abstract

The properties of the \(2^+_1\) and \(2^+_2\) excited states in \(^{14}\mathrm {C}\) were studied in an experiment conducted at the Argonne National Laboratory. A \(^9\mathrm {Be}\)(\(^6\mathrm {Li}\),\(p\gamma \)) fusion–evaporation reaction and the GRETINA–ORRUBA setup were employed to populate states of \(^{14}\mathrm {C}\) and detect \(\gamma \)-particle coincidence events. The precise determination of the \(2^+_1\) level energy, complemented by the estimation of the \(\gamma \)-ray branch of the \(2^+_2\) near-threshold state, will serve as a benchmark to test the Shell Model Embedded in the Continuum calculations.

abstract

We study shape coexistence of differently deformed states within \(^{28}\mathrm {Si}\) using shell-model and beyond-mean-field techniques. Experimentally, \(^{28}\mathrm {Si}\) exhibits shape coexistence between an oblate ground state and an excited prolate structure. The oblate rotational band is described well within the \(sd\) shell using the USDB interaction. However, for the prolate band, a modification of this interaction is required, lowering the single-particle energy of the \(1d_{3/2}\) orbital. Furthermore, we explore the possibility of a superdeformed configuration in \(^{28}\mathrm {Si}\). Our calculations, spanning both the \(sd\) and \(pf\) shells, disfavour the existence of a superdeformed \(0^+\) bandhead within an excitation energy range of 10–20 MeV.

abstract

The electromagnetic structure of \(^{45}\mathrm {Sc}\) at low excitation energy was investigated via low-energy Coulomb excitation at the Heavy Ion Laboratory (HIL) of the University of Warsaw and at the Inter-University Accelerator Centre (IUAC) in New Delhi. A set of reduced E2, E3, and M1 matrix elements was extracted from the collected data using the GOSIA code. The reduced transition probability \(B\)(E2; \(11/2^- \rightarrow 7/2^-)\) has been determined, allowing us to deduce the lifetime of the \(11/2^-\) state at 1237 keV. In addition, the upper limit on the reduced transition probability \(B\)(E3; \(7/2^- \rightarrow 5/2^+)\) has been determined for the first time. New large-scale shell-model and beyond-mean-field calculations were performed to interpret the structure of this nucleus.

abstract

The excited states of neutron-rich Fe isotopes have been studied through a multinucleon transfer reaction of a \(^{70}\mathrm {Zn}\) beam on a \(^{238}\mathrm {U}\) target. Unambiguous identification of prompt \(\gamma \) rays belonging to each nucleus was performed by coincidence detection of the ions in a high-acceptance magnetic spectrometer. The observed spectra are compared with large-scale shell-model calculations in the fpgd model space.

abstract

In the present contribution, the experimental investigation of the possible occurrence of the shape coexistence phenomenon in the \(^{83}\mathrm {Se}\) (\(Z=34\), \(N=49\)) and \(^{84}\mathrm {Se}\) (\(Z=34\), \(N=50\)) isotopes is presented. The aim of the experiment was to identify excited states which may be associated with different deformed shapes, i.e. , spherical, oblate, and prolate. The structure of both nuclei was studied by using \(\gamma \)-ray spectroscopy techniques, and the states and transitions of interest were investigated in detail through lifetime measurements and angular correlations.

abstract

The structure of the lowest-lying positive-parity states in \(^{99}\)Rh was studied via in-beam fast-timing measurements performed with the hybrid ROSPHERE multidetector array. The half-life \(T_{1/2}=405\,(20)\) ps, obtained for the \(7/2_1^+\) state, suggests that the M1 component of the \(7/2_1^+\rightarrow 9/2_1^+\) transition is hindered with respect to the single-particle estimates by two orders of magnitude, while the E2 component is enhanced, similarly to other odd-\(A\) nuclei in this region.

abstract

The excited structure of \(A = 128\) isobars populated in the \(\beta \) decay of \(^{128}\)Cd has been investigated by means of high-resolution \(\gamma \)-spectroscopy and fast-timing measurements. The experiment was performed at the ISOLDE facility at CERN profiting from the production of intense and pure Cd beams by means of a temperature-controlled quartz transfer line, capable of suppressing surface-ionized species. The production yields and purity of Cd beams are presented. Results on sub-nanosecond lifetimes for excited states in \(^{128}\)In and \(^{128}\)Te are discussed.

