HAL Mines Nantes
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    7271 research outputs found

    Imaging of single barium atoms in a second matrix site in solid xenon for barium tagging in a 136^{136}Xe double beta decay experiment

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    HAL CCSD
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    International audienceNeutrinoless double beta decay is one of the most sensitive probes for new physics beyond the Standard Model of particle physics. One of the isotopes under investigation is 136^{136}Xe, which would double beta decay into 136^{136}Ba. Detecting the single 136^{136}Ba daughter provides a sort of ultimate tool in the discrimination against backgrounds. Previous work demonstrated the ability to perform single atom imaging of Ba atoms in a single-vacancy site of a solid xenon matrix. In this paper, the effort to identify signal from individual barium atoms is extended to Ba atoms in a hexa-vacancy site in the matrix and is achieved despite increased photobleaching in this site. Abrupt fluorescence turn-off of a single Ba atom is also observed. Significant recovery of fluorescence signal lost through photobleaching is demonstrated upon annealing of Ba deposits in the Xe ice. Following annealing, it is observed that Ba atoms in the hexa-vacancy site exhibit antibleaching while Ba atoms in the tetra-vacancy site exhibit bleaching. This may be evidence for a matrix site transfer upon laser excitation. Our findings offer a path of continued research toward tagging of Ba daughters in all significant sites in solid xenon

    Need for precise nuclear structure data for reactor studies

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    EDP Sciences
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    International audienceThis paper highlights the strong need for precise nuclear structure and decay data measurements in order to perform high-quality modelling on nuclear reactors and other applications. The context of nuclear data evaluation, as well as the importance of low uncertainty evaluations, will be first presented. The importance of such data for interpreting nuclear data experimental measurements is stressed throughout. To demonstrate this, we will explain how mass and charge-dependent fission yields, decay data (in particular for the purpose of residual heat calculations), and inelastic neutrons scattering cross section rely on nuclear structure and decay information and how new and higher quality in such data can lead to improved accuracy in the precision of evaluated nuclear data

    Supernova Electron-Neutrino Interactions with Xenon in the nEXO Detector

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    HAL CCSD
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    International audienceElectron-neutrino charged-current interactions with xenon nuclei were modeled in the nEXO neutrinoless double-beta decay detector (~5-tonne, 90% 136{}^{136}Xe, 10% 134{}^{134}Xe) to evaluate its sensitivity to supernova neutrinos. Predictions for event rates and detectable signatures were modeled using the MARLEY event generator. We find good agreement between MARLEY's predictions and existing theoretical calculations of the inclusive cross sections at supernova neutrino energies. The interactions modeled by MARLEY were simulated within the nEXO simulation framework and were run through an example reconstruction algorithm to determine the detector's efficiency for reconstructing these events. The simulated data, incorporating the detector response, were used to study the ability of nEXO to reconstruct the incident electron-neutrino spectrum and these results were extended to a larger xenon detector of the same isotope enrichment. We estimate that nEXO will be able to observe electron-neutrino interactions with xenon from supernovae as far as 5 to 8 kpc from earth, while the ability to reconstruct incident electron-neutrino spectrum parameters from observed interactions in nEXO is limited to closer supernovae

    Isospin diffusion from 40,48^{40,48}Ca+40,48+^{40,48}Ca experimental data at Fermi energies: Direct comparisons with transport model calculations

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    American Physical Society
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    International audienceThis article presents an investigation of isospin equilibration in cross-bombarding 40,48^{40,48}Ca+40,48+^{40,48}Ca reactions at 35 MeV/nucleon, by comparing experimental data with filtered transport model calculations. Isospin diffusion is studied using the evolution of the isospin transport ratio with centrality. The asymmetry parameter δ=(N−Z)/A\delta=(N-Z)/A of the quasiprojectile (QP) residue is used as isospin-sensitive observable, while a recent method for impact parameter reconstruction is used for centrality sorting. A benchmark of global observables is proposed to assess the relevance of the antisymmetrized molecular dynamics (AMD) model, coupled to GEMINI++, in the study of dissipative collisions. Our results demonstrate the importance of considering cluster formation to reproduce observables used for isospin transport and centrality studies. Within the AMD model, we prove the applicability of the impact parameter reconstruction method, enabling a direct comparison to the experimental data for the investigation of isospin diffusion. For both, we evidence a tendency to isospin equilibration with an impact parameter decreasing from 9 to 3 fm, while the full equilibration is not reached. A weak sensitivity to the stiffness of the equation of state employed in the model is also observed, with a better reproduction of the experimental trend for the neutron-rich reactions

