Measurement of the Nucleon F 2 n / F 2 p Structure Function Ratio by the Jefferson Lab MARATHON Tritium/Helium-3 Deep Inelastic Scattering Experiment
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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
SEARCH · Engineering Papers
Results for “nuclear structures and reactions”
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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Probabilistic Multi-Hazard Performance Assessment of Concrete Structures in Nuclear Installations
Concrete structures in nuclear installations are subject to time-dependent degradation mechanisms that can deteriorate their physical and mechanical properties, potentially exacerbating the risk of structural failure under external forces such as a seismic event. Previous research has extensively investigated the seismic response of nuclear concrete structures and the associated risk, as well as their effect on structural components safety margins. However, substantial work is still necessary to incorporate concrete aging effects into such evaluations. In fact, most models in the literature assume pristine concrete conditions and do not account for the impact of aging on the structural components’ fragility curves. This work identifies relevant time-dependent degradation mechanisms and provides simplified models to predict the the evolution of key material properties based on data from the literature. Namely, this work focuses on the aging effects of corrosion, alkali–silica reaction (ASR), and irradiation on reinforced concrete within US Department of Energy (DOE) nuclear facilities and nuclear power plants (NPP) structures. Furthermore, degradation models based on literature data are presented that define the relationship between probabilistic material properties and the concrete’s age. In this work, sampled material properties served as input for a simplified finite element model (FEM) of a critical nuclear structural system, with the output of the FEM being the seismic response for a given ground motion. The results of the FEM were then used within a probabilistic performance assessment with a statistically significant number of samples. The research presented herein addresses the detrimental effects of hazards caused by natural phenomena on deteriorated concrete elements of nuclear installations. This work directly benefits the safety analysis performed on US DOE/ National Nuclear Security Administration (NNSA) nuclear facilities located in areas prone to seismic activity. The results presented herein could aid in the improvement of DOE-STD-1020, the DOE Standard that addresses seismic risk analysis and capacity evaluation in DOE facilities. DOE-STD-1020 refers to the requirements in American Society of Civil Engineers (ASCE) 4-98, now superseded by ASCE 4-16, that shall be met in performing dynamic response analyses and generating in-structure response spectra, provided that such requirements are consistent with the requirements of ASCE/Structural Engineering Institute (SEI) 43-05. Moreover, the results presented herein could also aid in the updating of section C3.1.1. of ASCE 4-16 to account for the effects of aging on the stiffness of reinforced elements and American Concrete Institute (ACI) 349.3R-18, “Report on Evaluation and Repair of Existing Nuclear Safety-Related Concrete Structures.” Ultimately, this work can assist the risk assessment of potential lifetime extension of the existing US commercial nuclear fleet (light water reactors) and the safety analysis of the emerging advanced nuclear reactors. The proposed proof-of-concept methodology employs open-source DOE computational tools and is transferable to commercial software commonly used by engineering firms.
42 ENGINEERING↗
Theoretical and Phenomenological Studies of the Nucleon Structure in High Energy Reactions
The understanding of the internal structure of the proton and other strongly interacting particles is at the forefront of modern nuclear physics research. Generalized Parton Distribution Functions (GPDs) are a powerful tool to advance the understanding of hadron structure. In addition to the information about the one- dimensional collinear momentum distributions of partons (quarks, anti-quarks, and gluons) known from studies of high energy deep-inelastic reactions, GPDs also carry information on the distribution of partons in the transverse plane, and allow us in this way to access the three-dimensional structure of the nucleon. GPDs can be studied in hard-exclusive reactions and contain also information on the energy-momentum tensor form factors which will allow us to gain insights on quantities like pressure or angular momentum distribution inside the nucleon. The goal of this thesis is to deepen our understanding of the three-dimensional structure of the nucleon. We investigate energy-momentum tensor form factors and densities, and all leading-twist GPDs in the bag model. This quark model provides a consistent theoretical framework to investigate many general concepts that have recently attracted interest, and allows one to study insightful limits like the large-Nc limit, heavy-quark limit or the non-relativistic limit. Another important aspect of this thesis is the discussion of the monopole and quadrupole contributions to the angular momentum density. Finally, the description of pseudoscalar meson production in exclusive processes in terms of GPDs is discussed in the Goloskokov-Kroll model and implemented in the PARTONS framework, a software development project which will provide direct support for experiments at the Jefferson National Lab and the future Electron-Ion Collider.