abstract

The EC/\(\beta ^+\) decay of \({^{182}\mathrm {Au}}\) was studied at the ISOLDE facility at CERN. Method of prompt \(\gamma \)–\(\gamma \) coincidences was used to build the level scheme of its daughter isotope, \({^{182}\mathrm {Pt}}\). The intensity of observed transitions was determined and used to calculate the amount of \(\beta \)-decay feeding into excited levels in \(^{182}\)Pt. These values are compared with \(\beta \)-decay feeding intensity values from the latest measurement of \({^{182}\mathrm {Au}}\) \(\beta \) decay.

abstract

The low-spin structures of the \(^{205}\mathrm {Pb}\) and \(^{207}\mathrm {Pb}\) isotopes, populated by thermal-neutron capture, have been studied by the \(\gamma \)-ray coincidence technique with the FIPPS HPGe array at the Institut Laue-Langevin (Grenoble, France). Preliminary results of the data analysis provided information on the decay schemes of the capture states located at 6.7 MeV in both nuclei. The spins of several states in \(^{205}\mathrm {Pb}\) have been established owing to \(\gamma \gamma \)-angular correlations analysis.

abstract

The level structure of \(^{202}\mathrm {Po}\) was studied using the \(^{195}\mathrm {Pt}\)(\(^{12}\mathrm {C}\), \(5n\)) reaction at a beam energy of 83 MeV. Improved lifetime measurements have been performed for the \(8^+\) and \(11^-\) isomeric states by the decay slope method using high-purity germanium clover detectors. The half-lives of these isomeric states were found to be \(T_{1/2}(8^+)\!=\!114\pm 5\) ns and \(T_{1/2}(11^-)\!=83\pm 6 \) ns. The variation of the reduced transition probabilities with neutron and proton number in the decay of these proton-dominated isomeric states is discussed.

abstract

A tool to analyse internal conversion electron energy spectra measured simultaneously with \(\gamma \) rays has been developed. It is based on the calculation of an electron energy spectrum by means of obtained \(\gamma \)-ray data, including resolution and efficiency parameters associated with the experimental setup and its comparison with the measured spectrum. Here, we present the working principle of the tool, demonstrate its performance with a standard \(^{133}\)Ba calibration source, and report on conversion coefficients of three transitions feeding the 9\(^-\) isomeric state in \(^{190}\)Tl, measured in an in-beam spectroscopy experiment.

abstract

The NEEDLE setup is designed and built to study exotic neutron-deficient nuclei. It allows for increased sensitivity to explore the nuclear structure close to the proton drip line. This detector setup combines the EAGLE \(\gamma \)-ray spectrometer and the capabilities of the NEDA array to identify the events in which a number of neutrons were emitted from the compound nucleus. Within this contribution, the first NEEDLE campaign and future plans are discussed.

abstract

The DIAMANT \(4\pi \) light-charged-particle detector array has been recently commissioned at the Heavy Ion Laboratory, University of Warsaw, and began a physics campaign there, for the first time coupled to NEEDLE: EAGLE (central European Array for Gamma Levels Evaluations) and NEDA (NEutron Detector Array) detector systems. Properties of this experimental setup and its performance during commissioning are discussed.

abstract

The resistance of a prototype planar electrically segmented p-type high-purity germanium (HPGe) detector to neutron damage and subsequent annealing procedures was investigated. The detector possesses 4 segment contacts made of laser-diffused Sb. To test its neutron resistance, the detector was subjected to a fast-neutron flux generated by the \(^{7}\mathrm {Li}(p,n)^7\mathrm {Be}\) reaction. The detector underwent irradiation, annealing, and repeated irradiation to simulate prolonged operational conditions. Our study reveals the gradual deterioration in resolution and efficiency as neutron fluence increases. The detector’s recovery after annealing was successfully demonstrated. The results highlight the importance of understanding neutron damage effects on p-type HPGe detectors. Further experiments and investigations are necessary to fully characterize this type of detector and understand all effects.

