The history of Coulomb-excitation measurements with AGATA dates back to the very first physics experiment with this array, which took place in April 2010 and aimed at investigation of a highly-deformed structure in $^{42}$Ca [1,2]. The measurement provided magnitudes and relative signs of numerous E2 matrix elements coupling the low-lying states in $^{42}$Ca. The shape parameters obtained for...
Away from the valley of stability, the imbalance between the number of protons and neutrons serves as a magnifying lens for specific components of the nuclear interaction that cannot be studied otherwise. In such regions of the nuclear chart, new phenomena as appearance or disappearance of magic numbers, shape coexistence or transitions, are examples of the manifestation of the influence of...
Exotic nuclei, far from stability, are a perfect laboratory to probe the specific components of the nuclear interaction. The imbalance between the number of protons and neutrons can lead to the appearance of phenomena such as sudden shape transitions and shape coexistence. The nuclei with Z and N around 40 and 60, respectively, show one of the most remarkable examples of sudden nuclear shape...
The search for chargeless nuclei consisting only of neutrons has been a long-lasting challenge in nuclear physics, dating more than six decades back (see Ref. [1] for a recent review). The tetraneutron, in particular, has attracted a lot of experimental and theoretical attention. Most models agree that nuclear forces cannot bind four neutrons together without destroying many of the other...
In the shell model framework, the two-body nuclear force can be divided into a central, spin-orbit (SO) and tensor parts. The vast majority of studies performed so far in the chart of nuclides shows that the amplitude of the SO splitting scales with the function presented by G.Mairle [1], from systematics of nuclei studied so far in the valley of stability. Two exceptions to this trend have...
Proton-removal reactions along the Be-Li chain close to the drip-line have been investigated with the aim of establishing the role of the Geometrical Mismatch Factor (GMF) and NN effects [1] in lowering the cross sections, as observed previously in He-Li nuclei [2].
The experiment was performed at GANIL using 10Be and 12Be beams at 30 AMeV impinging a CD2 target, with an intensity of 3 ·...
The pygmy dipole resonance (PDR) is a vibrational mode described as the oscillation of a neutron skin against a core symmetric in number of protons and neutrons. The PDR has been the subject of numerous studies, both experimental and theoretical [1,2,3]. Indeed, the study of the PDR has been and still is of great interest since it allows to constrain the symmetry energy, an important...
Since 2016, while PARIS array has been in its initial development phase, one cluster of phoswich detectors has been available for tests and experiments at IJCLab. Hence there has been an excellent synergy between the IJCLab facility and the PARIS detector in its development phase. In 2018, 33 PARIS phoswich detectors (almost 4 clusters) were coupled to the ν−ball1 gamma-ray spectrometer...
An experimental campaign of measurements of the γ decay from states excited in nuclei using proton inelastic scattering reaction have been performed at CCB facility of IFJ PAN. The main goal of the experiments was to study the decay to the ground state of isoscalar giant quadrupole resonance (ISGQR) via γ-ray emission. Previously such phenomenon was observed only once, in 1980s [1].
The...
Nuclear materials define a class of solid of interest for the nuclear industry with the specificity of being submitted to intense irradiation fields. Nuclear fuels and transmutation matrices deserve special attention due to their location at the core of the reactor, and due to the complexity of irradiation sources to which they are subjected, leading to both physical (radiation damage, atomic...
Fission at low excitation energy has shown over the past decades to be an ideal playground for studying fundamental nuclear properties, in general, and dynamical aspects of nuclear reactions, in particular. While the importance of structural effects in the nascent fragments has been established through numerous studies, the VAMOS campaigns performed during the last few years definitively...
