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Research on radioactive ion beams produced with in-flight separation of relativistic beams has advanced significantly over the past decades, with contributions to nuclear physics, nuclear astrophysics, atomic physics, and other fields. Central to these advancements are improved production, separation, and identification methods.The FRS Ion Catcher at GSI/FAIRexemplifies these technological advancements. The system facilitates high-precision experiments by efficiently stopping and extracting exotic nuclei as ions and making these available at thermal energies. High-energy synchrotron beams enhance the system's capabilities, enabling unique experimental techniques such as multi-step reactions, mean range bunching, and optimized stopping, as well as novel measurement methods for observables such as beta-delayed neutron emission probabilities. The FRS Ion Catcher has already contributed to various scientific fields, and the future with the Super-FRS at FAIR promises to extend research to even more exotic nuclei and new applications. [ABSTRACT FROM AUTHOR]

We aim to explore the bubble nature of the exotic nucleus 20 N within the microscopic antisymmetrized molecular dynamics (AMD) approach. Constraining its structural parameters, we analyse its static properties. Subsequently, we use the AMD infused finite range distorted wave Born approximation theory to calculate the Coulomb breakup of 20 N as an indirect approach to estimate the 19 N (n , γ) 20 N radiative capture rate. [ABSTRACT FROM AUTHOR]

The field of nuclear science has considerably advanced since its beginning just over a century ago. Today, the science of rare isotopes is on the cusp of a new era with theoretical and computing advances complementing experimental capabilities at new facilities internationally. In this article we present a vision for the science of rare isotope beams (RIBs). We do not attempt to cover the full breadth of the field; rather, we provide a perspective and address a selection of topics that reflect our own interests and expertise. We focus in particular on systems near the drip lines, where one often finds nuclei that are referred to as exotic and where the role of the nuclear continuum is only just starting to be explored. An important aspect of this article is its attempt to highlight the crucial connections between nuclear structure and the nuclear reactions required to fully interpret and leverage the rich data to be collected in the next years at RIB facilities. Further, we connect the efforts in structure and reactions to key questions of nuclear astrophysics. [ABSTRACT FROM AUTHOR]

Fast beam collinear laser spectroscopy is the established method to investigate nuclear ground state properties such as the spin, the electromagnetic moments, and the charge radius of exotic nuclei. These are extracted with high precision from atomic observables, i.e., the hyperfine splitting and the isotope shift, which become possible due to a large reduction of the Doppler broadening by compressing the velocity width of the ion beam through electrostatic acceleration. With the advancement of experimental methods and applied devices, e.g., to measure and stabilize the laser frequency, the acceleration potential became the dominant systematic uncertainty contribution. To overcome this, we present a custom-built high-voltage divider, which was developed and tested at the German metrology institute, and a feedback loop that enabled collinear laser spectroscopy to be performed at a 100-kHz level. Furthermore, we describe the impact of field penetration into the laser–ion interaction region. This affects the determined isotope shifts and hyperfine splittings if Doppler tuning is applied, i.e., the ion beam energy is altered instead of scanning the laser frequency. Using different laser frequencies that were referenced to a frequency comb, the field penetration was extracted laser spectroscopically. This allowed us to define an effective scanning potential to still apply the faster and easier Doppler tuning without introducing systematic deviations. [ABSTRACT FROM AUTHOR]

One of the overarching goals in nuclear science is to understand how the nuclear chart emerges from the underlying fundamental interactions. The description of the structure of nuclei from first principles, using ab initio methods for the solution of the many-nucleon problem with inputs from chiral effective field theory, has advanced dramatically over the past two decades. We present an overview over the available ab initio tools with a specific emphasis on electromagnetic observables, such as multipole moments and transition strengths. These observables still pose a challenge for ab initio theory and are one of the most exciting domains to exploit synergies with modern experiments. Precise experimental data are vital for the validation of the theory predictions and the refinement of ab initio methods. We discuss some of the past and future experimental efforts highlighting these synergies. This article is part of the theme issue 'The liminal position of Nuclear Physics: from hadrons to neutron stars'. [ABSTRACT FROM AUTHOR]

The formation of isomeric states in atomic nuclei is sensitive to the underlying shell structure, which alters in accordance with variation in the number of constituent protons or neutrons and with changes of major configurations through particle–hole excitations inside one nucleus. In this article, I will overview some of the effects of the monopole component of proton–neutron interactions on the energy and decay properties of characteristic isomers in neutron-rich N = 80 nuclei below the doubly magic nucleus 132 Sn. I will also discuss the presence of a deformed sub-shell closure at N = 104 and its impact on the emergence of K isomers in neutron-rich dysprosium isotopes around double midshell. [ABSTRACT FROM AUTHOR]

