On the use of the (π−,K0) reaction on nuclear targets for the precise determination of the lifetime of the hydrogen hyperisotopes and other neutron-rich Λ-hypernuclei

Recent results reported by experiments with relativistic (heavy) ions have raised again the question whether the lifetime of ill is very close to the lifetime of the free A hyperon. An updated careful analysis of all the existing experimental data shows that it is not, contrary to theoretical calculations. A similar conclusion can be drawn for the neighbor H-4(Lambda). A clear cut high precision measurement performed with the straightforward method of time delay spectra is however lacking and it is eagerly needed. The idea of using the (pi(-), K-0) charge-exchange associated production reaction on targets of liquid He-3,He-4 is discussed. A possible realization exploiting a large part of existing facilities at J-PARC is presented. A measurement with a 5% precision seems within reach with a modest effort and in a reasonable amount of time. The same set-up would also serve very well for the measurement of the lifetime of several neutron-rich Lambda-hypernuclei of the p-shell, in particular of B-12(Lambda). More importantly, the Weak Decay partial widths Gamma(pi-), Gamma(p) and Gamma(pi 0) could be simultaneously determined in order to confirm their predicted strong variation with mass number, A, due to nuclear structure effects. (C) 2016 Elsevier B.V. All rights reserved.