Nuclear Reaction Studies Research Articles

17O Destruction Rate in Stars

In recent years, several laboratory studies of CNO cycle-related nuclear reactions have been carried out. Nevertheless, extant models of stellar nucleosynthesis still adopt CNO reaction rates reported in old compilations, such as NACRE or CF88. In order to update these rates, we performed new calculations based on a Monte Carlo R-Matrix analysis. In more detail, a method was developed that is based on the collection of all the available data, including recent low-energy measurements obtained by the LUNA collaboration in the reduced background environment of the INFN-LNGS underground laboratory, on R-Matrix cross-section calculations with the AZURE2 code and on uncertainty evaluations with a Monte Carlo analysis. As a first scientific benchmark case, the reactions 17O(p,γ)18F and 17O(p,α)14N were investigated. Among the different stellar scenarios they can influence, the 16O/17O abundance ratio in RGB and AGB stars is the one that can be directly confirmed from spectroscopic measurements. The aim is to reduce the nuclear physics uncertainties, thus providing a useful tool to constrain deep mixing processes eventually taking place in these stars. In this work, we present the procedure we followed to calculate the 17O(p,γ)18F and the 17O(p,α)14N reaction stellar rates and preliminary comparisons with similar rates reported in widely used nuclear physics libraries are discussed.

Nuclear Data Sheets for A=30

Evaluated spectroscopic data and level schemes from radioactive decay and nuclear reaction studies are presented for 30F, 30Ne, 30Na, 30Mg, 30Al, 30Si, 30P, 30S, 30Cl, and 30Ar. The recommended values for the level energies and their percentage decay modes, level lifetimes, γ energies, γ branching ratios, transition probabilities, etc. are presented. Among these nuclides, 30F is unobserved and most likely particle unbound. Additional experimental data are required for firm spin-parity assignments of the low-lying excited levels of 30Ne. The most well studied nuclide is 30Si followed by 30P. The data for the most proton-rich nuclide 30Ar are presented following the recent work of 2018Xu04 and 2015Mu13. This evaluation for A=30 supersedes the previous one, 2010Ba29.

Development of a charged particle-[formula omitted] coincidence system for nuclear structure and reaction studies at TIFR

A new detector system for measurements of charged particles and γ-rays in coincidence has been developed at TIFR Mumbai, by coupling an annular double-sided segmented Si detector with an array of Compton-suppressed clover HPGe detectors. Digital data acquisition system has been configured for the setup, which has been calibrated and tested using the 229Th radioactive source that emits α-particles along with γ-rays. The functionality and performance of the coincidence apparatus for Doppler correction of γ-transitions emitted during the in-flight de-excitation of the projectile and the target in the 30Si + 197Au Coulomb excitation experiment have been demonstrated.

Microjet printing of metal salt or oxide targets for nuclear reaction studies on radionuclides

Radioactive targets for direct measurements of neutron-induced reactions are required to improve evaluated cross-section data and, ultimately, the fidelity of neutron reaction network simulations. Electrodeposition and molecular plating are the current state-of-the-art radioactive target production techniques, but not all metals can be electrodeposited or molecular plated with high yields. Alternative techniques can be expensive or may produce targets that are unsatisfactory in terms of thickness, yield, or purity. Microjet printing is a new, rather inexpensive technique that utilizes equipment with a small footprint and has the potential to produce thin, highly radioactive targets with good uniformity and minimal impurities from the target fabrication process. This study involved optimizing the process of producing microjet printed targets to allow for the fabrication of a stable vanadium(V) oxide (V2O5) target that was compared with an analogous electrodeposition V2O5 target manufactured via the application of a vanadium chemical conversion coating on aluminum (Al) foil. The results from these studies suggest microjet printing could be used to produce relatively uniform target layers with adequate film thicknesses (<15μm). V2O5 microjet printed targets, when compared with chemical conversion coating V2O5 targets, appeared to be qualitatively less uniform and quantitatively larger in thickness (11.7(27) μm vs. 5.3(18) μm). However, the conversion coating target contained more impurities and the Al backing had a higher background contribution to measurements of neutron-induced reactions as opposed to targets produced via microjet printing. Overall, the results from this study suggest microjet printing has the capability to be an excellent alternative target production technique to the electrodeposition and molecular plating methods.

Synergistic Effect of He for the Fabrication of Ne and Ar Gas-Charged Silicon Thin Films as Solid Targets for Spectroscopic Studies.