Facilities equipped with two major types of isotope separators—Isotope Separation On-Line (ISOL) and in-flight separators—have produced many types of unstable nuclei and have provided opportunities to study their exotic properties successfully. Gas-cell systems have been developed for both types of radioactive-ion (RI) facilities, enabling the performance of a great variety of nuclear-spectroscopic measurements by compensating for their respective disadvantages in the production and purification of the RI beams. Although many nuclear-spectroscopic studies have been performed in both types of RI facilities by applying 238 U target (ISOL) or 238 U beam (in-flight), two major unexplored regions remain on the nuclear chart located in the regions of the refractory elements in the vicinity of Z = 73–78 and N = 126 and in the actinide elements. Because it is hard or almost impossible to produce the neutron-rich nuclei, which require specific nuclear reactions for the productions, in these unexplored regions. To access these regions and perform nuclear spectroscopy there, the KEK Isotope Separation System (KISS)—an argon-gas-cell-based laser ion source—has been developed and operated. The gas-cell system at the KISS facility is dedicated to multinucleon transfer (MNT) reactions for producing heavy, neutron-rich nuclei in the unexplored regions. Here, we introduce some of the experimental results and discuss a plan to upgrade the facility to promote further nuclear spectroscopy of the nuclei in the unexplored regions. [ABSTRACT FROM AUTHOR]

In this article, we address the occurrence and properties of exotic point-group symmetries in nuclei. We focus on the relations between the specific gap openings in the single-nucleon spectra, which represent a measure of nuclear stability studied with the help of the nuclear mean-field theory and accompanying octupole shape properties manifesting the link between the particular stability configurations (magic octupole gaps) and resulting exotic geometrical forms. We employ a realistic phenomenological realisation of the nuclear mean-field theory with the so-called universal Woods–Saxon Hamiltonian and the group representation theory to formulate the experimental identification criteria of the addressed symmetries. We use the newest parameterisations of the Hamiltonian obtained employing the inverse problem theory. To stabilise the modelling predictions, we detect and eliminate parametric correlations. Following earlier articles introducing the octupole "fourfold magic numbers" and "universal magic numbers", N = 136 and 198 , examined in the heavy and super-heavy nuclei, we generalise these concepts for the whole mass table for the octupole magic chain N = 32 , 40 , 56 , 64 , 70 , 90 , 112 , 136 , 198 . They bring in the so-called high-rank tetrahedral and octahedral point groups strengthening the specific shell effects and gap openings and implying the unique hindrance factors: at the exact tetrahedral symmetry limit, the collective electric quadrupole and dipole reduced transition probabilities vanish provoking new isomerism. Under these circumstances, many rotational states which in other nuclei manifest strong decay probabilities, in the high-rank symmetry case become isomeric—forming a new class of nuclear high-rank symmetry isomers. The consequences for the future experimental studies of those isomers are discussed especially in the domain of exotic nuclei. [ABSTRACT FROM AUTHOR]

We report the charge-changing cross sections ( σ cc ) of 24 p -shell nuclides on both hydrogen and carbon at about 900 A MeV, of which 8,9Li, 10–12Be, 10,14,15B, 14,15,17–22N and 16O on hydrogen and 8,9Li on carbon are for the first time. Benefiting from the data set, we found a new and robust relationship between the scaling factor of the Glauber model calculations and the separation energies of the nuclei of interest on both targets. This allows us to deduce proton radii ( R p ) for the first time from the cross sections on hydrogen. Nearly identical R p values are deduced from both target data for the neutron-rich carbon isotopes; however, the R p from the hydrogen target is systematically smaller in the neutron-rich nitrogen isotopes. This calls for further experimental and theoretical investigations. [ABSTRACT FROM AUTHOR]

The article provides an overview of the Super-FRS instrument at the FAIR facility and its capabilities for studying exotic nuclei. The Super-FRS is equipped with various detector systems and has the unique feature of placing ancillary detectors between magnetic stages, allowing for new experimental opportunities. The article also mentions planned experiments in hadron physics and the search for superheavy nuclei beyond the proton drip-line. Overall, the article emphasizes the importance of these experiments in advancing our understanding of nuclear physics and the potential for groundbreaking discoveries at FAIR. [Extracted from the article]

