INFN Sezione di Perugia

The LHCb Ring-Imaging Cherenkov detectors are built to provide charged hadron identification over a large range of momentum. The upgraded detectors are also capable of providing an independent measurement of the luminosity for the LHCb experiment during LHC Run 3. The modelling of the opto-electronics chain, the application of the powering strategy during operations, the calibration procedures and the proof of principle of a novel technique for luminosity determination are presented. In addition, the preliminary precision achieved during the 2023 data-taking year for real-time and offline luminosity measurements is reported.

We present the results of Phase I of an ongoing review of Monte Carlo tools relevant for low-energy hadronic cross sections. This includes a detailed comparison of Monte Carlo codes for electron–positron scattering into a muon pair, pion pair, and electron pair, for scan and radiative-return experiments. After discussing the various approaches that are used and effects that are included, we show differential cross sections obtained with AfkQed, BabaYaga@NLO, KKMC, MCGPJ, McMule, Phokhara, and Sherpa, for scenarios that are inspired by experiments providing input for the dispersive evaluation of the hadronic vacuum polarisation.

We present the first measurement of cosmic-ray fluxes of ^{6} Li and ^{7} Li isotopes in the rigidity range from 1.9 to 25GV. The measurements are based on 9.7×10^{5} ^{6} Li and 1.04×10^{6} ^{7} Li nuclei collected by the Alpha Magnetic Spectrometer on the International Space Station from May 2011 to October 2023. We observe that over the entire rigidity range the ^{6} Li and ^{7} Li fluxes exhibit nearly identical time variations and, above ∼4 GV, the time variations of ^{6} Li, ^{7} Li, He, Be, B, C, N, and O fluxes are identical. Above ∼7 GV, we find an identical rigidity dependence of the ^{6} Li and ^{7} Li fluxes. This shows that they are both produced by collisions of heavier cosmic-ray nuclei with the interstellar medium and, in particular, excludes the existence of a sizable primary component in the ^{7} Li flux.

Secondary cosmic ray fluxes are important probes of the propagation and interaction of high-energy particles in the Galaxy. Recent measurements of primary and secondary cosmic ray nuclei have revealed unexpected spectral features that demand a deeper understanding. In this work we report the direct measurement of the cosmic ray boron spectrum from 10 GeV/n to 8 TeV/n with eight years of data collected by the Dark Matter Particle Explorer (DAMPE) mission. The measured spectrum shows a hardening at 182±24 GeV/n with a spectral index of γ_{1}=3.02±0.01 before the break and an index change of Δγ=0.31±0.05 after the break. A simple power law model is disfavored at a confidence level of 8σ. Compared with the hardenings measured in the DAMPE proton and helium spectra, the secondary boron spectrum hardens roughly twice as much as these primaries, which is consistent with a propagation related mechanism to interpret the spectral hardenings of cosmic rays observed at hundreds of GeV/n.

The use of a new optoelectronic readout chain with 𝒪(100)ps time resolution is a major milestone in the development of RICH detectors for environments with a high number of particle interactions per bunch crossing, such as the High-Luminosity LHC. A prototype chain, based on MAPMT and SiPM photon sensors coupled to readout electronics integrating the FastIC ASIC and a TDC-in-FPGA, is presented. The FastIC is an 8-channel ASIC for analogue-to-digital conversion with 25 ps time resolution. This ASIC is the predecessor of the FastRICH ASIC for the LHCb RICH upgrades. The signals from the photon detectors are timestamped in a custom multi-channel TDC-in-FPGA designed using a multi-phase clock sampling architecture with an average bin width of 150 ps. The prototype optoelectronic readout chain was tested in a charged particle beam of 180 GeV/c hadrons at the CERN SPS facility. The reference time-of-arrival of the particle tracks was measured with about 100 ps time resolution and the number of tracks per event was registered using a particle tracking system. The single-photon time resolution of the MAPMT sensors is extracted using a binned method in order to correct for the calibrated TDC bin widths and detector time-walk. The resulting best estimate of σ = 182 ± 24 ps is in agreement with pulsed-laser measurements in the lab and consistent with the expectations from the manufacturer.

