Nuclear Reaction Channels Research Articles

Study of trends in cross-section values of primary reactions of most abundant isotope of elements with Z= 6 to 116 induced by 14 MeV neutrons using TALYS code and the EXFOR database

Study was carried out to understand the trends of variation of cross-section values of all possible primary reactions induced by 14 MeV neutrons incident on the most abundant isotope of elements from atomic number 6 to 116. The available nuclear reaction channels and cross-section values of all possible primary reactions were obtained using the theoretical values calculated using TALYS nuclear code version 1.96. The trends were explained on the basis of nuclear binding energy curve, the pairing effect and shell effect. Most of the trends show a regular variation except at some points, which give interesting information for the nucleus where trend is irregular. The variation of the available experimental cross-section values obtained from the EXFOR database, if any, was also obtained and compared with the trends obtained from the theoretical values. The discrepancies in the trends of theoretical and experimental cross-section values of various possible reactions were explained on the basis of the possible errors in experiments and the assumptions of the theoretical model of the TALYS nuclear code.

Positron spectroscopy of γ-flashes in the earth atmoshear

The registration of the fast thermonuclear transformation in Earth’s atmosphere is considered. One of them is γ-flashes from thunder lightning. The atmospheric chemical composition and bound conditions in the thunder lightning plasma tubes were associated with thermonuclear transformation. Nuclear reaction channel cross-sections were selected for the calculation of the γ-ray spectra. It was found that under existing conditions the γ-spectrum is formed due to the formation of unstable proton-excess nuclei with their further decay. It has been shown that electron-atom collisions are important and only initiate the formation of proton and fully ionized He (after sufficient acceleration, we call them α-particles) current flows. In this case, protons and α-particles initiate nuclear transformation after collisions with atmospheric He, C, N, O, and Ne atoms. The time scale of γ-fluorescence is estimated and related to observation with traditional γ-ray detectors. Separately calculated contribution of pollution admixture from dust into γ-spectra.

Candidate-nuclei for observation of a bound dineutron. Part I: The (n,2n) nuclear reaction

Current research has been performed for the stable isotopes within the 90 < A < 210 mass range in order to select properly those of them to be irradiated with neutrons for observation of a bound dineutron in the output channel. To this end, the neutron capture reaction cross sections were calculated in the (0 - 30) MeV energy range with the TALYS-1.96 code. That was performed in accordance with the purpose of this study to meet the criteria based on the (n, γ) resonance cross section analysis to find the appropriate candidates to be used for the possible future experimental confirmation of the formation of the dineutron in the (n,n2) nuclear reaction channel.

Determination of the experimental yield of 99mTc in (p,2n) nuclear reaction on enriched 100Mo sample with application of 11-MeV medical cyclotron

This paper presents the measured thick target yield of 99mTc from molybdenum sample with 92.2% enrichment in 100Mo isotope via the (p,2n) nuclear reaction channel. The yield was determined experimentally with application of the 11-MeV medical cyclotron Eclipse RD, equipped with a new target assembly developed for solid sample irradiations. The experimental physical yield was measured to be 30.9 ± 1.3 MBq/μAh. This result was compared with theoretical calculations and results of other authors. The features of irradiation conditions that may have an influence on produced activity were studied and analyzed.

Statistically significant observation of and cross-sections for a new nuclear reaction channel on 197Au with bound dineutron escape

A new nuclear reaction channel on 197Au with the neutron as a projectile and a bound dineutron (2n) as an ejectile in the output channel is considered based on available experimental observations. The dineutron is assumed to be formed as a particle satellite, separated from the volume but not from the potential well of the 196Au nucleus. The dineutron was identified by statistically significant radioactivity detection due to decay of Au nuclei. Cross-sections for the 197Au Au reaction are determined as and for [6.09–6.39] and [6.175–6.455] MeV energy ranges, correspondingly. Possible outcomes of dineutron detection near the surface of deformed nuclei are also raised and discussed.

PARAMETERS OF OPTICAL POTENTIAL IN p+11Li ELASTIC SCATTERING AT 62 MeV

This paper is a calculation of the differential cross section for the elastic scattering of hydrogen nuclei on exotic nuclei of a neutron-rich lithium-11 isotope by determining the optimal parameters of optical potential via the FRESCO 2.8 software using the strongly coupled nuclear reaction channel method with the spin-orbit and Coulomb interaction included. For lithium, the JP=3/2−- state was selected. The shapes of the elements of the scattering potential were chosen in the Woods-Saxon form. The selection of the parameters of the potential was based on the data extracted from the p+11Li scattering experiment conducted at 62 MeV in the laboratory coordinate system on the RIKEN cyclotron in Japan in 1992. In this work, it was found that the volume and spin-orbital parts of the potential, as well as the diffusion of the interaction, have values of zero or close to zero. The resulting cross section in the forward hemisphere of scattering is 70–75 times largerтthan the corresponding Rutherford cross section, and in the rear hemisphere, on the contrary, Coulomb forces dominate. The theoretical values confidently coincide with the experimental ones.

