Search Results (9)

In this work, a review of recent studies concerning rare nuclear processes in Hf isotopes is presented. In particular, the investigations using HP-Ge spectrometry and Hf-based crystal scintillators are focused; the potentiality and the results of the “source = detector” approach are underlined. In addition, a short introduction concerning the impact of such kind of research in the context of astroparticle and nuclear physics is pointed out. In particular, the study of $\alpha$ decay and double beta decay of ${}^{174}$Hf, ${}^{176}$Hf, ${}^{177}$Hf, ${}^{178}$Hf, ${}^{179}$Hf, ${}^{180}$Hf isotopes either to the ground state or to the lower bounded levels have been discussed. The observation of $\alpha$ decay of ${}^{174}$Hf isotope to the ground state with a T${}_{1/2}=7.0\left(1.2\right)\times {10}^{16}$ y is reported and discussed. No decay was detected for $\alpha$ decay of ${}^{174}$Hf isotope at the first excited level of daughter and of ${}^{176}$Hf, ${}^{177}$Hf, ${}^{178}$Hf, ${}^{179}$Hf, ${}^{180}$Hf isotopes either to the ground state or to the lower bounded levels. The T${}_{1/2}$ lower limits for these decays are at the level of ${10}^{16}$–${10}^{20}$ y. Nevertheless, the T${}_{1/2}$ lower limits for the transitions of ${}^{176}$Hf$\to {}^{172}$Yb ($0^{+}\to 0^{+}$) and ${}^{177}$Hf$\to {}^{173}$Yb ($7/2^{-}\to 5/2^{-}$) are near to the theoretical predictions, giving hope to their observation in the near future. All the other experimental limits ($\sim {10}^{16}$–10${}^{20}$ y) are absolutely far from the theoretical expectations. The experiments investigating the $2ϵ$ and $ϵ{\beta }^{+}$ processes in ${}^{174}$Hf are also reported; the obtained half-life limits are set at the level of ${10}^{16}$–${10}^{18}$ y. Moreover, we estimate the T${}_{1/2}$ of $2\nu 2ϵ$ of ${}^{174}$Hf decay at the level of (0.3–6) × ${10}^{21}$ y (at now the related measured lower limit is $7.1\times {10}^{16}$ y). Full article

This paper reviews the main experimental techniques and the most significant results in the searches for the $2ϵ$, $ϵ{\beta }^{+}$ and $2{\beta }^{+}$ decay modes. Efforts related to the study of these decay modes are important, since they can potentially offer complementary information with respect to the cases of $2{\beta }^{-}$ decays, which allow a better constraint of models for the nuclear structure calculations. Some positive results that have been claimed will be mentioned, and some new perspectives will be addressed shortly. Full article

Crystal scintillators and in particular inorganic scintillators play an important role in the investigation of Dark Matter (DM) and other rare processes. The investigation of a DM signature, as the annual modulation, or the directionality technique requires the use of highly radiopure detectors able to explore the very low energy region maintaining a high stability of the running conditions. In this paper, the cases of NaI(Tl), ZnWO${}_4$ and SrI${}_2$(Eu) crystal scintillators are described in the framework of our activities at the Gran Sasso National Laboratory of the INFN. Their role, the obtained results in DM investigation, as well as their potential and perspectives for the future are reviewed. Full article

The deep inferior epigastric perforator (DIEP) flap is used with increasing frequency in post-mastectomy breast reconstruction. Preoperative mapping with CT angiography (CTa) is crucial in reducing surgical complications and optimizing surgical techniques. Our study’s goal was to investigate the accuracy of conventional CT (cCT), performed during disease staging, compared to CTa in preoperative DIEP flap planning. In this retrospective, single-center study, we enrolled patients scheduled for mastectomy and DIEP flap breast reconstruction, subjected to cCT within 24 months after CTa. We included 35 patients in the study. cCT accuracy was 95% (CI 0.80–0.98) in assessing the three largest perforators, 100% (CI 0.89–100) in assessing the dominant perforator, 93% (CI 0.71–0.94) in assessing the perforator intramuscular course, and 90.6% (CI 0.79–0.98) in assessing superficial venous communications. Superficial inferior epigastric artery (SIEA) caliber was recognized in 90% of cases (CI 0.84–0.99), with an excellent assessment of superficial inferior epigastric vein (SIEV) integrity (96% of cases, CI 0.84–0.99), and a lower accuracy in the evaluation of deep inferior epigastric artery (DIEA) branching type (85% of cases, CI 0.69–0.93). The mean X-ray dose spared would have been 788 ± 255 mGy/cm. Our study shows that cCT is as accurate as CTa in DIEP flap surgery planning. Full article