abstract

In recent years, a great deal of effort has been devoted to developing arrays of highly segmented germanium detectors, signal-processing electronics, and \(\gamma \)-ray tracking algorithms. With this advancement, the interaction points associated with a particular \(\gamma \)-ray can be identified in terms of spatial coordinates and deposited energy. The tracking provides the direction of the \(\gamma \)-ray emission and the position of its first interaction inside the detector. The detectors have a complex geometry and require sophisticated characterization/scanning systems. The prime objective of the present work is to improve the GSI 3D scanning system, particularly regarding position detector readout, its resilience, and speed, allowing for faster scanning of the entire segmented detector. In the proposed advancement, Silicon PhotoMultiplier (SiPM), i.e. , an array of square Avalanche PhotoDiodes, is employed to replace the previous position-sensitive Photo Multiplier Tube. A scanning device using a LYSO scintillator crystal coupled to an array of 96 position-sensitive SiPMs has been developed and coupled with a GSI-developed electronics TAMEX system. Before scanning any segmented detector, the scanner has been fully characterized. The work presents preliminary results of the performance evaluation and characterization of the new \(\gamma \)-ray scanner at GSI, Germany.

abstract

New beam position monitors were developed for the NA61/SHINE experiment. Detectors are based on the single-sided silicon strip detector produced by Hamamatsu (S13804). The detector’s readout allows for saving waveform for each strip, and it is based on DRS4 chips. The main goals required from the designed detectors are: they should work efficiently with proton and lead beams with beam intensity on the level of 100 kHz, the detectors’ material on the beamline should be minimized, the detectors should be able to determine the position of \(X\) and \(Y\) hit of each beam particle with maximum possible accuracy. In this contribution, detector design and construction will be presented. The developed procedure of the signal and position reconstruction will also be shown. Finally, detector performance during measurement will be discussed.

abstract

The Coulomb excitation of \(^{124,128,130,132,134}\)Sn isotopes in the electric field of a Pb target have been studied using the \(\mathrm {R^3B}\) setup as a part of the FAIR Phase-0 program. The experiment was motivated by the possibility of using the nuclear dipole response to infer valuable information on the slope of the symmetry energy of the nuclear equation of state. Measurements were performed in inverse kinematics at relativistic energies of 750 MeV/\(u\) and 904 MeV/\(u\). The analysis method and preliminary results for the decay channel with a single outgoing neutron for \(^{124}\)Sn are reported.

abstract

A fundamental framework to describe nuclear matter as a function of pressure and nuclear isospin asymmetry is the nuclear Equation of State (EoS). Constraining the parameters of the EoS is one of the central issues in nuclear physics, especially since the slope parameter \(L\) has not yet been constrained well experimentally. It has been identified that a precise determination of the neutron-removal cross section in neutron-rich nuclei, which correlates with the neutron-skin thickness, would provide a more precise constraint on \(L\). To this end, an experiment was performed at the \(\mathrm {R}^3\mathrm {B}\) setup in the GSI Helmholtzzentrum für Schwerionenforschung GmbH as a part of the FAIR Phase-0 program. The reactions are studied in inverse kinematics with neutron-rich tin isotopes in the mass range of \(A=124\)–134 on carbon targets of different thicknesses. The reaction products have been measured at beam energies of 400–900 MeV/\(u\) in a kinematically complete manner. In this communication, the analysis of \(^{124}\mathrm {Sn}+{^{12}\mathrm {C}}\) at 900 MeV/\(u\) is presented. The charge-exchange reactions, resulting processes, and their role in the calculation of other reaction cross sections are discussed.