Single event upset on static random access memory devices due to spallation, reactor, and monoenergetic neutrons**Project supported by the National Natural Science Foundation of China (Grant Nos. 11690040 and 11690043) and the Foundation of State Key Laboratory of China (Grant Nos. SKLIPR1801Z and 6142802180304).

This paper presents new neutron-induced single event upset (SEU) data on the SRAM devices with the technology nodes from 40 nm to 500 nm due to spallation, reactor, and monoenergetic neutrons. The SEU effect is investigated as a function of incident neutron energy spectrum, technology node, byte pattern and neutron fluence rate. The experimental data show that the SEU effect mainly depends on the incident neutron spectrum and the technology node, and the SEU sensitivity induced by low-energy neutrons significantly increases with the technology downscaling. Monte–Carlo simulations of nuclear interactions with device architecture are utilized for comparing with the experimental results. This simulation approach allows us to investigate the key parameters of the SEU sensitivity, which are determined by the technology node and supply voltage. The simulation shows that the high-energy neutrons have more nuclear reaction channels to generate more secondary particles which lead to the significant enhancement of the SEU cross-sections, and thus revealing the physical mechanism for SEU sensitivity to the incident neutron spectrum.

Features of Correlated States and a Mechanism of Self-Similar Selection of Nuclear Reaction Channels Involving Low-Energy Charged Particles

Features of the Robertson–Schrodinger coordinate–momentum and energy–time uncertainty relations and connection between them have been considered. A method has been proposed to determine the duration of giant energy fluctuations of particles in a correlated coherent state. This method makes it possible to justify both a huge (many orders of magnitude) increase in the probability of the tunnel effect with the subsequent low-energy nuclear reaction and the automatic selection of low-energy reaction channels involving charged particles and the exclusion of the production of radioactive daughter isotopes. It has been shown that the same mechanism of formation of correlated coherent states explains a very significant suppression of gamma radiation observed in such reactions stimulated by the virtual energy as compared to similar reactions proceeding at a high “real” energy of particles.

Natural nickel as a proton beam energy monitor for energies ranging from 15 to 30 MeV

The degradation of proton beam energy within a target stack was monitored via product nuclide ratios at the Los Alamos Isotope Production Facility (LANL-IPF). Nuclear reaction channels employed as energy monitors included NatNi(p,x)57Co and NatNi(p,x)57Ni. Natural nickel foils (thicknesses 0.025 mm) were used to determine proton beam energies ranging from 15 to 30 MeV. Energy values were estimated from a fitted 57Ni/57Co production activity ratio curve, which, in turn, was calculated from formation cross section data. Isotope production yields in the low energy “C” slot at LANL-IPF are very sensitive to beam energy, and differences of several MeV can translate into a drastic effect on overall production yields and radiochemical purity. Proton energies determined in this target stack position using nickel foils will serve as a basis to optimize radionuclide production in terms of product yield maximization and by-product minimization.

Isomeric yield ratio of 152m1Eu(8−)–152m2Eu(0−) produced in (γ, n) photonuclear reaction in the giant dipole resonance region

In this work, the isomeric ratio of 152m1Eu(8−)–152m2Eu(0−) produced from the 153Eu(γ, n)152Eu reaction have been measured in the whole giant dipole resonance region by the activation method. In order to improve the accuracy of the experimental results, the necessary corrections were made in the gamma activity measurements and data analysis. The results were discussed and compared with the similar data from literature to examine the excitation energy, the spin difference and the nuclear reaction channel effects and can be used for the interpretation on the structure of the nucleus and the mechanisms of nuclear reactions. The data for bremsstrahlung end-point energies of 19–23 MeV are first-time measurements.

Theoretical study of cross sections of proton-induced reactions on cobalt

Abstract Nuclear fusion may be among the strongest sustainable ways to replace fossil fuels because it does not contribute to acid rain or global warming. In this context, activated cobalt materials in corrosion products for fusion energy are significant in determination of dose levels during maintenance after a coolant leak in a nuclear fusion reactor. Therefore, cross-section studies on cobalt material are very important for fusion reactor design. In this article, the excitation functions of some nuclear reaction channels induced by proton particles on 59 Co structural material were predicted using different models. The nuclear level densities were calculated using different choices of available level density models in ALICE/ASH code. Finally, the newly calculated cross sections for the investigated nuclear reactions are compared with the experimental values and TENDL data based on TALYS nuclear code.