D. Doré1), D. Ramos2), E. Berthoumieux1), J.-E. Ducret2),
X. Ledoux2), P. Marini2,3), S. Oberstedt4), J. Pancin2),
M. Ballu1), P. Herran1), G. Kaur1), A. Letourneau1), T. Materna1), P. Miriot-Jaubert1),
B. Mom1), L. Thulliez1), M. Vandebrouck1), A.-M. Frelin2), P. Sharma2), I. Jangid2),
A. Cheboubbi5), O. Litaize5), O. Serot5), A. Porta6), M. Estienne6), M. Fallot6),
E. Bonnet6), J....
Nuclear fission is a complex, dynamical process involving a dramatic re-arrangement of nuclear matter. Even after much experimental and theoretical investigations over many years this fascinating nuclear reaction is stil not fully understood due to the large number of degrees of freedom and final multitude of final states which can be populated. The gamma rays emitted in nuclear fission...
Fission of atomic nuclei is often affected by quantum effects leading to asymmetric mass splits. These shell effects can be investigated at the mean-field level with single particles level densities, indicating that several proton and neutron shell effects are usually at play prior to scission [1]. In addition to shell effects in the compound nucleus, quantum shells stabilising fission...
Neutron star (NS) is believed to be created as a remnant of supernova explosion. The property of neutron star can be described with the thermodynamical character (Equation of State, EoS) of nuclear matter.
For the determination of outer core NS-EoS, we have performed a series of measurements using heavy ion accelerator of RIKEN Radio Isotope Beam Factory (RIBF).
An international...
Heavy-ion collisions in the intermediate energy regime (20-100 MeV/nucleon) are a widespread tool to probe the properties of nuclear matter far from equilibrium: among other topics, they allow to investigate isospin transport phenomena, which can be interpreted in the framework of the Nuclear Equation of State (NEoS), i.e. the thermodynamic description of nuclear matter.
The INDRA-FAZIA...
The understanding of neutron star properties from fundamental physics is still far from being completed. One of the reasons is that the theory for strong force, QCD, does not apply simply to neutron star matter at a few times the nuclear saturation density. At low density, chiral effective field theory is fixing a limit which can be incorporated in the description of the crust of neutron...
We present the first triaxial beyond-mean-field studies of super-heavy nuclei. They include the restoration of the particle-number and angular-momentum symmetries and the mixing of different shapes using the generator coordinate method. The importance of the $\gamma$ degree of freedom is highlighted by comparing the triaxial to axial-symmetric calculations performed within the same framework....
One of the long-standing topics in nuclear physics is the competition between the symmetric and asymmetric modes of quasi-fission in collisions of heavy and very heavy nuclear systems. The separation of these modes from the excited compound nucleus fission is quite difficult experimentally. Theoretical calculations may give valuable insight into ascertaining contributions from these various...
New accelerators are being developed, either for medical applications (X-ray radiotherapy, hadrontherapy, radiotherapy by synchrotron radiation and "flash" therapies), or for nuclear physics. These developments create the need for very precise beam monitoring with fast counting in a highly radiative environment. An important issue is the adaptation to the temporal beam structures, which vary...
Glioblastoma (GBM) are brain tumors resistant to conventional therapies, in particular to radiotherapy based on X-rays. Therefore, the use of hadrontherapy appears as very appealing strategy thanks to their finite dose deposition to spare normal brain tissue but also to their greater biological efficacy toward radioresistant tumor cells and their low sensitivity to hypoxia, a well know factor...
Exploiting closed-path ion trajectories in an electrostatic ion trap, the multi-reflection time-of-flight mass spectrograph (MRTOF-MS) [1] is one of the most promising techniques for precise mass measurements of short-lived isotopes. Exotic ions produced at radioisotope facilities are stored in an electrostatic trap at kinetic energies on the order of a few keV, reflected back and forth...
The Super Separator Spectrometer-Low Energy Branch (S$^3$-LEB) is a low-energy radioactive ion beam experiment under commissioning as part of the GANIL-SPIRAL2 facility [1-3]. It will be used for the production and study of exotic nuclei by in-gas laser ionization and spectroscopy (IGLIS), decay spectroscopy, and mass spectrometry.
Development work has been ongoing at the S$^3$-LEB setup...
Optical spectroscopy of superheavy elements is an experimental challenge. The production yields of the elements are about one atom per second or even less, the half-lives are extremely short, and the atomic structure is uncharted experimental territory. Conventional spectroscopy techniques based on fluorescence detection are no longer suitable because they lack the sensitivity required to...