Tezgin, Kemal↗
Coupling of TIGRESS and EMMA with Auxiliary Array TIP at TRIUMF
The combination of a germanium detector array and recoil mass spectrometer allows for high-sensitivity experiments in nuclear structure and astrophysics by enabling high-energy-resolution -ray spectroscopy and reaction measurements of weak fusion-evaporation, transfer or radiative-capture reactions in the presence of dominant background reaction channels. The TIGRESS -ray spectrometer with an upgraded data acquisition system has been coupled with the EMMA mass spectrometer alongside a suite of auxiliary detectors housed within TIGRESS such as TIP. This paper reviews the unique combination of radioactive beams at TRIUMF with the capabilities of TIGRESS and EMMA in the context of fusion-evaporation with TIP and radiative-capture reactions without an auxiliary array.
A/Q identification↗
Simple relativistic quark models
A class of phenomenological relativistic models of hadronic systems motivated by quantum chromodynamics that have dual representations as models of mesons and nucleons or quarks and gluons is investigated. These models are designed to provided qualitative insight into the role of sea quarks in hadronic structure and reactions. The model assumption is that the Hamiltonian can be divided into two parts: one that involves degrees of freedom in the same connected local and global color singlet and the remaining interactions that allow the connected local and global color singlets to interact. The first class of interactions results in infinite towers of bare “particles” with hadronic quantum numbers. All but a finite number of these remain stable when the second class of interactions is included. The model interactions are expressed in terms of subhadronic degrees of freedom, which determine the bare hadronic spectrum and the interactions involving the bare hadrons in terms of a small number of subhadronic model parameters. As a first test, this paper considers the simplest case of mesons that interact via a string-breaking interaction. One virtue of this model is that all of the bare meson masses and eigenfunctions can be computed analytically. In addition, the string-breaking interaction leads to production vertices that can also be computed analytically. The relativistic wave functions have a light-front kinematic symmetry. The goal is to find a simple relativistic quantum mechanical model based on subhadronic degrees of freedom that can provide an efficient, qualitatively consistent description of hadronic masses, lifetimes, cross sections, sea quark effects, and electromagnetic properties. The simplicity of the model makes it a potentially useful tool to study the impact of sea quarks on hadronic structure and reactions.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Multidifferential study of identified charged hadron distributions in Z -tagged jets in proton-proton collisions at $\sqrt{s} =13$ TeV
Jet fragmentation functions are measured for the first time in proton-proton collisions for charged pions, kaons, and protons within jets recoiling against a Z boson. The charged-hadron distributions are studied longitudinally and transversely to the jet direction for jets with transverse momentum 20 < p T < 100 GeV and in the pseudorapidity range 2.5 < η <4. The data sample was collected with the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 1.64 fb –1 . Triple differential distributions as a function of the hadron longitudinal momentum fraction, hadron transverse momentum, and jet transverse momentum are also measured for the first time. This helps constrain transverse-momentum-dependent fragmentation functions. Differences in the shapes and magnitudes of the measured distributions for the different hadron species provide insights into the hadronization process for jets predominantly initiated by light quarks.
79 ASTRONOMY AND ASTROPHYSICS↗
Abundance anomalies produced by nuclear reactions in stellar surface layers. II.
