Beta Decay Research Articles

Exploring the Sensitivity of MiniPix Devices to the Detection of a Variety of Particles

The MiniPix EDU devices by ADVACAM have been used to study electrons, muons and alpha particles from both thoriated tungsten rods and natural sources. The natural radiation experiments looked at muons, focusing on the determination of muon count as a function of detector altitude and inclination with respect to the horizon. This included taking readings at ground level compared to those atop a building, and the floors in between, and rotating the detector face a certain angle to find the optimal angle to detect muons. The experiments involving a radiation source looked at alpha and beta decay. This included using the detector’s measurement of kinetic energy to explore the relativistic nature of electrons produced via beta decay, and the decay characteristics of alpha radiation. The material attenuation of alpha particles has also been explored. Insights from these experiments provide data on the capabilities of the detector. Through these experiments, particle behaviour and interactions unfold, shedding light on fundamental scientific principles. The project's experiments and results have been simplified to cater to secondary school education, specifically GCSE-level students. The experiments are designed to be performed within a school setting, helping students to understand these fundamental scientific principles of physics.

Response of G-NUMEN LaBr3(Ce) Detectors to High Counting Rates

The G-NUMEN array is the future gamma spectrometer of the NUMEN experiment (nuclear matrix element for neutrinoless double beta decay), to be installed around the object point of the MAGNEX magnetic spectrometer at the INFN-LNS laboratory. This project aims to explore double-charge exchange (DCE) reactions in order to obtain crucial information about neutrinoless double beta decay (0νββ). The primary objective of the G-NUMEN array is to detect the gamma rays emitted from the de-excitation of the excited states that are populated via DCE reactions with a good energy resolution and detection efficiency, amidst a background composed of the transitions from competing reaction channels with far higher cross sections. To achieve this, G-NUMEN signals will be processed in coincidence with those generated by the detection of reaction ejectiles by the MAGNEX focal plane detector (FPD). Under the expected experimental conditions, G-NUMEN detectors will operate at high counting rates, of the order of hundreds of kHz per detector, while maintaining excellent energy and timing resolutions. The complete array will consist of over 100 LaBr3(Ce) scintillators. Initial tests were conducted on the first detectors of the array, allowing for the determination of their performance at high rates.

A multiparametric study on the behavior of mesoporous silica under electron irradiation

Grafted mesoporous silica is believed to be a candidate for the decontamination of radioactive effluents and the final storage of radionuclides. Under this condition, silica is subjected to continuous electron irradiation due to beta decay of radionuclides. This paper examined two mesoporous silica (SBA-15 and MCM-41) under high-energy electron beam irradiation (0.6 MeV <E < 2.4 MeV). The results showed that the pore structure of both mesoporous silica pellets shrank for all the samples (with 40 % < ΔVpores < 60 % at 8 × 1018 e-/cm2), while no significant damage was observed in the amorphous silica network. The main reason for the structural changes was attributed to electron beam radiation-induced fluidization. Additional experiments conducted with numerous incident electron energies provided more detailed support, confirming that the radiolytic process was the primary cause of fluidization. These findings contribute to a better understanding of electron-irradiation-induced damage and may lead to novel approaches for handling radionuclides with mesoporous materials.

Rapid analysis of 226Ra in ultrapure gadolinium sulfate octahydrate

Abstract Numerous particle physics experiments utilize gadolinium (Gd), a rare earth element with the most significant neutron capture cross-section among all elements, to detect anti-neutrinos via inverse beta decays or to remove neutron-induced background events. For example, to load Gd into water Cherenkov detectors, Gd2(SO4)3 · 8H2O is dissolved and rare event search experiments are required to screen for radioactive impurities in Gd2(SO4)3 · 8H2O before dissolution. This study developed a new method to rapidly measure the radium-226 (226Ra) concentration in Gd2(SO4)3 · 8H2O. This method requires only 3 days to measure a batch of samples, as opposed to the usual method using high-purity germanium detectors, which takes approximately 20 days after arrival. The detection limit for the measurement of 226Ra concentration in Gd2(SO4)3 · 8H2O is 0.43 mBq/kg. This method has been already used for Gd2(SO4)3 · 8H2O screening at the Super-Kamiokande Gd (SK-Gd) project, and it can be applied to future experiments.

