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Study of gap evolution around : new structure information for Ge
No full textInternational audienceMedium spin states of light N = 50 isotones have been populated using fast neutron-induced fission of Th. Online prompt spectroscopy has been performed using the hybrid spectrometer Ball coupled to the LICORNE directional neutron source at the ALTO facility of IJCLab. Medium spin states of the neutron-rich nucleus Ge have been investigated using - and -- coincidence data to exploit the resolving power of Ball. Two new transitions were assigned to this nucleus and a new level was placed in the level scheme. We tentatively assigned to this new state a () spin-parity, which is interpreted as a new core breaking state. This provides further insight into the energy evolution of the shell gap toward Ni
System size dependence of hadronic rescattering effect at LHC energies
No full textInternational audienceThe first measurements of resonance production as a function of charged-particle multiplicity in XeXe collisions at 5.44 TeV and pp collisions at 5.02 TeV using the ALICE detector are presented. The resonance is reconstructed at midrapidity () using the hadronic decay channel . Measurements of transverse-momentum integrated yield, mean transverse-momentum, nuclear modification factor of , and yield ratios of resonance to stable hadron (/K) are compared across different collision systems (pp, pPb, XeXe, and PbPb) at similar collision energies to investigate how the production of resonances depends on the size of the system formed in these collisions. The hadronic rescattering effect is found to be independent of the size of colliding systems and mainly driven by the produced charged-particle multiplicity, which is a proxy of the volume of produced matter at the chemical freeze-out. In addition, the production yields of in XeXe collisions are utilized to constrain the dependence of the kinetic freeze-out temperature on the system size using HRG-PCE model
Probing Earth's Missing Potassium using the Unique Antimatter Signature of Geoneutrinos
No full textInternational audienceThe formation of the Earth remains an epoch with mysterious puzzles extending to our still incomplete understanding of the planet's potential origin and bulk composition. Direct confirmation of the Earth's internal heat engine was accomplished by the successful observation of geoneutrinos originating from uranium (U) and thorium (Th) progenies, manifestations of the planet's natural radioactivity dominated by potassium (40K) and the decay chains of uranium (238U) and thorium (232Th). This radiogenic energy output is critical to planetary dynamics and must be accurately measured for a complete understanding of the overall heat budget and thermal history of the Earth. Detecting geoneutrinos remains the only direct probe to do so and constitutes a challenging objective in modern neutrino physics. In particular, the intriguing potassium geoneutrinos have never been observed and thus far have been considered impractical to measure. We propose here a novel approach for potassium geoneutrino detection using the unique antimatter signature of antineutrinos to reduce the otherwise overwhelming backgrounds to observing this rarest signal. The proposed detection framework relies on the innovative LiquidO detection technique to enable positron (e+) identification and antineutrino interactions with ideal isotope targets identified here for the first time. We also provide the complete experimental methodology to yield the first potassium geoneutrino discovery
Measurement of Non-prompt -meson Elliptic Flow in Pb-Pb Collisions at = 5.02 TeV
No full textInternational audienceThe elliptic flow () of mesons from beauty-hadron decays (non-prompt ) was measured in midcentral (30-50%) Pb-Pb collisions at a centre-of-mass energy per nucleon pair = 5.02 TeV with the ALICE detector at the LHC. The mesons were reconstructed at midrapidity () from their hadronic decay , in the transverse momentum interval GeV/. The result indicates a positive for non-prompt mesons with a significance of 2.7. The non-prompt -meson is lower than that of prompt non-strange D mesons with 3.2 significance in GeV/, and compatible with the of beauty-decay electrons. Theoretical calculations of beauty-quark transport in a hydrodynamically expanding medium describe the measurement within uncertainties
Equation of State, Compressibility, and Vibrational Properties of Brucite over Wide Pressure and Temperature Ranges: Atomistic Computer Simulations with the Modified ClayFF Classical Force Field
No full textInternational audienceThe behavior of brucite over wide ranges of temperatures and pressures is of great interest for fundamental geochemistry and geophysics. Brucite layers and their octahedral Mg(OH)6 structural units constitute an important structural part of layered dense magnesium hydrous silicates (DMHS), which play a major role in mineral equilibria controlling water balance in the subduction zones of the upper mantle. The ClayFF force field was originally developed for atomistic computer simulations of clays and other layered minerals and their hydrated interfaces. The crystallographic parameters of brucite at 25 °C and 1 bar were used, among several others, to develop the original ClayFF parametrization. Its new recent modification, ClayFF-MOH, can more accurately account for the bending of Mg–O–H angles in the brucite structure, and it was used here to test the applicability of this simple classical model over very wide ranges of temperature and pressure well beyond the range of its original implementation (up to 600 °C and 15 GPa). The pressure and temperature dependencies of brucite crystallographic parameters, the compressibility of the crystal lattice, the coefficients of thermal expansion, and the vibrational spectra were calculated in a series of classical molecular dynamics simulations using the ClayFF-MOH model and compared with a diverse set of available experimental data, including X-ray diffractometry, neutron scattering, IR and Raman spectroscopy. These new results demonstrated that ClayFF-MOH, as simple and approximate as it is, can be quite accurate in predicting many mineral properties at subduction zone conditions, which greatly expands the area of its applicability.</jats:p
