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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.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Recent results on intermediate-energy nucleon knockout reactions

Nucleon knockout reactions using fast rare isotope beams are a well-suited tool to study single-particle properties of exotic nuclei and the evolution of nuclear shell structure towards the drip-lines. In particular the sudden removal of two protons from an intermediate-energy neutron-rich projectile has been shown to proceed as a direct reaction. In addition to giving spectroscopic information, this type of reaction promises a rather unique tool assign spins by measuring the momentum distributions of the heavy reaction residues. In the present experiment, the heavy reaction residues were measured in coincidence with the removed. These more final-state-exclusive measurements are key for further validation of this direct reaction and its use for quantitative spectroscopy of highly neutron-rich nuclei.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2015

Hyperon production from neutrino-nucleon reaction

The neutrino induced hyperon production processes ν¯ e/μ + p → e + /μ + + π + Λ/Σ may provide a unique clean place for studying low energy πΛ/Σ interaction and hyperon resonances below KN threshold. The production rates for some neutrino induced hyperon production processes are estimated with theoretical models. Lastly, suggestions are made for the study of hyperon production from neutrino–nucleon reaction at present and future neutrino facilities.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS1990

Risk assessment methodologies for target fragments produced in high-energy nucleon reactions

Collisions of energetic protons with target nuclei yield nuclear products of large linear energy transfer, and it is usually assumed that the energy of the heavy products is absorbed locally with a quality factor of 20. Past methods of risk assessment have relied on the Bertini (1969) model to evaluate the nuclear reaction products. If the Q(F) of 20 is correct, then a significant underestimate of biological risk from the nuclear products could result from the use of Bertini's model. On the other hand, a Q(F) of 20 is probably too large for some of the lighter fragments, leaving prior risk estimates as possibly correct or even conservative. This issue is discussed here in the context of the recently proposed nuclear data set of Wilson et al. (1989).

Shinn, J. L.↗
DOE OSTI2015

Electroweak meson production reaction in the nucleon resonance region

We report on our recent study of the the neutrino-nucleon reaction in the nucleon resonance region. The dynamical reaction model of meson production reaction on the nucleon for the pion and photon induced reaction has been developed in order to investigate the spectrum of nucleon excited state. We have extended this model in order to describe the weak meson production reactions with the πN, ηN, KΛ, KΣ and ππN final states. We also studied the role of the final state interaction in the photon and the neutrino induced pion production reaction on the deuteron around the Δ(1232) resonance region.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

From nucleons to nuclei to fusion reactions

Nuclei are prototypes of many-body open quantum systems. Complex aggregates of protons and neutrons that interact through forces arising from quantum chromo-dynamics, nuclei exhibit both bound and unbound states, which can be strongly coupled. In this respect, one of the major challenges for computational nuclear physics, is to provide a unified description of structural and reaction properties of nuclei that is based on the fundamental underlying physics: the constituent nucleons and the realistic interactions among them. This requires a combination of innovative theoretical approaches and high-performance computing. In this contribution, we present one of such promising techniques, the ab initio no-core shell model/resonating-group method, and discuss applications to light nuclei scattering and fusion reactions that power stars and Earth-base fusion facilities.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2023

Nuclear structure advancements with multi-nucleon transfer reactions

Multi-Nucleon Transfer (MNT) reactions have been used for decades as a reaction mechanism, in order to populate excited states in nuclei far from stability and to perform nuclear structure studies. Nevertheless, the development of set-ups involving high acceptance tracking magnetic spectrometers (mainly existing in Europe), coupled with the Advanced GAmma Tracking Array (AGATA) opens new possibilities, especially if they are used in conjunction with high-intensity stable beams or ISOL RIBs. In this article, we will discuss the capabilities of such set-ups aiming at different goals, including complete information in high-resolution spectroscopy as well as lifetime measurements.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2022

Mirror nucleon removal reactions in p-shell nuclei

Nucleon removal reactions have been shown to be an effective tool for studying the single particle structure of nuclei. This work continues efforts to experimentally probe and benchmark the reaction and structure models used to calculate the removal reaction cross sections when using microscopic nuclear structure inputs. Here, three different single nucleon removal reactions were performed, from p -shell nuclei with masses A = 7, 9, and 10. The residual nuclei from the reactions were detected in coincidence with γ rays to determine partial cross sections to individual final states. The eikonal direct-reaction model is combined with overlap functions and residual nucleus densities from microscopic, variational Monte Carlo calculations to provide consistent nuclear structure input to the partial cross section calculations. Comparisons of measured and calculated cross sections, including for mirror reactions, are presented. The analysis of the partial cross sections leading to the ground states shows a similar behavior to the one observed from analyses of inclusive cross sections using shell model nuclear structure input: the theoretical description of the removal process is in better agreement with the data when removing weakly bound nucleons, than when removing well-bound ones. The two mirror reaction pairs presented here show consistent results between the respective members of the pairs. The results obtained for the population of the excited states, however, show a systematically different trend that appears connected to the structure part of the calculation. Additional cases are needed to better understand the respective roles of structure and dynamical effects in the deviations.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS1986

Transport model of nucleon-nucleus reaction

A simplified model of nucleon-nucleus reaction is developed and some of its properties are examined. Comparisons with proton production measured for targets of Al-27, Ni-58, Zr-90, and Bi-209 show some hope for developing an accurate model for these complex reactions. It is suggested that binding effects are the next step required for further development.

