An experiment on isospin-changing parity violation involving hadrons in nuclei

An experiment is reported on the parity-violating reaction d(α,γ)6Li, leading to the Jsup(P)=0+, I=1, Esub(kappa)=3.562 MeV state, which, being a ΔI=1 transition, could be strongly enhanced by the presence of neutral currents in hadronic weak interactions in nuclei. The experiment has been carried out by exposing a deuterium target to a beam of α-particles reaching the resonant energy in the region in the middle of the tube containing the gas. Gamma-rays from this region are detected by a 90 cm3Ge(Li) counter connected to a 4096 channel analyser through an amplifying and analysing chain. The various sources of the background of spurious counting in the Ge(Li) and the procedure adopted to reduce their effect are discussed. No evidence has been found for a nonzero parity-violating width of the 3.562 MeV state of 6Li and can set an upper limit for this width of 8.10-4eV, which is an order of magnitude or more lower than that obtained in the previous experiments on this reaction