International Journal of Modern Physics: Conference Series

PANDA (antiProton ANihilation at DArmstadt) is the central experiment to fully exploit the physics research potential of antiproton beams at the international accelerator Facility for Antiproton and Ion Research in Europe (FAIR), currently under construction at GSI. Phase-space cooled high intensity antiproton beams up to 15 GeV/c will be provided by the High Energy Storage Ring (HESR) at FAIR to interact with PANDA internal proton or nuclear targets enabling a broad range of exciting studies in Particle and Nuclear Physics. The PANDA detector features two spectrometers, the Target Spectrometer with a superconducting solenoid magnet of 2 T around the interaction region with hermetic coverage and the Forward Spectrometer with a 2 Tm dipole magnet for coverage of the forward boosted particles. Several modern particle detector systems are employed in PANDA to provide excellent charged particle tracking, particle identification, calorimetry and muon detection, over the full momentum range in both spectrometers throughout the lifetime of the experiment. Focusing on the various PANDA detector systems we present an overview of recent developments, the detector construction progress and conclude with an outline for a phased deployment of PANDA at FAIR.

SHiP (Search for Hidden Particles) is a new general purpose fixed target facility, proposed at the CERN SPS accelerator. In its initial phase the 400 GeV protons beam will be dumped on a heavy target with the aim of integrating $2\times 10^{20}$ pot in five years. A dedicated detector downstream the target will allow to probe a variety of models with the light long-lived exotic particles and masses below O(10) GeV/c². The beam dump is also a copious source of neutrinos and in particular it is an ideal source of tau neutrinos, the less known particle in the Standard Model. We report the physics potential of such an experiment. We also describe an ancillary measurement of the charm cross-section carried out in July 2018.

Cosmological observations indicate that most of the matter in the Universe is Dark Matter. Dark Matter in the form of Weakly Interacting Massive Particles (WIMPs) can be detected directly, via its elastic scattering off target nuclei. Most current direct detection experiments only measure the energy of the recoiling nuclei. However, directional detection experiments are sensitive to the direction of the nuclear recoil as well. NEWSdm is meant to be the first experiment with a solid target for directional dark matter searches: the use of a nuclear emulsion based detector, acting both as target and tracking device, would allow to extend dark matter searches beyond the neutrino floor and provide an unambiguous signature of the detection of Galactic dark matter.

The DArk Matter Particle Explorer (DAMPE) is a particle detector hosted on board a satellite orbiting around the Earth since December 2015. The space mission has been promoted by the Chinese Academy of Science and results from an international effort also including Italian and Swiss institutions. The scientific goals include: indirect detection of Dark Matter signatures in cosmic lepton spectra, study of Cosmic Ray energy spectra up to energies of hundreds of TeV and high-energy gamma ray astronomy. A general overview of the mission will be presented and its main results about the all-electron, proton, helium, light-component (p+He) and heavier nuclei energy spectra, as well as studies on gamma-ray sources, will be discussed.

We present results on Spin Density Matrix Elements (SDMEs) measured in hard exclusive muoproduction of ${\rho }^0$ and $\omega$ mesons on the proton at COMPASS using 160 GeV/$c$ polarized ${\mu }^{+}$ and ${\mu }^{-}$ beams scattering off a liquid hydrogen target. The measurements cover the range 5 GeV/$c^2$ $<W<$ 17 GeV/$c^2$, 1.0 (GeV/$c$)² $<Q^2<$ 10.0 (GeV/$c$)² and 0.01 (GeV/$c$)² $<p_T^2<$ 0.5 (GeV/$c$)². Here, $Q^2$ denotes the virtuality of the exchanged photon, $W$ the mass of the final hadronic system and $p_T$ the transverse momentum of the vector meson with respect to the virtual-photon direction. The measured non-zero SDMEs for transitions of transversely polarized virtual photons to longitudinally polarized vector mesons (${\gamma }_T\to V_L$) indicate a violation of $s$-channel helicity conservation. Additionally, for ${\rho }^0$ production we observe a dominant contribution of natural-parity-exchange transitions and a small contribution of unnatural-parity-exchange transitions. On the contrary, the contribution of unnatural-parity-exchange for $\omega$ production is significant and it decreases with increasing $W$, being still non-negligible at the largest $W$ values accessible at COMPASS. The results provide an important input for modeling Generalized Parton Distribution (GPDs).

