The gamma rays emitted by the T(D,γ)5He fusion reaction have been measured at the FNG neutron irradiation facility in ENEA-Frascati by using a large 3”x3” LaBr3 scintillator crystal. Since the gamma ray emission probability by the DT reaction is 10-5 lower with respect to the main fusion reaction channel T(D,n)4He a neutron attenuator is needed. In this paper we present the design of a neutron attenuator based on a combination of different materials. The neutron attenuator performances have been studied with a series of MCNP simulations benchmarked with an experiment performed with a 137Cs gamma ray source. The analysis of the experimental results shows a gamma component in the region of interest that is compatible with the T(D,γ)5He reaction. Although the results obtained at FNG indicate that the gamma rays emitted by the T(D,γ)5He can be measured with the present set-up, they also show that an improvement of the experimental set-up is needed. An analysis of the background induced by the scattered neutrons is provided and improvements to the neutron attenuator are proposed.

The INFN Laboratori Nazionali di Frascati was established in 1954 to host an electro-synchrotron, the first particle accelerator built in Italy, and since then played a crucial role in the field of nuclear and particle physics and for the development of acceleration and detection technologies. Within this historical tradition, a workshop was organized at LNF in the framework of the Nuclear Physics Mid Term Plan Italy, an initiative of the Nuclear Physics Division of the Istituto Nazionale di Fisica Nucleare, to discuss the detection techniques employed in nuclear physics and to identify the open issues to be addressed to realize the scientific programs of the experiments foreseen in a midterm perspective. The present report summarizes the outcome of the discussions.

Low-lying states of ^94Zr were investigated via low-energy multi-step Coulomb excitation. From the measured γ-ray yields, 16 reduced E2 transition probabilities between low-spin states were determined, together with the spectroscopic quadrupole moments of the 2_1,2^+ states. Based on this information, for the first time in the Zr isotopic chain, the shapes of the 0_1,2^+ states including their deformation softness were inferred in a model-independent way using the quadrupole sum rules approach. The ground state of ^94Zr possesses a rather diffuse shape associated with a spherical configuration, while the 0_2^+ state is triaxial tending towards oblate and more strongly deformed. The observed features of shape coexistence in ^94Zr are consistent with both Monte-Carlo shell-model predictions and IBM-CM calculations, and provide model-independent constraints on the shape character assigned in the IBM-CM to the intruder configuration in ^92–96Zr.

Low-energy multi-step Coulomb excitation measurements have been performed to study the structure of low-lying excitations in the zirconium isotopes, which are particularly interesting as, in recent years, evidence has come to light that they are excellent cases for exhibiting shape evolution and shape coexistence. In order to provide definitive information on the shapes of the low-lying states of 94,96 Zr, two Coulomb excitation experiments were performed at INFN-LNL using γ-ray spectrometers coupled with the heavy-ion detector array SPIDER. In the 94 Zr experiment SPIDER was coupled to the resident array GALILEO, based on HPGe detectors, and 6 lanthanum bromide scintillators. In the 96 Zr experiment the γ-ray tracking spectrometer AGATA was used in conjunction with SPIDER. The information obtained from the measured yields for γ-particle coincidences indicates the presence of coexisting shapes in these nuclei and will allow for an in-depth comparison with theoretical predictions.

Neutron emission spectroscopy is an effective nuclear fusion plasma diagnostics technique for diagnosing the fuel ion populations on fusion plasma experiments. The state of the art 2.5 MeV neutron spectrometer for deuterium plasmas is based on the time of flight (TOF) technique, which however requires the development of large scale instruments. No compact alternatives that approach the performance of TOF have been found so far. Liquid and plastic scintillators have limited spectroscopic capabilities due to their non-peaked response to monoenergetic neutrons. In the last years, Chlorine based scintillators have been explored. In these instruments, neutron detection is based on the Cl-35(n,p)S-35 nuclear reaction, which results in a Gaussian peak in the recorded neutron energy spectrum. In this context, one option is offered by CLYC scintillators, which have the drawback of a limited counting rate capability (a few tens of kHz). Another option is offered by the LaCl3:(Ce) scintillators, which combine a comparable energy resolution and, most importantly, a faster signal (<1 s) enabling measurements at higher counting rates. On the other hand, LaCl3 has a more challenging particle discrimination. The standard method based on pulse shape analysis provides a limited particle identification and poses restrictions in the counting rate capability of the instruments. An innovative particle identification algorithm based on Fourier Transforms has been developed providing higher accuracy and effectiveness. In this paper, we present the performance of a 2.5 MeV neutron spectrometer based on a LaCl3 scintillator in terms of pulse shape discrimination and energy resolution. Results are used to discuss their use for neutron spectroscopy applications in tokamak plasmas.