Sputtering of silicon in a He magnetron discharge (MS) has been reported as a bottom-up procedure to obtain He-charged silicon films (i.e., He nanobubbles encapsulated in a silicon matrix). The incorporation of heavier noble gases is demonstrated in this work with a synergistic effect, producing increased Ne and Ar incorporations when using He-Ne and He-Ar gas mixtures in the MS process. Microstructural and chemical characterizations are reported using ion beam analysis (IBA) and scanning and transmission electron microscopies (SEM and TEM). In addition to gas incorporation, He promotes the formation of larger nanobubbles. In the case of Ne, high-resolution X-ray photoelectron and absorption spectroscopies (XPS and XAS) are reported, with remarkable dependence of the Ne 1s photoemission and the Ne K-edge absorption on the nanobubble's size and composition. The gas (He, Ne and Ar)-charged thin films are proposed as "solid" targets for the characterization of spectroscopic properties of noble gases in a confined state without the need for cryogenics or high-pressure anvils devices. Also, their use as targets for nuclear reaction studies is foreseen.

Experimental and theoretical multichannel study of direct nuclear reactions: A tool to provide data driven information on neutrino-less double-beta decay

The search for neutrino-less double beta decay has attracted much interest in the last years due to the extraordinary consequences that could derive from its observation. In the view to provide experimental information on the nuclear matrix elements involved in the expression of neutrino-less double beta decay half-life, the NUMEN project is measuring cross-sections of double charge exchange and other quasi-elastic nuclear reactions using the MAGNEX magnetic spectrometer. In particular, the newly proposed multichannel approach, applied both to the experimental and theoretical analysis, will be discussed.

Principal Component Analysis Applied to Digital Pulse Shape Analysis for Isotope Discrimination

Digital pulse shape analysis (DPSA) techniques are becoming increasingly important for the study of nuclear reactions since the development of fast digitizers. These techniques allow us to obtain the (A, Z) values of the reaction products impinging on the new generation solid-state detectors. In this paper, we present a computationally efficient method to discriminate isotopes with similar energy levels, with the aim of enabling the edge-computing paradigm in future field-programmable gate-array-based acquisition systems. The discrimination of isotope pairs with analogous energy levels has been a topic of interest in the literature, leading to various solutions based on statistical features or convolutional neural networks. Leveraging a valuable dataset obtained from experiments conducted by researchers in the FAZIA Collaboration at the CIME cyclotron in GANIL laboratories, we aim to establish a comparative analysis regarding selectivity and computational efficiency, as this dataset has been employed in several prior publications. Specifically, this work presents an approach to discriminate between pairs of isotopes with similar energies, namely, 12,13C, 36,40Ar, and 80,84Kr, using principal component analysis (PCA) for data preprocessing. Consequently, a linear and cubic machine learning (ML) support vector machine (SVM) classification model was trained and tested, achieving a high identification capability, especially in the cubic one. These results offer improved computational efficiency compared to the previously reported methodologies.

Study of Nuclear Reactions in Microscale Targets Providing Generation of Ultrastrong Quasi-Stationary Fields under the Action of Laser Radiation

Study of Nuclear Reactions in Microscale Targets Providing Generation of Ultrastrong Quasi-Stationary Fields under the Action of Laser Radiation

Developing system arrays for new experimental approach in nuclear astrophysics

The advent of facilities providing high-intensity and high-resolution gamma ray beams and/or ultra-short and high-repetition laser pulses can potentially open a new path of astrophysical research. Indeed, a pencil size gamma beams with tunable energies from few keV up to tens MeV will offer distinctive chances to conduct precise measurements of small cross sections (on the scale of μb or even smaller) pertaining to nuclear reactions in the field of astrophysics. Consequently, it provides essential data for modeling astrophysical S-factors crucial to stellar evolution. On the other hand, the possibility to mimic the stellar conditions by laser-matter interaction generating a controlled laboratory plasma with thermodynamical status not too different from stellar conditions will open the way for the study of nuclear reactions of utmost importance for nuclear astrophysics.For photonuclear reactions with astrophysical significance, as photodissociations occur at photon energies slightly above particle emission thresholds due to typical stellar temperatures, the resulting fragments possess low energies spanning from a few hundred keV to a few MeV. Consequently, detectors with low thresholds become imperative in such cases. Also, in the case of laser-induced reactions, in order to detect the fusion products and to measure the laser-accelerated ion distribution a proper system of detection is needed. Depending on the available exit channels of the nuclear reaction of interest, both charged particles and neutrons are foreseen.Here, we present the Asfin’s efforts on developing new detectors arrays suitable for the experimental requirements in these challenging measurements. Indeed, an experimental campaign is ongoing in order to test the feasibility of excitation functions and angular distributions determinations using versatile silicon strip arrays (namely LHASA and/or ELISSA). Moreover, extensive studies and simulations will be presented regarding the developing of a dedicated detection system comprising a cryogenically cooled supersonic nozzle, an appropriate interaction chamber, an array of neutron and charged particle detectors and two compact ion spectrometers for performing systematic study of laser-induced nuclear fusion reactions.

