The decay scheme of 64As into 64Ge is revisited in this paper, together with the discussion of the isospin assignment to the excited states based on the M1 transition “quasi-rule”.

Radionuclides are widely applied in different medical techniques for diagnosis and treatment. The efficacy of the treatments, as well as the off-target dose minimisation in both diagnosis and treatment depend, among other things, on the decay characteristics of the radionuclide in use: the different particles and radiation emitted, the emission energies and the emission probabilities. These are essential for the calculation of the dose administered to the patient or to medical personnel or caretakers in medical imaging or treatment with radionuclides. In this work we present the Total Absorption Spectroscopy of 152 Tb for its relevance in medicine and whose decay properties were not well enough established.

Nuclear beta decay provides a sensitive and rich tool for studying the structure of atomic nuclei as well as assessing the limits of our understanding of the weak interaction. In this chapter the history of the topic is presented. The main quantities associated with beta-decay spectroscopy are defined. Nuclear structure studies are illustrated by some selected examples of the beta decay of exotic nuclei, also aimed at presenting the most up-to-date techniques. The examples include the decay of 52Ni, 100Sn, and 132Sn and a discussion about the islands of inversion. The studies of the structure of the weak interaction and the tests of fundamental symmetries are illustrated through the most precise measurement of spectroscopic quantities and correlation terms, which have the largest impact on searches for new physics beyond the standard electroweak model. These measurements are motivated by the extraction of the strength of the weak interaction, the search for exotic couplings, and tests of parity and time-reversal symmetries.

The shape of the electron spectrum emitted in β decay carries a wealth of information about nuclear structure and fundamental physics. In spite of that, few dedicated measurements have been made of β-spectrum shapes. In this work we present a newly developed detector for β electrons based on a telescope concept. A thick plastic scintillator is employed in coincidence with a thin silicon detector. The first measurements employing this detector have been carried out with mono-energetic electrons from the high-energy resolution electron-beam spectrometer at Bordeaux. Here we report on the good reproduction of the experimental spectra of mono-energetic electrons using Monte Carlo simulations. This is a crucial step for future experiments, where a detailed Monte Carlo characterization of the detector is needed to determine the shape of the β-electron spectra by deconvolution of the measured spectra with the response function of the detector. A chamber to contain two telescope assemblies has been designed for future β-decay experiments at the Ion Guide Isotope Separator On-Line facility in Jyväskylä, aimed at improving our understanding of reactor antineutrino spectra.

Nucleosynthesis in Type I X-ray bursts (XRB) proceeds eventually through the rp-process near the proton drip-line. Several N=Z nuclei act as waiting points in the reaction network chain. Astrophysical calculations of XRB light curves depend upon the theoretical modelling of the beta decays of interest, with the N=Z waiting points 64Ge, 68Se, 72Kr, 76Sr, and their second-neighbours N=Z+2 being key nuclei in this context. We have carried out different experimental campaigns at ISOLDE (CERN) to determine the B(GT) distributions, in the decay of several N=Z, N=Z+2 and their daughters, of particular relevance in rp-process calculations. To this aim the Total Absorption Spectroscopy technique is applied. Here we present results on the beta decay of 64Ga and the status of the analysis of 64Ge. Our results provide benchmarks for testing and constraining models under terrestrial conditions that can be used later for predictions in stellar environments.

The accurate determination of reactor antineutrino spectra remains a very hot research topic, where new questions have emerged in recent years. Indeed, after the “reactor anomaly” – a deficit of measured antineutrinos at short baseline reactor experiments with respect to spectral predictions – the three international reactor neutrino experiments Double Chooz, Daya Bay and Reno have evidenced spectral distortions in their measurements with respect to the same spectral predictions. This puzzle is called the “shape anomaly”. Recently summation calculations of reactor antineutrino spectra based on the use of nuclear data have obtained the best agreement to date with the reactor neutrino flux measurements at the level of 2% thanks to a decade of Total Absorption Gamma-ray Spectroscopy (TAGS) measurements at the radioactive beam facility of the University of Jyväskylä in two experimental campaigns. A selection of the results obtained so far is presented.