abstract

Even though the hypernuclei, which are sub-atomic nuclei that contain the quark \(s\), have been studied with nuclear emulsions for more than 50 years, their current understanding has been challenged in recent years by experiments using high-energy heavy-ion beams. Firstly, the significantly shorter hypertriton lifetime reported by three independent state-of-the-art experiments, namely ALICE, STAR, and HypHI, compared to the predictions of theoretical models was poorly understood for some time. Notwithstanding, the current status of the hypertriton puzzle is evolving with the latest experimental efforts. Secondly, the observed enhancement in the invariant mass distributions of the \(t+\pi ^-\) and \(d+\pi ^-\) final states, as reported by the HypHI Collaboration, cannot be accounted for by existing theoretical calculations, which indicate the absence of a neutral \(nn{\mit \Lambda }\) bound state. Consequently, the WASA-FRS HypHI Experiment aims at obtaining new accurate results for the invariant mass and lifetime of \(^3_{\mit \Lambda }\)H and \(^4_{\mit \Lambda }\)H to produce more precise and statistically significant experimental results that can provide clarification on the potential existence of \(nn{\mit \Lambda }\). This experiment was successfully conducted in 2022 at GSI-FAIR. Data analysis is still ongoing, while several preliminary results are reported.

abstract

The study of strangeness production in heavy-ion collisions has been an active research area for several decades, as it provides crucial insights into the studies of the properties of strongly interacting matter. The NA61/SHINE experiment at CERN’s Super Proton Synchrotron (SPS) is one of the leading experiments in this field, thanks to systematic studies of hadron production in a wide range of collision energies and system sizes. The paper emphasizes the importance of measuring the strangeness production for the discussion concerning the onset of deconfinement. The latest results from the NA61/SHINE experiment on strangeness production in heavy-ion collisions are discussed and compared to available world data and selected theoretical models.

abstract

To synthesize a new superheavy element, \(Z=119\), the RIKEN Nishina Center (RNC) has upgraded the existing heavy-ion linac system (called RILAC) to the superconducting linear accelerator system (SRILAC) to enable a hot fusion reaction of \(^{51}\mathrm {V}+{^{248}\mathrm {Cm}}\). The upgraded project, called the ‘SHE project’, was completed in 2020. After the commissioning of SRILAC, the first step was to measure the Coulomb barrier distribution for the \(^{51}\mathrm {V}+{^{248}\mathrm {Cm}}\) system in order to deduce the optimal bombarding energy of the \(^{51}\mathrm {V}\) beam. The measurement of the synthesis of \(Z=119\) was then started and is still going. The side-collision effect due to nuclear deformation should play an important role in maximising the synthesis cross section. Since \(^{159}\mathrm {Tb}\) and \(^{248}\mathrm {Cm}\) have a similar amount of deformation (\(\beta \sim 0.28\)), the \(^{51}\mathrm {V}+{^{159}\mathrm {Tb}}\) reaction was used to study the deformation effect. The \(^{51}\mathrm {V}+{^{159}\mathrm {Tb}}\) reaction has large fusion reaction cross sections and, therefore, the Coulomb barrier distribution as well as the evaporation residues for the \(xn\), \(pxn\), and \(\alpha xn\) exit channels could be measured. The evaporation residue cross sections are compared with those of the simple statistical decay model calculation.

abstract

The systematics of fission-barrier scaling in the complete-fusion reactions leading to neutron-deficient astatine and radon compound nuclei is derived and discussed. The available cross-section data complemented by the newly-analysed unpublished experimental data were compared with the theoretical calculations by the statistical model code Hivap. The linear trend between barrier scaling and the mass number of compound nuclei was observed. The calculations for the most neutron-deficient nuclei required a significantly larger decrease in the fission-barrier height to reproduce the experimental data. A potential effect of quasi-fission causing this sudden trend change is outlined.

abstract

A comparative study of the quasielastic barrier distributions of the \(^{20}\mathrm {Ne}+{^{92,94,95}\mathrm {Mo}}\) systems was performed at the Heavy Ion Laboratory (HIL) of the University of Warsaw. The experiment aimed to study the influence of dissipation due to single-particle excitations on the barrier distribution structure. The preliminary results indicate that the larger number of single-particle excitations for the heaviest Mo isotopes leads to the smoothing of the barrier distribution, which loses the structure foreseen by the coupling to only collective excitations. Theoretical calculations performed including the coupling to the non-collective excitation are in good agreement with the experimental barrier distributions for the \(^{20}\mathrm {Ne}+{^{92,94,95}\mathrm {Mo}}\) systems.

