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All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

SCWR Once-Through Calculations for Transmutation and Cross Sections

It is the purpose of this report to document the calculation of (1) the isotopic evolution and of (2) the 1-group cross sections as a function of burnup of the reference Super Critical Water Reactor (SCWR), in a format suitable for the Fuel Cycle Option Campaign Transmutation Data Library. The reference SCWR design was chosen to be that described in [McDonald, 2005]. Super Critical Water Reactors (SCWR) are intended to operate with super-critical water (i.e. H2O at a pressure above 22 MPa and a temperature above 373oC) as a cooling – and possibly also moderating – fluid. The main mission of the SCWR is to generate lower cost electricity, as compared to current standard Light Water Reactors (LWR). Because of the high operating pressure and temperature, SCWR feature a substantially higher thermal conversion efficiency than standard LWR – i.e. about 45% versus 33%, mostly due to an increase in the exit water temperature from ~300oC to ~500oC – potentially resulting in a lower cost of generated electricity. The coolant remains single phase throughout the reactor and the energy conversion system, thus eliminating the need for pressurizers, steam generators, steam separators and dryers, further potentially reducing the reactor construction capital cost. The SCWR concept presented here is based on existing LWR technology and on a large number of existing fossil-fired supercritical boilers. However, it was concluded in [McDonald, 2005], that: “Based on the results of this study, it appears that the reference SCWR design is not feasible.” This conclusion appears based on the strong sensitivity of the design to small deviations in nominal conditions leading to small effects having a potentially large impact on the peak cladding temperature of some fuel rods. “This was considered a major feasibility issue for the SCWR” [McDonald, 2005]. After a description of the reference SCWR design, the Keno V 3-D single assembly model used for this analysis, as well as the calculated results, are presented. Additionally, the follwing information, presented in the appendixes, is intended to provide enough guidance that a researcher repeating the same task in the future should be able to obtain a vector of nuclei and cross sections ready for insertion into the transmutation library without any need for further instructions: (1) Complete TRITON/KENO-V input used for the analysis; (2) Inputs and detailed description of the usage of the OPUS utility, used to postproces and to extract the nuclei concentrations for the transmutation library; (3) Inputs and detailed description of the usage of the XSECLIST utility, used to postproces and to extract the 1-group cross sections for the transmutation library; (4) Details of an ad-hoc utility program developed to sort the nuclei and cross sections for the transmutation library.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2014

Measurement of the photon electroproduction cross section at JLAB with the goal of performing a Rosenbluth separation of the DVCS contribution

The study of the inner structure of hadrons allows us to understand the nature of the interactions between partons, quarks and gluons, described by Quantum Chromodynamics. The elastic scattering reactions, which have been studied in order to measure the nucleon form factors, are included in this frame. The inelastic scattering reactions are also included in this frame, they allow us to obtain information about the nucleon structure thanks to the development of the parton distribution functions (PDFs). While through elastic scattering we can obtain information about the charge distribution of the nucleon, and hence, about the spatial distribution of the partons, through inelastic scattering we obtain information about the momentum distributions of partons, by employing the PDFs. However, we can study the exclusive inelastic scattering reactions, such as the Deeply Virtual Compton Scattering (DVCS), wich allow us to access to the spatial and momentum distributions simultaneously. This is possible thanks to the generalized parton distributions (GPDs), which allow us to correlate both types of distributions. The process known as DVCS is the easiest way to access the GPDs. This process can be expressed as the scattering of an electron by a proton by means of a virtual photon with the result of the scattered initial particles plus a real photon. We find a process competing with DVCS known as Bethe-Heitler (BH), in which the real photon is radiated by the lepton rather than the quark. Due to the small cross section of DVCS, of the order of nb, in order to conduct these kind of experiments it is necessary to make use of facilities capable of providing high beam intensities. One of these facilities is the Thomas Jefferson National Accelerator Facility , where the experiment JLab E07-007, "Complete Separation of Virtual Photon and π⁰ Electroproduction Observables of Unpolarized Protons", took place during the months of October to December of 2010. The main goal of this experiment is the isolation of the contribution from the term coming form the DVCS from the interference term, resulting from the BH contribution. This isolation is known as "Rosenbluth Separation". The work presented in this thesis focuses on the analysis of the data stored by the electromagnetic calorimeter, employed for the detection of real photons. There is also a a theoretical introduction to the study of the nucleon structure, reviewing the concepts of form factors and parton distributions through elastic and inelastic processes. The computation of the photon leptoproduction cross section is described in detail, as well as the goals of experiment E07-007. This thesis also describes the analysis of the data stored by the electromagnetic calorimeter, with the purpose of obtaining the kinematic variables of the real photons resulting from DVCS reactions. Finally, it describes the selection of events from stored data, the applied cuts to kinematical variables and the background subtraction. Also, the process of extraction of the necessary observables for computing the photon leptoproduction cross section is described, along with the main steps followed to perform the Monte Carlo simulation used in this computation. The resulting cross sections are shown at the end of this thesis.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2012

