Search

This paper addresses some of the of open problems in photonuclear physics which await to be resolved using high-brilliance γ-ray beams, such as precise measurements of total or partial cross sections of photonuclear reactions related to astroparticle physics and nuclear astrophysics. The readiness for such measurements at ELI-NP, as well as the state-of-the-art instrumentation which is available are discussed. The possibility to utilize γ-beams with orbital angular momentum in photonuclear experiments is addressed, too.

A γ-ray spectroscopic study of 10B is reported. Excited states in 10B were populated in inelastic proton scattering and their γ-decays were measured with the ELIFANT array, a state-of-the-art spectrometer with large volume LaBr3:Ce and CeBr3 detectors placed in anti-Compton shields and having unprecedented efficiency for high-energy γ rays. A few weak transitions were observed in the experiment, namely M3 transition between Jπ, T = 0+1, 1 isobaric analog state to the Jπ, T = 3+1,0 ground state and E2 transition between the Jπ, T = 2+1,0 state and the isobaric analog state. The results are compared to a new set of ab initio no-core shell model calculation using the newest version of the local position-space chiral N3LO nucleon-nucleon interaction, which correctly reproduces the spectrum of the excited states in 10B, a problem of the theory in previous years.

An overview of the main directions of present-day studies with quasimonochromatic γ beams is discussed with an emphasis on the research opportunities which will be offered at the Extreme Light Infrastructure Nuclear Physics (ELI-NP) facility at Magurele near Bucharest in Romania. Experiments with γ beams at the extremes of high temperatures are outlined, with an emphasis on prospective studies related to nuclear astrophysics and astroparticle physics. Some of the experimental setups for nuclear structure, reaction, and astrophysics studies, which are available at ELI-NP, are described.

An experiment was conducted at the High Intensity γ-ray Source (HIγS) facility at the Triangle Universities Nuclear Laboratory (TUNL) in Durham, NC, USA to measure the cross-section of the key astrophysical thermonuclear reaction 12C(α,γ)16O by means of its inverse photo-disintegration process. A high-intensity monochromatic γ-ray beam interacted with the CO2 gas in the active volume of the Warsaw active target TPC detector. The reaction products were detected and their momenta reconstructed, so to also determine angular correlations. Data were collected at 15 beam energies ranging from 8.51 to 13.9 MeV. Preliminary results are presented.

An active-target time-projection chamber (TPC) optimised for studying nuclear reactions of astro-physical interest was developed by the University of Warsaw for studying photo-disintegration reactions using intense, monochromatic γ-ray beams. Different reactions can be studied by tuning composition and density of the gaseous target for particular energy of the gamma beam. The Warsaw TPC detector, with its active volume of about 33x20x20 cm3 centred around the beam axis and micro-pattern structures (GEMs) employed to amplify the primary ionisation induced by charged particles produced in reactions in the gaseous target, is characterised by a readout based on signal strips, arranged into 3-coordinate redundant system. The 3D kinematics of charged particles in the event are reconstructed from a total of about 103 channels read out by digitising front-end electronics based on the General Electronics for TPCs (GET). In this paper the principles of detector operation and basic track reconstruction methods are discussed and illustrated by means of preliminary results from pilot measurements conducted in 2021-22.

Fluorine is one of the most interesting elements in nuclear astrophysics. Its abundance can provide important hints to constrain the stellar models since fluorine production and destruction are strictly connected to the physical conditions inside the stars. The F 19 (p,α)16O reaction is one of the fluorine burning processes and the correction evaluation of its reaction rate is of pivotal importance to evaluate the fluorine abundance. Moreover, the F 19 (p,α)16O reaction rate can have an impact for the production of calcium in the first-generation of Population III stars. Here, we present the AsFiN collaboration efforts to the study of the F 19 (p, α)16O reaction by means of direct and indirect measurements. On the direct measurements side, an experimental campaign aimed to the measurement of the F 19 (p, α 0 , π )16O reaction is ongoing, taking advantage of the new versatile arrays of silicon strip detectors, LHASA and ELISSA. Moreover, the Trojan Horse Method (THM) was used to determine the F 19 (p, α 0 )16O reaction S(E)-factor in the energy range of astrophysical interest ( E c m ≈ 0–1 MeV), showing, for the first time, the presence of resonant structures within the astrophysical energy range. THM has been also applied for the study of the F 19 (p, α π )16O reaction; data analysis is ongoing. [ABSTRACT FROM AUTHOR]

A very intense γ beam of the Gamma Factory facility proposed at CERN can be used to generate radioactive ion beams (RIBs) with high production yields and study the structure of exotic neutron‐rich nuclei. The radioactive nuclides are generated via photo‐fission in several actinide targets and thermalized in high‐purity cryogenic helium, filling a gas cell which is enclosing the targets. Electric fields are used to extract heavy ions and form RIBs which can be send to various selection and measurement stations. Estimates for the production and extraction yields of exotic neutron‐rich nuclei with such a setup are provided. A study of the impact of space charge, build‐up inside the gas cell, on the extraction properties is presented and it is demonstrated that the beam needs to be chopped for achieving optimal extraction yields. [ABSTRACT FROM AUTHOR]