Here we report on the measurements of the gamma -ray strength functions and nuclear level densities of 112,114Sn performed for the first time at the 9-MV Tandem accelerator facilities at Horia Hulubei Institute for Physics and Nuclear Engineering using the Oslo method. We extract thermodynamic properties and gross and fine properties of the pygmy dipole resonance for systematic comparison in the chain of Sn isotopes. The results are compared with microscopic models implemented in the TALYS reaction code and the fully microscopic quasiparticlephonon model for the underlying nuclear structure of the dipole strength in 112,114Sn. The quasiparticle-phonon model results show the importance of complex configurations to the low-energy dipole response in the pygmy dipole resonance energy region. The experimental data are further included in the cross section and reaction rate calculations for the (n, gamma ) reaction of the p-process nuclei 112,114Sn showing a significant increase in reaction rates at high temperatures compared to existing nuclear databases.

Monolithic gamma-ray detectors can be used in single photon emission computed tomography systems for monitoring the delivered dose during boron neutron capture therapy treatments. Gamma-ray hit localization in thick monolithic scintillator crystals is a challenging task due to internal reflections and Compton scattering. Existing methods like the center of gravity (CoG) are susceptible to reconstruction uncertainties at the crystal edges, while approaches, including nonlinear analytical and statistical models, such as the maximum-likelihood, require significant computational resources. Artificial neural networks (ANNs) offer significant improvements in terms of accuracy and computational speed. In this study, we develop a supervised ANN regression algorithm for real-time position reconstruction in a thick square lanthanum bromide crystal [LaBr3(Ce+Sr) ] with 5cm x 5cm x 2cm dimensions, coupled with an 8 x 8 matrix of silicon photomultipliers. The implemented neural network was trained and tested using calibration data acquired irradiating the crystal with a collimated 137Cs source (pencil-beam irradiation). The detector in combination with the ANN model achieves a positioning accuracy for single-gamma-ray events of approximately 2.6 mm in the central region, evaluated as the full width at half maximum (FWHM) of the prediction error distribution, slightly worsening toward the edges. The imaging capabilities of the detector in combination with a channel-edge pinhole collimator were then evaluated by acquiring images of a movable uncollimated Cs-137 point source. The source was shifted in nine different positions at 3 mm distance from each other and the resolution of the system was evaluated fitting the images with a Gaussian curve. An image spatial resolution of around 8 mm FWHM was obtained, dominated as expected by the collimator geometry, with an accuracy of 0.7 mm in estimating the position of the point source.

The isospin mixing was deduced in the compound nucleus 72Kr at a low nuclear temperature around 1.3 MeV, from the gamma decay of the giant dipole resonance. The gamma rays from two compound-nucleus reactions were measured: from the 32 S + 40Ca at bombarding energy of 90 MeV characterized by isospin I = 0, and from the 31 P + 40Ca at 82 MeV used as a reference. The ELIFANT array was employed at the Bucharest Tandem Laboratory, consisting of Compton-suppressed scintillator detectors. The statistical-model analysis of the measured spectra provided a mixing parameter of (3.5 +/- 0.8)%. This new point, being at the lowest temperature compared with the few other existing ones, can validate the predictions of the temperature dependence of the isospin mixing. The isospinsymmetry-breaking correction, delta c, used for the Fermi super-allowed transitions was extracted from the present result of the isospin mixing and found to be consistent with beta decay data, theoretical predictions, and previous experimental results.