Measurement of $Z/\gamma^* + b$-jet Production Cross section in $p\bar{p}$ collisions at $\sqrt{s}= 1.96$ TeV with the CDF detector

Processes at hadron colliders, such as the production of jets, are described by the Quantum Chromodynamics theory (QCD). Precise descriptions of processes involving jets in association with a vector boson have nowadays large relevance as they represent irreducible background to other Standard Model (SM) processes and searches for new physics. The experimental study and understanding of the b-jet production in association with a Z boson are crucial for many reasons. For one side, it is the most important background for a light Higgs boson decaying into a bottom-antibottom quark pair and produced in the ZH mode.This is one of the most promising channels for the Higgs search at Tevatron in particular since the latest results have excluded the high mass region (MH > 127 GeV/c 2 ). For another side the signature of b-jets and a Z boson is also background to new physics searches, such as supersymmetry, where a large coupling of the Higgs boson to bottom quarks is allowed. The produ ction cross section measurement of b-jets in events with a Z boson has already been performed at hadron colliders, at the Tevatron by CDF and D0 experiments and are now pursued at the LHC by ATLAS and CMS. In particular the CDF measurement was performed with only 2 fb -1 and was limited by the statistical uncertainty. This PhD thesis presents a new measurement of the $Z/\gamma^* + b$-jet production cross section using the complete dataset collected by CDF during the Run II. $Z/\gamma^*$ bosons are selected in the electron and muon decay modes and are required to have 66 < MZ < 116 GeV/c 2 while jets, reconstructed with the MidPoint algorithm, have to be central (|Y| < 1.5) with pT > 20 GeV/c . The per jet cross section is measured with respect to the $Z/\gamma^*$ inclusive and the $Z/\gamma^* +$ jets cross sections. Results are compared to leading order (LO) event generator plus parton shower and next-to-leading order (NLO) predictions corrected for non perturbative effects such as hadronizat ion and underlying event. Differential distributions as a fu! nction of jet transverse moment and jet rapidity are also presented together with the comparison to NLO pQCD predictions for different renormalization and factorization scales and various PDF sets.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Measurement of the $W+$ jets differential cross-sections in $p\bar{p}$ collisions at $\sqrt{s} = 1.96$ TeV using the CDF II Detector

In this thesis the measurements of differential cross sections for the production of the $W$-boson in association with jets in $p\bar{p}$ collisions at $\sqrt{s} = 1.96$ TeV are presented. The measurements are based on 9.0 fb$^{-1}$ of CDF Run II data (i.e., the full dataset). Only events in which the W-boson decays leptonically (i.e., W → ev and W → μv)and at least one jet is present are considered. The lepton candidates are required to have a transverse energy $E^{\ell}_T > 25$GeV and pseudorapidity in the range |n ℓ | < 1 whereas, the jets are reconstructed using the JETCLU algorithm with a radius of 0.4 requiring transverse energy $E^{jet}_T > 25$GeV and pseudorapidity in the range |η jet| < 2. The reconstructed W-boson transverse mass should be greater than 40GeV/c 2 . The differential cross sections as a function of the jet multiplicity ($N$ > or = to 1, 2, 3, 4) and the leading jet transverse energy, are measured separately for each decay channel and then combined. For a meaningful comparison with theory the measured cross-sections are unfolded to remove detector effects. The resulting particle-level cross-sections are compared to theoretical predictions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Nuclear Forensics and Radiochemistry: Cross Sections

The neutron activation of components in a nuclear device can provide useful signatures of weapon design or sophistication. This lecture will cover some of the basics of neutron reaction cross sections. Nuclear reactor cross sections will also be presented to illustrate the complexity of convolving neutron energy spectra with nuclear excitation functions to calculate useful effective reactor cross sections. Deficiencies in the nuclear database will be discussed along with tools available at Los Alamos to provide new neutron cross section data.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2019

Evaluation and Validation of 28,29,30SI Cross Sections in the Resolved Resonance Region

Resonance parameter evaluations of the three stable silicon isotopes 28;29;30 Si, were performed at Oak Ridge National Laboratory in 2002 and the results of those evaluations were restored from the archives in 2018. The evaluations also accounted for the contribution of the direct component of the capture cross sections computed over the neutron resonance range. For the most abundant isotope, 28 Si, the value of the thermal capture cross sections was increased by 10% on the basis of analyses devoted to reevaluating the thermal radiative neutron capture cross sections. The contribution of the direct capture cross sections was recomputed for each isotope, and its energy-dependent behavior improved. Results of benchmark calculations performed at the International Atomic Energy Agency showed an excellent agreement with integral measurements.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2017

