Neutron decay from the isobaric analog state inSb120populated inSn

Abstract

The ' Sn( He, t) ' Sb charge-exchange reaction has been investigated at E( He) = 200 MeV and 8=0' to study neutron decay from the isobaric analog state at E, =10.20 MeV in ' Sb. The low-energy neutrons (average energy -0.85 MeV) were detected in coincidence with tritons observed in the focal plane of a high-resolution magnet spectrometer. Four small deuterated NE230 scintillation detectors were mounted at distances of 9.5 cm from the target resulting in an overall neutron detection efficiency including solid angle of )1%.This efficiency was obtained by combining the measured dependence on neutron energy with a calculated neutron evaporation spectrum. From the measured ratio of coincidence to singles events a branching ratio of & 86% was deduced for neutron decay. The observation of isospin-violating neutron decay with a branching ratio close to 100% is in agreement with the expectation that the escape width (I'") of the isobaric analog state in ' Sb is small compared to its spreading width (I "). Triton spectra measured in coincidence with y rays from the deexcitation of the final nucleus display pronounced structures related to the thresholds for neutron emission, in agreement with the characteristics of calculated evaporation spectra. PACS number(s): 24.30.Gd, 25.55.Kr, 27.60. +j

Deuterated scintillators and their application to neutron spectroscopy

“…Another experiment in that era involved the measurement of the energy spectrum of neutrons from decay of 120 Sb [11]. In this measurement, neutrons were detected in coincidence with charged particles, and the deuteron recoil peak served as the basis for determining the neutron energy spectrum.…”

Can the nuclear matrix elements of neutrinoless double beta decay be measured?

“…The IAS has been observed as a prominent and extremely narrow resonance and its various features have well been studied by means of (p,n), ( 3 He,t) and other chargeexchange reactions, see, e.g. [18]. This gives us hope that a measurement of 0 f |T − |IAS in the (n, p) chargeexchange channel might be possible.…”