Exotic neutron-rich nuclei play an important role in r -process nucleosynthesis. We study the effect of including proper nuclear structure to calculate neutron capture and photodisintegration rates, especially for 19C and 20N, under the aegis of post-form distorted wave Born approximation (FRDWBA). Considering a network of neutron-rich C–N–O isotopes, we show the effect on abundance calculations in a neutrino-driven wind environment of a core-collapse supernova at two critical temperatures T 9 = 3.4 and 0.62. The results are compared for nuclear physics inputs sourced from the FRDWBA, statistical estimates, and standard databases. At temperatures T 9 = 3.4, where alpha capture, or at T 9 = 0.62, where the neutron capture dominates, one can distinguish the effect of accounting for the exotic nature of the nuclei involved. Furthermore, we assess the impact of varying neutron capture and photodisintegration rates involving halo or bubble structures on the abundances within the network. [ABSTRACT FROM AUTHOR]

The nuclear shell model was used to investigate the bulk properties of lithium isotopes ( 6,7,8,9,11Li), i.e., the ground state density distributions and C0 and C2 components of charge form factors. The theoretical treatment was based on supposing that the Harmonic-oscillator (HO) potential governs the core nucleons while the valence nucleon(s) move through Hulthen potential. Such assumptions were applied for both stable and exotic lithium isotopes. The HO size parameters (bn and bp), the core radii (rc ) and the attenuation parameters (kn and kp) were fixed to recreate the available empirical size radii for lithium isotopes under study. [ABSTRACT FROM AUTHOR]

The transverse magnetic electron scattering form factors of 19O and 21Na exotic nuclei were studied in the plane wave Born approximation (PWBA). The shell model calculations with three sd-shell interactions, USDA, USDB, and Wildenthal, were carried out for the ground and low-lying excited states. The exact center of mass correction in the Born approximation picture through the translation-invariant shell model (TISM) was included to modify the transverse form factors. The measured magnetic dipole moments were well reproduced with the core polarization (CP) effect introduced through the effective g-factors. The occupancies percentage with respect to the valence nucleons was also calculated. [ABSTRACT FROM AUTHOR]

The discovery of halos, one of the most interesting phenomena in exotic nuclei, has opened up a new field in nuclear physics. To understand this unique property, the level structures of 14 B, 15 C, 22 N, 23 O, 24 F, and 25 Ne are studied with the complex momentum representation (CMR) method. We calculate the single-particle energies of bound and resonant states, and examine the occupation probabilities, density distribution, wavefunctions of the valence neutron occupied levels, and the root mean square (RMS) radii of the single-particle orbits. These results show that 14 B, 15 C, and 22 N are neutron halo nuclei dominated by s-wave configurations in - 0.08 ≤ β 2 ≤ 0 , 0.1 ≤ β 2 ≤ 0.3 , and - 0.1 ≤ β 2 ≤ 0.08 , respectively. Although the last valence neutron of 23 O, 24 F, and 25 Ne all occupy the 2 s 1 / 2 orbit (the orbit with a dominant s-wave configuration), the single-particle levels occupied by the valence neutrons are rather bound. It implies a neutron skin structure in 23 O, 24 F, and 25 Ne with spherical shape or prolate deformation. The halo phenomena are not only related to the orbital occupied by the last valence neutron but also to its separation energy. This prediction has reference value for further exploration of neutron halo in experiments. [ABSTRACT FROM AUTHOR]

The study of neutron-rich nuclei's form factors, root-mean-square radius (rms), and nuclear density distributions is the focus of this work for the nuclei (22N, 23 O and 24F). With the use of a strong short-range effect and a strong tensor force, the nucleons distribution function of the two oscillating harmonic particles in a two-frequency shell model operates with two different parameters: the first (bcore), for the inner (core) orbits, and the second (bvalence) for the outer (halo) orbits. This work demonstrated the existence of neutron halo nuclei for the nuclei (22N, 23O and ²4F) in the (2s1/2) shell. The computed density distribution of neutron, proton and matter for these nuclei displayed the long tail performance. Using the Borne approximation of the plane wave, the elastic form factor of the electron scattering from the alien nucleus was calculated, this form factor is independent of the neutrons that make up the halo, but rather it results from a difference in the proton density distribution of the last proton in the nuclei. Fortran 95 power station program was used to the neutron, proton and matter density, elastic electron scattering form factor, and rms radii. The calculated outcomes for these exotic nuclei were in good agreement with the experimental data. [ABSTRACT FROM AUTHOR]

