HAL Mines Nantes
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Neutrinoless double beta decay search in XENON1T and XENONnT
No full textInternational audienceWith the lowest background level ever reached by detectors searching for rare-events, XENON1Tproved to be the most sensitive dark matter direct detection experiment on earth. The unprecedentedlow level of radioactivity reached, made the XENON1T experiment suitable also for otherinteresting rare-events searches including the neutrinoless double beta decay of 136Xe. In thisproceeding, I will report on the current status of neutrinoless double beta decay of 136Xe searchin XENON1T. Furthermore, in the context of the advancement of the XENON program, the nextgeneration experiment, XENONnT, designed with a high level of background reduction aimingto increase the predecessor sensitivity in rare-events searches is currently under commissioningphase in the underground National Laboratory of Gran Sasso (LNGS): it hosts 5.9 tonnes ofliquid xenon as a target mass. I will also discuss the ongoing sensitivity projection studies forneutrinoless double beta decay search in XENONnT
Heavy Ion Physics: Hard probes for QGP at LHC: a selection of recent results
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Direct Experimental Evidence of the Effects of Clay Particles’ Basal-to-Lateral Surface Ratio on Methane and Carbon Dioxide Adsorption
No full textInternational audienceThe amount and size of the charge-balancing cations on the exposed faces of clay particles are supposed to be one of the key factors affecting the specificity of adsorption of gases at clay surfaces. However, the trends characterizing the thermodynamics of gas adsorption, reported for different members of 2:1 phyllosilicate phases, do not systematically follow neither the difference in their layer charge, determining the number of charge-balancing cations, nor the nature of the latter. To better understand the specificity of CH4 and CO2 molecular interactions with different clay phases, the adsorption isotherms were measured for isoionic pure-phase illite and montmorillonite up to pressures of 9 MPa at ambient temperature. For both gases, higher adsorption capacities per unit of specific surface area for montmorillonites in comparison to illites could not be explained by the existing theory relying on the properties of exposed charge-balancing cations on the surface. Instead, the slopes of the isotherms perfectly correlate with the shape of clay particles, characterized by their basal-to-lateral faces’ aspect ratio, which is assessed by derivative isotherm summation (DIS) using argon adsorption at 77 K. Montmorillonite clays, characterized by higher fractions of high-energy hydroxylated particles’ edges (∼45%) in the total specific surface area, featured stronger adsorption interactions with CO2 and CH4 in comparison to illites, for which the contribution of edges to the surface area is only 20%. This introduces a new important factor controlling the mechanism of CH4 and CO2 adsorption by clay minerals
New results on proton-induced reactions on Vanadium for Sc production and the impact of level densities on theoretical cross sections
No full textInternational audienceNew data for the natV(p,x) reactions have been measured in the range 26–70 MeV, with production of the nuclides Sc47, Sc43, 44mSc, 44gSc, Sc46, Sc48, K42, K43, V48, Cr48, Cr49, and Cr51. The focus is on the production of Sc47, a β− emitter suitable for innovative radiotheranostic applications in nuclear medicine. The measured cross sections for this radionuclide and its contaminants are compared with the theoretical excitation functions calculated with the talys code. In view of novel radiopharmaceutical applications, it is essential to accurately describe these cross sections for the evaluation of yields, purities, and dose releases. Hence, we optimize the level-density parameters of the microscopic models in the talys code to obtain the best possible descriptions of the new data. We consider different irradiation conditions to estimate the production yields from the cross sections determined in this paper
A Monte Carlo Determination of Dose and Range Uncertainties for Preclinical Studies with a Proton Beam
No full textInternational audienceProton therapy (PRT) is an irradiation technique that aims at limiting normal tissue damage while maintaining the tumor response. To study its specificities, the ARRONAX cyclotron is currently developing a preclinical structure compatible with biological experiments. A prerequisite is to identify and control uncertainties on the ARRONAX beamline, which can lead to significant biases in the observed biological results and dose–response relationships, as for any facility. This paper summarizes and quantifies the impact of uncertainty on proton range, absorbed dose, and dose homogeneity in a preclinical context of cell or small animal irradiation on the Bragg curve, using Monte Carlo simulations. All possible sources of uncertainty were investigated and discussed independently. Those with a significant impact were identified, and protocols were established to reduce their consequences. Overall, the uncertainties evaluated were similar to those from clinical practice and are considered compatible with the performance of radiobiological experiments, as well as the study of dose–response relationships on this proton beam. Another conclusion of this study is that Monte Carlo simulations can be used to help build preclinical lines in other setups.</jats:p
A combined DGT - DET approach for an in situ investigation of uranium resupply from large soil profiles in a wetland impacted by former mining activities
