The neutron lifetime has been measured by comparing the decay rate with the reaction rate of $^3$He nuclei of a pulsed neutron beam from the spallation neutron source at the Japan Proton Accelerator Research Complex (J-PARC). The decay rate and the reaction rate were determined by simultaneously detecting electrons from the neutron decay and protons from the $^3$He(n,p)$^3$H reaction using a gas chamber, the working gas of which contains diluted $^3$He. The measured neutron lifetime was $898\,\pm\,10\,_{\rm stat}\,^{+15}_{-18}\,_{\rm sys}\,$s.
Double differential thick target neutron yields from 5and 9 MeV deuteron incidence on aluminum and SUS304st ainless steel were measured at the Kyushu University Tandem Accelerator Laboratory. An aluminum, and a SUS 304 foil which were thick enough for a deuteron to stop in the foils were placed at the center of a vacuum chamber. AnNE213 liquid organic scintillator was employed to detect neutrons emitted from targets. To consider the contribution of scattered neutrons from the floor, we also measured neutron yields with an iron shadow bar located in front of the scintillator. Because incident deuteron beam was not pulsed and the Time-of-Flight method was not applied, the energy spectrum was derived from unfolding the light output spectrum using the FORIST code. The re sponse function of the detector was calculated with the SCINFUL-QMD code. The experimental results were compared with the calculation data of the TALYS and PHITS code, and it turned out that the calculation data does not reproduce the experimental ones satisfactorily.
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