The article explores the possibility of a mesonic nuclear state and discusses the presence of exotic forms of hadrons. It describes an experiment conducted to search for a kaonic nuclear bound state and discusses the formation and decay processes of the particle "K-pp." The study focuses on the advantages of studying the invariant mass of the particle and the ability to deduce the invariant mass and momentum transfer from the initial K-meson. The authors observe a clear peak formation below the kaon binding threshold, indicating the presence of a kaonic nuclear bound state. This is the first convincing signal that a K-meson can form a nuclear bound state with two nucleons. The state has a large binding energy but is unstable and decays through the strong interaction. The study of light kaonic nuclei is important for understanding the strong interaction and exploring physics beyond normal nuclear density. [Extracted from the article]

The neutron drip line presents exotic nuclear structures. In this work, we study 22C, a Borromean isotope of carbon. The Gamow Shell model was used to understand its properties. A Woods-Saxon plus Gaussian mean field defined the single-particle basis. The root means square of the radius was calculated.

Since Mayer and Jensen employed the single-particle shell model to interpret the magic numbers, various microscopic nuclear models have been developed to study the nuclear force and structure. The configuration–interaction shell model (CISM), performed in truncated model space with the inclusion of the residual interaction, is one widely-used nuclear structure model. In the last decade, CISM has progressed in investigating the cross-shell excitation in exotic light nuclei, the similarity and difference in mirror nuclei, and the isomerism and seniority conservation in medium and heavy nuclei. Additionally, researchers have attempted to construct effective Hamiltonians for nuclei near 1 3 2 Sn and 2 0 8 Pb through a unified way in the CISM framework. In parallel, related models, including the nucleon-pair approximation (NPA) approach, the Monte Carlo shell model (MCSM), the projected shell model (PSM), the Gamow shell model (GSM), etc., have also been extensively developed and validated in the last decade. This paper reviews the recent progress in CISM and some related models. [ABSTRACT FROM AUTHOR]

The article discusses the Stored Particle Atomic Physics Research Collaboration (SPARC) and its work with highly charged ions at the Facility for Antiproton and Ion Research (FAIR). SPARC aims to perform precision experiments with cooled, highly charged, heavy ions and exotic nuclei to probe fundamental laws of physics in extreme electromagnetic fields. The article highlights the various experimental facilities at FAIR and the research program of SPARC, which includes studying atomic matter subject to extreme electromagnetic fields and exploring the intersection of atomic and nuclear physics. The article also mentions the installation of CRYRING at FAIR and the potential for high-precision experiments in the future. [Extracted from the article]

In this paper, a nice theoretical scheme is presented to investigate resonant and bound states in weakly bound nuclear systems by the use of isospectral potentials together with hyperspherical harmonics expansion. In this scheme, a new potential is constructed which is strictly isospectral with the original shallow potential and has properties that are desirable to calculate resonances more accurately and elegantly. The effectiveness of the method has been checked in terms of its application to the 0+ resonances in the neutron-rich isotopes 18,20C in the two-neutron plus core three-body cluster model. The results are in excellent agreement with the available data. [ABSTRACT FROM AUTHOR]

The single-ion Penning trap (SIPT) at the Low-Energy Beam Ion Trapping Facility has been developed to perform precision Penning trap mass measurements of single ions, ideal for the study of exotic nuclei available only at low rates at the Facility for Rare Isotope Beams (FRIB). Single-ion signals are very weak—especially if the ion is singly charged—and the few meaningful ion signals must be disentangled from an often larger noise background. A useful approach for simulating Fourier transform ion cyclotron resonance signals is outlined and shown to be equivalent to the established yet computationally intense method. Applications of supervised machine learning algorithms for classifying background signals are discussed, and their accuracies are shown to be ≈65% for the weakest signals of interest to SIPT. Additionally, a deep neural network capable of accurately predicting important characteristics of the ions observed by their image charge signal is discussed. Signal classification on an experimental noise dataset was shown to have a false-positive classification rate of 10.5%, and 3.5% following additional filtering. The application of the deep neural network to an experimental 85Rb+ dataset is presented, suggesting that SIPT is sensitive to single-ion signals. Lastly, the implications for future experiments are discussed. [ABSTRACT FROM AUTHOR]

The beta-decay rates of neutron-rich nuclei far from the stability are still very limited due to the lack of experimental data. In this paper, we calculated the half-lives of the exotic nuclei close to the neutron drip line by using a recent semi-empirical formula (FZh). The β-decay Q-values calculated using the finite-range droplet macroscopic (FRDM) model and taken from the AME2020 database (with and without uncertainty) were used in the calculations to investigate the impact of the mass uncertainty on the half-life predictions. We found that a deviation of 7% in the Q-value can lead to an uncertainty of 40% in the half-life and a large change, up to two orders of magnitude, in the r-process abundance. The approach combining the AME2020 Q-value and FZh model has emerged as a good tool for the half-life prediction. The estimated half-lives are necessary for the precise mass measurements and r-process simulations. [ABSTRACT FROM AUTHOR]