    Measurement of the production cross section of prompt Ξc0\Xi^0_{\rm c} baryons in p−-Pb collisions at sNN = 5.02\sqrt{s_{\mathrm{NN}}}~=~5.02 TeV

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    HAL CCSD
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    International audienceThe transverse momentum (pTp_{\rm T}) differential production cross section of the promptly-produced charm-strange baryon Ξc0\Xi_{\rm c}^{0} (and its charge conjugate Ξc0‾\overline{\Xi_{\rm c}^{0}}) is measured at midrapidity via its hadronic decay into π+Ξ−{\rm \pi^{+}}\Xi^{-} in p−-Pb collisions at a centre-of-mass energy per nucleon−-nucleon collision sNN = 5.02\sqrt{s_{\mathrm{NN}}}~=~5.02 TeV with the ALICE detector at the LHC. The Ξc0\Xi_{\rm c}^{0} nuclear modification factor (RpPbR_{\rm pPb}), calculated from the cross sections in pp and p−-Pb collisions, is presented and compared with the RpPbR_{\rm pPb} of Λc+\Lambda_{\rm c}^{+} baryons. The ratios between the pTp_{\rm T}-differential production cross section of Ξc0\Xi_{\rm c}^{0} baryons and those of D0\mathrm {D^0} mesons and Λc+\Lambda_{\rm c}^{+} baryons are also reported and compared with results at forward and backward rapidity from the LHCb Collaboration. The measurements of the production cross section of prompt Ξc0\Xi^0_{\rm c} baryons are compared with a model based on perturbative QCD calculations of charm-quark production cross sections, which includes only cold nuclear matter effects in p−-Pb collisions, and underestimates the measurement by a factor of about 50. This discrepancy is reduced when the data is compared with a model in which hadronisation is implemented via quark coalescence. The pTp_{\rm T}-integrated cross section of prompt Ξc0\Xi^0_{\rm c}-baryon production at midrapidity extrapolated down to pTp_{\rm T} = 0 is also reported. These measurements offer insights and constraints for theoretical calculations of the hadronisation process. Additionally, they provide inputs for the calculation of the charm production cross section in p−-Pb collisions at midrapidity

    Charm fragmentation fractions and cc‾{\rm c\overline{c}} cross section in p−-Pb collisions at sNN=5.02\sqrt{s_{\rm NN}}=5.02 TeV

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    HAL CCSD
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    International audienceThe total charm-quark production cross section per unit of rapidity dσ(cc‾)/dy\mathrm{d}\sigma({\rm c\overline{c}})/\mathrm{d}y, and the fragmentation fractions of charm quarks to different charm-hadron species f(c→hc)f(\mathrm{c}\rightarrow {\rm h_{c}}), are measured for the first time in p−-Pb collisions at sNN=5.02\sqrt{s_\mathrm{NN}} = 5.02 TeV at midrapidity (−0.96<y<0.04-0.96<y<0.04 in the centre-of-mass frame) using data collected by ALICE at the CERN LHC. The results are obtained based on all the available measurements of prompt production of ground-state charm-hadron species: D0\mathrm{D}^{0}, D+\mathrm{D}^{+}, Ds+\mathrm{D}_\mathrm{s}^{+}, and J/ψ\mathrm{J/\psi} mesons, and Λc+\Lambda_\mathrm{c}^{+} and Ξc0\Xi_{\rm c}^{0} baryons. The resulting cross section is dσ(cc‾)/dy=219.6±6.3  (stat.)  −11.8+10.5  (syst.)  −2.9+7.6  (extr.)±5.4  (BR)±4.6  (lumi.)±19.5  (rapidity shape)+15.0  (Ωc0)\mathrm{d}\sigma({\rm c\overline{c}})/\mathrm{d}y =219.6 \pm 6.3\;(\mathrm{stat.}) {\;}_{-11.8}^{+10.5}\;(\mathrm{syst.}) {\;}_{-2.9}^{+7.6}\;(\mathrm{extr.})\pm 5.4\;(\mathrm{BR})\pm 4.6\;(\mathrm{lumi.}) \pm 19.5\;(\text{rapidity shape})+15.0\;(\Omega_{\rm c}^{0}) mb, which is consistent with a binary scaling of pQCD calculations from pp collisions. The measured fragmentation fractions are compatible with those measured in pp collisions at s=5.02\sqrt{s} = 5.02 and 1313 TeV, showing an increase in the relative production rates of charm baryons with respect to charm mesons in pp and p−-Pb collisions compared with e+e−\mathrm{e^{+}e^{-}} and e−p\mathrm{e^{-}p} collisions. The pTp_\mathrm{T}-integrated nuclear modification factor of charm quarks, RpPb(cc‾)=0.91±0.04  (stat.)−0.09+0.08  (syst.)−0.03+0.04  (extr.)±0.03  (lumi.)R_\mathrm{pPb}({\rm c\overline{c}})= 0.91 \pm 0.04\;{\rm (stat.)}{}^{+0.08}_{-0.09}\;{\rm (syst.)}{}^{+0.04}_{-0.03}\;{\rm (extr.)}{}\pm 0.03\;{\rm (lumi.)}, is found to be consistent with unity and with theoretical predictions including nuclear modifications of the parton distribution functions