Total Reflection Xray Fluorescence (TXRF) spectrometry as a powerful and broad-spectrum analytical tool in the nuclear sciences

X-ray spectroscopy is widely used in nuclear reaction and structure studies. To aid such studies the technological envelope is continually being pushed to achieve higher quality such as superior power and brilliance, higher resolution and sensitivity. We present the discussion of a relatively new form of X-ray fluorescence spectrometry - Total Reflection X-ray Fluorescence (TXRF) spectrometry that can achieve analytical sensitivities of the order of parts per billion (ppb). An overview of the TXRF technique is presented and its utility for nuclear materials analysis discussed. Polarized Energy Dispersive X-ray Fluorescence (PEDXRF) spectrometry is also an XRF technique that can complement TXRFS where it may not be applicable. That scenario is discussed with respect to our results using PEDXRF on geothermal samples that serve to corroborate the recent findings of the Borexino Geoneutrino Experiment regarding the high Th, U concentrations in the earth’s mantle.

Experimental and theoretical multi-channel study of direct nuclear reactions: a tool to provide data driven information on the 76Ge neutrino-less double-beta decay

The study of heavy-ions induced double charge-exchange (HI-DCE) nuclear reactions is a promising way to access data-driven information on neutrino-less double-beta decay nuclear matrix elements. In the following, particular attention is given to the (18O,18Ne) and (20Ne,20O) HI-DCE reactions as tools for β + β + and β − β − decays, respectively. The experiments are performed in Catania at the Laboratori Nazionali del Sud of the Istituto Nazionale di Fisica Nucleare (INFN-LNS). The MAGNEX magnetic spectrometer is used to momentum analyse the ejectiles of a large network of nuclear reactions. New preliminary experimental data for the 76Se(18O,18F)76As and 76Ge(20Ne,20F)76As single charge exchange (SCE) and for the 76Se(18O,18Ne)76Ge and 76Ge(20Ne,20O)76Se DCE nuclear reactions were also investigated.

Study of Nuclear Reactions in Therapy of Tumors with Proton Beams.

This paper presents an assessment of nuclear reaction yields of protons, α-particles, and neutrons in human tissue-equivalentmaterial in proton therapy using a simulation with Geant 4. In this study, we also check an enhancement of nuclear reactions due to the presence of Bi, Au, 11B, and 10B radiosensitizer nanoparticles. We demonstrate that a proton beam induces a noticeable amount of nuclear reactions in the tissue. Nevertheless, the enhancement of nuclear reaction products due to radiosensitizer nanoparticles is found to be negligible.

First bromine doped cryogenic implosion at the National Ignition Facility

We report on the first experiment dedicated to the study of nuclear reactions on dopants in a cryogenic capsule at the National Ignition Facility (NIF). This was accomplished using bromine doping in the inner layers of the CH ablator of a capsule identical to that used in the NIF shot N140520. The capsule was doped with 3 × 1016 bromine atoms. The doped capsule shot, N170730, resulted in a DT yield that was 2.6 times lower than the undoped equivalent. The Radiochemical Analysis of Gaseous Samples (RAGS) system was used to collect and detect 79Kr atoms resulting from energetic deuteron and proton ion reactions on 79Br. RAGS was also used to detect 13N produced dominantly by knock-on deuteron reactions on the 12C in the ablator. High-energy reaction-in-flight neutrons were detected via the 209Bi(n,4n)206Bi reaction, using bismuth activation foils located 50 cm outside of the target capsule. The robustness of the RAGS signals suggests that the use of nuclear reactions on dopants as diagnostics is quite feasible.

