New limits on double-beta decay of $$^{190}$$Pt and $$^{198}$$Pt

A search for double-beta decay of $$^{190}$$ 190 Pt and $$^{198}$$ 198 Pt with emission of $$\gamma $$ γ -ray quanta was realized at the HADES underground laboratory with a 148 g platinum sample measured by two ultralow-background HPGe detectors over 8946 h. The isotopic composition of the platinum sample has been measured with high precision using inductively coupled plasma mass spectrometry. New lower limits for the half-lives of $$^{190}$$ 190 Pt relative to different channels and modes of the decays were set on the level of $$\lim T_{1/2}\sim 10^{14}$$ lim T 1 / 2 ∼ 10 14 –$$10^{16}$$ 10 16 year. A possible exact resonant $$0\nu KN$$ 0 ν K N transition to the 1,2 1326.9 keV level of $$^{190}$$ 190 Os is limited for the first time as $$T_{1/2} \ge 2.5 \times 10^{16}$$ T 1 / 2 ≥ 2.5 × 10 16 year. A new lower limit on the double-beta decay of $$^{198}$$ 198 Pt to the first excited level of $$^{198}$$ 198 Hg was set as $$T_{1/2} \ge 3.2\times 10^{19}$$ T 1 / 2 ≥ 3.2 × 10 19 year, one order of magnitude higher than the limit obtained in the previous experiment.

Neutrons magnetic Mass

In Quantum Physics, the Spin of an elementary particle is defined to be an intrinsic,inherent property. The same to the magnetic moment (μ) due to the spin of chargedparticles - like Electron (me) and Proton (mp). So the intrinsic spin (S=1/2h-bar) of theelectron entails a magnetic moment because of charge (e). However, a magnetic momentof a charged particle can also be generated by a circular motion (due to spin) of anelectric charge (e), forming a current. Hence the orbital motion (of charge around a massnucleus)generates a magnetic moment by Ampère’s law. This concept must lead to analternative way calculating the neutrino mass (mν) while looking at the beta decay of aneutron into fragments: proton, electron, neutrino and corresponding kinetic energies. Thechange of neutrons magnetic moment (μn) during the decay process is a fact based onenergy and spin and charge conservation, so should allow to calculate the restmass ofthe charge-less neutrino due to a significant change of: μe= -9.2847647043(28)E-24J/Tdown to μev= -9.2847592533(28)E-24J/T (while assuming mv=0.30eV to be absorbed and if(g-2)/2 from QED remains constant). As always the last word has the experiment.

The NUMEN Technical Design Report

NUMEN proposes an innovative technique to access the nuclear matrix elements entering the expression of the lifetime of the double beta decay by cross-section measurements of heavy-ion induced Double Charge Exchange (DCE) reactions. Despite the fact that the two processes, namely neutrinoless double beta decay and DCE reactions, are triggered by the weak and strong interaction respectively, important analogies are suggested. The basic point is the coincidence of the initial and final state many-body wave functions in the two types of processes and the formal similarity of the transition operators. The main experimental tools for this project are the K800 Superconducting Cyclotron and MAGNEX spectrometer at the INFN-LNS laboratory. However, the tiny values of DCE cross-sections and the resolution requirements demand beam intensities much higher than those manageable with the present facility. The on-going upgrade of the INFN-LNS facilities promoted by the POTLNS * project in this perspective is intimately connected to the NUMEN project. This paper describes the solutions proposed as a result of the R&D activity performed during the recent years. The goal is to develop suitable technologies allowing for the measurements of DCE cross-section under extremely high beam intensities. * PIR01_00005 — potenziamento dell’infrastruttura di ricerca Laboratori Nazionali del Sud per la produzione di fasci di ioni ad alta intensitá.

