Elastic scattering of 21-MeV protons from nitrogen 14, oxygen 16, argon 40, nickel 58, and tin 116
Elastic scattering of 21 MeV protons from nitrogen 14, oxygen 16, argon 40, nickel 58, and tin 116
Baron, N.↗
SEARCH · Engineering Papers
Results for “TIN 116”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Advancing the Theory of Nuclear Reactions with Rare Isotopes: From the Laboratory to the Cosmos
The Main goal of my research is to develop indirect methods, which allows one to connect the reactions measured in the labs with astrophysical reactions.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
New approach to analyzing and evaluating cross sections for partial photoneutron reactions
The presence of substantial systematic discrepancies between the results of different experiments devoted to determining cross sections for partial photoneutron reactions-first of all, ({gamma}, n), ({gamma}, 2n), and ({gamma}, 3n) reactions-is a strong motivation for studying the reliability and authenticity of these data and for developing methods for taking into account and removing the discrepancies in question. In order to solve the first problem, we introduce objective absolute criteria involving transitional photoneutron-multiplicity functions F{sub 1}, F{sub 2}, F{sub 3}, Horizontal-Ellipsis ; by definition, their values cannot exceed 1.0, 0.5, 0.33, Horizontal-Ellipsis , respectively. With the aim of solving the second problem, we propose a new experimental-theoretical approach. In this approach, reaction cross sections are evaluated by simultaneously employing experimental data on the cross section for the total photoneutron yield, {sigma}{sup expt}({gamma}, xn) = {sigma}{sup expt}({gamma}, n) + 2{sigma}{sup expt}({gamma}, 2n) + 3{sigma}{sup expt}({gamma}, 3n) + Horizontal-Ellipsis , which are free from drawbacks plaguing experimental methods for sorting neutrons in multiplicity, and the results obtained by calculating the functions F{sub theor}{sup 1}, F{sub theor}{sup 2}, F{sub theor}{sup 3}, Horizontal-Ellipsis on the basis of the modern model of photonuclear reactions. The reliability and authenticity of data on the cross sections for ({gamma}, n), ({gamma}, 2n), and ({gamma}, 3n) partial reactions-{sigma}{sup eval}({gamma}, in) = F{sub i}{sup theor}{sigma}{sup expt}({gamma}, xn)-were evaluated for the {sup 90}Zr, {sup 115}In, {sup 112,114,116,117,118,119,120,122,124}Sn, {sup 159}Tb, and {sup 197}Au nuclei.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Double-differential spectra of the secondary particles in the frame of pre-equilibrium model
An approach was developed to describe the double-differential spectra of secondary particles formed in heavy-ion reactions. Griffin model of nonequilibrium processes was used to account for the nonequilibrium stage of the compound system formation. Simulation of de-excitation of the compound system was carried out using the Monte-Carlo method. Analysis of the probability of neutron, proton, and {alpha}-particle emission was performed both in equilibrium, and in the pre-equilibrium stages of the process. Fission and {gamma}-ray emission were also considered after equilibration. The analysis of the experimental data on the double-differential cross sections of p, {alpha} particles for the {sup 16}O + {sup 116}Sn reaction at the oxygen energy E = 130 and 250 MeV were performed.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Evolution of the pygmy dipole resonance in Sn isotopes
Nuclear level density and {gamma}-ray strength functions of {sup 121,122}Sn below the neutron separation energy are extracted with the Oslo method using the ({sup 3}He,{sup 3}He{sup '{gamma}}) and ({sup 3}He,{alpha}{gamma}) reactions. The level densities of {sup 121,122}Sn display steplike structures, interpreted as signatures of neutron pair breaking. An enhancement in both strength functions, compared to standard models for radiative strength, is observed in our measurements for E{sub {gamma}} > or approx. 5.2 MeV. This enhancement is compatible with pygmy resonances centered at {approx_equal}8.4(1) and {approx_equal}8.6(2) MeV, respectively, and with integrated strengths corresponding to {approx_equal}1.8{sub -5}{sup +1}% of the classical Thomas-Reiche-Kuhn sum rule. Similar resonances were also seen in {sup 116-119}Sn. Experimental neutron-capture cross reactions are well reproduced by our pygmy resonance predictions, while standard strength models are less successful. The evolution as a function of neutron number of the pygmy resonance in {sup 116-122}Sn is described as a clear increase of centroid energy from 8.0(1) to 8.6(2) MeV, but with no observable difference in integrated strengths.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Application of the Bruyeres Jeukenne-Lejeune-Mahaux model potential to composite nuclei with a single-folding approach