Abundance anomalies in stellar surface layers by proton and alpha particle bombardment caused nucleus breakdown and buildup to lower and higher mass numbers respectively
NUCLEAR REACTION↗
In situ chemical analyses of extraterrestrial bodies
One of the most important tasks on any sample return mission will have to be a quick sample characterization in order to guarantee a variety of collected samples. An alpha particle instrument with alpha, proton and X-ray modes can provide a quick and almost complete chemical analysis of Mars samples. This instrument is based on three interactions of the alpha particles from a radioactive source with matter: elastic scattering of the alpha particles by nuclei (alpha mode), (alpha,p) nuclear reaction with some light elements (proton mode), and excitation of the atomic structure of atoms by alpha particles, leading to emission of characteristic X-rays of the lunar surface at three sites during the Surveyor mission of 1967 to 1968. Since then the instrument has been improved and miniaturized substantially. As shown in the past, the alpha particle instrument can operate under Martian conditions without any degradation in the performance. The alpha and proton modes can provide vital information about the light elements, while the X-ray mode with its ambient temperature X-ray detector will be useful for the heavier elements. The excitation of the atomic structure is provided by the same alpha radioactive source that is used by alpha and proton modes or by an auxiliary X-ray source that is selected to enhance the sensitivity to some important geochemical elements.
Economou, Thanasis E.↗
MeV ion-beam analysis of optical data storage films
Our objectives are threefold: (1) to accurately characterize optical data storage films by MeV ion-beam analysis (IBA) for ODSC collaborators; (2) to develop new and/or improved analysis techniques; and (3) to expand the capabilities of the IBA facility itself. Using H-1(+), He-4(+), and N-15(++) ion beams in the 1.5 MeV to 10 MeV energy range from a 5.5 MV Van de Graaff accelerator, film thickness (in atoms/sq cm), stoichiometry, impurity concentration profiles, and crystalline structure were determined by Rutherford backscattering (RBS), high-energy backscattering, channeling, nuclear reaction analysis (NRA) and proton induced X-ray emission (PIXE). Most of these techniques are discussed in detail in the ODSC Annual Report (February 17, 1987), p. 74. The PIXE technique is briefly discussed in the ODSC Annual Report (March 15, 1991), p. 23.
Leavitt, J. A.↗
Evaluation of Spacecraft Shielding Effectiveness for Radiation Protection
The potential for serious health risks from solar particle events (SPE) and galactic cosmic rays (GCR) is a critical issue in the NASA strategic plan for the Human Exploration and Development of Space (HEDS). The excess cost to protect against the GCR and SPE due to current uncertainties in radiation transmission properties and cancer biology could be exceedingly large based on the excess launch costs to shield against uncertainties. The development of advanced shielding concepts is an important risk mitigation area with the potential to significantly reduce risk below conventional mission designs. A key issue in spacecraft material selection is the understanding of nuclear reactions on the transmission properties of materials. High-energy nuclear particles undergo nuclear reactions in passing through materials and tissue altering their composition and producing new radiation types. Spacecraft and planetary habitat designers can utilize radiation transport codes to identify optimal materials for lowering exposures and to optimize spacecraft design to reduce astronaut exposures. To reach these objectives will require providing design engineers with accurate data bases and computationally efficient software for describing the transmission properties of space radiation in materials. Our program will reduce the uncertainty in the transmission properties of space radiation by improving the theoretical description of nuclear reactions and radiation transport, and provide accurate physical descriptions of the track structure of microscopic energy deposition.
Cucinotta, Francis A.↗
Level Structure of {sup 31}S Via {sup 32}S({ital p,d}) {sup 31}S
Background: Properties of proton-unbound S-31 states determine the P-30(p, gamma) S-31 reaction rate, which has a significant impact on explosive hydrogen burning in classical novae and type-I x-ray bursts. Despite several previous studies, uncertainties still remain with respect to the nuclear structure of S-31 near the proton threshold. Purpose: The level structure of S-31 has been presently investigated via a charged-particle spectroscopy experiment using the S-32(p, d) S-31 reaction. Method: Deuterons corresponding to S-31 excited states with 3.285 <= E-x <= 10.8 MeV were momentum analyzed via an Enge split-pole spectrograph at six laboratory angles between 10 degrees and 62 degrees. Differential cross sections of the S-32(p, d)S-31 reaction were measured at E-p = 34.5 MeV. Distorted-wave Born approximation calculations were performed to constrain the spin-parity assignments of several of the observed levels. Results: We have detected 72 excited states of S-31, out of which 17 are within the astrophysical region of interest corresponding to the temperature range of 0.1-1.5 GK. We have resolved the discrepancy in the spin and parity of an excited state with E-x = 6542 keV, showing that is it not J(pi) = 3/2(-), and therefore the contribution of this state to the P-30(p, gamma) reaction rate is likely much less significant than previously thought owing to the larger angular-momentum transfer required to populate this excited state. Moreover, our measurement results help consolidate the spin-parity assignments for the 6377 and 6636 keV states in S-31. Conclusions: This work presents the most comprehensive spin-parity assignments to date from a single-neutron transfer reaction on S-32 to S-31 excited states in the region between 6 to 7 MeV excitation energy. This region is significant for the determination of the P-30(p, gamma)S-30 reaction rate over the temperatures characteristic of explosive hydrogen burning in novae.