The Joint European Torus performed its second deuterium–tritium (DT) campaign at the end of 2021. This unique opportunity was exploited to carry out the first absolute measurement in a magnetic confinement plasma of the total gamma-ray emission from the DT fusion reaction, namely the less probable (branching ratio = 2.4 ⋅ 10 − 5 ) electromagnetic counterpart of the main neutronic decay channel. A single line of sight gamma-ray spectrometer was employed for this purpose. Numerous challenges had to be addressed in order to pursue the goal: (1) characterise the detector beamline and its detection efficiency in absolute terms, (2) dealing with an extended and non-uniform source, (3) suppress the intense neutron background, (4) handle the high event rate at the detector and (5) discriminate between signal and background in the acquired energy spectrum. This paper describes the procedure adopted for measuring the total DT gamma-ray yield of 96 DT plasma discharges with event rates below hundred kHz. The results were validated through a comparison with the neutron yields provided by the Joint European Torus neutron monitors, revealing an outstanding 0.983 linear correlation. This work proves the feasibility to employ the gamma-ray emission of the DT fusion reaction as a secondary indicator for measuring the fusion power in magnetically confined DT plasmas.

In the field of hadrontherapy, Prompt Gamma Imaging (PGI) is a technique considered for range verification purposes. Prompt Gamma (PG) measurements are strongly affected by the presence of a neutron background, which can limit the possibility to perform range monitoring, especially in the framework of Carbon Ion therapy. A detector system based on Pulse Shape Discrimination (PSD) for neutron background reduction in Prompt Gamma range monitoring is here proposed. The detector, based on a $5 \mathrm{~cm} \times 5 \mathrm{~cm} \times 2 \mathrm{~cm}$ CLYC (Cs2LiY Cl6: Ce) scintillator crystal, read out by near-ultraviolet high density (NUV-HD) SiPM tiles and compact electronics, acquires and converts in real time the Pulse Shape Discrimination coefficients, allowing to discard during the acquisition the range uncorrelated signal caused by neutrons. The effectiveness of the discrimination capability of the crystal was confirmed with experimental measurements performed at CNAO (Centro Nazionale di Adroterapia Oncologica), with the detection of PG and neutrons following an RW3 phantom irradiation.

Prompt Gamma Imaging (PGI) is a promising technique for range verification in Particle Therapy. This technique was already tested in clinical environment with a knife-edge-collimator camera for proton treatments but remains relatively unexplored for Carbon Ion Radiation Therapy (CIRT). Previous FLUKA simulations suggested that PG profile shifts could be detected in CIRT with a precision of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sim$$\end{document} 4 mm (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$2 \sigma$$\end{document}) for a particle statistic equal to \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$5 \cdot 10<^>{7}$$\end{document} C-ions using a 10 x 10 cm2 camera. An experimental campaign was carried out at CNAO (Pavia, Italy) to verify these results, using a knife-edge-collimator camera prototype based on a 5 x 5 cm2 pixelated LYSO crystal. PG profiles were measured irradiating a plastic phantom with a C-ion pencil beam at clinical energies and intensities, also moving the detector to extend the FOV to 13 x 5 cm2. The prototype detected Bragg-peak shifts with \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sim$$\end{document} 4 mm precision for a statistic of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sim 4 \cdot 10<^>{8}$$\end{document} C-ions (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$3 \cdot 10<^>{8}$$\end{document} for the extended FOV), slightly larger than expected. Nevertheless, the detector demonstrated significant potential for verifying the precision in dose delivery following a treatment fraction, which remains fundamental in the clinical environment. For the first time to our knowledge, range verification based on PGI was applied to a C-ion beam at clinical energy and intensities.

The electric dipole strength above the one-neutron separation energy has been measured in the neutron-rich nucleus 52Ca using the Coulomb excitation at 223 MeV/nucleon in inverse kinematics. The gamma-ray detector array CATANA, the neutron detector NeuLAND demonstrator, and the SAMURAI spectrometer at RIKEN Nishina Center were combined to reconstruct the excitation energy of 52Ca. A observed sharp peak at the very low neutron energy in the 52Ca -> 51Ca +n channel indicates that 52Ca has a sizable amount of dipole strength just above the one neutron threshold.