Atomic exchange correction in forbidden unique beta transitions

The theoretical modelling of the atomic exchange effect, until now only available for allowed beta decays, has been extended to the forbidden unique transitions. The required computing power for such calculations being important, an extensive tabulation of the correction factors has been conducted. These tables will be included in the future version of the BetaShape code, which atomic screening has also been revised to ensure the same level of accuracy as for exchange. Results for several radionuclides are discussed.

A simplest modular S3 model for leptons

We present minimalist constructions for lepton masses and mixing based on flavour symmetry under the modular group ΓN of lowest level N = 2. As opposed to the only existing model of Γ2 ≅ S3 formulated in a SUSY framework, the only non-SM field is the modulus τ, and a generalised CP symmetry is implemented. Charged-leptons masses are reproduced through symmetry arguments, without requiring fine-tuning of the free parameters. As a result, all lepton observables (masses and mixing) are reproduced within 1σ experimental range using a minimum of nine free real parameters (including the real and imaginary parts of the modulus). A normal ordering for the neutrino masses is predicted. We also obtain predictions for the CP violating phases: the Dirac CP phase is predicted around 1.6π, the Majorana phases lie in narrow regions near ±π. The sum of neutrino masses is within the current bound at ∼ 0.09 eV. Furthermore, we provide predictions for the neutrinoless double beta decay and tritium decay effective masses, around 20 meV. Given the reduced number of free input parameters as compared to the existing literature on modular S3, this work renews interest for a unified predictive model of quark-lepton sectors based on Γ2 ≅ S3.

Decay Characteristics of Neutron Excess Chlorine Nuclei

In neutron star mergers, neutron excess nuclei and the r-process are important factors governing the production of heavier nuclear systems. A single-particle model evaluation of chlorine nuclei suggests that the heaviest Z = 17 nucleus will have mass 62 with filling of the 1g9/2 neutron shell. A = 48 – 62 chlorine isotopes have limited experimental half-life data, but the model predicts beta decay half-lives in the range of 0.535 – 51.9 ms. Based on previous calculations for Z = 9 - 16, 20, 26, and 30 systems and comparisons to the 48Cl - 53Cl, and 55Cl calculations, summarized in the Japanese Nuclear Data Compilation, the single-particle model results likely overestimate the half-lives of A = 48 – 62 neutron excess chlorine nuclei.

Measurement of 90Sr and 87Sr/86Sr isotope ratio in Japanese cow milk sample using thermal ionization mass spectrometry

The pure beta emitter 90Sr (T1/2 = 28.8y) is a typical contaminant released by nuclear accidents and nuclear explosions. In the event of a nuclear disaster, it is crucial to identify radioactive pollutants quickly, to expedite the public's awareness of radiation exposure. In this work, a rapid 90Sr analysis protocol using thermal ionization mass spectrometry (TIMS) was developed for milk samples. With the improved sample preparation, Sr separation, and a newly developed TIMS method, 18 milk samples can be analyzed in less than 30 h and only 1 mL of cow milk is required for the complete analysis. The minimum detectable activity concentration of 90Sr is affected by the stable Sr concentration therefore, it is around 500 mBq·kg−1 (∼100ag·g−1). Additionally, 87Sr/86Sr isotope ratios (0.71518(9)–0.74132(4)) were determined for the first time in Japanese cow milk samples.

Antineutrino detection concepts for safeguarding spent nuclear fuel

Abstract. Spent nuclear fuel (SNF) from nuclear power generation requires long-term safeguards in interim storage and final disposal. Current safeguarding approaches for spent fuel storage facilities (SFSFs) propose a combination of material accountancy, containment and surveillance, and design information verification. Antineutrino emissions from the ongoing beta decay of fission fragments could provide complementary information on the potential diversion of nuclear material and misuse of the facility or assist in reverification scenarios as antineutrinos pass through any shielding, structure, or geology effectively unhindered. Antineutrino-based safeguards approaches have been discussed and have been under development for nuclear reactor sites for several years. In this relatively recent field of applied antineutrino monitoring, several approaches have been developed, ranging from scintillator-based technologies to large water Cherenkov detectors, each of which is suitable for different deployment scenarios. Utilising this principle for SNF is uniquely challenging, as the antineutrino flux of cooling fuel elements is several orders of magnitude lower than of an active core. In addition, the typical beta decays in SNF emit a softer antineutrinos energy spectrum, requiring large detectors sensitive to signals close to the inverse beta decay energy threshold. This study investigates a range of current technologies that have been proposed for reactor monitoring, along with a novel antineutrino detection concept using a liquid organic (LOr) time projection chamber (TPC). The LOr-TPC concept combines the scalability and high-resolution particle reconstruction of TPCs with the large quantity of target hydrogen atoms provided by organic compounds. The expected signal rate, sensitivity to inventory changes, and directional capabilities of all technologies are estimated and compared against each other for two simplified storage sites, namely one based on an interim storage facility and one based on a geological repository. For each simplified site, varying fuel ages, cask distributions, and detector deployment scenarios are investigated. This comparison will be used to determine the feasibility and potential of antineutrino monitoring as a complementary safeguards tool for SNF storage sites.

