counting the beta decays of the reaction products in the expanding neutral gas after an ICF shot with a doped target.  To do this, the Short-Lived Isotope Counting System (SLICS) uses a dE-E phoswich detector telescope to identify beta particles, and can measure the decay curve for isotopes with half-lives from about 20 ms to 20 s.  To test the ability of SLICS to identify the desired beta events in the intense radiation environment just outside the OMEGA-60 target chamber immediately after a high-yield cryogenic DT shot, a ride-along experiment was carried out at the Laboratory for Laser Energetics.  A sample of natural boron placed directly in front of the SLICS scintillators was activated by the primary 14.1 MeV DT neutrons via the ¹¹B(n, α)⁸Li reaction.  SLICS events falling in a particular region of the 2D histogram formed by the energy lost in the thin dE versus the thick E scintillators were considered to be beta particles, and the time distribution of these events was used to fit the 840 ms decay curve of ⁸Li.