Study Of Beta Decay Research Articles

Study of neutron beta decay with the Nab experiment

The current three sigma tension in the unitarity test of the Cabbibo-Kobayashi-Maskawa (CKM) matrix is a notable problem with the Standard Model of elementary particle physics. A long-standing goal of the study of free neutron beta decay is to better determine the CKM element Vud through measurements of the neutron lifetime and a decay correlation parameter. The Nab collaboration intends to measure a, the neutrino-electron correlation, with accuracy sufficient for a competitive evaluation of Vud based on neutron decay data alone. This paper gives a status report and an outlook.

Laser isotope separation to study for the neutrino-less double beta decay of 48Ca

The laser isotope separation (LIS) system is being developed for the study of neutrino-less double beta decay of 48Ca. A proof-of-principle experiment has been successfully conducted, and development of a mass production (∼1 mol/year) system is currently underway. For stable and efficient production, we are preparing an atomic beam system capable of producing a well-collimated beam with sufficient flux and a high-power semiconductor laser system with stable frequency over a long period of time.

Shell model study of first-forbidden beta decay around 208Pb

In the present work, we report a systematic theoretical study of the log ft values for the forbidden β − decay transitions in the 208Pb region. For this, we have considered 206Hg → 206Tl, 208Hg → 208Tl, 206Tl → 206Pb and 208Tl → 208Pb transitions. We have performed shell model calculations using KHH7B interaction in valence shell 58-114 for protons and 100-164 for neutrons by considering 1p − 1h excitations for both protons and neutrons simultaneously for daughter nuclei. This study presents the first shell model results of β −-decay corresponding to the recent experimental data.

Beta decay study of 126Sb and 126mSb

Beta decay study of 126Sb and 126mSb

Development of Large‐Diameter and Very High Purity Ge Crystal Growth Technology for Devices (Crystal Research and Technology 5/2023)

Crystal Research and TechnologyVolume 58, Issue 5 2370009 Cover PictureFree Access Development of Large-Diameter and Very High Purity Ge Crystal Growth Technology for Devices (Crystal Research and Technology 5/2023) First published: 12 May 2023 https://doi.org/10.1002/crat.202370009AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Graphical Abstract A 3-inch diameter, 3-kg mass, high-purity germanium crystal is grown with a net free carrier concentration equivalent to one part per trillion and a dislocation density (EPD values) of 103−104 per cm2. Usually, such single crystals with these dimensions are prerequisite to fabricate larger detectors for “rare events” like neutrinoless double beta decay (0νββ) and dark-matter studies to understand the origin and constituents of our Universe. For further details on the growth of this crystal, see article number 2200286 by Rajappan Radhakrishnan Sumathi and co-workers. Volume58, Issue5May 20232370009 RelatedInformation

Neutrinoless double beta decay and sterile neutrino dark matter in extended left right symmetric model

Abstract We have studied a flavor symmetry-based extended left-right symmetric model(LRSM) with a dominant type-II seesaw mechanism and have explored the associated neutrino phenomenology. The particle content of the model includes usual quarks and leptons along with additional sterile fermion per generation in the fermion sector while the scalar content contains Higgs doublets and scalar bidoublet. This extension of LRSM has been realized by using $A_{4}\times Z_{4}$ discrete symmetries. In this work, we have included the study of sterile neutrino dark matter(DM) phenomenology and neutrinoless double beta decay within the framework.

A method to load tellurium in liquid scintillator for the study of neutrinoless double beta decay

A method has been developed to load tellurium into liquid scintillator so as to permit searches for neutrinoless double beta decay with high sensitivity. The approach involves the synthesis of an oil-soluble tellurium compound from telluric acid and an organic diol. The process utilises distillable chemicals that can be safely handled underground and affords low radioactive backgrounds, low optical absorption and high light yields at loading levels of at least several percent Te by weight.