T2K is an accelerator-based neutrino experiment providing world-leading measurements of the parameters governing neutrino oscillations. T2K data enabled the first 3 $\sigma$ exclusion for some intervals of the CP-violating phase ${\delta }_{CP}$ and precision measurements of the atmospheric parameters $\mathrm{\Delta }{m}_{32}^2$, ${sin}^2{𝜃}_{23}$. T2K uses a beam of muon neutrinos and antineutrinos produced at the Japan Proton Accelerator Research Centre (J-PARC) and a series of detectors located at J-PARC and in Kamioka, 295km away, to measure oscillations from neutrino event rates and spectra. The T2K beam will be upgraded with increased power in 2022 and, combined with an upgrade of the ND280 near detector, will usher in a new important physics period for T2K. In preparation for the new physics run, the T2K collaboration is working on an updated oscillation analysis to improve the control of systematic uncertainties. The status of the new analysis developments and the plan to deploy the beam and ND280 upgrade are reviewed.

NUSES is a new project aiming to explore and test innovative technological and observational approaches for satellite-borne particle detectors dedicated to the study of cosmic radiation, astrophysical neutrinos, Sun-Earth environment, Space weather and Magnetospheric-Ionospheric-Lithospheric Coupling (MILC). The satellite will host two payloads, named TERZINA and ZIRÈ. TERZINA will test innovative observational techniques devoted to the hunt for astrophysical neutrino signals, looking at the Cherenkov light produced by extensive air showers generated in the atmosphere. The ZIRÈ experiment will exploit new technological approaches devoted to flux measurements of electrons, protons and light nuclei with energies spanning from few to hundreds of MeVs, but also to the detection of cosmic MeV photons and to the monitoring of eventual MILC signals. The main scientific objectives and features of the NUSES project will be presented in this work.

We review here recent results on $e^{+}{e}^{-}$ annihilation to hadrons below 2 GeV obtained with the SND detector at the VEPP-2000 collider. Among others we report cross sections and dynamics properties for the $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}$, $e^{+}{e}^{-}\to n\bar{n}$, $e^{+}{e}^{-}\to \eta {\pi }^0\gamma$, and $e^{+}{e}^{-}\to \eta \eta \gamma$.

Recently, efforts on the building of Hf-based crystal scintillators have been performed. The so-called “source = detector” approach has been implemented to study rare nuclear processes in Hf isotopes with higher efficiency with respect to the HP-Ge spectrometry. In this work, a review of recent studies concerning rare nuclear processes in Hf isotopes are presented.

The ZnWO₄ crystal scintillator is a promising detector for low counting experiments thanks to the high level of radiopurity and reasonably high optical and scintillation properties. In particular, ZnWO₄ scintillators can be utilized in the searches for double beta processes, in the investigation of rare alpha decays and Dark Matter. In fact, one of its main characteristics is to be an anisotropic detector. In the case of interaction of heavy particles or nuclear recoils, the light output and the time profile of the scintillation pulse depend on the direction of the particles with respect to the crystal axes; no difference is observed for $\gamma /\beta$ radiation. These anisotropic features can offer a unique possibility to exploit the so-called directionality approach in order to investigate the presence of the Dark Matter candidates which induces nuclear recoils. In fact, their use can overcome the difficulty of detecting extremely short nuclear recoil traces.

DAMA/LIBRA is an experiment investigating the presence of Dark Matter particles in the Galactic halo. The target detectors are ultra-radiopure NaI(Tl) crystal scintillators. They are placed inside a low-background set-up at the underground Gran Sasso National Laboratory (LNGS) of the I.N.F.N.. DAMA/LIBRA has been in operation in two phases by pursuing the annual modulation as signature to point-out in a model-independent way the presence and the features of the Dark Matter (DM) signal in the counting rate. In its second phase of measurement, DAMA/LIBRA–phase2, it has been working with a lower software energy threshold with respect to DAMA/LIBRA–phase1. DAMA/LIBRA–phase2 confirms the evidence of a signal that meets all the requirements of the model independent Dark Matter annual modulation signature, at 11.8 $\sigma$ C.L. in the energy region (1–6) keV. In the energy region (2–6) keV, where data are also available from DAMA/NaI and DAMA/LIBRA–phase1, the achieved C.L. for the full exposure (2.86 ton × yr, 22 annual cycles) is 13.7 $\sigma$; the modulation amplitude of the single-hit scintillation events is: $(0.01014\pm 0.00074)$ cpd/kg/keV, and the measured period and phase are well in agreement with those expected for DM particles. Detailed studies have excluded that the observed modulation is due to systematics or side reaction. In this proceedings the results achieved so far by the DAMA/LIBRA experiment and the new ones corresponding to two new annual cycles of data will be presented. Future perspectives of the experiment will be addressed.