    Production Cross Section Measurements of the natNi(d,x)61Cu Reaction

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    HAL CCSD
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    International audienc

    Innovative radioisotopes: Innovative radioisotopes for health

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    HAL CCSD
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    École thématiqueLesson on innovative radioisotope production for healt

    A search using GEO600 for gravitational waves coincident with fast radio bursts from SGR 1935+2154

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    HAL CCSD
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    International audienceThe magnetar SGR 1935+2154 is the only known Galactic source of fast radio bursts (FRBs). FRBs from SGR 1935+2154 were first detected by CHIME/FRB and STARE2 in 2020 April, after the conclusion of the LIGO, Virgo, and KAGRA Collaborations' O3 observing run. Here we analyze four periods of gravitational wave (GW) data from the GEO600 detector coincident with four periods of FRB activity detected by CHIME/FRB, as well as X-ray glitches and X-ray bursts detected by NICER and NuSTAR close to the time of one of the FRBs. We do not detect any significant GW emission from any of the events. Instead, using a short-duration GW search (for bursts ≤\leq 1 s) we derive 50% (90%) upper limits of 104810^{48} (104910^{49}) erg for GWs at 300 Hz and 104910^{49} (105010^{50}) erg at 2 kHz, and constrain the GW-to-radio energy ratio to ≤1014−1016\leq 10^{14} - 10^{16}. We also derive upper limits from a long-duration search for bursts with durations between 1 and 10 s. These represent the strictest upper limits on concurrent GW emission from FRBs

    Search for the Chiral Magnetic Effect with charge-dependent azimuthal correlations in Xe–Xe collisions at <math altimg="si1.svg"><msqrt><mrow><msub><mrow><mi>s</mi></mrow><mrow><mi mathvariant="normal">NN</mi></mrow></msub></mrow></msqrt><mo linebreak="goodbreak" linebreakstyle="after">=</mo><mn>5.44</mn></math> TeV

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    HAL CCSD
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    International audienceCharge-dependent two- and three-particle correlations measured in Xe–Xe collisions at sNN=5.44 TeV are presented. Results are obtained for charged particles in the pseudorapidity range |η|&lt;0.8 and transverse momentum interval 0.2≤pT&lt;5.0 GeV/c for different collision centralities. The three-particle correlator γαβ≡〈cos⁡(φα+φβ−2Ψ2)〉, calculated for different combinations of charge sign α and β, is expected to be sensitive to the presence of the Chiral Magnetic Effect (CME). Its magnitude is similar to the one observed in Pb–Pb collisions in contrast to a smaller CME signal in Xe–Xe collisions than in Pb–Pb collisions predicted by Monte Carlo (MC) calculations including a magnetic field induced by the spectator protons. These observations point to a large non-CME contribution to the correlator. Furthermore, the charge dependence of γαβ can be described by a blast wave model calculation that incorporates background effects and by the Anomalous Viscous Fluid Dynamics model with values of the CME signal consistent with zero. The Xe–Xe and Pb–Pb results are combined with the expected CME signal dependence on the system size from the MC calculations including a magnetic field to obtain the fraction of CME contribution in γαβ, fCME. The CME fraction is compatible with zero for the 30% most central events in both systems and then becomes positive. This yields an upper limit of 2% (3%) and 25% (32%) at 95% (99.7%) confidence level for the CME signal contribution to γαβ in the 0–70% Xe–Xe and Pb–Pb collisions, respectively

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