The pygmy dipole resonance (PDR) has been the subject of numer-ous studies, both experimental and theoretical. Indeed, the study of the PDR has been and still is of great interest since it allows to constrain the symmetry energy, an important ingredient of the equation of state of nuclear matter that describes the matter within neutron stars. Moreover, the PDR is predicted to play a key role in the r-pro cess via the increase of the neutron capture rate. However, despite numerous experiments dedicated to the study of the PDR, a consistent description is still missing. In this context, we have proposed to study the PDR using a new probe: the neutron inelastic scattering reaction (n,n'-y). An experiment to study the pygmy resonance in 140Ce using the (n,n'-y) reaction has been performed in Septem-ber 2022. This experiment has been made possible thanks to the high-intensity proton beam of the new accelerator SPIRAL2 at GANIL and the NFS (Neutron For Science) facility. The experimental setup was composed of the new generation multi-detectors PARIS, for the detection of-y-rays coming from the de-excitation of the PDR, and MONSTER, for the detection of scattered neutrons. In this article, the experiment motivation and description are presented.

The ITER Radial Gamma-Ray Spectrometer (RGRS) consists of three gamma-ray detectors observing the plasma through three collimated, coplanar, radial lines of sight (LoS). The system was initially designed to monitor the runaway electron emission and the alpha-particle density profile [Nocente et al., Nucl. Fusion 57, 076016 (2017)]. This work presents a novel technique for measuring the fusion power during D-T operation using the RGRS. This method is based on the absolute measurement of the 17 MeV fusion gamma-rays and a semi-analytical computation of their transport from the plasma source to the detectors. This approach was initially developed and tested at JET during the second D-T campaign (DTE2) on a single LoS diagnostic [Dal Molin et al., Phys. Rev. Lett. (submitted) (2024); Rebai et al., Phys. Rev. C (submitted) (2024); and Marcer et al., Nucl. Fusion (unpublished) (2024)]. This work exploits the multiple LoS of the RGRS to create a combined virtual diagnostic whose detected fraction of the total plasma emission is less affected by variations in the plasma emission profile, reducing systematic uncertainties on the estimated total emission, compared to the individual detectors.

The paper reports on a fast neutron efficiency study with CLYC scintillators of different sizes useful for various fast neutron spectroscopy applications such as medical physics, security, space missions, and nuclear physics experiments. In nuclear physics experiments to study the collective properties of nuclei, neutron and $\gamma$ spectroscopy are required. CLYC scintillators are good candidates to build an array for such experiments, thanks to their ability to measure and discriminate both $\gamma$ rays and neutrons. This paper presents the results of fast neutron efficiencies of different sizes (1” x 1”, 2” x 2”, 3” x 3”) of CLYC scintillators in the energy range 0.8-10 MeV using an AmBe source with a continuous spectrum, in order to select the most suitable size for a future array. The found efficiencies were somewhat unexpected and did not scale with crystal volume. In this paper we give two explanations: i) neutrons lose energy in the crystal and are no longer detected, and ii) neutrons interact by scattering and escape from the lateral surface of the detector. We present the results of measurements to quantify and disentangle the effects. Furthermore, these results show that it is better to cover a large solid angle than to have a single long crystal.

The spectral 𝛾 ray emission from the reaction 3H⁡(2H,𝛾)⁢5He has been measured for the first time in a magnetic confinement deuterium-tritium plasma experiment at the Joint European Torus. A custom developed gamma ray spectrometer system based on a La⁢Br3 scintillator combined to a LiH neutron attenuator and a zero dead time fast digital data acquisition allowed to measure the weak 𝛾 ray emission under the ≈105 more intense 14MeV neutron field. The 𝑅-matrix analysis of the 5He nucleus has been used to predict the expected gamma ray spectrum which has been compared with the measurement, but cannot predict the relative intensity of the 𝛾 lines. The data analysis has identified the energy and width of the known 16.75 MeV 𝛾 ray emission (𝛾0), from the second excited state to the ground state of the formed 5He nucleus, and confirmed the presence of a second emission (𝛾1) at ≈14⁢MeV due to the transition from the second to the first excited state. The analysis has shown that the 𝛾1 emission is broad and has assessed for the first time in a magnetic confinement experiment the relative yield 𝛾1 to 𝛾0 equal to 1.09±0.25.Received 2 January 2024Accepted 20 March 2024DOI:https://doi.org/10.1103/PhysRevC.110.014625©2024 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasElectromagnetic transitionsFusion productsGamma-ray generation in plasmasMagnetic confinement fusionNuclear fusionPlasma fusionResonance reactionsPhysical SystemsFusion reactorsMagnetically confined plasmasTokamaksPropertiesA ≤ 5TechniquesGamma ray spectroscopyRadiation detectorsX-ray & gamma ray plasma measurementsNuclear PhysicsEnergy Science & TechnologyPlasma Physics