The Z=6 shell gap in neutron-rich carbon isotopes has been a subject of debate, with recent studies claiming its prevalence in this region of the nuclear chart [1], in contradiction with recent measurements [2] and shell model predictions [3].
In order to shed more light into this subject, the structure of $^{19}$N was investigated through the proton-removal d($^{20}$O, $^{3}$He) reaction...
Coulomb barrier scattering of the proton halo nucleus 17Ne
I. Martel(a), J. Díaz-Ovejas(b), D. Dell’Aquila(c,d),L. Acosta(e), J. L. Aguado(a), G. de Angelis(f), M. J. G. Borge(b), J. A. Briz(b), A. Chbihi(g), G. Colucci(h), C. Díaz-Martín(a), P. Figuera(d), D. Galaviz(i), C. García-Ramos(a), J. A. Gómez-Galán(a), C. A. Gonzales(a), N. Goyal(g), N. Keeley(j), K. W. Kemper(k), T....
MUGAST [1] is a state-of-the-art silicon array combining trapezoidal and square shaped double-sided silicon strip detectors (DSSD) to four MUST2 [2] telescopes. Coupled to a gamma-ray spectrometer, the excellent angular coverage and compacity of the MUGAST array make it an ideal tool for the study of transfer reactions. It is a first step toward the development of the new generation of silicon...
We have thoroughly investigated the influence of entrance channel effects on the spin distribution and angular momentum in heavy ion collisions, employing three-dimensional dissipative dynamics. The microscopically derived Langevin equations were numerically solved using the distance, neck, asymmetry and the three angular macroscopic variables, which allow for an adequate description of the...
Heavy-ion collisions at Fermi energies allow to investigate various phenomena, such as the isospin transport phenomena. These can be interpreted in the framework of the Nuclear Equation of State (NEoS), which describes the properties of nuclear matter in terms of thermodynamic variables.
In this talk we will show the preliminary results of the study of the $^{58}$Ni+$^{58}$Ni reaction at...
The development and improvement in terms of performances of accelerator facilities and detectors has paved the way for extending the study of nuclear structure towards more exotic nuclei and experimental quantities that have been, until now, less accessible.
In parallel, theoretical methods have advances in precision and prediction capabilities.
In recent years, \textit{ab-initio}...
Shell evolution in the region around the magic numbers $N=28$ and $Z=20$ is of great interest in nuclear structure physics. Moving away from the doubly-magic isotope $^{48}$Ca, in the neutron-rich direction there is evidence of an emergent shell gap at $N=34$ [1], and in the proton-deficient direction, the onset of shape deformation suggests a weakening of the $N=28$ magic number [2]. The...
The main subject of this study is the experimental investigation of the nuclear structure of exotic neutron-rich nuclei in the vicinity of shell closures in order to constrain the description of the nucleon-nucleon interaction, and in particular its tensor term. Previous studies have shown that a deformation region develops along the N=28 isotonic chain between the doubly magical and spherical...
Reactor antineutrino energy spectra are the subject of active experimental researches nowadays, one of them being dedicated to nuclear physics measurements of the properties of the fission products. Some of these measurements were motivated by two observed anomalies in the antineutrino spectra. The reactor anomaly (RAA), first, was observed in 2011 as a deficit in the reactor antineutrino flux...
The DESIR low-energy beam facility is dedicated to nuclear physics, astrophysics, and fundamental interaction studies using exotic nuclei provided by the SPIRAL1 and S3 production sites of GANIL-SPIRAL2. The commissioning of beam preparation devices is ongoing at LP2iB, where a high-resolution mass-separator (HRS-1P) and a double Penning trap (PIPERADE) coupled to a RFQ cooler and buncher...
The DESIR facility at GANIL will receive neutron-deficient ion beams produced by fusion evaporation at S3 (Super Separator Spectrometer) and exotic light nuclei produced by fragmentation at SPIRAL1. DESIR* is an experimental hall dedicated to the study of nuclear structure, astrophysics and weak interaction using beta decay spectroscopy, laser spectroscopy and trap-based experiments at low...