abstract

An attempt has been made to understand the effect of transfer channels on reaction dynamics for the \(^{16}\mathrm {O}+{^{165}\mathrm {Ho}}\) system through the measurement of a quasi-elastic excitation function at backward angles, which was translated to the corresponding barrier distribution. The results were explained in light of coupled channel calculations performed with the inclusion of different possible coupling schemes describing the structure of the projectile and target nuclei. Analysis reveals that the rotational coupling of the target nuclei along with the coupling due to the \(2n\)-transfer (pick-up) channel satisfactorily reproduces the experimental data.

abstract

We have studied the mass distribution of \(^{256, 260}\mathrm {Rf}\) compound nuclei produced in the \(^{48}\mathrm {Ti}+{^{208}\mathrm {Pb}}\) and \(^{28}\mathrm {Si}+{^{232}\mathrm {Th}}\) reactions at an excitation energy of 57 MeV. The results confirmed the presence of quasi-fission processes in the \(^{48}\mathrm {Ti}+{^{208}\mathrm {Pb}}\) system and a non-negligible contribution in the \(^{28}\mathrm {Si}+{^{232}\mathrm {Th}}\) system. The observed mass distributions of the fission fragments are also compared with the predictions from dinuclear system calculations.

abstract

In this work, channel-by-channel excitation functions of evaporation residues, \(^{201}\mathrm {Bi}\) \((4n)\), \(^{201}\mathrm {Pb}\) \((p3n)\), and \(^{198}\mathrm {Tl}\) \((\alpha 3n)\), populated via complete and/or incomplete fusion in the \(^{12}\mathrm {C}+{^{193}\mathrm {Ir}}\) system, have been measured at energies \(\approx \) 64–84 MeV using an activation technique followed by the off-line \(\gamma \)‑spectroscopy and compared with the PACE4 calculations. The reaction residues have been identified based on their characteristic \(\gamma \)-lines and decay curve analysis. The preliminary analysis suggests that the \(xn/pxn\) channels are predominantly populated via a complete fusion of \(^{12}\mathrm {C}\) with \(^{193}\mathrm {Ir}\) and \(\alpha \)‑emitting channels show a contribution from both the complete and incomplete fusion at the studied energy range.

abstract

The article discusses the underlying reaction dynamics in the \(^{6}\mathrm {Li}+{^{93}\mathrm {Nb}}\) reaction through the excitation function analysis within the 24–43 MeV energy domain employing an activation technique followed by off-beam \(\gamma \)‑spectroscopy. The comparison of measured data with equilibrium and preequilibrium-based statistical model calculations implies a fair reproduction of \(n\)-channel data by the EMPIRE EGSM level density predictions, suggesting the production of Ru radionuclides via the complete fusion mechanism. The enhancement in \(\alpha \)-channel cross sections relative to the theory is evident of competing incomplete fusion (ICF) process owing to the weak binding of the \(^{6}\)Li projectile. The estimated ICF strength fraction from the \(\alpha \)-channels obeys an increasing trend with incident energy.

abstract

In the present work, a systematic attempt has been made to understand the dependence of low-energy (\(\approx 4\)–7 MeV/nucleon) incomplete fusion reactions on different entrance channel parameters through the excitation functions and recoil range distribution measurements of evaporation residues populated through the complete and incomplete fusion reactions. The present analysis clearly demonstrates that the \(xn/pxn\) channels are populated, to a large extent, through the complete fusion processes. However, the production cross sections of the \(\alpha \) emitting channels were found to be significantly under-estimated by the statistical model predictions. Dependence of low-energy incomplete fusion reactions on various entrance channel parameters was studied. Additionally, efforts have been exerted to explore certain general systematics, with the system parameter (\(\zeta \)) appearing to provide a more satisfactory explanation for the low-energy incomplete fusion data compared to other entrance channel parameters.

abstract

In this paper, we conducted a scientific exploration of cluster radioactivity, with a specific focus on lanthanide parents such as \(^{120-124}\mathrm {Ce}\), \(^{124-128}\mathrm {Sm}\), and \(^{130-134}\mathrm {Gd}\) originating from the trans-tin region. The primary objective of this study is to gain insights into the fragmentation and structural characteristics of these nuclei. To achieve this, we have employed Skyrme Energy Density Formalism (SEDF) within the framework of the Preformed Cluster Model (PCM). This model addresses the cluster emission process, which involves tunneling through a potential barrier, with the fragments preformed and having a relative probability denoted as \(P_0\). Our investigation highlights the influence of deformation and orientation effects on potential energy surfaces, preformation probability, barrier penetrability, and decay half-live, shedding light on the crucial role of nuclear shape and structure in view of cluster radioactivity.