ASPECT-BET: An sdd-SPECTrometer for BETa decay studies

We present the status of the ASPECT-BET (An sdd-SPECTrometer for BETa decay studies) project which is aimed at developing a new detection strategy to perform high-precision, high-accuracy measurements of the energy spectra of beta decays of interest for the physics community, in particular in the field of nuclear physics, double beta decay and reactor neutrinos. The aim is to exploit a relatively novel spectroscopic technique based on Silicon Drift Detectors. An SDD-spectrometer, equipped with all the ancillary detectors required to reject events with only a partial energy deposition in the main sensitive elements, will provide high-statistics and virtually zero-background data. In order to isolate and study the systematic uncertainties, the statistical error on the measured spectra has to be reduced to a negligible level, balancing source activity, measurement duration and background. Reliable and well understood Montecarlo simulations are a key component of this application, as they provide a model for the response functions of the spectrometer, to be deconvolved from the data in order to correctly reconstruct the original spectral shapes. Thanks to the flexibility of the SDD detector technology, the here presented spectrometer could be coupled to a variety of beta sources, ranging from nuclei deposited on the surface of SDDs to minimise source self-absorpion to short-lived isotopes created and collected at unstable isotope beams like ISOLDE at CERN or the exotic beams at LNS, Catania. The current status of the technology, as well as some preliminary sensitivity studies, are presented and discussed.

R-Matrix study of the β+decay of 8B to the highly excited states of 8Be

Experiment IS633 was conducted at the ISOLDE facility with the aim of studying the 2+ isospin doublet of 8Be, the only expected case of nearly equal isospin configuration mixing. The doublet was previously probed by reaction studies where the feeding does not depend on the isospin. Beta decay studies are sensitive to the isospin composition of the doublet since the Fermi and Gamow-Teller strengths are heavily dependent of isospin. In this experiment the doublet was probed through the EC/β+ feeding from 8B. A four-particle telescope setup with a C-foil in the centre was employed to stop the 8B beam, the implanted nucleus would decay and populate the doublet that breaks up in two alpha particles that are detected. The statistics achieved in this experiment were two orders of magnitude higher than that of any previous experiment, enabling the first experimental observation of both contributions to the doublet.

Lattice QCD calculation of the light sterile neutrino contribution in 0ν2β decay

We present a lattice QCD study of the neutrinoless double beta decay involving light sterile neutrinos. The calculation is performed at physical pion mass using five gauge ensembles generated with the $2+1$-flavor domain wall fermions. We obtain the low-energy constants $g_{\text{LR}}^{\pi\pi}(m_\nu)$ with the neutrino mass $m_\nu$ from $0$ GeV to $3$ GeV. The lattice results are reasonably consistent with the previous interpolation method with a $\sim20\%$ deviation at small $m_\nu$. We provide an explanation on the discrepancy at vanishing neutrino mass. At large $m_\nu$, a good consistence between our results and the previous lattice determination of $g_{4}^{\pi\pi}(\mu)$ is found at $\mu=m_\nu=3$ GeV.

New level of precision in study of neutron beta-decay. Theoretical basics and experimental backgrounds

The article provides a theoretical substantiation for a significant increase in the level of accuracy in determining the neutron lifetime using an alternative concept of neutron beta decay. Neutrons are distributed among different subsets depending on the sign of the scalar product of the neutron spin vector and momentum of the emitted electron during decay. Therefore, the neutron lifetime can be determined separately for each of the subsets as the inverse frequency of its decay, which is to be averaged over the number of neutrons in this subset. The total neutron lifetime on the total set of neutrons is calculated by averaging the partial (basic) lifetimes, considering their weights. The weights of the basic lifetimes are calculated for two weighing methods, leading, respectively, to the so-called lifetime of "nonpolarized" neutrons, the weighted average lifetime of neutrons and the central lifetime, i.e. the arithmetic mean for the basic lifetimes of neutrons. The dependence between different average neutron lifetimes through the integral asymmetry parameter calculated by using known experimental data leads to simple analytical expressions. The numerical estimate of the weighted average neutron lifetime gives a value that is in good agreement with the results of well-known experiments, which proves the validity of the proposed concept of neutron beta decay. This article includes necessary conditions for a new experiment to bring the neutron lifetime determination to a new level of accuracy.

