Study of proton-unbound states in 24Al^{24}{\rm Al} relevant for the 23Mg(p,γ)^{23}{\rm Mg}(p,\gamma) reaction in novae

Background: The nucleosynthesis of several proton-rich nuclei is determined by radiative proton-capture reactions on unstable nuclei in nova explosions. One such reaction is $^{23}{\rm Mg}(p,\gamma)^{24}{\rm Al}$, which links the NeNa and MgAl cycles in oxygen-neon (ONe) novae. Purpose: To extract $^{23}{\rm Mg}(p,\gamma)^{24}{\rm Al}$ resonance strengths from a study of proton-unbound states in $^{24}{\rm Al}$, produced via the $^{24}$Mg($^{3}$He,$t$) reaction. Methods: A beam of $^3 {\rm He}^{2+}$ ions at 50.7 MeV was used to produce the states of interest in $^{24}$Al. Proton-triton angular correlations were measured with a $K=600$ QDD magnetic spectrometer and a silicon detector array, located at iThemba LABS, South Africa. Results: We measured the excitation energies of the four lowest proton-unbound states in $^{24}$Al and place lower-limits on $\Gamma_p/\Gamma$ values for these four states. Together with USD-C shell-model calculations of partial gamma widths, the experimental data are also used to determine resonance strengths for the three lowest $^{23}{\rm Mg}(p,\gamma)^{24}{\rm Al}$ resonances. Conclusions: The energy of the dominant first $^{23}{\rm Mg}(p,\gamma)$ resonance is determined to be $E_{r} = 481.4 \pm 1.1$ keV, with a resonance strength $\omega \gamma = 18 \pm 6$ meV

From the stable to the exotic: clustering in light nuclei

A great deal of research work has been undertaken in alpha-clustering study since the pioneering discovery of 12C+12C molecular resonances half a century ago. Our knowledge on physics of nuclear molecules has increased considerably and nuclear clustering remains one of the most fruitful domains of nuclear physics, facing some of the greatest challenges and opportunities in the years ahead. The occurrence of "exotic" shapes in light N=Z alpha-like nuclei is investigated. Various approaches of the superdeformed and hyperdeformed bands associated with quasimolecular resonant structures are presented. Evolution of clustering from stability to the drip-lines is examined: clustering aspects are, in particular, discussed for light exotic nuclei with large neutron excess such as neutron-rich Oxygen isotopes with their complete spectroscopy.Comment: 15 pages, 5 figures, Presented at the International Symposium on "New Horizons in Fundamental Physics - From Neutrons Nuclei via Superheavy Elements and Supercritical Fields to Neutron Stars and Cosmic Rays" held at Makutsi Safari Farm, South Africa, December 23-29, 2015. arXiv admin note: substantial text overlap with arXiv:1402.6590, arXiv:1303.0960, arXiv:1408.0684, arXiv:1011.342

Recent results on Heavy-Ion induced reactions of interest for 0νββ decay

An updated overview of recent results on Heavy-Ion induced reactions of interest for neutrinoless double beta decay is reported in the framework of the NUMEN project. The NUMEN idea is to study heavy-ion induced Double Charge Exchange (DCE) reactions with the aim to get information on the nuclear matrix elements for neutrinoless double beta (0νββ) decay. Moreover, to infer the neutrino average masses from the possible measurement of the half- life of 0νββ decay, the knowledge of the nuclear matrix elements is a crucial aspec

Recent results on heavy-ion direct reactions of interest for 0νββ decay at INFN LNS

Neutrinoless double beta decay of nuclei, if observed, would have important implications on fundamental physics. In particular it would give access to the effective neutrino mass. In order to extract such information from 0νββ decay half-life measurements, the knowledge of the Nuclear Matrix Elements (NME) is of utmost importance. In this context the NUMEN and the NURE projects aim to extract information on the NME by measuring cross sections of Double Charge Exchange reactions in selected systems which are expected to spontaneously decay via 0νββ. In this work an overview of the experimental challenges that NUMEN is facing in order to perform the experiments with accelerated beams and the research and development activity for the planned upgrade of the INFN-LNS facilities is reported

Dosimetry and calorimetry performance of a scientific CMOS camera for environmental monitoring