Wilson, J. W.↗
DOE OSTI2015

Syntheses of transuranium isotopes with atomic numbers Z ≤ 103 in multi-nucleon transfer reactions

First, in Section 1 we will discuss multi-nucleon transfer reactions with light heavy ions, which can be thought of as competing with complete fusion at higher impact parameters. Quasi-elastic and multi-nucleon transfer reactions with the heaviest projectiles will be discussed in Section 2. Lastly, in Section 3 we will cover recent developments focusing on theoretical predictions of cross sections of superheavy nuclei, cover some new possibilities and look into the existing experimental challenges.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2019

The Xe 136 + Pt 198 reaction: A test of models of multi-nucleon transfer reactions

The yields of 42 projectile-like fragments (PLFs) and fission fragments and 36 target-like fragments (TLFs) were measured using off-line γ-ray spectroscopy in a thin target experiment involving the 136 Xe+ 198 Pt reaction. The center of target beam energy was 760.5 MeV (E c.m. =450 MeV). The reported yields are compared with those from previous measurements for this reaction and with predictions of the GRAZING, di-nuclear systems (DNS), and improved quantum molecular dynamics (ImQMD) models. Here, the yields of the TLFs and PLFs are, in general, substantially smaller than those previously observed at a beam energy of 1085 MeV. Neither the GRAZING nor the DNS model correctly describes the measured TLF and PLF yields in this lower- energy reaction but the ImQMD model describes these yields adequately.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2017

Radiochemical study of the kinematics of multi-nucleon transfer reactions in 48 Ca + 248 Cm collisions 10% above the Coulomb barrier

In this paper, the kinematics of multi-nucleon transfer reactions in 48 Ca + 248 Cm collisions at 262 MeV (center of target) was investigated by using a stacked-foil technique and radiochemical separations of trans-curium elements. Trans-curium isotopes were identified by α-particle spectroscopy. For Fm isotopes, by comparing the centroids of the measured post-neutron emission isotope distributions with the most probable primary mass number predicted by Volkov's generalized Q g g systematics, the missing mass (number of evaporated neutrons) is estimated. The latter is compared with that deduced from the measured centroid of the laboratory angular distribution peaked closely to the grazing angle and the centroid of the range distribution, being used to determine the average total kinetic energy loss (TKEL) and the average excitation energy. The latter agrees within the uncertainties with the missing mass so that a consistent picture of the reaction mechanism emerges. For products closer to the target Z, e.g., Cf and Bk, the distributions of kinetic energies are much broader than for Fm, reflecting the fact that in the former, values of TKEL reach from quasi-elastic scattering all the way to deep inelastic scattering. Finally, the measured laboratory angular distribution and the average laboratory kinetic energy of the Fm isotopes, being the prototypes for multi-nucleon transfer products, are benchmark values for the design of electromagnetic separators to be constructed for the separation and detection of unknown neutron-rich transactinides produced in this nuclear reaction type.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2023

Relative population of states in 21 Mg from few-nucleon removal reactions

Nuclear reactions with intermediate-energy beams in which three, four, and five nucleons are removed are expected to proceed through a combination of nondissipative and statistical processes. In an experiment at the National Superconducting Cyclotron Laboratory, in-beam γ-ray spectroscopy was utilized to study few-nucleon removal reactions from incoming beams of 24 Mg, 25 Al, and 26 Si projectiles to the same reaction product, 21 Mg. Here, new γ-ray transitions and γ-γ coincidences in 21 Mg were established using the CsI(Na) array CAESAR and the inclusive cross section for three-neutron removal from 24 Mg was measured. Significant differences in the relative population of states in 21 Mg from 25 Al compared to 26 Si were observed and found to be correlated with the spins of the 21 Mg states. As a result, this intermediate regime between direct and statistical nucleon removal may have potential as a tool to deliver unique patterns of level populations in fast-beam experiments and alter isomer to ground state ratios in the production of exotic beams.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2018

Time-Dependent Description of Incomplete Fusion of Nuclei and Cluster and Nucleon-Transfer Reactions

A numerical solution of the time-dependent Schrödinger equation is applied in studying the dynamics of incomplete fusion of nuclei and cluster- and nucleon-transfer reactions at energies near the Coulomb barrier. The evolution of wave functions for all nucleons is used to describe multineutron- and multiproton-transfer reactions in {sup 40}Ca+{sup 124}Sn collisions. The results of the calculations are in satisfactory agreement with experimental data. The evolution of the alpha-cluster wave function in the {sup 12}C nucleus is used to calculate the incomplete-fusion cross section for the {sup 12}C+{sup 51}V reaction. Agreement with experimental data for the ({sup 12}C, α) and ({sup 12}C, 2α) channels is attained.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2014