Search for tri-nucleon decays of ^{76}Ge in GERDA

We search for tri-nucleon decays of ^{76}Ge in the dataset from the GERmanium Detector Array (GERDA) experiment. Decays that populate excited levels of the daughter nucleus above the threshold for particle emission lead to disintegration and are not considered. The ppp-, ppn-, and pnn-decays lead to ^{73}Cu, ^{73}Zn, and ^{73}Ga nuclei, respectively. These nuclei are unstable and eventually proceed by the beta decay of ^{73}Ga to ^{73}Ge (stable). We search for the ^{73}Ga decay exploiting the fact that it dominantly populates the 66.7 keV ^{73m}Ga state with half-life of 0.5 s. The nnn-decays of ^{76}Ge that proceed via ^{73m}Ge are also included in our analysis. We find no signal candidate and place a limit on the sum of the decay widths of the inclusive tri-nucleon decays that corresponds to a lower lifetime limit of 1.2times 10^{26} yr (90% credible interval). This result improves previous limits for tri-nucleon decays by one to three orders of magnitude.

Detection of recoil ion in the beta decay of laser oriented trapped radioactive isotopes for the MORA Project

The Matter’s Origin from RAdioActivity (mora) project focuses on ion manipulation in traps and laser orientation methods for the searches of New Physics (np) in nuclear beta decay by precisely measuring the D correlation parameter. We predominantly have focussed here on the detection configuration of mora and alongside talked in detail about the Recoil Ion DEtection system (ride) and its characterization focusing mainly on the methods applied to achieve high order position correction.

Study of weak magnetism by precision spectrum shape measurements in nuclear beta decay

Nuclear beta decays play an important role in uncovering the nature of the weak interaction. The weak magnetism (WM) form factor, b WM, is generally a small correction to the beta decay rate that arises at first order as an interference term between the dominant Gamow-Teller and the magnetic dipole contributions to the weak current. This form factor is still poorly known for nuclei with higher atomic number. We performed a careful analysis of the measured beta spectrum shape for Gamow-Teller transitions in 114In and 32P nuclei. The precision spectrum shape measurements were carried out using the miniBETA spectrometer consisting of a low-mass, low-Z multi-wire gas tracker and a plastic scintillator energy detector. The preliminary results for the weak magnetism extraction for 114In and 32P nuclei are presented.

New high intensity Heavy - Ion beams @ INFN-LNS: NUMEN project status and perspective

The upgrade project POTLNS to produce high-intensity beams has already started at INFN- Laboratori Nazionali del Sud in Catania (Italy). The POTLNS project was triggered by the NUMEN physics case that aims to provide experimental information on the Nuclear Matrix Elements (NMEs) that enter in the expression of the neutrino-less double beta (0νββ) decay half-life. The tools proposed by NUMEN project are the cross-section measurements of nuclear Double Charge Exchange (DCE) reactions. The search for 0νββ decay is currently a key topic in physics, due to its possible wide implications for nuclear physics, particle physics and cosmology: the NUMEN project could provide a crucial contribution in this search.