Studies of O18 impurity trapping at interstitial dislocation loops in ion implanted Fe (1 1 0) by ion channeling and ab initio calculations

Abstract The O18 and self ions are implanted at same depth in Fe (1 1 0) crystal and annealed to study the oxygen trapping under excess self interstitial defects. Rutherford backscattering spectrometry, nuclear reaction analysis and channeling measurements have been performed to determine the lattice site position of O18. The presence of dislocation loops is confirmed by energy-dependent dechanneling parameter measurements. From the tilt angular scans of Fe and O18 signals along 〈1 0 0〉, 〈1 1 0〉 axes, O18 is found to be displaced 0.2 A from tetrahedral towards octahedral interstitial site in O18. Similar lattice site location of oxygen with the displacement of 0.37 A is predicted by density functional theory calculations for the interaction of oxygen with 〈1 0 0〉 interstitial dislocation loop structure. Our results provide strong evidence on oxygen trapping at interstitial dislocation loops in the presence of excess interstitial defects in iron.

Simultaneous quantification of Zr, Cr and Cu in copper alloy matrix using charged particle activation analysis

The charged particle activation analysis (CPAA) technique has been applied for quantitative estimation of Zr, Cr and Cu simultaneously in copper alloy. An ion beam of 13 MeV proton was found to be suitable to use (p,n) nuclear reaction channel in CPAA. The optimization of irradiation conditions were performed to apply instrumental approach by minimizing the production of matrix activity. The results of CPAA have been compared with those obtained by using instrumental neutron activation analysis and energy dispersive X-ray fluorescence techniques. Analysis of variance test indicated the statistical parity of the results obtained in the above mentioned three methods.

Determining concentrations of elements with different reaction channels in photon activation

In photon activation, same element may be activated by the bremsstrahlung beam through different nuclear reaction channels and produce different radioisotopes. These radioisotopes follow their own decay schemes and generate characteristic gamma rays. This phenomenon usually is an interference in spectra analysis, but it also offers a theoretical feasibility to determine the concentration of one element through different reaction channels.To realize this theoretical feasibility, we conducted series of photon activation experiments with sample and reference of known concentrations. Irradiation of the samples and the references were conducted with electronic LINAC with different photon converters at a peak energy around 30MeV. Several elements and their corresponding reaction channels were chosen to validate this procedure. Calculations of PAA were based on the internal monitor method. Our results have confirmed the advantages of current PAA reaction channel selection, and show that it might be beneficial to calculate the concentration of same elements with different reaction channels in some certain occasions. N-values, which indicate the relative intensity of reaction channels, were calculated and compared with those values generated from the photon activation at the Federal Institute for Materials Research and Testing in Germany (BAM). Results suggested that N values are impacted by several parameters of electron beam, and the design of electron-gamma converter may play a dominant role in determining N values.

Prompt gamma-ray emission for future imaging applications in proton-boron fusion therapy

Recently, an approach exploiting the proton therapy biological enhancement by using Boron atoms injected inside a tumor, has been proposed [1-3]. Here, the 11B(p,α)2α nuclear fusion reaction channel, where three alpha particles are produced with an average energy around 4 MeV, is considered [4]. These alphas are able to penetrate the cells nucleus and strongly damage their DNA. In addition, gamma prompts emitted by the proton Boron nuclear reactions can be used for on-line proton beam imaging purposes. In this work an experimental study of the gamma prompt emissions from the proton Boron nuclear reactions has been carried out with the main aim to understand and quantify the most probable emission for future clinical applications.

Characterization of specific nuclear reaction channels by deconvolution in the energy space of the total nuclear cross-section of protons - applications to proton therapy and technical problems (transmutations)

The total nuclear cross-section Q tot (E) resulting from the interaction of protons with nuclei is decomposed in 3 different contributions: (1) elastic scatter at the complete nucleus, which adopts a part of the proton kinetic energy; (2) inelastic scatter at a nucleus, which changes its quantum numbers by vibrations, rotations, transitions to excited states; 3. proper nuclear reactions with change of the mass and/or charge number. Then different particles leave the hit nucleus (neutrons, protons, etc.), which is now referred to as 'heavy recoil' nucleus. The scatter parts of Q tot (E) according to points 1 and 2 can be removed by a deconvolution acting at Q tot (E) in the energy space. The typical nuclear reaction channels are mainly characterized by resonances of a reduced cross-section function Q red (E). The procedure is applied to cross-sections of therapeutic protons and also to Cs 55 137 as an example with technical relevance (transmutations with the goal to drastically reduce its half-time.