A systematic study of the β-decay of neutron-deficient nuclei has been carried out and has provided spectroscopic information of importance for both nuclear structure and nuclear astrophysics. Following an overview of the most relevant achievements, we focus on the latest results on the β decay of 60Ge and 62Ge. We also summarise our results on the mass excesses in comparison with systematics and a recent measurement. Finally, we present updated half-life trends for Tz = -1/2, -1 and -2 neutron-deficient nuclides.

During the last decade we have carried out a systematic study of the β decay of neutron-deficient nuclei, providing rich spectroscopic information of importance for both nuclear structure and nuclear astrophysics. We present an overview of the most relevant achievements, including the discovery of a new exotic decay mode in the fp-shell, the β-delayed γ-proton decay in 56Zn, the first observation of the 2+ isomer in 52Co and the latest results on the heavier systems 60Ge and 62Ge. We also report on our deduced mass excesses in comparison with systematics and a recent measurement. Finally, we summarise our results on the half-lives of Tz = -1/2, -1 and -2 neutron-deficient nuclides, and analyse their trend.

An experiment was performed at GSI with the objective of measuring theβ-intensity distribution in the decay of Hg, Au and Pt isotopes around N=126 using the total absorption gamma-ray spectroscopy technique. The aim is to benchmark theoretical models used to make predictions of half-life and neutron emission probabilities of exotic nuclei involved in the rapid neutron capture process, leading to the synthesis of very heavy elements. This paper presents some experimental details and the current status of the analysis.

The ss decays of more than twenty fission fragments were measured in the first experiments with radioactive-ion beams employing the Decay Total Absorption.-ray Spectrometer. In this work, we summarize the main results obtained so far from this experimental campaign carried out at the Ion Guide Isotope Separator On-Line facility. The advances introduced for these studies represent the state-of-the-art of our analysis methodology for segmented spectrometers.

The very proton-rich 71 Kr isotope was produced through the in-flight fragmentation of 78 Kr on a beryllium target at RIKEN – Nishina Center in order to study its β-decay properties. A stack of double-sided silicon strip detectors, called WAS3ABi, was used as the decay station, where the detection of ion implants, β-decays and β-delayed protons took place. Beta-delayed γ-rays were measured using a system of 84 HPGe detectors, called EURICA, surrounding the decay station. The main goal of the present study was the precise measurement of the half-life of 71 Kr, as in the literature there is an almost 10 σ difference between the most precise independent results. Implant–β time correlations, implant–proton time correlations and implant–β–γ time correlations were all used to derive the half-life value, followed by a thorough investigation of systematic uncertainties for each method. As these values were found to be consistent, the weighted average t 1 / 2 = 94.40 +19 ms is reported as a new half-life value in this work. Furthermore a total of 26 previously unreported γ following the β-decay of 71 Kr were also identified in the analysis.

Nuclear reactors antineutrino measurements at short baselines do not fully agree with model predictions calculated with the Conversion Method. An alternative method to calculate the antineutrino spectra is theSummation Method. Both methods require the shapes of beta spectra as inputs. For that reason a new setup to measure the shape of the beta spectrum of relevant fission products for the calculation of the antineutrino spectra of reactors has been developed. Some preliminary measurements performed at IGISOL with isotopically clean beams are presented in this contribution.

The β-decay of the even-even nucleus 70Kr with Z=N+2, has been investigated at the Radioactive Ion Beam Factory (RIBF) of the RIKEN Nishina Center using the BigRIPS fragment separator, the ZeroDegree Spectrometer, the WAS3ABI implantation station and the EURICA HPGe cluster array. Fifteen γ-rays associated with the β-decay of 70Kr into 70Br have been identified for the first time, defining ten populated states below Eexc=3300 keV. The half-life of 70Kr was derived with increased precision and found to be t1/2=45.19±0.14 ms. The β-delayed proton emission probability has also been determined as εp=0.545(23)%. An increase in the β-strength to the yrast 1+ state in comparison with the heaviest Z=N+2 system studied so far (62Ge decay) is observed that may indicate increased np correlations in the T=0 channel. The β-decay strength deduced from the results is interpreted in terms of the proton-neutron quasiparticle random-phase approximation (pnQRPA) and also with a schematic model that includes isoscalar and isovector pairing in addition to quadrupole deformation. The application of this last model indicates an approximate realization of pseudo-SU(4) symmetry in this system.