Setoodehnia, K.↗
Neutron diffraction: a primer
Because of the neutron’s special properties, neutron diffraction may be considered one of the most powerful techniques for structure determination of crystalline and related matter. Neutrons can be released from nuclear fission, from spallation processes, and also from low-energy nuclear reactions, and they can then be used in powder, time-of-flight, texture, single crystal, and other techniques, all of which are perfectly suited to clarify crystal and magnetic structures. With high neutron flux and sufficient brilliance, neutron diffraction also excels for diffuse scattering, for in situ and operando studies as well as for high-pressure experiments of today’s materials. For these, the wave-like neutron’s infinite advantage (isotope specific, magnetic) is crucial to answering important scientific questions, for example, on the structure and dynamics of light atoms in energy conversion and storage materials, magnetic matter, or protein structures. In this primer, we summarize the current state of neutron diffraction (and how it came to be), but also look at recent advances and new ideas, e.g., the design of new instruments, and what follows from that.
36 MATERIALS SCIENCE↗
9 Li($\textit{d,p}$) reaction as a specific probe of 10 Li, the paradigm of parity-inverted nuclei around the $\textit{N}$ = 6 closed shell
In this work, we show, within the framework of renormalized nuclear field theory and of the induced reaction surrogate formalism, that the highly debated 10 Li structure, studied in a recent high statistics 9 Li ($\textit{d,p}$) 10 Li one-neutron transfer experiment, is consistent with, or better, requires, the presence of a virtual 1/2 + state of similar single-particle strength than that of the 1/2 – resonance at 0.45 ± 0.03 MeV. Based on continuum spectroscopy self-energy techniques, we find that the physical mechanism responsible for parity inversion in $^{10}_3$Li is the same as that at the basis of the similar phenomenon observed in $^{11}_4$Be and as that needed in 11 Li to have an important $\textit{s}$-wave ground-state component. In particular the strong dynamical coupling between the $s_{1/2}$ and the $d_{5/2}$ states, mediated by the quadrupole vibration of the core 9 Li. A phenomenon which also affects the strength distribution of the $d_{5/2}$ state, in particular, in the energy range of 3–4.5 MeV. Furthermore, this mechanism is also consistent with the (normal) sequence of the $1_{p_{1/2}}$ and $2_{s_{1/2}}$ levels in the $\textit{N}$ = 7 isotones $^{12}_5$B and $^{13}_6$C. The main aim of the present Rapid Communication is that of treating structure and reactions on equal footing and in a common language. In other words, the calculation of the 9 Li ($\textit{d,p}$) 10 Li reaction as a single conceptual step from individual single-particle motion and collective vibrations to absolute double differential cross sections of renormalized virtual and resonant final states, which can be directly compared with experiment.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Investigation of the 244 Pu ( 48 Ca,𝑥𝑛) 292−𝑥 Fl reaction with the LBNL SHREC detector: Investigation of decay chains of isotopes of flerovium (𝑍=114)
The 244 Pu ( 48 Ca,𝑥𝑛) 292−𝑥 Fl reaction was investigated at Lawrence Berkeley National Laboratory’s 88 Inch Cyclotron using the Berkeley Gas-filled Separator (BGS), the newly installed Superheavy Recoil detector, along with an upgraded digital electronics and data acquisition system. Seven decay chains were observed starting with an evaporation residue, followed by a single 𝛼 decay and a spontaneous fission. The decay characteristics of these seven decay chains led to an assignment to 288 Fl , the product of the 4𝑛 reaction channel. Two additional chains were (tentatively) assigned to the decay of the 3𝑛 exit channel, 289 Fl . Cross sections for the 4𝑛 and 3𝑛 exit channels were 𝜎 prod =6.7($^{36}_{25}$) pb and 𝜎 prod =1.6($^{22}_{11}$) pb, respectively. Another decay chain, tentatively assigned to the 5𝑛 exit channel through the 48 Ca + 244 Pu reaction or the 3𝑛 exit channel of the 48 Ca + 242 Pu reaction, was also detected. Detailed information regarding the observed decay chains and their nuclear structure aspects is discussed, along with the performance of the BGS and the new detection system.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