13C(n, $\alpha_{0}$ )10Be cross section measurement with sCVD diamond detector

This paper presents 13C(n, $\alpha_{0}$ )10Be cross section measurements performed at the Van de Graaff facility of the Joint Research Centre Geel. The 13C(n, $\alpha_{0}$ )10Be cross section was measured relative to the 12C(n, $\alpha_{0}$ )9Be cross section at 14.3 MeV and 17.0 MeV neutron energies. The measurements were performed with an sCVD (single-crystal chemical vapor deposition) diamond detector which acted as sample and as sensor simultaneously. A novel analysis technique was applied, which is based on the pulse-shape analysis of the detector’s ionization current. This technique resulted in an efficient separation of background events and consequently in a well-determined selection of the nuclear reaction channels 12C(n, $\alpha_{0}$ )9Be and 13C(n, $\alpha_{0}$ )10Be.

Some Insights into Cluster Structure of &amp;lt;sup&amp;gt;9&amp;lt;/sup&amp;gt;Be from &amp;lt;sup&amp;gt;3&amp;lt;/sup&amp;gt;He + &amp;lt;sup&amp;gt;9&amp;lt;/sup&amp;gt;Be Reaction

The study of inelastic scattering and multi-nucleon transfer reactions was performed by bombarding a 9Be target with a 3He beam at the incident energy of 30 MeV. Angular distributions for 9Be(3He, 3He) 9Be, 9Be (3He, 3He) 8Be, 9Be (3He, 7Be) 5He, 9Be (3He, 6Li) 6Li and 9Be (3He, 7Li) 5Li reaction channels were measured. Experimental angular distributions for the corresponding ground states (g.s.) were analyzed within the framework of the optical model, the coupled-channel approach and the distorted-wave Born approximation. Cross sections for channels leading to unbound 5Heg.s., 5Lig.s. and 8Be systems were obtained from singles measurements where the relationship between the energy and the scattering angle of the observed stable ejectile was constrained by two-body kinematics. Information on the cluster structure of 9Be was obtained from the transfer channels. It was concluded that cluster transfer was an important mechanism in the investigated nuclear reaction channels. In the present work an attempt was made to estimate the relative strengths of the interesting (n + 8Be) and (α + 5He) cluster configurations in 9Be. The contributions of different exit channels have been determined confirming that the (α + 5He) configuration plays an important role. The configuration of 8Be consisting of two bound helium clusters (5He + 6He) is significantly suppressed, whereas the two-body configurations (n + 8Be) and (α + 5He) including unbound 8Be and 5He are found more probable.

Uncertainty Analysis on Reactivity and Discharged Inventory due to 235,238U, 239,240,241Pu, and Fission Products: Application to a Pressurized Water Reactor Fuel Assembly

Uncertainty analysis on reactivity and discharged inventory for a typical pressurized water reactor fuel element as a result of uncertainties in 235,238U, 239,240,241Pu, and fission products nuclear data was performed. A typical Westinghouse three-loop fuel assembly fueled with UO2 fuel with 4.8% enrichment was selected. The Total Monte Carlo method was applied using the deterministic transport code DRAGON. This code allows the generation of the few-groups nuclear data libraries by directly using data contained in the nuclear data evaluation files. The nuclear data used in this study are from the JEFF3.1 evaluation, with the exception of the nuclear data files for U, Pu, and fission products isotopes (randomized for the generation of the various DRAGON libraries). These are taken from the TALYS evaluated nuclear data library TENDL-2012. Results show that the calculated total uncertainty in keff (as a result of uncertainties in nuclear data of the considered isotopes) is virtually independent of fuel burnup, and amounts to 700 pcm. The uncertainties in the inventory of the discharged fuel are dependent on the element considered and lie in the range 1% to 15% for most fission products, and are <5% for the most important actinides. The total uncertainty on the reactor parameters was also split into different components (different nuclear reaction channels), and the main sources of uncertainties were identified.

A charged particle detector array for detection of light charged particles from nuclear reactions

A 4π charged particle detector array (CPDA), for detecting low-Z charged particles from nuclear reactions, was built to improve selection of fusion evaporation channels for in-beam gamma spectroscopy measurements at Inter University Accelerator Centre, New Delhi. The array consists of fourteen fast–slow plastic phoswich detectors coupled to photomultiplier tubes through indigenously developed optical light guides. This paper describes design of optical light guide, target chamber, front-end electronics and presents in-beam performance of the array. Custom made analogue electronic device enables online selection of nuclear reaction channel. The charged particle detection efficiency and improvement in peak to background ratio obtained using CPDA in conjunction with a gamma-detector array demonstrates its usefulness in selection of specific nuclear reaction channel. This array has been used in a number of nuclear spectroscopic and reaction investigations.