No full textInternational audienceAn in situ methodology combining DET and DGT probes was applied in a wetland soil, downstream of a former uranium mine (Rophin), to evaluate metal resupply by calculating the R ratio (R = [U]DGT/[U]pore water) from a high resolution and large (75 cm) soil profile. Our study confirms its applicability in soil layers with varying properties; only soil layers with low water content or coarse texture appear to be limiting factors. For soil profiles, DET provides new insights of the distribution of Uranium as soluble species (free ions, small inorganic complexes,…) along the pore water profile, whereas DGT highlights the presence of other “DGT labile” species. The pairing of DET and DGT, plus the calculation of the R, highlights two U behaviors in combining results from red-ox sensitive elements (Mn, Fe). First, in the organic topsoil layer, an increase in [U]DET and [U]DGT at 3-4 cm reflects the desorption of U probably trapped onto Fe- and Mn-oxohydroxides in a DGT-labile form. However, the resupply from soil to pore water is close to a diffusion only case (R < 0.2) meaning that a portion of U is certainly tightly bound by OM in soil as non-labile species. Second, a peak in [U]DGT perfectly corresponding to the former mine deposit layer signifies the presence of U under DGT-labile species. Moreover, a maximum R values of 0.87 demonstrates the near complete resupply of U from a labile fraction in this layer, as opposed to other elements like Pb
JUNO sensitivity to low energy atmospheric neutrino spectra
No full textInternational audienceAtmospheric neutrinos are one of the most relevant natural neutrino sources that can be exploited to infer properties about cosmic rays and neutrino oscillations. The Jiangmen Underground Neutrino Observatory (JUNO) experiment, a 20 kton liquid scintillator detector with excellent energy resolution is currently under construction in China. JUNO will be able to detect several atmospheric neutrinos per day given the large volume. A study on the JUNO detection and reconstruction capabilities of atmospheric and fluxes is presented in this paper. In this study, a sample of atmospheric neutrino Monte Carlo events has been generated, starting from theoretical models, and then processed by the detector simulation. The excellent timing resolution of the 3'' PMT light detection system of JUNO detector and the much higher light yield for scintillation over Cherenkov allow to measure the time structure of the scintillation light with very high precision. Since and interactions produce a slightly different light pattern, the different time evolution of light allows to discriminate the flavor of primary neutrinos. A probabilistic unfolding method has been used, in order to infer the primary neutrino energy spectrum from the detector experimental observables. The simulated spectrum has been reconstructed between 100 MeV and 10 GeV, showing a great potential of the detector in the atmospheric low energy region
Quarkonia as probe of the initial stages of the pp, pPb and PbPb collisions with ALICE
No full textInternational audienceQuarkonia are considered a distinguished tool to study the strongly-interacting medium formed in ultrarelativistic heavy-ion collisions and they are sensitive to the dense gluonic system at low-x in the initial state of heavy-ion collisions. This can be investigated in photonuclear or proton-nuclear collisions. Furthermore a modification of the quarkonium vector states polarization in heavy-ion collisions with respect to pp collisions may give insights on QGP dynamics. Moreover, quarkonium measurements in high-multiplicity proton-proton (pp) collisions can shed light on the role of multiparton interactions (MPI) which are expected to be relevant for the production of heavy quarks at the LHC energies. ALICE measures quarkonium production down to zero transverse momentum, at forward rapidity (2.5 < y < 4) and midrapidity (|y| < 0.9). In this contribution, we will report on the first measurement of J/ψ polarization in Pb-Pb collisions at the LHC as a function of transverse momentum and centrality. The coherent J/ψ photoproduction cross section measurement in Pb-Pb collisions with nuclear overlap at sNN−−−√=5.02 TeV will be shown for the first time considering the full Run 2 data sample, and extended towards most central collisions. Final results on the nuclear modification factor for ψ(2S),Υ(1S) and Υ(2S) at forward and backward center-of-mass rapidities in p-Pb collisions at sNN−−−√=8.16 TeV will be shown, with a focus on the new centrality dependent ψ(2S) results. A broad collection of multiplicity-dependent quarkonium measurements in pp at s√=13 TeV at mid- and forward-rapidity will be also presented. This includes, among others, recent results on the inclusive ψ(2S) and bottomonium production at forward rapidity
Isospin diffusion measurement from the direct detection of a quasiprojectile remnant
No full textInternational audienceThe neutron-proton (n-p) equilibration process in Ca48+Ca40 at 35 MeV/nucleon bombarding energy is experimentally estimated by means of the isospin transport ratio. Experimental data are collected with a subset of the FAZIA telescope array, which permits us to determine the Z and N of detected fragments. For the first time, the quasiprojectile (QP) evaporative channel is compared with the QP breakup one in a homogeneous and consistent way, pointing to comparable n-p equilibration, which suggests a close interaction time between projectile and target independently of the exit channel. Moreover, in the QP evaporative channel n-p equilibration is compared with the prediction of the antisymmetrized molecular dynamics model coupled with the Gemini statistical model as an afterburner, showing a higher probability of proton and neutron transfers in the simulation with respect to the experimental data
A comment on instantons and their fermion zero modes in adjoint QCD_2
No full textInternational audienceThe adjoint 2-dimensional with the gauge group admits topologically nontrivial gauge field configurations associated with nontrivial . The topological sectors are labelled by an integer . However, in contrast to and , this topology is not associated with an integral invariant like the magnetic flux or Pontryagin index. These instantons may admit fermion zero modes, but there is always an equal number of left-handed and right-handed modes, so that the Atiyah-Singer theorem, which determines in other cases the number of the modes, does not apply. The mod. 2 argument suggests that, for a generic gauge field configuration, there is either a single doublet of such zero modes or no modes whatsoever. However, the known solution of the Dirac problem for a wide class of gauge field configurations indicates the presence of zero mode doublets in the topological sector . In this note, we demonstrate in an explicit way that these modes are not robust under a generic enough deformation of the gauge background and confirm thereby the mod. 2 conjecture. The implications for the physics of this theory (screening vs. confinement issue) are briefly discussed