Development of a position-sensitive large-area microchannel plate (MCP) detector based detection system is reported. Two MCPs with 120 mm active diameter, mounted in chevron configuration, with delay-line anode are read out by a digital data-acquisition system consists of fast-timing amplifier unit and CAEN v1751 waveform digitizer. Details of the digital pulse processing, programmed triggering and calibration setup are described. The obtained position resolution was studied using α -particles, the best resolutions on X and Y axes are 460 ± 1 μ m and 579 ± 1 μ m in FWHM, respectively. [ABSTRACT FROM AUTHOR]

RAPTOR, Resonance ionization spectroscopy And Purification Traps for Optimized spectRoscopy, is a new collinear resonance ionization spectroscopy device constructed at the Ion Guide Isotope Separator On-Line (IGISOL) facility at the University of Jyväskylä, Finland. By operating at beam energies of under 10 keV, the footprint of the experiment is reduced compared to more traditional collinear laser spectroscopy beamlines. In addition, RAPTOR is coupled to the JYFLTRAP Penning trap mass spectrometer, opening a window to laser-assisted nuclear-state selective purification, serving not only the mass measurement program, but also supporting post-trap decay spectroscopy experiments. Finally, the low-energy ion beams used for RAPTOR will enable high-precision laser-radiofrequency double-resonance experiments, resulting in spectroscopy with linewidths below 1 MHz. In this contribution, the technical layout of RAPTOR and a selection of ion-beam optical simulations for the device are presented, along with a discussion of the current status of the commissioning experiments. [ABSTRACT FROM AUTHOR]

The novel technique of mean range bunching has been developed and applied at the projectile fragment separator FRS at GSI in four experiments of the FAIR phase-0 experimental program. Using a variable degrader system at the final focal plane of the FRS, the ranges of the different nuclides can be aligned, allowing to efficiently implant a large number of different nuclides simultaneously in a gas-filled stopping cell or an implantation detector. Stopping and studying a cocktail beam overcomes the present limitations of stopped-beam experiments. The conceptual idea of mean range bunching is described and illustrated using simulations. In a single setting of the FRS, 37 different nuclides were stopped in the cryogenic stopping cell and were measured in a single setting broadband mass measurement with the multiple-reflection time-of-flight mass spectrometer of the FRS Ion Catcher. [ABSTRACT FROM AUTHOR]

High-resolution experiments with stored and cooled exotic nuclei have been pioneered and applied with the FRS-ESR facilities at GSI since 1991. Exotic nuclei have been produced, spatially separated in flight with the FRS and injected in the longitudinal dispersive storage ring ESR for high-resolution mass and lifetime measurements. For very short-lived nuclei, i.e., with lifetimes shorter than the cooling time, the ion-optical system of the ring has to be operated in the so-called isochronous mode. Under this condition, the inherent momentum spread of the fragments does not limit the accuracy of experiments if both the revolution time and the magnetic rigidity are simultaneously measured for the circulating ions. In this contribution, we demonstrate a novel feature for the ESR operated in the isochronous mode and the phase-space matching of FRS and ESR. [ABSTRACT FROM AUTHOR]

In the present work, we have analyzed the elastic scattering data of 6He+p at 25.6, 38.6, 40.9, and 71 MeV/A and 8He+p at 15.6, 25.6, 32.5, 66, and 72 MeV/A, using the microscopic local optical potential calculated within the framework of the Brueckner–Hartree–Fock (BHF) formalism. The calculation requires mainly two inputs: (1) the nucleon–nucleon (NN) interaction and (2) the nucleon distributions in target nuclei. In the present work, realistic internucleon (NN) potential from Argonne v18 (AV18) and the Urbana IX (UVIX) model of three-body forces with several nucleon density distributions are used for generating the nucleon–nucleus optical potential. We have used the exact method for calculating both the direct and the exchange parts of the spin–orbit potential. We confirm the earlier results that the spin–orbit potential for these neutron-rich nuclei is diffused and extended. Our results show that the different density distributions reproduce rather well the experimental differential cross sections for both isotopes, while the phenomenological density with a two-neutron halo gives satisfactory results for 6He-p analyzing power data. None of the densities used for 8He can reproduce the experimentally analyzed power data. Our analysis reveals that the calculated microscopic optical potentials, with and without three-body forces using the BHF approach, provide satisfactory agreement with the elastic scattering data for 6,8He+p. [ABSTRACT FROM AUTHOR]