Bolometric Double Beta Decay Experiments: Review and Prospects

This review aims to cover the history and recent developments on cryogenic bolometers for neutrinoless double beta decay (0ν2β) searches. A 0ν2β decay observation would confirm the total lepton charge non-conservation, which is related to a global U(1)LC symmetry. This discovery would also provide essential information on neutrino masses and nature, opening the door to new physics beyond the Standard Model. The bolometric technology shows good prospects for future ton-scale experiments that aim to fully investigate the inverted ordering region of neutrino masses. The big advantage of bolometers is the high energy resolution and the possibility of particle identification, as well as various methods of additional background rejection. The CUORE experiment has proved the feasibility of ton-scale cryogenic experiments, setting the most stringent limit on 130Te 0ν2β decay. Two CUPID demonstrators (CUPID-0 and CUPID-Mo) have set the most stringent limits on 82Se and 100Mo isotopes, respectively, with compatibly low exposures. Several experiments are developing new methods to improve the background in the region of interest with bolometric detectors. CUPID and AMoRE experiments aim to cover the inverted hierarchy region, using scintillating bolometers with hundreds of kg of 100Mo. We review all of these efforts here, with a focus on the different types of radioactive background and the measures put in place to mitigate them.

Interacting Shell Model Calculations for Neutrinoless Double Beta Decay of 82Se With Left-Right Weak Boson Exchange

In the present work, the λ mechanism (left-right weak boson exchange) and the light neutrino-exchange mechanism of neutrinoless double beta decay is studied. In particular, much attention is paid to the calculation of nuclear matrix elements for one of the neutrinoless double beta decaying isotopes 82Se. The interacting shell model framework is used to calculate the nuclear matrix element. The widely used closure approximation is adopted. The higher-order effect of the pseudoscalar term of nucleon current is also included in some of the nuclear matrix elements that result in larger Gamow-Teller matrix elements for the λ mechanism. Bounds on Majorana neutrino mass and lepton number violating parameters are also derived using the calculated nuclear matrix elements.

Beta Decay in Medium-Mass Nuclei with the In-Medium Similarity Renormalization Group

We review the status of ab initio calculations of allowed beta decays (both Fermi and Gamow–Teller), within the framework of the valence-space in-medium similarity renormalization group approach.

Nuclear Structure Investigations of some Medium-Weight Isotopes

<p>This thesis describes the methods and results of investigations made to determine the decay schemes of three short-lived isotopes 112Ag, 114Ag and 116Ag. A total of 76 gamma-rays was observed with a Ge(Li) detector in the gamma-radiation which follows the Beta-decay of 112Ag to levels of 112Cd. gamma- gamma coincidence and angular correlation measurements were made with Ge(Li)-NaI(T1) and NaI(T1)-NaI(T1) systems. A decay scheme consistent with the present data is proposed. Cross sections for the reactions 112Cd(n,p)112Ag and 115In(n, alpha)112Ag were measured, and the half-life of the 112Ag decay was found to be 3.14 plus-minus 0.01 hr. The decay scheme of 114Ag was studied with Ge(Li) gamma-ray detectors and plastic Beta-ray detectors. 9 of the 11 gamma-rays observed in the decay were incorporated into 114Cd level structure previously determined by conversion electron measurements on the 113Cd(n,gamma)114Cd reaction. The endpoint energy of the Beta-decay was determined as 4.90 plus-minus 0.26 MeV; no branching was evident in the Beta-spectrum. A decay scheme is proposed for which the Beta-branching was deduced from the measured gamma-ray yield and a calculated cross section value for the 114Cd(n,p)114Ag reaction. The 114Ag half-life was determined as 4.52 plus-minus 0.03 sec; a search for a previously reported isomeric state of 114Ag was unsuccessful. Ge(Li) and NaI(T1) gamma-ray detectors were used to study the direct and coincidence spectra that result from the decay of 116Ag, the half-life of which was found to be 2.50 plus-minus 0.02 min. 53 gamma-rays were observed from this decay. The Beta-branching to the 17 excited states of 116Cd in the proposed decay scheme was derived from the measured gamma-ray yield and a calculated cross section value for the 116Cd(n,p)Ag reaction. Spin and parity assignments for ihe energy levels of 116Cd are made. An investigation of the applicability of two collective models to nuclear structure typical of the Cd nuclei studied demonstrated that one of the models was misleading when applied to vibrational nuclei. A potential function was developed in the other model to extend the investigation to include a study of the transition between extremes of collective motion. This was used to examine the correspondence between nuclear level schemes representative of rotational and vibrational excitations.</p>