The use of exotic states of matter allows us to probe the underlying symmetries of the universe to ever greater precision and expose shortcomings of the Standard Model of particle physics (SM), arguably the most successful physical theory created to date. Radioactive ion beams (RIB), in particular, significantly expand the number of available experimental systems to address the SM's lack of...
Around us we see an universe filled with galaxies, stars and planets like ours. But when we look back to the Big Bang and the processes that created the matter in it, at first we observe that there should have been created the same amount of matter and antimatter, thus the universe would be empty or different than it is. Sakharov proposed several mechanisms to explain the matter-antimatter...
The neutron lifetime discrepancy between beam and bottle experiments of 4σ could be interpreted as a possible sign of the neutron decaying into dark particles [1]. If such a decay exists, it could also occur in unstable nuclei with sufficiently low neutron binding energy, a quasi-free neutron decay into a dark matter particle χ; as is the case of 6He with S2n = 975.45keV < mn −mχ [2]. This...
For several years, many radionuclides (RN) are routinely used in nuclear medicine either for imaging ($\gamma$ and $\beta^+$ or positron) or for therapy ($\alpha$, $\beta^–$, Auger electron emitters). They are most-often administered in the form of a radiopharmaceutical, composed of the selected RN and a targeting unit (nanoparticles or biological vectors, like peptides or antibodies)...
The REPARE ANR project aims at developping a high power targetry to optimize the production of the promising alpha emitter $^{211}$At in the $^{4}$He($^{209}$Bi,2n)$^{211}$At fusion-evaporation reaction. For this, a first task is the precise measurements of several cross-sections to control the production of potential contaminants and to optimize the synthesis of $^{211}$At. Several...
Targeted Alpha Therapy (TAT) offers a promising approach to treat cancer, particularly micrometastases, by utilizing the short range of alpha particles and their high linear energy transfer. Astatine-211, which belongs to the halogen family also shares chemical properties with Iodine, a radioisotope commonly used for imaging and also widely used to treat thyroid cancer. This similarity enables...
Multi-Nucleon Transfer (MNT) reactions is a useful mechanism, to perform nuclear structure studies in nuclei moderately far from stability line. Moreover, MNT allows to directly populate the low lying states in the reaction products.
The development of set-ups involving high acceptance tracking magnetic Spectrometers as VAMOS++ [1], coupled with the Advanced GAmma Tracking Array (AGATA) [2]...
Nuclear radii and densities are key quantities that naturally bridge nuclear structure and reactions and open a window towards a detailed understanding of the nuclear interaction within a given theoretical framework. Long restricted to light systems due to model-space convergence limitations as well as interactions deficiencies, recent progress on both accounts now allow for accurate ab initio...
In the last decade, a considerable progress in the understanding of the structure of nuclei in the vicinity of 132Sn, the heaviest doubly-magic nucleus far-off stability accessible for experimental studies, was achieved. The vast amount of results obtained in several experimental campaigns performed at the Radioactive Isotope Beam Facility (RIBF) in Japan, in combination with state-of-the-art...
The study of the structure of neutron-deficient actinides is of particular interest since several theoretical calculations predict strong octupole deformations in this region of the nuclear chart [1, 2, 3]. However experimental data are scarce due to very low production rates.
There is an ongoing program at the IGISOL (Ion Guide Isotope Separation On-Line) facility, University of Jyväskylä,...
The superconducting LINAC (LINear ACcelerator) of SPIRAL2-GANIL will deliver very intense heavy-ion beams up to uranium by virtue of the additional NEWGAIN (NEW GAnil Injector) with mass to charge ratio (A/Q = 7)[1]. The S$^3$ (Super Separator Spectrometer) of SPIRAL2 was designed to have high transmission, high beam rejection and high mass resolving power capabilities to study rare isotopes...
Systems far from $\beta$ stability are good candidates for solving nuclear structure anomalies in such exotic regions and for the improvement of our knowledge about $NN$ interaction. Odd zirconium isotopes, lay from proton drip-line to neutron one, provide encouraging opportunities to progress nuclear model development. This work aims to investigate the odd $^{77-89}Zr$ isotopes in $^{78}Ni$...
