Animé par Eamonn Weitz
jeudi 10 juin 2021 à 14:00
Cluster and hypernuclei production in heavy-ion collisions is an area of renewed interest from both a theoretical and experimental point of view. The dynamics of such objects as clusters are related to the n-body problem, as such an n-body dynamical approach is needed to treat them. In the existing literature there are two main approaches to solve this kind of problem, those based on QMD (such as QMD,IQMD,UrQMD) and those based on mean field calculation (Vlasov)Boltzmann-Uehling-Uhlenbeck ((V)BUU) models (such as Buu AMPT HSD PHSD GiBUU SMASH). While the latter are capable of reproducing a wide array of observables, cluster formation is based on n-body correlations that are smeared out due to the nature of these approaches. The former are limited to no relativistic energies (with the exception of UrQMD which is mainly used for coalescence). Based on the well established PHSD (Parton-Hadron-String Dynamics) transport approach, supplemented by QMD (Quantum Molecular Dynamics) PHQMD allows us to have a microscopic description of collisions, and general particle production. This approach allows us to dynamically form the clusters from the interactions of the baryons described by QMD. The FOPI collaboration results at 1.5 AGeV showed that up to 35 % of the protons were bound in clusters, therefore a robust description of these dynamics is necessary if we wish to compare with experimental results. Further experimental setups to explore this energy range (2 AGeV - 100 AGeV) are under construction, at the Facility for Anti-Proton and Ion Research (FAIR) in Darmstadt and the Nuclotron-based Ion Collider fAcility (NICA) in Dubna. Here we will present some results obtained at beam energies in the 1 AGeV range for which we currently have experimental data (FOPI Au+AU and HADES Au+Au and Ag+Ag).
DAMIC-M (Dark Matter in CCDs at Modane) is a near-future experiment aiming to search for low-mass dark matter particles through their interactions with silicon atoms in the bulk of charge-coupled devices (CCDs). This technique was pioneered by the DAMIC experiment at SNOLAB. Its successor DAMIC-M will have a 25 times larger detector mass and will employ a novel CCD technology (skipper amplifiers) which allows it to achieve a readout noise of 0.07 e-. With these novelties, DAMIC-M will reach unprecedented sensitivities to dark matter candidates of the so-called hidden sector. A challenging requirement is the control of the radiogenic background at the level of a fraction of events per keV per kg-day of target exposure. Accurate Geant4 simulations are being employed to optimise the detector design and drive the material selection and handling. This presentation provides a comprehensive overview of the explored detector designs, the estimated background, and the strategies for its mitigation.