The halo phenomenon in exotic nuclei has long been an important frontier in nuclear physics research since its discovery in 1985. In parallel with the experimental progress in exploring halo nuclei, the covariant density functional theory has become one of the most successful tools for the microscopic study of halo nuclei. Based on spherical symmetry, the relativistic continuum Hartree–Bogoliubov theory describes the first halo nucleus 11 Li self-consistently and predicts the giant halo phenomenon. Based on axial symmetry, the deformed relativistic Hartree–Bogoliubov theory in continuum has predicted axially deformed halo nuclei 42 , 44 Mg and the shape decoupling effects therein. Based on triaxial symmetry, recently the triaxial relativistic Hartree–Bogoliubov theory in continuum has been developed and applied to explore halos in triaxially deformed nuclei. The theoretical frameworks of these models are presented, with the efficacy of exploiting symmetries highlighted. Selected applications to spherical, axially deformed, and triaxially deformed halo nuclei are introduced. [ABSTRACT FROM AUTHOR]

An analysis of the capabilities of AGATA for in-beam γ -ray spectroscopy at relativistic energies is presented. AGATA's ability to determine the position of γ -ray interaction points in the Germanium crystal provides the crucial ingredient for attaining high γ -ray energy resolution when the emitting nucleus is traveling at more than half the speed of light. This is the typical velocity of exotic nuclei exiting the SuperFRS spectrometer at the future FAIR facility, where AGATA will be deployed as part of the high-resolution in-beam spectroscopy project, HISPEC. A discussion of different experimental techniques using AGATA under these conditions is presented, including analysis of the different Doppler-based methods for lifetime determination. The properties of the key reaction mechanisms expected to be applied for in-beam γ -ray spectroscopy at FAIR are discussed, along with the aspects of those reactions that can be exploited by the advanced capabilities of the AGATA array. [ABSTRACT FROM AUTHOR]

Abstract: The distributions of nuclear density, root mean square radii, and elastic electron scattering form factor are calculated for nuclei (9C) (core +2p) and (26F) (core +2n) with the two different nuclear potential parameters for (bc) and (bv), were correlations for both the (effects tensor force and short-range) are used, and the appearance of the long extension is observed in Nuclear density distributions for these nuclei. Fortran 95 power station was used to program nuclear properties such as nucleon density (matter, neutron, and proton), elastic electron scattering form factor, and rms radii. The computed results for these exotic nuclei are determined to correspond pretty well with the experimental data.

The study of proton-rich nuclei's form factors, root-mean-square radius (rms), and nuclear density distributions is the focus of this work for nuclei (23Al and 27P), use two body charge density distributions (2BCDD's). With the effects of the strong tensor force and short range, the nucleon distribution function of the two oscillating harmonic particles in a two-frequency shell model operates with two different parameters: bc for the inner (core) orbits and bv for the outer (halo) orbitals. This work demonstrated the existence of proton halo nuclei for the nuclei (23Al and 27P) in the shell (2s1/2), and the computed proton, neutron, and matter density distributions for these nuclei both displayed the long tail of the performance. Using the Borne approximation of the plane wave, the elastic form factor of the electron scattering from the alien nucleus was calculated, this form factor is dependent on the difference in the proton density distribution of the last proton in the nucleus. The Fortran 95 power station program was used to calculate the neutrons, protons, matter density, elastic electron scattering form factor, and rms radii. The calculated outcomes for these exotic nuclei agree well with the experimental data.

Results of offline commissioning tests for a new dedicated gas cell for the Mass Analysing Recoil Apparatus (MARA) Low-Energy Branch are reported. Evacuation time, ion survival and transport efficiency in helium buffer gas were characterized with a radioactive 223 Ra α -recoil source. Suppression of the ion signal, originating from non-neutralized species in the gas cell, was explored with 219 Rn ions, the daughter recoil of 223 Ra , as a function of voltage applied to one of the ion-collector electrodes. Two-step laser resonance ionization of stable tin isotopes produced inside the gas cell from a heated bronze filament was demonstrated, and broadening of the atomic resonances in argon buffer gas was studied. These tests indicate the suitability of the new gas cell for future in-gas laser spectroscopy studies of exotic nuclei at the Accelerator Laboratory of the University of Jyväskylä. [ABSTRACT FROM AUTHOR]