The RD53 collaboration has since 2013 developed new hybrid pixel detector chips with 50 × 50 μm2 pixels for the HL-LHC upgrades of the ATLAS and CMS experiments at CERN. A common architecture, design and verification framework has been developed to enable final pixel chips of different sizes to be designed, verified and tested to handle extreme hit rates of 3 GHz/cm2 (up to 12 GHz per chip) together with an increased trigger rate of 1 MHz and efficient readout of up to 5.12 Gbits/s per pixel chip. Tolerance to an extremely hostile radiation environment with 1 Grad over 10 years and induced SEU (Single Event Upset) rates of up to 100 upsets per second per chip have been major challenges to make reliable pixel chips. Three generations of pixel chips, and many specific mixed signal building blocks and radiation test chips, have been submitted and extensively tested to get to final production chips. The large, complex and high rate pixel chips have been developed with a strong emphasis on low power consumption together with a concurrent development and qualification of novel serial powering at chip, module and system level, to minimize detector material budget.

Nonadiabatic effects in the electron-phonon coupling are important whenever the ratio between the phononic and the electronic energy scales---the adiabatic ratio---is non-negligible. For superconducting systems, this gives rise to additional diagrams in the superconducting self-energy, the vertex, and cross-corrections. In this work, we explore these corrections in a two-dimensional single-band system through the crossover between the weak-coupling Bardeen-Cooper-Schrieffer (BCS) and strong-coupling Bose-Einstein regimes. By focusing on the pseudogap phase, we identify the parameter range in which the pairing amplitude is amplified by nonadiabatic effects and, due to controlled approximations, we map them throughout the BCS-BEC crossover. These effects become stronger as the system is driven deeply in the crossover regime, for phonon frequencies of the order of the hopping energy and for large enough electron-phonon coupling. Finally, we provide the phase space regions in which the effects of nonadiabaticity are more relevant for unconventional superconductors.

We present results over an 11-year Solar cycle of cosmic antiprotons based on 1.1×10^{6} events in the rigidity range from 1.00 to 41.9GV. The p[over ¯] fluxes exhibit distinct properties. The magnitude of the p[over ¯] flux temporal variation is significantly smaller than those of p, e^{-}, and e^{+}. A hysteresis between the p[over ¯] fluxes and the p fluxes is observed, whereas the p[over ¯] and e^{-} fluxes show a linear correlation. With a model-independent analysis, we found a universal relation between the shape of the rigidity spectrum and the magnitude of flux temporal variation over an 11-year Solar cycle for both positively and negatively charged particles. The simultaneous results on p[over ¯] and p, e^{-}, and e^{+} provide unique information for understanding particle transport in the Solar System as a function of mass, charge, and spectral shape.

Neutron-induced nuclear reactions play an important role in the Big Bang Nucleosynthesis. Their excitation functions are, from an experimental point of view, usually difficult to measure. Nevertheless, in the last decades, big efforts have led to a better understanding of their role in the primordial nucleosynthesis network. In this work, we apply the Trojan Horse Method to extract the cross section at astrophysical energies for the 3He(n,p)3H reaction after a detailed study of the 2H(3He,pt)H three-body process. Data extracted from the present measurement are compared with other published sets. The reaction rate is also calculated, and the impact on the Big Bang nucleosynthesis is examined in detail.

Recent advancements in sensor technology have paved the way for the development of high-resolution 4D-tracking detectors capable of simultaneously measuring the position and time of passage of charged particles within a single sensitive device. The key point is the use of resistive read-out in thin Low Gain Avalanche Diode (LGAD) sensors, which introduces combined intrinsic signal sharing and internal gain. This contribution focuses on the development of a thin LGAD with a DC-coupled resistive read-out (DC-coupled Resistive Silicon Detector - DC-RSD). The aim is to achieve a spatial resolution of a few micrometers and an excellent time resolution of approximately 30 ps, using relatively large pixels (150-200 micrometers), which enables detectors with low channel density and low power consumption. A strong effort has been put into the simulation of the device, supported by experimental measurements of the AC-coupled resistive read-out sensors, which can be used to extrapolate the DC-RSD performance. This contribution describes the design and implementation strategy of the first DC-RSD production, presently in progress at Fondazione Bruno Kessler. Several test structures and application-oriented devices have been designed, which will enable detailed studies of the charge sharing optimization. The production is expected to be completed in early Fall 2024. The initial characterization of the production in the laboratory will provide us with immediate feedback on the soundness of the DC-RSD concepts.