Despite major and numerous recent progresses in \textit{ab initio} calculations, it is not yet possible to describe ground state nuclear properties over the whole chart with this approach. Therefore, Energy Density Functionals remain the tool of choice to such end so far. If one wishes then to build a functional with free parameters suited for astrophysical applications, one must \textit{at...
SPIRAL2/NFS is equipped with a the system for irradiation by charged particles and subsequent measurements of activation. The IC (Irradiation Chamber) and PTS (Pneumatic Transfer System) allow for cross-section measurements of short-lived isotopes produced on LINAC charged particle beams. Experiments on proton and deuteron beams were performed with Fe and Mo samples, respectively. Current...
The mutli-reflection time-of-flight mass spectrograph (MRTOF-MS) has proven to be a valuable tool for online atomic mass measurements. We have shown it to be capable of approaching $R_m$=10$^6$ with measurements times $t<20$ ms, allowing high-precision determinations of the masses of even very short-lived species. The MRTOF-MS has been shown to be a particularly powerful tool for online...
The electric dipole (E1) and magnetic dipole (M1) excitations of nuclei are excellent probes to study the nuclear structure and dynamics from both experimental and theoretical point of view. Also, the behavior of dipole excitations is known to be highly sensitive to extreme conditions of temperature and neutron excess [1-4]. In this work, the finite temperature relativistic quasiparticle...
Recent advancements in active target detectors, enabling the detection gas to act as a target for nuclear reactions, have provided a significant boost to the exploration of nuclei near the drip lines and the exotic nuclear phenomena associated with them. ACTAR-TPC at GANIL is a novel detector of such kind that can construct a 3-D mapping of the decay or reaction products from two-dimensional...
This research is focused on studying nuclear structure in the A ~ 100 region, with a particular emphasis on the N ~ 56 isotone group. The presence of the h11/2 intruder orbital in this group significantly impacts the nuclear shape. The main goal of this study is to investigate the existence of a two-quasi-neutron octupole band within this isotone group.
For this purpose, fusion-evaporation...
In reactors, oxygen is present in abundance in the form of water, and/or in the form of oxide in the fuel used (in the case of Pressurised Water Reactors and Fast Reactors). These oxygen nuclei are responsible for 25% of helium formation in nuclear reactors due to the reaction 16O(n,α)13C. However, this reaction still shows significant discrepancies between experimental and evaluated data that...
Study of exotic nuclei interesting for applied and fundamental nuclear physics with Total Absorption Gamma Spectroscopy (TAGS)
*J.Pépin¹⁾ ²⁾ for the IGISOL I241 collaboration
1) IFIC, CSIC Spain
2) SUBATECH, CNRS/IN2P3, IMT-Atlantique, Nantes Université, France
jpepin@subatech.in2p3.fr
Abstract: Beta decay of neutron rich nuclei is particularly important...
The study of nuclear fission [1] plays a crucial role in understanding the fundamental aspects of nuclear physics and holds significant applications across various fields, including power production, space exploration, and the synthesis of radioisotopes for medical applications. In the ongoing fission campaign at the VAMOS++ facility [2], located at GANIL, we investigate the phenomenon of...
NUMEN proposes to measure the absolute cross section of Double Charge Exchange reactions in nuclei of interest for the 0νββ decay since the two processes present important similarities even if they are mediated by different interactions. The existing large acceptance spectrometer MAGNEX has been used for pilot runs with $^{20}$Ne and $^{18}$O beams provided from the existing cyclotron at...
The fusion probability for the production of superheavy nuclei (SHN) in cold fusion reactions (1n channel) on $^{208}$Pb and $^{209}$Bi targets drops by approximately five orders of magnitude, from $10^{-1}$ to $10^{-6}$, with the change of projectile atomic number from 20 (Ca) to 30 (Zn). Recent experimental results for reactions induced on $^{20 8}$Pb target by $^{48}$Ca, $^{50}$Ti, and...