This paper explores the prospect of CMOS devices to assay lead in drinking water, using calorimetry. Lead occurs together with traces of radioisotopes, e.g.,210 Pb, producing γ-emissions with energies ranging from 10 keV to several 100 keV when they decay; this range is detectable in silicon sensors. In this paper we test a CMOS camera (OXFORD INSTRUMENTS Neo 5.5) for its general performance as a detector of X-rays and low energy γ-rays and assess its sensitivity relative to the World Health Organization upper limit on lead in drinking water. Energies from 6 keV to 60 keV are examined. The CMOS camera has a linear energy response over this range and its energy resolution is for the most part slightly better than 2%. The Neo sCMOS is not sensitive to X-rays with energies below ∼ 10 keV. The smallest detectable rate is 40 ± 3 mHz, corresponding to an incident activity on the chip of 7 ± 4 Bq. The estimation of the incident activity sensitivity from the detected activity relies on geometric acceptance and the measured efficiency vs. energy. We report the efficiency measurement, which is 0.08(2)% (0.0011(2)%) at 26.3 keV (59.5 keV). Taking calorimetric information into account we measure a minimal detectable rate of 4 ± 1 mHz (1.5 ± 0.1 mHz) for 26.3 keV (59.5 keV) γ-rays, which corresponds to an incident activity of 1.0 ± 0.6 Bq (57 ± 33 Bq). Toy Monte Carlo and Geant4 simulations agree with these results. These results show this CMOS sensor is well-suited as a γ-and X-ray detector with sensitivity at the few to 100 ppb level for210 Pb in a sample

Population Parameters of Triatoma spinolai (Heteroptera: Reduviidae) under Different Environmental Conditions and Densities

Population parameters of Triatoma spinolai Porter were studied using specimens collected in the north and central region of Chile. Two cohorts of 17 and 44 first instars were maintained at a constant temperature of 28°C and 70% RH. Two similar cohorts of bugs were exposed to 16-24°C and 55-75% RH and maintained under a photoperiod of 14:10 (L:D) h for 16 mo. The preimaginal period ranged between 285 and 372 d under constant conditions. The lower-density cohort required 9.5 mo to reach the adult stage compared with 12.4 mo for the high-density cohort. Bugs placed under variable temperature and relative humidity conditions did not survive long. Cohorts with higher densities had similar mortality rates with greater mortality occuring in cohorts that had lower numbers of bugs. Cohorts under constant temperature and relative humidity reproduced and basic reproduction rates (Ro, intrinsic growth rate [r], and generation time [G]) were estimated. Cohorts with higher numbers of bugs had highe

Laser joining of different polymer-metal configurations : analysis of mechanical performance and failure mechanisms

International audienceDirect thermal laser joining of plastic and metallic materials is nowadays arising as an alternative technology for the generation of hybrid joints. The focus of this study is on analyzing the mechanical behavior and failure mechanisms of three polymer-metal configurations: lap, T and Arcan joint configurations. The metal was locally structured by pulsed laser radiation producing micro-patterns to improve adhesion of the polymeric part. Two micro-patterns were considered: low and high distance between pattern centers. Secondly, the opposite side of the micro-structured metal was irradiated by a Continuous Wave (CW) fibre laser to achieve the mechanical interlock between the two materials.The mechanical performance of lap, T and Arcan joint configurations was assessed by tensile-shear, pull-out and Arcan tests respectively. A comprehensive inspection of the interface was carried out after the mechanical tests. The mechanical performance revealed a meaningful influence of the distance between patterns for the three joint configurations. Furthermore, the Arcan results evidenced a meaningful influence of the angle between the joining plane and the orientation of the applied load. The morphological features of the detached surfaces showed different failure modes depending on the join configuration

Laser joining of different polymer-metal configurations : analysis of mechanical performance and failure mechanisms

International audienceDirect thermal laser joining of plastic and metallic materials is nowadays arising as an alternative technology for the generation of hybrid joints. The focus of this study is on analyzing the mechanical behavior and failure mechanisms of three polymer-metal configurations: lap, T and Arcan joint configurations. The metal was locally structured by pulsed laser radiation producing micro-patterns to improve adhesion of the polymeric part. Two micro-patterns were considered: low and high distance between pattern centers. Secondly, the opposite side of the micro-structured metal was irradiated by a Continuous Wave (CW) fibre laser to achieve the mechanical interlock between the two materials.The mechanical performance of lap, T and Arcan joint configurations was assessed by tensile-shear, pull-out and Arcan tests respectively. A comprehensive inspection of the interface was carried out after the mechanical tests. The mechanical performance revealed a meaningful influence of the distance between patterns for the three joint configurations. Furthermore, the Arcan results evidenced a meaningful influence of the angle between the joining plane and the orientation of the applied load. The morphological features of the detached surfaces showed different failure modes depending on the join configuration

Effect of gestational and postnatal environmental temperature on metabolic rate in the altricial rodent, Phyllotis darwini

1.In the altricial rodent, Phyllotis darwini, we found higher body temperatures and faster developmental rates of the thermoregulatory capacity in neonates born from cold- than warm-acclimated mothers.2.This difference could be explained by maternal effects on the litter, such as high levels of catecholamines and thyroxin levels, high concentration of the uncoupled protein and larger quantity of brown adipose tissue as a consequence of cold acclimation.3.The exposition of mothers and the maintenance of cold condition during the early development might be responsible of the high metabolism and better thermoregulatory capacity of newborns. © 2009 Elsevier Ltd. All rights reserved