We perform a fitting procedure to differential elastic scattering cross section data of antiproton at intermediate energy on three different nuclei to evaluate parameters of a six-parameters Woods-Saxon optical potential. Then, with these values, we calculate the reaction cross sections at different momenta and evaluate the differential elastic cross sections for low-momenta antiproton ($p\le 100\mathrm{\text{MeV/c}}$). We find that our analysis underestimates the reaction cross sections for data over the momentum-range 50 MeV/c to 1000 MeV/c. We predict measurable effect for antiprotons with momentum above 50 MeV/c at large angles ($𝜃>90°$), in agreement with other recent results. Finally, we consider possible improvements to the model and the analysis.

With the revolutionary development in the design of heavy-ion cooler storage rings and detectors, increasing interest is being focused on ion-atom collisions, in which the projectiles with a velocity comparable to the speed of light and the electronic transitions in inner shells of high-$Z$ ions are involved. For this purpose, a fundamental interaction mechanism between a photon and an atomic electron in the presence of a strong Coulomb field is reviewed from the perspective of radiative electron capture into highly-charged ions. This is followed by the discussions of photon-electron interactions beyond the dipole approximation, which can be unambiguously visible in the photon angular distributions. In addition, the interference between the leading electric dipole transition $E1$ and the magnetic multipole transition $M2$ for the case of Lyman-${\alpha }_1$ radiation in hydrogen-like projectiles is also discussed.

The $\mu$Net program developed by the EAP Physics Laboratory is a long-term vision for the transfer of knowledge and research practice in secondary education. The students’ involvement is divided into two axes, the construction and calibration of detection devices on the one hand, and the collection and processing of the measurements collected by these devices on the other. The quarknet card is used to collect the data, which records data in hexadecimal format. In this work, the methodology developed is presented, so that the data can be converted into the decimal format familiar to the students, so that they understand exactly what was measured and it is easy to process the experimental data and draw conclusions from them in a modern computing environment.

The International Masterclass - Hands on Particle Physics is an outreach event proposed by the International Particle Physics Outreach Group since 2004. Its traditional format had a worldwide success during the last years, reaching thousands of high school students and introducing them to the world of particle physics. During the last two years, the COVID-19 pandemics forced all the groups proposing the activity to find an online alternative to preserve the spirit of the initiative. The local committee of University of Trento proposed an online event, divided into several short events carried out over two weeks. The introduction of an analysis challenge among the students has made it possible to obtain a very good response and to achieve, with less than 20 students, enough statistics to discuss physical results of the analysis. The contribution describes the details of the organization, results, and feedback from the students, with some proposals to improve the experience for the next years.

In the next years the Baryonic Matter at Nuclotron (BM@N) experiment at Joint Institute for Nuclear Research (JINR) will carry out the physics program with heavy ion beams with energies up to 3.9 AGeV and intensities up to 2 $\cdot 10^6$ ions/s. The experiment is devoted to measure observables sensitive to the equation of state of dense baryonic matter. To meet this goal the existing BM@N set-up will be upgraded with fast hybrid tracking system, which includes beam tracking detectors, a large aperture silicon tracking system, gas electron multiplier stations and cathode strip chambers. The measurement of the event plane and centrality will be achieved with a forward hadron calorimeter and granular hodoscopes. The physics program and configuration of the upgraded BM@N set-up are presented.

We report on the measurement of the central exclusive production process $pp\to pXp$ in proton-proton collisions at $\sqrt{s}=510$ GeV with the STAR detector at RHIC. At this energy, the process is dominated by a double Pomeron exchange mechanism. The tracks of the centrally produced system $X$ were reconstructed in the central detector of STAR, the time projection chamber and the time of flight systems. Particles were identified using the ionization energy loss and the time of flight method. The diffractively scattered protons, moving intact inside the RHIC beam pipe after the collision, were measured in the Roman Pots system allowing full control of the interaction’s kinematics and verification of its exclusivity. Preliminary results on the invariant mass distributions of centrally produced ${\pi }^{+}{\pi }^{-}$, $K^{+}{K}^{-}$, and $p\bar{p}$ pairs measured within the STAR acceptance are presented.