abstract

Neutron-rich light nuclei are pivotal contributors in the nucleosynthesis process and the degree of alpha (\(\alpha \)) clustering exerts significant influence on astrophysical reaction rates. Therefore, it is imperative to investigate the \(\alpha \)-clustering in the isotopic chain of light mass nuclei. In this study, we have examined the evolution of the probability of \(\alpha \)-cluster preformation in \(^{41,45,49}\mathrm {Ca}^{*}\) nuclei formed through neutron-induced reactions within the quantum mechanical fragmentation theory (QMFT). The results indicate a monotonous decrease in the \(\alpha \)-cluster preformation factor as one moves from \(^{41}\mathrm {Ca}^{*}\) toward the neutron-rich \(^{49}\mathrm {Ca}^{*}\) nuclear system. Further, we have incorporated within QMFT, for the first time, the microscopic nuclear potential derived from folding the Fermi form fitted cluster densities from relativistic mean field theory and M3Y nucleon–nucleon interaction. We have varied the neutron skin thickness of the Ar cluster, which is complementary to the \(\alpha \)-cluster, and its subsequent impact on the nuclear interaction potential and \(\alpha \)-cluster preformation factor has been analyzed. The results demonstrate that, with the growth of neutron skin of the Ar cluster, the \(\alpha \)-cluster preformation factor decreases. It highlights a relationship between neutron skin thickness and \(\alpha \)-cluster preformation factor in these light mass \(^{41,45,49}\mathrm {Ca}^{*}\) nuclei.

abstract

Characterization of the excited states of \(^{11}\mathrm {C}\), \(^{12}\mathrm {C}\), \(^{13}\mathrm {C}\) isotopes was performed using experimental data collected at the INFN-LNL in Italy. The study employed a 95 MeV \(^{14}\mathrm {N}\) beam on \(^{10}\mathrm {B}\) targets to probe clustering phenomena in carbon isotopes. The experimental setup included a detector system covering polar angles from 15\(^{\circ }\) to 72\(^{\circ }\), enabling the study of reactions with two and three products in the exit channel. Analysis of the three-product exit channels is presented to provide insight into the process of analyzing such reactions. Presented results for the \(^{7}\mathrm {Be}+{^{4}\mathrm {He}}\), \(^{8}\mathrm {Be}+{^{4}\mathrm {He}}\), and \(^{9}\mathrm {Be}+{^{4}\mathrm {He}}\) decays of \(^{11}\mathrm {C}\), \(^{12}\mathrm {C}\), \(^{13}\mathrm {C}\), respectively, unveil states at 7.6, 9.7, and 14.1 MeV in \(^{12}\mathrm {C}\), 8.1 and 8.4 MeV in \(^{11}\mathrm {C}\), as well as a broad peak centered at 13.6 MeV with a possible contribution of states from 13.4 to 14.1 MeV in \(^{13}\mathrm {C}\). The detection of these states serves as a crucial validation of the analysis and data selection procedures, representing an initial step before exploring other exit channels.

abstract

The \(2^+\) doublet in \(^{8}\mathrm {Be}\) is a well-known example of nearly equal isospin mixing between two states. However, the degree of mixing has not been experimentally determined as the studies of reaction feeding to the doublet do not distinguish isospin easily, and the \(\beta ^+/\)EC feeding rate is very low. The IS633 experiment is the first beta decay study to resolve the \(2^+\) doublet thanks to the high statistics and, therefore, gives a chance to determine the mixing through the study of the Gamow–Teller and Fermi population of these states. Two approaches have been followed: an R-matrix analysis and the \(\beta \) recoil study. Preliminary results are presented in this contribution.