An alternative viewpoint on the nuclear structure towards 100 Sn: Lifetime measurements in 105 Sn
This work aims at presenting an alternative approach to the long standing problem of the B(E2) values in Sn isotopes in the vicinity of the N=Z double-magic nucleus 100 Sn, until now predominantly measured with relativistic and intermediate-energy Coulomb excitation reactions. The direct measurement of the lifetime of low-lying excited states in odd-even Sn isotopes provides a new and precise guidance for the theoretical description of the nuclear structure in this region. Lifetime measurements have been performed in 105 Sn for the first time with the coincidence Recoil Distance Doppler Shift technique. The lifetime results for the $7/2^+_1$ first excited state and the $11/2^+_1$ state, $2^+ (^{104}$Sn) Ⓧ $v1g_{7/2}$ multiplet member, are discussed in comparison with state-of-the-art shell model and mean field calculations, highlighting the crucial contribution of proton excitation across the core of 100 Sn. The reduced transition probability B(E2) of the $11/2^+_1$ core-coupled state points out an enhanced staggering with respect to the B(E2; $2^+_1$ → $0^+_1$) in the even-mass 104 Sn and 106 Sn isotopes.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Bringing the “Real World” into the TEM: New Opportunities for In Situ Gas-Metal Reaction Research
• In Situ TEM – a new technique? • Developments/Approaches for Gas-Metal reactions in real time • Oxidation / Reduction applications • Developments post-~2010 • Application to environment-sensitive degradation of structural materials • Future?
11 - NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
Tritium targets for use in solenoidal spectrometers
Nucleon adding and removing reactions are an ideal probe to study the single-particle foundations of nuclear structure. For experiments far away from the valley of stability, one needs to use radioactive beams in inverse kinematics. To maintain excellent resolution, solenoidal spectrometers like HELIOS at Argonne National Laboratory (ANL), ISS at CERN or SOLARIS at the Facility for Rare Isotope Beams (FRIB) are used. Typically, deuterated plastic foils are the targets of choice. Depending on the energy deposited, these targets might degrade quickly in beam. The potential of using tritium-implanted targets in conjunction with the solenoidal spectrometers was realized for access to even more exotic nuclei with outstanding resolving power. While no tritiated polyethylene is commercially available at the moment, tritium-containing titanium targets have been produced in the past. Unfortunately the loading fraction of tritium for the latter was often very low and not reproducible. The progress in the production of tritium-containing targets is presented, including the characterization of the foils.
Müller-Gatermann, Claus↗
Lifetime measurements of excited states in neutron-rich 53 Ti: Benchmarking effective shell-model interactions
Level lifetimes of the yrast (5/2 - ) to 13/2 - states in the neutron-rich nucleus 53 Ti, produced in a multinucleon-transfer reaction, have been measured for the first time. The recoil distance Doppler-shift method was employed and lifetimes of the excited states were extracted by a lineshape analysis aided by GEANT4-based Monte-Carlo simulations. The experiment was performed at the Grand Accelerateur National d'Ions Lourds facility in Caen, France, by using the Advanced Gamma Tracking Array for the gamma-ray detection coupled to the large-acceptance variable mode spectrometer for an event-by-event particle identification and the Cologne plunger for deep-inelastic reactions. Reduced transition probabilities, deduced from the lifetimes, give new information on the nuclear structure of 53 Ti, and are used to benchmark different shell-model calculations using established interactions in the fp shell.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