Modeled Neutron and Charged-Particle Induced Nuclear Reaction Cross Sections and their Uncertainties in the Region 37 < A < 47 (Rb-Ag)

A modeling effort to calculate nuclear reaction cross sections for use in radiochemical di-agnostics is presented. Systematics for the input parameters required by the Hauser-Feshbachstatistical model were developed and used to calculate neutron, proton, and deuteron inducednuclear reaction cross sections for targets ranging from Rubidium (Z= 37) to Silver (Z= 47).This is an expansion of the previous modeling effort described in Hoffman et. al. 2006(UCRL-TR-222275) that allows us to now calculate all new cross sections for radiochemical detector sets Rb, Rh, and Ag. We have also developed new systematics affecting our treatments of the nuclear level density and the gamma-ray strength function. Coupled with a range of the main parameter that affects pre-equilibrium, we develop upper and lower bounds to our recommended cross sections

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2019

A Section 110 Evaluation of the Project 57 Rad-Safe Area Personnel Decontamination Building, Nye County, Nevada

Project 57 was an open-air, plutonium-dispersal safety test conducted by the United States in 1957 on a portion of the Nevada Test and Training Range (NTTR) (formerly the Las Vegas Bombing and Gunnery Range). The Project 57 test area, once known as Area 13, was a block of land abutting the northeastern boundary of the Nevada Test Site (NTS). The NTS was renamed the Nevada National Security Site (NNSS) in 2010. In keeping with the historical Cold War period designation, NTS will be used when discussing historic period events, while NNSS will be applied for contemporary activities. During Project 57, the high explosives of a nuclear weapon were triggered asymmetrically to simulate an accidental detonation. The test was conducted to study the extent of plutonium contamination from a nonnuclear yield accident, as well as assess the biological and environmental hazards such an event could create. Following the conclusion of the experiment, the contaminated area surrounding the ground zero (GZ) was fenced off and some of the contaminated equipment was buried in place. The Project 57 Rad-Safe area was abandoned. In 1981, the U.S. Department of Energy (DOE) decontaminated and decommissioned the Project 57 site. This Section 110 documentation was prompted by recognition that more than five decades have passed since the abandonment of the Project 57 Rad-Safe area, particularly the personnel decontamination building, which leaves the temporary structure vulnerable to natural forces of weathering and decay. However, these temporary facilities remain partially standing, allowing for a condition assessment and recommendations regarding the Rad-Safe area’s historical significance. The National Nuclear Security Administration, Nevada Field Office (NNSA/NFO) determined there was no area of potential effect (APE) (direct, indirect, or visual) because there is no planned undertaking and the Project 57 Rad-Safe area will continue to remain unused. Instead, a 4.5-acre study area was established to facilitate recording the Project 57 personnel decontamination building and the remaining accessory resources. The study area is bounded on the east by Valley Road and it extends to the east far enough to encompass the former Project 57 Rad-Safe area (Figure A-2). The Section 110 study area is located in the northwest quarter of Section 35, Township 07S Range 54E Mount Diablo Base and Meridian. It is on the 1962 Groom Mine SW USGS 7.5-minute series topographic quadrangle. Desert Research Institute (DRI) surveyed the Section 110 study area, resulting in the recording and evaluation of the Project 57 Rad-Safe area personnel decontamination building and four accessory resources (AR-1 through AR-4). Copies of the building form and report are on file at DRI and with the NNSA/NFO in Las Vegas, Nevada.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2019

Measurement of the (e,e') cross section for12C, 48Ti, 27Al and 40Ar

Many experiments have found that neutrinos have three different flavors, and they can transform from each other. Each flavor is a mixture of three nonzero mass states. In neutrino oscillation experiments, the uncertainty of the extracted oscillation parameters is dependent on the neutrino-nucleus cross section. In recent years various experiments provided precise neutrino and anti-neutrino cross section measurements and they have shown the inability of current Monte Carlo simulations to reproduce the data. A more accurate nuclear structure model of the target employed in neutrino detector is urgently needed to improve the precision of long baseline neutrino experiments. Electron scattering has been one of the most powerful methods of obtaining information about cross sections in the past. In the upcoming deep underground neutrino experiment (DUNE), Liquid Argon Time Projection Chambers (LArTPCs) will be used as the detector technology and argon will be used as the nuclear target. There are very few data available on argon and there is not an accurate nuclear model that describes them accurately, at ~5% level. We have performed an electron-argon scattering experiment at Jefferson Lab (E12-14-012) to provide accurate data that will help build a reliable nuclear model for describing neutrino-argon scattering. The JLab E12-14-012 experiment has successfully taken data in Hall A at the Thomas Jefferson National Accelerator Facility between February and March of 2017. We collected data for the inclusive (e,e') and exclusive (e,e'p) processes for a variety of targets (argon, titanium, aluminum, carbon) at a wide range of kinematic settings. This thesis will present the results of the inclusive double differential cross sections for carbon, titanium, aluminum and argon at beam energy E = 2:222 GeV and scattering angle theta = 15:541 deg with total uncertainties smaller than 5%. The kinematic settings covered a broad range of energy transfers, including deep inelastic scattering (DIS), delta production, and quasielastic scattering.