abstract

The measurement of \(^{12}\mathrm {C}\!+\!{^{12}\mathrm {C}}\) at astrophysical energies is mandatory to well understand stellar evolution. First, fusion hindrance has been observed in most medium–heavy fusion systems, but the effect on light–medium systems is still unclear. Second, the presence of resonances in the \(^{12}\mathrm {C}\!+\!{^{12}\mathrm {C}}\) fusion reaction, that can be a strong indication of molecular states in the \(^{24}\mathrm {Mg}\), can also have an impact on our understanding of stellar evolution of massive stars. The precise measurements of these reaction cross sections at deep sub-barrier energies are highly challenging, as the cross section is at a sub-nanobarn level with a dominating background. To overcome this challenge, the STELLA (STELla LAboratory) experiment combined with the UK-FATIMA (FAst TIMing Array) allows for a coincident measurement of gammas and charged particles from the fusion reaction to efficiently suppress the background and achieve precise measurements at deep sub-barriers energies in the astrophysical region of interest. The first experimental campaign in 2016/2017 revealed hints of hindrance and a potential resonance at low energies. This contribution will discuss data from the 2019 experimental campaign and give details about the experimental setup.

abstract

The \(^{16}\mathrm {O}(p,\gamma )^{17}\mathrm {F}\) nuclear reaction is a key part of the CNO cycle. The rate of this reaction strongly affects the relative abundances of oxygen isotopes formed in low and intermediate mass stars, particularly AGB stars. There are currently few experimental data for this reaction at low energies, and the data that exist have large uncertainties. An experimental campaign has been carried out at the LUNA laboratory in Italy, taking advantage of the ultra-low background rates available in its underground location to measure the weak \(^{16}\mathrm {O}(p,\gamma )\) reaction close to energies of astrophysical interest.

abstract

High-energy electron–positron (\(e^{+}e^{-}\)) emission in the deuteron–deuteron reaction supporting the existence of the single-particle threshold resonance in \(^{4}\mathrm {He}\) has been observed. This observation suggests a new decay channel in the deuteron–deuteron reaction at extremely low energies. The experiment was carried out by employing Si detectors of different thicknesses and various Al absorption foils placed in the front of the detector at the eLBRUS Ultra High Vacuum Accelerator Facility of the Szczecin University, Poland. A deuterium beam was accelerated to energies ranging between 7 and 14 keV. The measured electron energy spectrum and the electron–proton branching ratio show a strong alignment with our expectations for an \(e^{+}e^{-}\) pair creation decay from the deuteron–deuteron \(0^{+}\) threshold resonance to the ground state, which should be many orders of magnitude stronger than other electromagnetic channels. Our detailed Monte Carlo simulations of the experimental energy spectrum also confirmed this alignment and predict an increase in the electron–proton BR when lowering the deuteron energy.

abstract

A biological sample irradiation system consisting of a 50 mm diameter \(^{241}\mathrm {Am}\) disc source was developed at the Heavy Ion Laboratory of the University of Warsaw. Prior to biological experiments, an investigation was conducted on the irradiation system to accurately assess the dose distribution within cells by analyzing the \(\alpha \)-particle spectrum. A comprehensive numerical model of the irradiation system was developed to simulate and analyze the radiation process. The results of the numerical simulations were subsequently compared with measurements of \(\alpha \)-particle energies emitted from the source and were found to agree within 4% agreement. The measurements were performed using a silicon detector under vacuum conditions and a track detector.

abstract

Nitrogen is one of the most common elements in the human body, beyond hydrogen, oxygen, and carbon. Proton beams used in therapy induce nuclear reactions on these elements that cause a loss of fluence along the beam path. These reactions often lead to production of \(\beta ^+\) emitters with relatively short half-lives (less than 20 minutes). While the reaction on carbon leading to production of \(^{11}\)C has been extensively studied, the cross section for reactions on nitrogen and oxygen are not sufficiently known, particularly at proton energies above a few tens of MeV. This contribution presents the results of an experiment, where solid boron nitride targets were used to study nuclear reactions induced by protons with energy below 60 MeV on nitrogen. The proton beam was delivered by the AIC-144 cyclotron of the Institute of Nuclear Physics in Kraków. As a result, the cross section of \({^{14}\mathrm {N}}(p,x){^{13}\mathrm {N}}\) reaction was obtained.