A single-folding (SF) model analysis has been performed for {alpha} and deuteron elastic scattering from {sup 58}Ni, {sup 90}Zr, {sup 116}Sn, and {sup 208}Pb at incident energies between 10 and 100 MeV/nucleon with the Lane-consistent Bruyeres Jeukenne-Lejeune-Mahaux model nucleon-nucleus potential. The energy dependence of a set of only three potential parameters was derived, and the resulting global optical model potentials were found to account well for {alpha} and deuteron elastic scattering within their studied energy ranges. The energy dependence of a real potential form factor is found to be important for describing {alpha}-nucleus scattering within large energy ranges. Corrections due to the compositeness of projectiles to the SF potentials were studied and were compared with theoretical estimations through the renormalization factor. Systematic differences in renormalization factors between {alpha} particles and deuterons were observed.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Magnetic moments of the first excited 2{sup +} states in the semi-magic {sup 112,114,116,122,124}Sn isotopes
The g factors of the first excited 2{sup +} states in the {sup 112,114,116,122,124}Sn isotopes have been measured with high accuracy using the transient field technique in combination with Coulomb excitation in inverse kinematics. The experimental results are discussed in a qualitative way on the basis of empirical single-particle g factors of the relevant proton and neutron orbitals and are compared to a number of different theoretical calculations. The results are found to be best described by shell-model calculations in an extended configuration space. Clear evidence for the contribution of neutron pair excitations from the 1d{sub 3/2} to the 0h{sub 11/2} orbital to the wave function of the 2{sub 1}{sup +} state in {sup 122,124}Sn has been obtained.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
High-resolution measurement of the {sup 118,124}Sn(p,t){sup 116,122}Sn reactions: Shell-model and microscopic distorted-wave Born approximation calculations
The {sup 118,124}Sn(p,t){sup 116,122}Sn reactions have been investigated in high-resolution experiments at incident proton energies of 24.6 and 25 MeV, respectively. Angular distributions for 55 transitions to levels of {sup 116}Sn and 63 transitions to levels of {sup 122}Sn, up to excitation energies of {approx}3.850 and {approx}4.000 MeV, respectively, have been measured. The spin and parity identification was carried out by means of a distorted-wave Born approximation (DWBA) analysis, performed by using conventional Woods-Saxon potentials. A shell-model study of {sup 116}Sn and {sup 122}Sn nuclei was performed using a realistic two-body effective interaction derived from the CD-Bonn nucleon-nucleon potential. The doubly magic nucleus {sup 132}Sn was assumed as a closed core, with the 16 and 10 valence neutron holes occupying the five levels of the 50-82 shell. The energy spectra have been calculated and compared with the experimental ones, and the theoretical two-nucleon spectroscopic amplitudes, evaluated in a truncated seniority space, have been used in the microscopic DWBA calculation of some cross-section angular distributions of both reactions.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Cross sections for {alpha}-particle induced reactions on {sup 115,116}Sn around the Coulomb barrier
The cross sections of the {sup 115}Sn({alpha},{gamma}){sup 119}Te, {sup 115}Sn({alpha},n){sup 118}Te, and {sup 116}Sn({alpha},n){sup 119}Te reactions (both on ground and isomeric states) have been measured at effective center-of-mass energies from 9.3 to 14.8 MeV. During a first experiment, enriched self-supporting {sup 115}Sn (51.2%) + {sup 116}Sn (24.4%) foils were bombarded with an {alpha} beam delivered by the Bucharest IFIN-HH Tandem Accelerator. In a second experiment, a highly enriched {sup 116}Sn target was irradiated in order to disentangle the experimental cross section contributions due to {sup 115}Sn({alpha},{gamma}){sup 119}Te and {sup 115}Sn({alpha},n){sup 118}Te reactions obtained in the first measurement. The beam-induced activity was measured with two large volume HPGe detectors in close geometry. The experimental results were compared with theoretical predictions obtained in the framework of the statistical model.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Study of the (p, γ) and (α, γ) reactions for {sup 96,98,104}Ru and {sup 112,114,116}Sn at astrophysically relevant energies