. - The high-energy gamma-rays from the GDR decay of 56,60,62Ni* nuclei at finite temperature, produced in the reactions 32,34,36S + 24,26Mg at bombarding energies between 78 , 90 MeV, were measured and analyzed with statistical model using a Monte Carlo approach. It is found that the present analysis gives some evidence on the presence of an extra yield on the tail of the Giant Dipole Resonance which may be attributed to a Pygmy Dipole Resonance in an excited nucleus.

At present, magnetic confinement fusion devices rely solely on absolute neutron counting as a direct way of measuring fusion power. Absolute counting of deuterium-tritium gamma rays could provide the secondary neutron-independent technique required for the validation of scientific results and as a licensing tool for future power plants. However, this approach necessitates an accurate determination of the gamma-ray-to-neutron branching ratio. The gamma-ray-to-neutron branching ratio for the deuterium-tritium reaction 3 H ( 2 H, gamma ) 5 He / 3 H ( 2 H, n ) 4 He was determined in magnetic confinement fusion plasmas at the Joint European Torus in predominantly deuterium beam heated plasmas. The branching ratio was found to be equal to ( 2.4 + 0.5) ) x 10-5 - 5 over the deuterium energy range of ( 80 + 20) ) keV. This accurate determination of the deuterium-tritium branching ratio paves the way for a direct and neutron-independent measurement of fusion power in magnetic confinement fusion reactors, based on the absolute counting of deuterium-tritium gamma rays.

The γ decay of the elusive narrow, near-threshold proton resonance in 11B was investigated at Laboratori Nazionali di Legnaro (INFN) in a particle-γ coincidence experiment, using the 6Li(6Li,pγ) fusion-evaporation reaction and the GALILEO-GALTRACE setup. No clear signature was found for a possible E1 decay to the 1/21−, first-excited state of 11B, predicted by the Shell Model Embedded in the Continuum (SMEC) with a branching of 0.98−69+167×10−3 with respect to the dominant particle-decaying modes. The statistical analysis of the γ-ray spectrum provided an average upper limit of 2.37×10−3 for this γ-ray branching, with a global significance of 5σ. On the other hand, by imposing a global confidence level of 3σ, a significant excess of counts was observed for E=γ9300(20) keV, corresponding to a resonance energy of 11429(20) keV (namely 200(20) keV above the proton separation energy of 11B) and a γ-ray branching of 1.12(35)×10−3. This result is compatible with the SMEC calculations, potentially supporting the existence of a near-threshold proton resonance in 11B.

The spectral gamma ray emission from the reaction 3 H( 2 H , gamma )5He 5 He has been measured for the first time in a magnetic confinement deuterium-tritium plasma experiment at the Joint European Torus. A custom developed gamma ray spectrometer system based on a LaBr3 3 scintillator combined to a LiH neutron attenuator and a zero dead time fast digital data acquisition allowed to measure the weak gamma ray emission under the 105 5 more intense 14 MeV neutron field. The R-matrix analysis of the 5 He nucleus has been used to predict the expected gamma ray spectrum which has been compared with the measurement, but cannot predict the relative intensity of the gamma lines. The data analysis has identified the energy and width of the known 16.75 MeV gamma ray emission (gamma 0), gamma 0 ), from the second excited state to the ground state of the formed 5 He nucleus, and confirmed the presence of a second emission (gamma 1) gamma 1 ) at 14 MeV due to the transition from the second to the first excited state. The analysis has shown that the gamma 1 emission is broad and has assessed for the first time in a magnetic confinement experiment the relative yield gamma 1 to gamma 0 equal to 1.09 . 09 +/- 0.25. . 25.