Explore the vast range of titles available.

Recently, a group directed by A. J. Krasznahorkay observed an anomaly in the emission of electron–positron pairs in three different nuclear reactions, namely, the  3H(p,e −e +) 4He,  7Li(p,e −e +) 8Be, and  11B(p,e −e +) 12C processes. Kinematics indicate that this anomaly might be due to the de-excitation of  4He,  8Be, and  12C nuclei with the emission of a boson with a mass of about 17 MeV, rapidly decaying into e −e + pairs. The result of the experiments performed with the singletron accelerator of ATOMKI is reviewed, and the consequences of the so-called X17 boson in particle physics and in cosmology are discussed. Forthcoming experiments designed to shed light on the possible existence of the X17 boson are also reported.

The evolution of celestial bodies is regulated by gravitation and thermonuclear reaction rates, while the Big Bang nucleosynthesis is the result of nuclear processes in a rapidly expanding Universe. The LUNA Collaboration has shown that, by exploiting the ultra low background achievable deep underground, it is possible to study the relevant nuclear processes down to the nucleosynthesis energy inside stars and during the first minutes of Universe. In this paper the main results of LUNA are overviewed, as well as the scientific program the forthcoming 3.5 MV underground accelerator.

Big Bang Nucleosinthesis (BBN) theory provides definite predictions for the abundance of light elements produced in the early universe, as far as the knowledge of the relevant nuclear processes of the BBN chain is accurate. At BBN energies (30 ≲ Ecm ≲ 300 MeV) the cross section of many BBN processes is very low because of the Coulomb repulsion between the interacting nuclei. For this reason it is convenient to perform the measurements deep underground. Presently the world’s only facility operating underground is LUNA (Laboratory for Undergound Nuclear astrophysics) at LNGS (“Laboratorio Nazionale del Gran Sasso”, Italy). In this presentation the BBN measurements of LUNA are briefly reviewed and discussed. It will be shown that the ongoing study of the D(p, γ)3He reaction is of primary importance to derive the baryon density of universe Ωb with high accuracy. Moreover, this study allows to constrain the existence of the so called “dark radiation”, composed by undiscovered relativistic species permeating the universe, such as sterile neutrinos.

The workshop “Shedding light on X17” brings together scientists looking for the existence of a possible new light particle, often referred to as X17. This hypothetical particle can explain the resonant structure observed at ∼  17 MeV in the invariant mass of electron-positron pairs, produced after excitation of nuclei such as 8 Be and 4 He by means of proton beams at the Atomki Laboratory in Debrecen. The purpose of the workshop is to discuss implications of this anomaly, in particular theoretical interpretations as well as present and future experiments aiming at confirming the result and/or at providing experimental evidence for its interpretation.

The D(p, γ ) 3 He cross section at low energies affects the primordial deuterium abundance, that in turn depends on fundamental cosmological parameters such as the baryon density and the amount of relativistic particles permeating the early universe. This paper discusses a new measurement of the D(p, γ ) 3 He cross-section in the 30-280 keV energy range, performed at the Gran Sasso Laboratory (LNGS) with the LUNA facility. This measurement provides a new determination of the universal baryon density at the BBN epoch Ω b (BBN) with improved accuracy, in excellent agreement with the baryon density value derived from the Cosmic Microwave Background data Ω b (CMB). Furthermore, the LUNA result allows to better constrain the existence of dark radiation, i.e. the amount of light particles not considered in the standard model of particle physics, such as sterile neutrinos or hot axions. This paper also discusses the results of a new analysis showing that the D(p, γ ) 3 He differential cross section is in excellent agreement with recent ab-initio theoretical calculations.

The D(p,γ)3He cross section at low energies affects the primordial deuterium abundance, that in turn depends on fundamental cosmological parameters such as the baryon density and the amount of relativistic particles permeating the early universe. This paper discusses a new measurement of the D(p,γ)3He cross-section in the 30-280 keV energy range, performed at the Gran Sasso Laboratory (LNGS) with the LUNA facility. This measurement provides a new determination of the universal baryon density at the BBN epoch Ωb(BBN) with improved accuracy, in excellent agreement with the baryon density value derived from the Cosmic Microwave Background data Ωb(CMB). Furthermore, the LUNA result allows to better constrain the existence of dark radiation, i.e. the amount of light particles not considered in the standard model of particle physics, such as sterile neutrinos or hot axions. This paper also discusses the results of a new analysis showing that the D(p,γ)3He differential cross section is in excellent agreement with recent ab-initio theoretical calculations.

We present the state of the art of the n_TOF Collaboration Working Group activity dedicated to study how to solve the puzzle about the existence of the so called new particle X17, spotted for the first time few years ago by a team at ATOMKI in Hungary and since then never confirmed by other independent experimental collaborations but also never refuted. An “ad hoc” detection setup is under realization for this goal, in order to reach an angular resolution of the two emerging trajectories from the X17 decay and an energy resolution for the invariant mass reconstruction enough to cast light in a definitive way about this puzzle. To design the present detection setup we work in close contact with the Pisa Nuclear Theory team, that has deeply studied the implication of X17 existence and extracted by the ATOMKI results its eventual nature, kinematics and general properties.

OPERA is a neutrino oscillation experiment designed to perform a ντ appearance search in the future CNGS beam from CERN to Gran Sasso. The identification of the τ lepton produced by a CC ντ interaction is based on the use of the nuclear emulsion technique. The OPERA detector is presently under construction in the Gran Sasso underground laboratory, 730 km from CERN, and will receive its first neutrinos in 2006. The experimental technique is reviewed and the development of the project described. Foreseen performances in measuring ντ appearance and also in searching for νe appearance are discussed.

The PDF file contains the preface, a list of conference committees and a number of conference photographs.

In the context of the PTOLEMY project, the need for a site with a rather low cosmogenic induced background led us to measure the differential muon flux inside the bunker of Monte Soratte, located about 50~km north of Rome (Italy). The measurement was performed with the Cosmic Ray Cube (CRC), a portable tracking device. The simple operation of the Cosmic Ray Cube was crucial to finalise the measurements, as they were carried out during the COVID-19 lockdown and in a site devoid of scientific equipment. The muon flux measured at the Soratte hypogeum is above two orders of magnitude lower than the flux observed on the surface, suggesting the possible use of the Mt. Soratte bunker for hosting astroparticle physics experiments requiring a low environmental background.