Etude des réactions de transfert induites par un faisceau de 16C

Recent experiments have evidenced the existence of new shell gaps at N=14 and 16 in the neutron-rich oxygen isotopes, associated with the vanishing of the N=20 shell gap. The aim of this work is to investigate the possible appearance of these new magic numbers in the neutron-rich carbon isotopes by locating the 0d5/2, 1s1/2 and 0d3/2 neutron orbitals in 17C with the 16C(d,p)17C transfer reaction.The experiment was carried out at the GANIL facility. A 16C beam at 17.2 AMeV produced by fragmentation was used to bombard a CD2 target. The light ejectiles were detected using the TIARA silicon strip array while a Si-Si-CsI telescope was placed at 0 degree to identify beam-like residues. In addition, four HPGe EXOGAM clover detectors were used to measure the gamma-rays emitted by 17C bound excited states.The measured angular distributions confirm the spin and parity assignments of 3/2+, 1/2+ and 5/2+ for the ground state and the first and second excited states located at 217 keV and 335 keV, respectively. The spectroscopic factors deduced for these excited states indicate a large single particle strength, in agreement with shell model calculations. On the other hand, the spectroscopic factor of the ground state reveals an important 0d3/2 component, largely underestimated by the shell model. With a strong ℓ=0 valence neutron configuration and a low separation energy, the first excited state of 17C appears as a very good one-neutron halo candidate.La disparition du nombre magique N=20 et l'apparition des nouveaux nombres magiques N=14 et 16 ont été observées dans les isotopes d'oxygène riches en neutrons. L'objectif de ce travail est d'étudier la présence éventuelle de ces nouveaux nombres magiques dans les isotopes de carbone riches en neutrons en localisant les orbitales de neutron 0d5/2, 1s1/2 et 0d3/2 dans le 17C à l'aide de la réaction de transfert 16C(d,p)17C.Dans notre expérience réalisée au GANIL, les états du 17C ont été peuplés par la réaction de transfert 16C(d,p)17C induite par un faisceau de 16C d'énergie 17,2 AMeV incident sur une cible de CD2. Le détecteur à pistes silicium TIARA a été utilisé pour détecter les particules légères, tandis qu'un télescope Si-Si-CsI a été placé à 0 degré pour identifier les fragments lourds. Quatre détecteurs HPGe EXOGAM ont été utilisés pour détecter les photons γ émis par les états excités liés du 17C.Les distributions angulaires confirment les spins et parités 3/2+, 1/2+ et 5/2+ pour l'état fondamental et les premier et deuxième états excités observés à des énergies d'excitation de 217 et 335 keV respectivement. Les facteurs spectroscopiques déduits pour ces états excités indiquent un caractère de particule indépendante marqué, en accord avec les calculs du modèle en couches. En revanche, le facteur spectroscopique de l'état fondamental révèle une composante 0d3/2 importante, nettement sous estimée par le modèle en couches. Du fait de sa faible énergie de séparation et de sa configuration ℓ=0 dominante, le premier état excité du 17C apparaît comme un très bon candidat d’état à halo d'un neutron

FKBP5 expression in human adipose tissue : potential role in glucose and lipid metabolism, adipogenesis and type 2 diabetes

Purpose Here, we explore the involvement of FKBP51 in glucocorticoid-induced insulin resistance (IR) in human subcutaneous adipose tissue (SAT), including its potential role in type 2 diabetes (T2D). Moreover, we assess the metabolic effects of reducing the activity of FKBP51 using the specific inhibitor SAFit1. Methods Human SAT was obtained by needle biopsies of the lower abdominal region. FKBP5 gene expression was assessed in fresh SAT explants from a cohort of 20 T2D subjects group-wise matched by gender, age and BMI to 20 non-diabetic subjects. In addition, human SAT was obtained from non-diabetic volunteers (20F/9M). SAT was incubated for 24 h with or without the synthetic glucocorticoid dexamethasone and SAFit1. Incubated SAT was used to measure the glucose uptake rate in isolated adipocytes. Results FKBP5 gene expression levels in SAT positively correlated with several indices of IR as well as glucose area under the curve during oral glucose tolerance test (r = 0.33, p < 0.05). FKBP5 gene expression levels tended to be higher in T2D subjects compared to non-diabetic subjects (p = 0.088). Moreover, FKBP5 gene expression levels were found to inversely correlate with lipolytic, lipogenic and adipogenic genes. SAFit1 partly prevented the inhibitory effects of dexamethasone on glucose uptake. Conclusions FKBP5 gene expression in human SAT tends to be increased in T2D subjects and is related to elevated glucose levels. Moreover, FKBP5 gene expression is inversely associated with the expression of lipolytic, lipogenic and adipogenic genes. SAFit1 can partly prevent glucose uptake impairment by glucocorticoids, suggesting that FKBP51 might be a key factor in glucocorticoid-induced IR

Study on the application of SiPM to γ ray and charged particle measurement using scintillation crystals

The characteristics of a Silicon Photo Multiplier (SiPM)-based scintillation detector system were studied. The influence of the bias voltage and the number of SiPMs on the energy resolution was identified. The single SiPM energy spectra in the multi-SiPM system showed their dependency on the position of the 60Co radiation source. The application of geometric mean on the multi-SiPM system was also considered to bypass single channel calibrations. Preliminary results on the performances of developing scintillation detectors with a CsI(Tl) crystal or a plastic scintillator are demonstrated. The capability of charged particle measurement for CsI(Tl) crystal and sub-nanosecond timing resolution of plastic scintillator were identified. © 2023 Elsevier B.V.11Nsciescopu

Development of the STARK detector for nuclear reaction studies

Silicon Telescope Array for Reaction studies in inverse Kinematics, STARK, is under development at the Center for Exotic Nuclear Studies to perform nuclear reaction experiments including elastic scattering and neutron transfer reaction. The array consists of 40 double-sided, resistive silicon strip detectors and 12 single-sided, non-resistive strip detectors, and they form three rings covering a large angular range. The expected angular resolution is less than 1°, and the angular coverage of polar angles is 43–78° and 105–150° in the lab frame. The GET (General Electronics for Time projection chamber project) electronics system is used to handle about 1000 channels from detectors. Several elastic scattering experiments are considered as the commissioning of the STARK at KoBRA in the early stage of RAON. © 2023 Elsevier B.V.11Nsciescopu

Search for Weak Side Branches in the Electromagnetic Decay Paths of the 6526-keV 10+ Isomer in 54Fe

High-spin nuclear isomers in (Formula presented.) nuclei between doubly magic (Formula presented.) Ca and (Formula presented.) Ni provide an excellent testing ground for the nuclear shell model and questions related to isospin symmetry breaking in the vicinity of the proton drip line. The purpose of the present study is to investigate the possibility of weak electromagnetic decay branches along the decay paths of the 6526-keV (Formula presented.) isomer in (Formula presented.) Fe. The isomer was strongly populated by means of the fusion-evaporation reaction (Formula presented.) Mg((Formula presented.) Ar, (Formula presented.)) (Formula presented.) Fe. The Gammasphere array was used to detect (Formula presented.) -ray cascades emitted from the isomeric state. By means of (Formula presented.) coincidences, weak non-yrast decay branches can be discriminated, with the isomer’s half-life confirmed at (Formula presented.) ns. The yrast (Formula presented.)   (Formula presented.) cross-over transition was interrogated. The observations are compared with shell-model calculations