Neutrinoless double beta decay via light neutralinos in R-parity violating supersymmetry

We perform a study of neutrinoless double beta (0νββ) decay mediated by the lightest neutralino of arbitrary mass in the minimal supersymmetric Standard Model (MSSM) under the presence of R-parity violating trilinear interactions. In this scenario, the exchange of the lightest neutralino can result in 0νββ decay of either long-range or short-range behaviour, depending on the neutralino mass. Using nuclear matrix elements calculated in the interacting boson model, we use an interpolation between the long- and short-range behaviours with an approximate formula. The non-observation of 0νββ decay is then used to place constraints on the supersymmetry parameter space, compatible with constraints from collider experiments. We compare these constraints to bounds from pion decays, CKM unitarity and big bang nucleosynthesis.

Isotope separation by DC18C6 crown-ether for neutrinoless double beta decay of 48Ca

The isotope separation via liquid-liquid extraction (LLE) using crown-ether (DC18C6) was carried out in order to demonstrate the feasibility of calcium isotope enrichment, which aimed to find a cost-effective way to enrich calcium-48 (48Ca) for the study of neutrinoless double beta decay (0vββ) in the CANDLES project. The LLE results revealed that the extraction was solvent dependent in the presence of HCl and the distribution coefficient (D) increased approximately threefold (0.0546±0.0012) with 12 M HCl solvent under a 3.9 M CaCl2 (aq) (30% w/w) system. Furthermore, the HCl solvent maintained the calcium content attached to the crown-ether at lower feed concentrations. The reaction cell ICP-MS (Agilent 7900) with an additional H2 gas was used to analyze the isotopic composition. The single-stage separation factor of organic phase was found to be 0.992±0.003, 0.994±0.003, 0.996±0.004 for 48Ca/42Ca, 48Ca/43Ca, and 48Ca/44Ca, respectively in the extracted organic phase of 3.3 M CaCl2 (aq) (30% w/w) system. The obtained results were comparable with the HCl solvent system. As a result, without the addition of an acidity reagent, the production of the enriched 48Ca isotope via LLE was highly feasible. To improve the mass production of enriched 48Ca, filter separation was applied in order to shorten the time required and to study various volumes of the extraction system. The results indicated that the extraction efficiency of filter LLE was comparable to conventional LLE. Filter LLE resulted in more than threefold reduction in time required (approximately 10 minutes for a complete single-stage separation) in comparison with a conventional LLE, consequently implying great potential in the enrichment and mass production via filter LLE.

One-proton transfer reaction for the O18+Ti48 system at 275 MeV

Single-nucleon transfer reactions are processes that selectively probe single-particle components of the populated many-body nuclear states. In this context, recent efforts have been made to build a unified description of the rich nuclear spectroscopy accessible in heavy-ion collisions. An example of this multichannel approach is the study of the competition between successive nucleon transfer and charge exchange reactions, the latter being of particular interest in the context of single and double beta decay studies. To this extent, the one-proton pickup reaction Ti48(O18,F19)Sc47 at 275 MeV was measured for the first time, under the NUMEN experimental campaign. Differential cross-section angular distribution measurements for the F19 ejectiles were performed at INFN-LNS in Catania by using the MAGNEX large acceptance magnetic spectrometer. The data were analyzed within the distorted-wave and coupled-channels Born approximation frameworks. The initial and final-state interactions were described adopting the São Paulo potential, whereas the spectroscopic amplitudes for the projectile and target overlaps were derived from shell-model calculations. The theoretical cross sections are found to be in very good agreement with the experimental data, suggesting the validity of the optical potentials and the shell-model description of the involved nuclear states within the adopted model space.1 MoreReceived 27 May 2021Accepted 8 September 2021DOI:https://doi.org/10.1103/PhysRevC.104.034617©2021 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasDirect reactionsDouble beta decayLow & intermediate energy heavy-ion reactionsNuclear reactionsTransfer reactionsTechniquesOptical, coupled-channel & distorted wave modelsSpectrometers & spectroscopic techniquesNuclear Physics

Beta Decay Studies of Nuclides in the Heavy Region

In the present work we studied the β-decay of various isotopes in the heavy region using the empirical formula of Fiset and Nix. It is found from the half-life that as the neutron number increases the possibility of β-decay increases. From the dependence of beta decay half-life on neutron number of parent and Q-value, we modified empirical formula of Fiset and Nix for beta decay half-life. We also developed an empirical formula for the Z-value of most stable isobar against β-decay. From the study of mass parabola for different isobars with mass number ranging from 200-223 it was found that the lowest point in the parabola, which is the Z-value of most stable isobar against β-decay, matches well with our formula predictions.