Studies of exotic nuclei with few-nucleon transfer reactions (Final Report)

This document serves as the final report on work done on the research supported by U. S. DOE Grant DE-FG02-ER-41320, A. H. Wuosmaa Principal Investigator, supporting institution Western Michigan University. The grant was first funded in 2004, and continued until the PI officially terminated his employ at Western Michigan University and moved to the University of Connecticut in August of 2014. Throughout its course, the goals of this project have been to determine the properties of exotic nuclei using few nucleon transfer reactions, and to develop new technical approaches to study such transfer reactions in inverse kinematics, in particular with rare-isotope beams. The work focused primarily on light-exotic nuclei studied using beams of rare-isotope beams produced at the ATLAS facility at Argonne National Laboratory. Additional research was conducted at the Michigan State University National Superconducting Cyclotron Laboratory, and the Western Michigan University Tandem Van de Graaff accelerator laboratory. A major goal and significant accomplishment of the program was the conceptual design, development, construction, commissioning and utilization of the HELIOS (HELIcal Orbit Spectrometer) device at Argonne National Laboratory. The concept of the solenoid spectrometer was presented in the first proposal submitted for this grant program, and with the close of this grant project the device is operating routinely and has been used in more than 20 experiments since its initial commissioning in 2008. The main physics goals of this project included producing new data for p and light-sd shell nuclei to test the predictions of ab-initio theoretical methods, as well as shell-model calculations for sd nuclei. Over its course, the project has generated data for (d,p), (d, 3 He) and (d, 4 He) reactions on many nuclei far from stability, and the data have informed both ab-initio and shell-model approaches.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2019

Experimental identification of the T = 1 , J π = 6 + state of Co 54 and isospin symmetry in A = 54 studied via one-nucleon knockout reactions

In this paper, new experimental data obtained from γ-ray tagged one-neutron and one-proton knockout from 55 Co are presented. A candidate for the sought-after T = 1, T z = 0, J π = 6 + state in 54 Co is proposed based on a comparison to the new data on 54 Fe, the corresponding observables predicted by large-scale-shell-model (LSSM) calculations in the full fp-model space employing charge-dependent contributions, and isospin-symmetry arguments. Furthermore, possible isospin-symmetry breaking in the A = 54, T = 1 triplet is studied by calculating the experimental c coefficients of the isobaric mass multiplet equation (IMME) up to the maximum possible spin J = 6 expected for the (1f 7/2 ) -2 two-hole configuration relative to the doubly magic nucleus 56 Ni. Lastly, the experimental quantities are compared to the theoretically predicted c coefficients from LSSM calculations using two-body matrix elements obtained from a realistic chiral effective field theory potential at next-to-next-to-next-to-leading order (N 3 LO).

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2017

Structure of the 1d2s Shell from the Data on Single-Nucleon-Transfer Reactions

For the stable silicon isotopes {sup 28}Si and {sup 30}Si, the energies and occupancies of single-particle states of the 1d2s shell are determined by analyzing the combined data for the nucleon stripping and pickup reactions. From the results of analysis and the available experimental data, the variation of the 1d2s proton-shell structure with increasing neutron number for the silicon isotopes with A = 26–34 is discussed.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2016

Deuteron-induced nucleon transfer reactions within an ab initio framework: First application to p -shell nuclei

Low-energy transfer reactions in which a proton is stripped from a deuteron projectile and dropped into a target play a crucial role in the formation of nuclei in both primordial and stellar nucleosynthesis, as well as in the study of exotic nuclei using radioactive beam facilities and inverse kinematics. Here, ab initio approaches have been successfully applied to describe the 3 H(d,n) 4 He and 3 He(d,p) 4 He fusion processes. An ab initio treatment of transfer reactions would also be desirable for heavier targets. In this work, we extend the ab initio description of (d,p) reactions to processes with light p-shell nuclei. As a first application, we study the elastic scattering of deuterium on 7 Li and the 7 Li(d,p) 8 Li transfer reaction based on a two-body Hamiltonian. We use the no-core shell model to compute the wave functions of the nuclei involved in the reaction, and describe the dynamics between targets and projectiles with the help of microscopic-cluster states in the spirit of the resonating group method. The shapes of the excitation functions for deuterons impinging on 7 Li are qualitatively reproduced up to the deuteron breakup energy. The interplay between d– 7 Li and p– 8 Li particle-decay channels determines some features of the 9 Be spectrum above the d+ 7 Li threshold. Our prediction for the parity of the 17.298 MeV resonance is at odds with the experimental assignment. Deuteron stripping reactions with p-shell targets can now be computed ab initio , but calculations are very demanding. Finally, a quantitative description of the 7 Li(d,p) 8 Li reaction will require further work to include the effect of three-nucleon forces and additional decay channels and to improve the convergence rate of our calculations.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