PRR Project

Summary

This profile is for a teaching position at the Assistant Professor level, for a PhD holder in Physics or Physics Engineering, for the scientific area of Physics, sub-area of Particle Physics, and a focus on data analysis.The successful candidate is expected to make significant contributions to the astroparticle physics experimental program at Laboratório de Instrumentação e Física Experimental de Partículas (LIP). This includes active participation in one or more international astroparticle experiments in which LIP is involved, namely in dark matter (DM) direct detection experiments. LIP, has played a prominent role in experiments of this kind for more than two decades, searching for new physics, such as: i) the detection of DM particles in the form of Weakly Interacting Massive Particles (WIMPs); ii) the search for nuclear decays forbidden by the standard model, such as the neutrinoless double decay. This involvement is expected to primarily focus on data analysis using advanced methods, including machine learning techniques, deep learning algorithms, Bayesian inference methods, clustering algorithms, and anomaly detection algorithms, as well as Monte Carlo simulation.This job/profile arises from the current participation of LIP in the LUX-ZEPLIN (LZ) experiment and the XLZD Consortium, the latter aiming at the construction of a 3rd generation (G3) dark matter detector. With 40-80 tonnes of xenon, it will be operating by the end of the decade and will serve as a Rare Event Observatory, with extreme sensitivity to multiple DM candidates and many other rare physics phenomena, such as neutrino physics and rare nuclear decays. LZ began data taking in 2022 and is expected to continue until 2027. In this context, the successful candidate will start by addressing the following topics related with LIP participation in LZ and XLZD:To develop methods to extend LZ sensitivity to lower mass WIMPs and other low mass dark matter particle candidates. Detectors based on dual-phase xenon TPCs like LZ have typical thresholds of the order of a few keV, which limits their sensitivity to low-mass WIMPs and other light DM candidates. Below a few keV, the detector signals are extremely small and cannot be handled by the standard techniques employed in LZ. This topic includes to envisage and implement methods that allow to characterise these small signals and discriminate them from the much larger backgrounds. Several strategies will be pursued, notably:To implement photon and electron counting techniques/algorithms. In this context, the potential benefits of adding faster electronics for signal processing in XLZD, exclusively dedicated to photon counting, should also be addressed.To develop new pulse shape analysis that will allow to discriminate these small signals. Machine learning algorithms (e.g. based in neural networks and convolutional neural networks) will be explored for this purpose.To carry out detailed Monte Carlo simulations of all the relevant backgrounds for XLZD, from the low energy WIMP search region to the high energy 0vbb limit (a few MeV). Given the size of the TPC, simulation of external gammas to obtain reasonable statistics will be extremely challenging. New strategies to maximise the efficiency of the simulations (e.g. bootstrapping in geometry shells) must be exploited. Accurate modelling and control of backgrounds is paramount in experiments searching for rare events in all energy ranges.To conduct comprehensive studies aimed at optimizing the XLZD design, in addition to the background studies mentioned above, including:Develop strategies to mitigate backgrounds (e.g. optimise shielding and vetoing for gammas, improve ability to efficiently veto muon induced neutrons producing Xe-137, develop the reconstruction in the horizontal plane as an additional multiple scatters (MS) discriminant, use MS events to better characterise the backgrounds).Use a more sophisticated statistical analysis for the sensitivity, based on the profile likelihood ratio (PLR) method.The successful candidate is expected to lead LIP´s participation in XLZD beyond the current design stage, involving a team of researchers and students in data analysis and physics of this rare events observatory. He/she will have to secure grants and projects in competitive calls and lead his(her) own team. He/she is also expected to be very active in offering and supervising dissertations at the M.Sc. degree and for Ph.D. students.This research program requires hiring an experienced researcher to lead its execution. The required scientific profile includes a strong track record in experimental astroparticle physics, namely DM direct detection experiments, extensive experience in advanced data analysis methods, recognition by the international scientific community and proved team leadership capabilities.