Optical potentials for the rare-isotope beam era

We review recent progress and motivate the need for further developments in nuclear optical potentials that are widely used in the theoretical analysis of nucleon elastic scattering and reaction cross sections. In regions of the nuclear chart away from stability, which represent a frontier in nuclear science over the coming decade and which will be probed at new rare-isotope beam facilities worldwide, there is a targeted need to quantify and reduce theoretical reaction model uncertainties, especially with respect to nuclear optical potentials. We first describe the primary physics motivations for an improved description of nuclear reactions involving short-lived isotopes, focusing on its benefits for fundamental science discoveries and applications to medicine, energy, and security. We then outline the various methods in use today to build optical potentials starting from phenomenological, microscopic, and ab initio methods, highlighting in particular, the strengths and weaknesses of each approach. We then discuss publicly-available tools and resources facilitating the propagation of recent progresses in the field to practitioners. Finally, we provide a set of open challenges and recommendations for the field to advance the fundamental science goals of nuclear reaction studies in the rare-isotope beam era. This paper is the outcome of the Facility for Rare Isotope Beams Theory Alliance (FRIB-TA) topical program ‘Optical Potentials in Nuclear Physics’ held in March 2022 at FRIB. Its content is non-exhaustive, was chosen by the participants and reflects their efforts related to optical potentials.

Development of the STARK detector for nuclear reaction studies

Silicon Telescope Array for Reaction studies in inverse Kinematics, STARK, is under development at the Center for Exotic Nuclear Studies to perform nuclear reaction experiments including elastic scattering and neutron transfer reaction. The array consists of 40 double-sided, resistive silicon strip detectors and 12 single-sided, non-resistive strip detectors, and they form three rings covering a large angular range. The expected angular resolution is less than 1°, and the angular coverage of polar angles is 43–78° and 105–150° in the lab frame. The GET (General Electronics for Time projection chamber project) electronics system is used to handle about 1000 channels from detectors. Several elastic scattering experiments are considered as the commissioning of the STARK at KoBRA in the early stage of RAON.

Nuclear Reaction Studies and Prospects for the New MARA-LEB Facility

Nuclear Reaction Studies and Prospects for the New MARA-LEB Facility

Experimental study of alpha-induced nuclear reactions on Tellurium isotopes for the astrophysical γ-process

Heavier p isotopes are believed to be produced through the γ-process. The path of γ-process can be modelled with network calculations. These calculations include about 20000 reactions on more than 2000, mostly unstable nuclei, many of these reactions involves alpha particles. Theoretical cross sections of reactions involving alpha particles are found to be very sensitive to the alpha-nucleus optical potential, which is not known well enough at low, astrophysical energies. This potential can be studied experimentally by measuring the cross section of (α,n) reactions close above the reaction threshold. The aim of the present work is thus to measure the cross section of the 122Te(α,n)125Xe, 124Te(α,n)127Xe and 130Te(α,n)133Xe reactions for which no data exist in literature. The half-life of the produced Xe isotopes allows us to use the activation technique. Tellurium targets with natural isotopic composition will be used in order to measure the three reactions in parallel. The experiments are in progress using the cyclotron accelerator of ATOMKI. In this paper details of the experimental technique and the preliminary results of the first test measurements are presented.

Nuclear astrophysics studies with γ-ray beams: What do we expect to learn from them?

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.

Nuclear reaction and structure studies using experimental facilities at Inter-University Accelerator Centre (IUAC)

Nuclear reaction and structure studies using experimental facilities at Inter-University Accelerator Centre (IUAC)

Nuclear Data Sheets for A=24

Evaluated spectroscopic data and level schemes from radioactive decay and nuclear reaction studies are presented for 24N, 24O, 24F, 24Ne, 24Na, 24Mg, 24Al, and 24Si. This evaluation for A=24 supersedes the earlier one by R. B. Firestone (2007Fi14).Highlights of this evaluation are the following:In 24O, the 7.4- and 7.65-MeV groups reported in 1H(24O,p′) (2012Ts03) and 9Be(26F,nX) (2011Ho05), respectively, are considered as separate states in this evaluation, since the former one was observed to decay by only one neutron emission to 23O, while the latter one by two sequential neutrons to 22O. Based on assigned configurations, the 7.4- and 7.6-MeV groups are tentatively assigned negative and positive parities, respectively. Additional study would be useful to determine if these states are same or different.In 24Na, 2014Fi01 (n,γ) proposed Jπ=(0,1,2)− for 4048.8 keV level based on weaker population from the capture state (Jπ=1+,2+) and mentioned to reexamine the Jπ=0+ assignment, suggested in earlier evaluations (1990En08, 2007Fi02).This evaluation includes the first observation of E0 transition, strength ρ2(E0)=0.380 70, for the 6432 keV transition from 0+ state at 6432 to 0+ g.s. in 24Mg reported in 2020Do10. Authors proposed the first-excited 0+ state of 24Mg to be superdeformed.In 24Al, the excited level energies deduced from (3He,t) measurements reported by different research groups vary significantly and it was not clear if some of those levels were same or different. Additional measurements are needed.