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Register a new userSearch for Rare Nuclear Decays with HPGe Detectors at the STELLA Facility of the LNGS
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Results on the search for rare nuclear decays with the ultra low background facility STELLA at the LNGS using gamma ray spectrometry are presented. In particular, the best T1/2 limits were obtained for double beta processes in 96Ru and 104Ru. Several isotopes, which potentially decay through different double beta decay channels, including also possible resonant double electron captures, were investigated for the first time (156Dy, 158Dy, 184Os, 192Os, 190Pt, 198Pt). Search for resonant absorption of solar 7Li axions in a LiF crystal gave the best limit for the mass of 7Li axions (< 8.6 keV). Rare alpha decay of 190Pt to the first excited level of 186Os (Eexc = 137.2 keV) was observed for the first time.
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An experiment to search for double beta decay processes in 96Ru and 104Ru, which are accompanied by gamma rays, has been realized in the underground Gran Sasso National Laboratories of the I.N.F.N. (Italy). Ruthenium samples with masses of about (0.5-0.7) kg were measured with the help of ultra-low background high purity Ge gamma ray spectrometry. After 2162 h of data taking the samples were deeply purified to reduce the internal contamination of 40K. The last part of the data has been accumulated over 5479 h. New improved half life limits on 2beta+/epsilon beta+/2epsilon processes in 96Ru have been established on the level of 10^{20} yr, in particular for decays to the ground state of 96Mo: T1/2(2 u 2beta+) > 1.4 10^{20} yr, T1/2(2 u epsilonbeta+) > 8.0 10^{19} yr and T1/2(0 u 2K) > 1.0 10^{21} yr (all limits are at 90% C.L.). The resonant neutrinoless double electron captures to the 2700.2 keV and 2712.7 keV excited states of 96Mo are restricted as: T1/2(0 u KL) > 2.0 10^{20} yr and T1/2(0 u 2L) > 3.6 10^{20} yr, respectively. Various two neutrino and neutrinoless 2beta half lives of 96Ru have been estimated in the framework of the QRPA approach. In addition, the T1/2 limit for 0 u 2beta- transitions of 104Ru to the first excited state of 104Pd has been set as > 6.5 10^{20} yr.
The Facility for Rare Isotope Beams (FRIB) will be a world-leading laboratory for the study of nuclear structure, reactions and astrophysics. Experiments with intense beams of rare isotopes produced at FRIB will guide us toward a comprehensive description of nuclei, elucidate the origin of the elements in the cosmos, help provide an understanding of matter in neutron stars, and establish the scientific foundation for innovative applications of nuclear science to society. FRIB will be essential for gaining access to key regions of the nuclear chart, where the measured nuclear properties will challenge established concepts, and highlight shortcomings and needed modifications to current theory. Conversely, nuclear theory will play a critical role in providing the intellectual framework for the science at FRIB, and will provide invaluable guidance to FRIBs experimental programs. This article overviews the broad scope of the FRIB theory effort, which reaches beyond the traditional fields of nuclear structure and reactions, and nuclear astrophysics, to explore exciting interdisciplinary boundaries with other areas. keywords{Nuclear Structure and Reactions. Nuclear Astrophysics. Fundamental Interactions. High Performance Computing. Rare Isotopes. Radioactive Beams.
We have studied the alpha decays of 214Po into 210Pb and of 212Po into 208Pb tagged by the coincidence with the preceding beta decays from 214Bi and 212Bi, respectively. The employed 222Rn, 232Th, and 220Rn sources were sealed inside quartz vials and inserted in the Counting Test Facility at the underground Gran Sasso National Laboratory in Italy. We find that the mean lifetime of 214Po is (236.00 +- 0.42(stat) +- 0.15(syst)) mu s and that of 212Po is (425.1 +- 0.9(stat) +- 1.2(syst)) ns. Our results, obtained from data with signal-to-background ratio larger than 1000, reduce the overall uncertainties and are compatible with previous measurements.
The MAJORANA DEMONSTRATOR is sensitive to rare events near its energy threshold, including bosonic dark matter, solar axions, and lightly ionizing particles. In this analysis, a novel training set of low energy small-angle Compton scatter events is used to determine the efficiency of pulse shape analysis cuts, and we present updated bosonic dark matter and solar axion results from an 11.17 kg-y dataset using a 5 keV analysis threshold.
Rare lepton decays of the B(s), D and K mesons are sensitive probes of New Physics. In particular, the search for the decays $B^0_(s) -> mu^+ mu^-$ provides information on the presence of new (pseudo-)scalar particles. LHCb is well suited for these analyses due to its large acceptance and trigger efficiency, as well as its excellent invariant mass resolution and lepton identification capabilities. The status of these analyses with $sim1$ fb$^{-1}$ of pp collisions collected by LHCb in 2011 at $sqrt{s}=7$ TeV is reviewed.
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