JUNO sensitivity to the annihilation of MeV dark matter in the galactic halo

We discuss JUNO sensitivity to the annihilation of MeV dark matter in the galactic halo via detecting inverse beta decay reactions of electron anti-neutrinos resulting from the annihilation. We study possible backgrounds to the signature, including the reactor neutrinos, diffuse supernova neutrino background, charged- and neutral-current interactions of atmospheric neutrinos, backgrounds from muon-induced fast neutrons and cosmogenic isotopes. A fiducial volume cut, as well as the pulse shape discrimination and the muon veto are applied to suppress the above backgrounds. It is shown that JUNO sensitivity to the thermally averaged dark matter annihilation rate in 10 years of exposure would be significantly better than the present-day best limit set by Super-Kamiokande and would be comparable to that expected by Hyper-Kamiokande.

INFN-LNS facility upgrade for the Nuclear Physics Renaissance

A broad range of Nuclear Physics research activities have been carried out at INFN-LNS until the summer 2020, when the accelerators were stopped for the upgrade. The upgrade of LNS is a project mainly funded by a PON-FESR (National Program for Research and Innovation) strategic line for boosting the research infrastructures, having its own goals, time-schedule and deadlines. In addition to such an action promoted by the Italian Ministry of Research, further funds have been made available from INFN budget. The end of the phase supported by the PON for procurement and tenders is currently set for the end of 2023. A series of actions will therefore be implemented to improve scientific opportunities for users. In particular, the focus is on the commissioning of the Tandem and Superconducting Cyclotron with the new set-up, completed by the renewal of the experimental areas and the commissioning of the new fragment separator FRAISE, also financed under the PON. The high-intensity program, including the determination of the nuclear matrix elements (NME) for the double beta decay and the study of EOS for nuclear matter with large neutron content, will be made feasible by these improvements to accelerators, beamlines and detectors. Some highlights of the whole activity as well as of the Applied Physics perspectives and the Astroparticle Physics multi-messenger program, strictly connected to the Nuclear Physics program, are given.

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.

Bayesian inference of supernova neutrino spectra with multiple detectors

We implement the Bayesian inference to retrieve energy spectra of all neutrinos from a galactic core-collapse supernova (CCSN). To achieve high statistics and full sensitivity to all flavours of neutrinos, we adopt a combination of several reaction channels from different large-scale neutrino observatories, namely inverse beta decay on proton and elastic scattering on electron from Hyper-Kamiokande (Hyper-K), charged current absorption on Argon from Deep Underground Neutrino Experiment (DUNE) and coherent elastic scattering on Lead from RES-NOVA. Assuming no neutrino oscillation or specific oscillation models, we obtain mock data for each channel through Poisson processes with the predictions, for a typical source distance of 10 kpc in our Galaxy, and then evaluate the probability distributions for all spectral parameters of theoretical neutrino spectrum model with Bayes' theorem. Although the results for either the electron-neutrinos or electron-antineutrinos reserve relatively large uncertainties (according to the neutrino mass ordering), a precision of a few percent (i.e., ±1% ∼ ±4% at a credible interval of 2σ) is achieved for primary spectral parameters (e.g., mean energy and total emitted energy) of other neutrino species. Moreover, the correlation coefficients between different parameters are computed as well and interesting patterns are found. Especially, the mixing-induced correlations are sensitive to the neutrino mass ordering, which potentially makes it a brand new probe to determine the neutrino mass ordering in the detection of galactic supernova neutrinos. Finally, we discuss limitations and perspectives for further improvement on our results.

The NUMEN project: probing nuclear response to weak interaction by nuclear reactions

Different reactions channels induced by the 18O + 40Ca collisions at 275 MeV incident energy are simultaneously measured and analysed consistently within the same reaction and structure frameworks within the NUMEN project. The project aims to provide data-driven information for the determination of the nuclear matrix elements involved in the neutrinoless double beta decay. In particular, the elastic and inelastic scattering, one- and two-proton transfer, one-neutron transfer, and single charge exchange reactions are explored. The full quantum-mechanical calculations, performed by including microscopic nuclear structure inputs, describe well all the experimental data, giving support to a multi-channel strategy for the analysis of heavy-ion induced direct reactions.

Double charge-exchange reactions for the nuclear matrix elements of neutrinoless double beta decay

Double charge exchange (DCE) reactions induced by heavy ions are crucial tools to access information relevant for neutrinoless double beta decay nuclear matrix elements. In this context the NUMEN project aims to investigate, for each system of interest, the DCE reaction channel together with the whole set of reactions promoted by the same projectile/target interaction in the same experimental conditions and within the same theoretical framework.

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.