This paper shortly reviews the sensitivities that can be achieved to unambiguously point out the presence of a signal of Galactic origin in dark matter experiments with solid-scintillator detectors. Examples of the experimental sensitivities obtained by exploiting the annual and diurnal modulation signatures are reported with particular regard to the investigations performed in the framework of the DAMA Collaboration. The directionality approach in solid scintillators is also presented and, in particular, the perspectives of the ADAMO project are discussed. Full article

In this paper we review results obtained in the searches of double beta decays to excited states of the daughter nuclei and illustrate the related experimental techniques. In particular, we describe in some detail the only two cases in which the transition has been observed; that is the $2{\beta }^{-}(0^{+}\to 0_1^{+})$ decay of ${}^{100}$Mo and ${}^{150}$Nd nuclides. Moreover, the most significant results in terms of lower limits on the half-life are also summarized. Full article

Studies on double beta decay processes in ${}^{106}$Cd were performed by using a cadmium tungstate scintillator enriched in ${}^{106}$Cd at 66% (${}^{106}$CdWO${}_4$) with two CdWO${}_4$ scintillation counters (with natural Cd composition). No effect was observed in the data that accumulated over 26,033 h. New improved half-life limits were set on the different channels and modes of the ${}^{106}$Cd double beta decay at level of $lim{T}_{1/2}\sim {10}^{20}-{10}^{22}$ yr. The limit for the two neutrino electron capture with positron emission in ${}^{106}$Cd to the ground state of ${}^{106}$Pd, $T_{1/2}^{2\nu \mathrm{EC}{\beta }^{+}}\ge 2.1\times {10}^{21}$ yr, was set by the analysis of the ${}^{106}$CdWO${}_4$ data in coincidence with the energy release 511 keV in both CdWO${}_4$ counters. The sensitivity approaches the theoretical predictions for the decay half-life that are in the range $T_{1/2}\sim {10}^{21}-{10}^{22}$ yr. The resonant neutrinoless double-electron capture to the 2718 keV excited state of ${}^{106}$Pd is restricted at the level of $T_{1/2}^{0\nu 2\mathrm{K}}\ge 2.9\times {10}^{21}$ yr. Full article

Recent developments, results, and perspectives arising from double beta decay experiments at the Gran Sasso National Laboratory (LNGS) of the INFN by using HPGe detectors and crystal scintillators and by exploiting various approaches and different isotopes are summarized. The measurements here presented have been performed in the experimental set-ups of the DAMA collaboration. These setups are optimized for low-background studies and operate deep underground at LNGS. The presented results are of significant value to the field, and the sensitivity achieved for some of the considered isotopes is one of the best available to date. Full article

The first results obtained by the DAMA/LIBRA–phase2 experiment are presented. The data have been collected over six independent annual cycles corresponding to a total exposure of 1.13 ton × year, deep underground at the Gran Sasso National Laboratory. The DAMA/LIBRA–phase2 apparatus, about 250 kg highly radio-pure NaI(Tl), profits from a second generation high quantum efficiency photomultipliers and of new electronics with respect to DAMA/LIBRA–phase1. The improved experimental configuration has also allowed to lower the software energy threshold. The DAMA/LIBRA–phase2 data confirm the evidence of a signal that meets all the requirements of the model independent Dark Matter annual modulation signature, at 9.5 $\sigma$ C.L. in the energy region (1–6) keV. In the energy region between 2 and 6 keV, where data are also available from DAMA/NaI and DAMA/LIBRA–phase1, the achieved C.L. for the full exposure (2.46 ton × year) is 12.9 $\sigma$ . Full article