Cross section and S factor of the proton- and alpha-induced reactions have been studied for the Ruthenium and tin isotopes in the effective energy range, i.e. Gamow window. These reactions are important for developing the understanding for nucleosynthesis, particularly for the synthesis of p nuclei (p process). In this work, cross sections and S factor have been calculated through TALYS in Hauser–Feshbach formalism using nuclear densities calculated in relativistic mean field (RMF) formalism. Calculated results of cross sections, S factor and nuclear structure have been compared with existing theoretical as well as experimental results available and are found to be in good agreement.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Investigation of double beta decay of {sup 116}Cd with the help of enriched {sup 116}CdWO{sub 4} crystal scintillators
An experiment to search for 2β processes in {sup 116}Cd with the help of enriched (to 82%) cadmium tungstate crystal scintillators is in progress at the Gran Sasso National Laboratory of the INFN (LNGS, Italy). After 11074 h of data taking in the last configuration, the preliminary estimate for the half-life of 116Cd relatively to 2ν2β decay is T{sub 1/2} = [2.52 ± 0.02(stat.) ± 0.14(syst.)] × 10{sup 19} yr. By using the data of previous stages of the experiment with a similar level of background (≈ 0.1 counts/(keV kg yr) in the energy interval 2.7 – 2.9 MeV; the total time of measurements is 19770 h) we have obtained a new limit on the 0ν2β decay of {sup 116}Cd to the ground state of {sup 116}Sn: T{sub 1/2} ≥ 1.9 × 10{sup 23} yr at 90% C.L. New limits on different 2β processes in {sup 116}Cd (decays with majorons, transitions to the excited levels) are obtained on the level of T{sub 1/2} ≥ 10{sup 20} – 10{sup 22} yr.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Effect of thermal neutrons on emission characteristics of InGaAs/AlGaAs heterolasers
It is studied how the threshold current of InGaAs/AlGaAs quantum-well injection heterolasers emitting near the wavelength λ = 0.7 μm changes under irradiation by thermal neutrons. It is found that the threshold pump current decreases at small doses (10{sup -2} neutron cm{sup -2}), while doses exceeding 6 × 10{sup 7} neutron cm{sup -2} cause an increase in this current and degradation of the structure. It is found that the main reasons for an increase in the threshold current at high irradiation doses are the nuclear reactions of the {sub 49}In{sup 115} (n, γ) → {sub 49}In{sup 116} type and the β-decay of the {sub 49}In{sup 116} isotope, which results in the appearance of {sub 50}Sn{sup 116} atoms. (lasers)
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Evaluated Cross Sections of Photoneutron Reactions on the Isotope {sup 116}Sn and Spectra of Neutrons Originating from These Reactions
With the aid of the results obtained by evaluating cross sections of partial photoneutron reactions on the isotope {sup 116}Sn and the energy spectra of neutrons originating from these reactions, the possible reasons for the well-known discrepancies between the results of different photonuclear experiments were studied on the basis of a combinedmodel of photonuclear reactions. On the basis of physical criteria of data reliability and an experimental–theoretical method for evaluating cross sections of partial reactions, it was found that these discrepancies were due to unreliably redistributing neutrons between (γ, 1n), (γ, 2n), and (γ, 3n) reactions because of nontrivial correlations between the experimentally measured energy of neutrons and their multiplicity.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Nuclear Data Sheets for A = 235
Spectroscopic data and level schemes from radioactive decay and nuclear reaction studies are presented here for all nuclei with mass number A=235. The highlight of this evaluation consists of the precise and comprehensive Coulomb excitation study (2012Wa35) on {sup 235}U, which in addition to the 7/2[743] ground state rotational band, extended the 1/2[631], 5/2[622], 5/2[752], and 3/2[631] rotational bands up to Jπ=53/2+, 49/2+, 441/2−, and 43/2+, respectively. This evaluation presents a study (2010Hu02) of the {sup 237}Np({sup 116}Sn, {sup 118}Snγ) reaction where the ground state rotational band 5/2[642] was observed up to Jπ=(53/2+). It is worth for historical knowledge to mention the report on the “Discovery of isotopes of the transuranium elements with 93≤Z≤98” (2013Fr02), where the information for elements Np, Pu, and Am with mass number A=235 is given. {sup 235}Cf has not been observed. The alpha hindrance factors (HF) presented in this evaluation were calculated using values of the radius parameter (r{sub 0}) interpolated from those for even–even adjacent nuclei given by 1998Ak04.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Nucleon-nucleon correlations in heavy ion transfer reactions: Recent investigations at energies far below the Coulomb barrier