The paper reviews the recent progress in the description of isospin-symmetry breaking within the nuclear shell model and applications to actual problems related to the structure and decay of exotic neutron-deficient nuclei and nuclei along the N = Z line, where N is the neutron number and Z the atomic number. The review recalls the fundamentals of the isospin formalism for two-nucleon and many-nucleon systems, including quantum numbers, the spectrum's structure and selection rules for weak and electromagnetic transitions; and at the end, summarizes experimental signatures of isospin-symmetry breaking effects, which motivated efforts towards the creation of a relevant theoretical framework to describe those phenomena. The main approaches to construct accurate isospin-nonconserving Hamiltonians within the shell model are briefly described and recent advances in the description of the structure and (isospin-forbidden) decay modes of neutron-deficient nuclei are highlighted. The paper reviews major implications of the developed theoretical tools to (i) the fundamental interaction studies on nuclear decays and (ii) the estimation of the rates of nuclear reactions that are important for nuclear astrophysics. The shell model is shown to be one of the most suitable approaches to describing isospin-symmetry breaking in nuclear states at low energies. Further efforts in extending and refining the description to larger model spaces, and in developing first-principle theories to deal with isospin-symmetry breaking in many-nucleon systems, seem to be indispensable steps towards our better understanding of nuclear properties in the precision era. [ABSTRACT FROM AUTHOR]

Large-scale models of nuclear structure are currently the only way to provide consistent datasets for the many properties of thousands of exotic nuclei that are required by nucleosynthesis simulations. In [W. Ryssens et al., Eur. Phys. J. A 58, 246 (2022)], we recently presented the new BSkG2 model based on an energy density functional of the Skyrme type. Relying on a flexible three-dimensional coordinate representation of the nucleus, the model takes into account both triaxial deformation and time-reversal symmetry breaking. BSkG2 achieves a state-of-the-art global description of nuclear ground state (g.s.) properties and reproduces in particular the known masses with a root-mean-square (rms) deviation of 678 keV. Moving beyond g.s. properties, the model also reproduces all empirical values for the primary and secondary barriers as well as isomer excitation energies of actinide nuclei with rms deviations below 500 keV, i.e. with unprecedented accuracy. Here we discuss in detail the extension of our framework to the calculation of the fission barriers of 45 actinide nuclei, including odd-mass and odd-odd systems. We focus in particular on the impact of symmetry breaking which is key to the accuracy of the model: we allow systematically for axial, reflection and time-reversal symmetry breaking. The effect of the latter on the fission properties of odd-mass and odd-odd nuclei is small, but we find that allowing for shapes with triaxial or octupole deformation, as well as shapes with both, is crucial to achieving this accuracy. The numerical accuracy of our coordinate space approach, the variety of nuclear configurations explored and the simultaneous successful description of fission properties and known masses makes BSkG2 the tool of choice for the large-scale study of nuclear structure. [ABSTRACT FROM AUTHOR]

The ground state density distributions and electron scattering Coulomb form factors of Helium (4,6,8He) and Phosphorate (27,31P) isotopes are investigated in the framework of nuclear shell model. For stable (4He) and (31P) nuclei, the core and valence parts are studied through Harmonic-oscillator (HO) and Hulthen potentials. Correspondingly, for exotic (6,8He) and (27P) nuclei, the HO potential is applied to the core parts only, while the Hulthen potential is applied to valence parts. The parameters for HO and Hulthen are chosen to reproduce the available experimental size radii for all nuclei under study. Finally, the CO component of electron scattering charge form factors are also investigated. Unfortunately, there is no analytic solution to the Hulthen potential except for the states which are harnessed to the current calculation. [ABSTRACT FROM AUTHOR]

Hans Geissel, a pioneer in radioactive ion beams, passed away on April 29, 2024. His career was closely tied to the development of the GSI Helmholtz-Center for Heavy-Ion Research in Germany, which laid the foundation for the Facility for Antiproton and Ion Research (FAIR). Geissel's work had a global impact and he made significant contributions to the field of nuclear physics, atomic physics, and ion optics. He was involved in the discovery of many exotic nuclei, the development of simulation programs, and the advancement of fragment separator facilities worldwide. Geissel received numerous awards for his groundbreaking work and was known for his international collaborations and openness to new ideas. [Extracted from the article]

In the mid-1980s, theoreticians predicted possible exotic states of an eta (η) meson and a nucleus bound by the strong interaction, so-called mesic nucleus. This led to extensive experimental efforts aimed at discovering such unstable states as well as understanding the underlying interactions via η meson production reactions. As experiments yielded new data, more and more sophisticated theoretical models were developed to understand the fundamental η-nucleon and η-nucleus interactions. After more than 35 years of research in this field, several signals have been identified as possible indications of hypothetical η-mesic nuclei, but there is still no general agreement or clear confirmation of their existence. In the paper, we review the study of the η-mesic nuclei with an emphasis on recent research activities.