Homogeneous Molten Salt Reactors (MSRs): The Molten Salt Fast Reactor (MSFR) concept
No full textInternational audienceLiquid-fueled reactors exhibit unusual and interesting properties compared to solid-fueled reactors, requesting a revision of some well-known conception and safety rules. Emphasis is thus put in this chapter on such differences and the need for innovative approaches with the focus on homogeneous molten salt reactors. The molten salt fast reactor concept, where the circulating fuel also plays the role of coolant and based on a fast neutron spectrum, is seen as a long-term alternative to solid-fueled fast reactors. It fulfills the Generation-IV criteria and is studied since a decade mainly by calculations and determination of basic physical and chemical properties in European Union and Russian Federation. The main characteristics of this concept are presented and discussed including transient simulation,
Measurements of the 161Tb production cross section for nuclear data and nuclear medicine
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Latest development of α emitter imaging and quantification on a large Field Of View for Targeted Alpha Therapy applications
No full textInternational audienceIntroductionAlthough very promising, the development of Targeted Alpha Therapy (TAT) requires the use of accurate techniques that can identify and quantify individual radionuclides in different matrices. However, currently, characterization of the nature and spatial distribution of radionuclides in a sample is time consuming and fastidious. Indeed, it necessarily requires the use of two distinct analytical techniques and detectors of different nature. Moreover, the resolutions of the two methods are often different from each other because they also depend on the nature of the detector used, which makes it difficult to integrate and interpret these two types of measurements together. To overcome these limitations, as well as to simplify and to accelerate the measurement process, it is now possible to use a digital autoradiograph capable of combining the measurement of the spatial distribution with the ability to separate and quantify each radionuclide.Description of the Work or ProjectFor this purpose, a set of temporal and energy spectrometry techniques had to be specifically developed. On the one hand, the use of instruments capable of recording the location of each decay product allows to measure the evolution of the activity of the sample and thus, to deduce the contributions of several radionuclides. On the other hand, the development of an innovative method of autoradiography spectroscopy in particle energy also allows to separate them by measuring their initial energy. Even if the efficiency of energy spectrum reconstruction is low (<5%) compared to the efficiency of a simple autoradiograph (50%), this novel measurement approach offers the opportunity to select areas on an autoradiograph to perform an energy spectrum analysis within that area. Although if the samples usable on this type of instrument must generally be of solid nature, recent developments show that it is possible to use fluid samples (liquid or gas) with a cell system. Eventually, the proposed measurement system could allow dynamic imaging of radionuclides of interest.ConclusionsFrom an application point of view, this opens up possibilities for theragnostic applications that typically use two radionuclides. Further upstream, it can optimize the production and distribution challenge of α radionuclides by allowing the identification and characterization of individual radionuclides in radionuclide chains such as 225Ac. Moreover, the measurement system and the associated method could strongly contribute to facilitate research on the biodistribution of α radionuclides.ReferencesLefeuvre, H., Donnard, J., Descostes, M., Billon, S., Duval, S., Oger, T., Toubon, H. & Sardini, P. (2022). Spectroscopic Autoradiography of Alpha Particles Using a Parallel Ionization Multiplier Gaseous Detector. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. https://doi.org/10.1016/j.nima.2022.16680
Development of a high pressure single-anode radial TPC for the search of 2β0ν decays
No full textInternational audienceThe objective of R&D R2D2 is to develop a very simple TPC filled with pressurized xenon for the search of neutrinoless double beta decays (2β0ν). After a quick experimental assessment of the developments made by the international community, the latest instrumental progress made by R2D2 are presented. In particular, we tested several chamber concepts (spherical (SPC) or cylindrical (CPC) geometries) with an argon-methane gas mixture at pressures up to 8 bars. We report the results obtained in ionization and proportional modes, especially in terms of signal shape and energy resolution. Furthermore, based on both an in-house simulation for the signal formation and our experimental observations, we have studied the possibilities of localization and discrimination of the interaction tracks within these detectors. Future developments are also presented
Heavy flavor production in the Parton-Hadron-String Dynamics (PHSD)
No full textInternational audienceRelativistic heavy-ion collisions produce a hot and dense nuclear matter, through which one can study the phase diagram of QCD. Open and hidden heavy flavors are promising probes to search for the properties of the hot and dense nuclear matter under extreme conditions. We present how the production and interactions of open and hidden heavy flavors in heavy-ion collisions are realized in the Parton-Hadron-String Dynamics, which is a non-equilibrium microscopic transport approach for the description of the dynamics of strongly interacting hadronic and partonic matter