Excitation functions of one- and two-neutron transfer channels have been measured for the {sup 96}Zr+{sup 40}Ca and {sup 116}Sn+{sup 60}Ni systems at bombarding energies ranging from the Coulomb barrier to ∼25% below. Target-like recoils have been identified in A, Z and velocity with the large solid angle magnetic spectrometer PRISMA. The experimental transfer probabilities have been compared, in absolute values and in slope, with semiclassical microscopic calculations which incorporate nucleon-nucleon pairing correlations. For the first time in a heavy ion collision, one was able to provide a consistent description of one and two neutron transfer reactions by incorporating, in the reaction mechanism, all known structure information of entrance and exit channels nuclei. In particular, there is no need to introduce any enhancement factor for the description of two neutron transfer, of course very important are the correlations induced by the pairing interaction.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Breakup threshold anomaly in the near-barrier elastic scattering of {sup 6}Li+{sup 116,112}Sn
We have measured the elastic scattering of the weakly bound {sup 6}Li on the {sup 116,112}Sn targets, at energies close to the Coulomb barrier. The energy dependence of the interaction potential has been investigated by two different methods and the presence of the breakup threshold anomaly is observed. We have also derived the total reaction cross sections for the above systems and compared them to those of other systems with halo, weakly bound, and tightly bound projectiles on targets with similar masses. The reaction cross sections are largest for systems with halo nuclei, then the systems with no-halo weakly bound nuclei, and the smallest cross sections are those for tightly bound systems.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Heavy-ion transfer reactions at large internuclear distance
The transfer reaction for the {sup 116}Sn+{sup 60}Ni system has been studied using the PRISMA magnetic spectrometer at different bombarding energies from above to well below the Coulomb barrier. The experiment has been done in inverse kinematics and light target-like ions have been detected with PRISMA placed at very forward angles. Good mass, nuclear charge and kinetic energy resolutions have been achieved. Sufficient statistics has been accumulated to extract angular distributions for different bombarding energies have been extracted and the response function of the spectrometer has been studied to correct for the aberration due to the transport of the ions in PRISMA. The comparison between the present case and the previously measured {sup 96}Zr+{sup 40}Ca system, superfluid and near closed shells nuclei, respectively, should significantly improve our understanding of nucleon-nucleon correlation properties in multinucleon transfer processes.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Investigation into the semimagic nature of the tin isotopes through electromagnetic moments
A complete set of electromagnetic moments, B(E2;0 + 1 2 + 1 ), Q(2 + 1 ), and g(2 + 1 ), have been measured from Coulomb excitation of semi-magic 112,114,116,118,120,122,124 Sn (Z = 50) on natural carbon and titanium targets. The magnitude of the B(E2) values, measured to a precision of ~4%, disagree with a recent lifetime study [Phys. Lett. B 695, 110 (2011)] that employed the Doppler- shift attenuation method. The B(E2) values show an overall enhancement compared with recent theoretical calculations and a clear asymmetry about midshell, contrary to naive expectations. A new static electric quadrupole moment, Q(2 + 1 ), has been measured for 114 Sn. The static quadrupole moments are generally consistent with zero but reveal an enhancement near midshell; this had not been previously observed. The magnetic dipole moments are consistent with previous measurements and show a near monotonic decrease in value with neutron number. The current theory calculations fail to reproduce the electromagnetic moments of the tin isotopes. The role of 2p-2h and 4p-4h intruders, which are lowest in energy at mid shell and outside of current model spaces, needs to be investigated in the future.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