Direct mass measurements of neutron-deficient nuclides around the N=50 shell closure below 100Sn were performed at the FRS Ion Catcher (FRS-IC) at GSI, Germany. The nuclei were produced by projectile fragmentation of 124Xe, separated in the fragment separator FRS and delivered to the FRS-IC. The masses of 14 ground states and two isomers were measured with relative mass uncertainties down to 1×10−7 using the multiple-reflection time-of-flight mass spectrometer of the FRS-IC, including the first direct mass measurements of 98Cd and 97Rh. A new QEC=5437±67 keV was obtained for 98Cd, resulting in a summed Gamow-Teller (GT) strength for the five observed transitions (0+⟶1+) as B(GT)=2.94−0.28+0.32. Investigation of this result in state-of-the-art shell model approaches accounting for the first time experimentally observed spectrum of GT transitions points to a perfect agreement for N=50 isotones. The excitation energy of the long-lived isomeric state in 94Rh was determined for the first time to be 293±21 keV. This, together with the shell model calculations, allows the level ordering in 94Rh to be understood.

This study investigates the production of charged particles and the kaonic nuclei K − p p and K + p ̄ p ̄ in Au + Au collisions at s = 1 3 0  GeV. The parton and hadron cascade model PACIAE 2.1 is used to calculate the yield of charged particles, and the Dynamically Constrained Phase–space Coalescence (DCPC) model is used to calculate the yield of kaonic nuclei. Results showed that the yield of charged particles was consistent with experimental data from the STAR detector at Brookhaven National Laboratory (United States). The data also revealed that the simulated yield of K − p p was greater than the yield of K + p ̄ p ̄. The kaonic nuclei K − p p and K + p ̄ p ̄ are probably formed by K + (or K − ) directly trapping two protons (or antiprotons). [ABSTRACT FROM AUTHOR]

Studies of the properties of nuclei remote from the "valley of nuclear stability" make it possible to predict the properties of new nuclides based on systematic accumulations of data on the structure of nuclear matter. New phenomena in the behavior of nuclear matter are also being discovered. Such cores are called "exotic". The production of exotic nuclei is a multi-stage process, during which various approaches of theoretical and experimental physics are applied. One of the ways to obtain nuclei are fragmentation reactions of relatively light nuclei with high energy (more than 100 MeV), as a result of which exotic nuclei with different A and Z can be obtained. In this article, a study of the applicability of the high-energy approximation (HEA) in modeling such direct nuclear reactions was conducted and the results of comparing this approach with the exact solution of the Schrodinger equation using the example of a rectangular potential barrier and a Gaussian potential barrier are presented. Comparison of different approaches provides an understanding of the limitations of their applicability for further study of the properties of nuclei in interaction with each other and for solving the Schrodinger equation with similar potentials considered.

The neutron-rich nucleus 11Be is one of the most enigmatic exotic nuclei in the periodic table. It exhibits a multitude of unique and intriguing phenomena within a single nucleus, including the halo phenomenon, clustering structure, and parity inversion. A unified description of these exotic properties represents a significant challenge for the nuclear physics field. By employing the axially deformed relativistic Hartree-Fock-Bogoliubov (D-RHFB) model, we have successfully reproduced the parity inversion and the one-neutron halo in 11Be, and revealed the underlying cluster structure. It is found that the intrusion of the sd -shell, which results in the parity inversion, is coherently connected with the halo and cluster structures. In particular, the s -wave is responsible for the halo formation, and the mixing of 2 s 1 / 2 - and 1 d 5 / 2 -waves enhances the cluster structure. This work elucidates the coherence between the parity inversion and the halo/cluster structures of 11Be, and addresses the long-standing challenge of providing a unified explanation for the multiple exotic phenomena observed in 11Be. [ABSTRACT FROM AUTHOR]

This work is concerned to give information of shell model calculations, limited to fp-shell with an accuracy and applicability in the work. The form factors have been calculated for J+=0+,2+,4+,6+,8+ for each nuclei depending on charge density q≤3 fm-1 using the harmonic oscillator potential based on GX1A effective interaction with ep=1.16e and en=0.7e. For charge density, the differences between proton and neutron densities increased with neutron increase while neutron radius increased as neutron number increase as an extension of neutron densities outwards on the nuclear surface (3< r