Cornering (quasi) degenerate neutrinos with cosmology

In light of the improved sensitivities of cosmological observations, we examine the status of quasi-degenerate neutrino mass scenarios. Within the simplest extension of the standard cosmological model with massive neutrinos, we find that quasi-degenerate neutrinos are severely constrained by present cosmological data and neutrino oscillation experiments. We find that Planck 2018 observations of cosmic microwave background (CMB) anisotropies disfavour quasi-degenerate neutrino masses at 2.4 Gaussian σ’s, while adding baryon acoustic oscillations (BAO) data brings the rejection to 5.9σ’s. The highest statistical significance with which one would be able to rule out quasi-degeneracy would arise if the sum of neutrino masses is ∑mv = 60 meV (the minimum allowed by neutrino oscillation experiments); indeed a sensitivity of 15 meV, as expected from a combination of future cosmological probes, would further improve the rejection level up to 17σ. We discuss the robustness of these projections with respect to assumptions on the underlying cosmological model, and also compare them with bounds from β decay endpoint and neutrinoless double beta decay studies.

Cyclotron radiation emission spectroscopy signal classification with machine learning in project 8

The cyclotron radiation emission spectroscopy (CRES) technique pioneered by Project 8 measures electromagnetic radiation from individual electrons gyrating in a background magnetic field to construct a highly precise energy spectrum for beta decay studies and other applications. The detector, magnetic trap geometry and electron dynamics give rise to a multitude of complex electron signal structures which carry information about distinguishing physical traits. With machine learning models, we develop a scheme based on these traits to analyze and classify CRES signals. Proper understanding and use of these traits will be instrumental to improve cyclotron frequency reconstruction and boost the potential of Project 8 to achieve world-leading sensitivity on the tritium endpoint measurement in the future.

Storytelling and Science Communication: how to turn (A, Z) → (A, Z + 2) + 2e− + 2v̄e into a story

This outreach workshop explains why narrative structure matters in communicating science to the public. It demonstrates the technique by converting a piece of textbook style introduction to an experiment of underground physics (SNO+’s Double Beta Decay study with 130Te) into a story for the general public.

Thermal neutron–induced γ-ray background in 124Sn

The thermal neutron-induced gamma-ray background in 124Sn is investigated in connection with neutrinoless double beta decay (0νββ) studies in 124Sn. For this purpose, a 99.26% enriched 124Sn sample was irradiated with a thermal neutron fluence of 3×1015/cm2 in the Dhruva reactor at the Bhabha Atomic Research Centre, Mumbai. The gamma ray spectra of the irradiated sample were measured in a low background counting setup to study both long-lived and short-lived activities. The present data give an independent measurement of the half-life of 125Sn*(32+) and 125Sn(112−) as 10.01(8) min and 9.63(2) d, respectively. The impact of the observed high-energy gamma rays and the residual activity due to 125Sb, on the background in the region of interest around the Qββ value of 124Sn (~2.291 MeV) is discussed.

Masses and Beta-decay Studies of Neutron-rich Nuclei using the X-array and Gammasphere

Properties of neutron-rich nuclei in the A˜160 region are important for achieving a better understanding of the nuclear structure in this region where little is known owing to diffculties in the production of these nuclei at the present nuclear physics facilities. These properties are essential ingredients in the interpretation of the rareearth peak at A˜160 in the r process abundance distribution, since theoretical models are sensitive to nuclear structure input. Predicated on these ideas, we have initiated a new experimental program at Argonne National Laboratory. During the first experiment, beams from the Californium Rare Isotope Breeder Upgrade radioactive beam facility were used in conjunction with the SATURN decay station and the X-array. We focused initially on several odd-odd nuclei, where β decays of both the ground state and an excited isomer were investigated. Because of the spin difference, a variety of structures in the daughter nuclei were selectively populated and characterized based on their decay properties. Mass measurements using the Canadian Penning Trap aimed at establishing the excitation energy of the β-decaying isomers were also carried out. Evidence was found for a change in the single-particle structure, which in turn results in the formation of a sizable N=98 sub-shell gap at large deformation. Results from the first experimental campaign using the newly-commissioned β-decay station at Gammasphere are also presented.