Dai, Hongxia↗
DOE OSTI2020

Preliminary Study on TRISO Fuel Cross Section Generation

Cross section self-shielding methodologies for TRISO fuel were assessed to provide accurate multigroup cross sections for a high-fidelity reactor physics code so that the code is able to accurately model and simulate advanced reactors with TRISO fuel. Initially, the two existing methodologies (the SCALE method and the Sanchez-Pomraning method) were studied and implemented to MC2-3 for detailed performance tests. Additionally, a new spatial self-shielding method, named the iterative local spatial self-shielding (ILSS) method, for particulate fuels was developed based on the disadvantage factor and implemented to MC2-3 as well. The new method approximately accounts for the effect of randomly distributed particles on the particle shadowing effect using a homogenized compact region surrounding a particle of interest at the center. The self-shielded cross sections of the particle at the center are determined iteratively since the cross sections of the homogenized compact region are calculated using them. For the energy range above 100 keV where the fuel-to-moderator ratio is more important than the random distribution of particles, a single particle unit-cell model is used by preserving the average amount of moderator per fuel particle in the system. The three self-shielding methods implemented in MC2-3 were tested using numerical benchmark problems made based on fuel compact problems of a prismatic-type very high temperature reactor. Test results indicated that the ILSS method produced slightly better results than the SCALE and Sanchez-Pomraning methods, compared to the Serpent-2 Monte Carlo results obtained with 25 independent random particle configurations. The SCALE and Sanchez-Pomraning methods tend to underestimate the heterogeneity effect by 150 and 100 pcm, respectively, while the new ILSS method overestimates the heterogeneity effect by 70 pcm. In future, the new self-shielding method will be extended to perform pebble calculations and compare results with those from the SCALE and Sanchez-Pomraning methods. Furthermore, the new method will be optimized for practical applications to on-the-fly resonance treatment for lattice or whole-core calculations for advanced reactors.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2021

DUNE and MINERvA Flux Studies and a Measurement of the Charged-Current Quasielastic Antineutrino Scattering Cross Section with $<E_{\nu}> \sim 6 $ GeV on a CH Target

One of the biggest open questions in physics is the prevalence of matter over anti-matter in the present universe. One of possible answers lies in the violation of charge and parity symmetry in the lepton sector that would favor matter over anti-matter so that the universe becomes dominated by matter over time. Recent results from neutrino experiments like T2K and NOvA have indicated that there is CP violation in the leptonic sector \citep{Abe:2019vii}. However, the precise measurement of CP violation will require an unprecedented level of accuracy in these oscillation experiments. One of the challenges lies with the systematic uncertainties that come with the measurements, which include uncertainties related to the neutrino flux modeling, interaction modeling and detector related systematic uncertainties.\\ The first part of this thesis will go through the challenges related to flux uncertainties. It will discuss the flux uncertainties related to hadron production in the LBN F beamli ne for the DUNE experiment. Hadron production models used in flux simulations vary widely depending on the simulation and choice of physics models used to simulate the hadron production. This thesis will explain the method of using existing hadron production data to constrain these uncertainties, a method which has been used in MINERvA experiment.\\ The second part of the thesis goes through the effect of possible flux mismodeling and MINERvA's approach to address this effect. In doing so, we discovered that the suspected mismodeling could also result from incorrect estimation of the energy scale of the muons. This project not only demonstrated the challenges of flux modeling but also led to a novel approach of using neutrino energy spectra to understand the correlation between detector and neutrino beamline parameters. \\ A high statistics measurement of the anti-neutrino scattering cross section in the charged current quasielastic (CCQE) channel is the final part of the th esis. Th e 2-body interactions in this channel have the advantage of allowing reconstruction of the interaction kinematics from the outgoing muon trajectory which can be measured very well. Double differential cross sections as a function of muon kinematics, one of the deliverables of this analysis, will help future oscillation experiments understand their data. The cross-section as a function of the four-momentum transferred from the leptonic system to the hadronic system ($Q^{2}_{QE}$) can be used to test models used in simulating antineutrino interactions and the nuclear effects that can modify the predicted cross sections. Nuclear effects arise from the complex nuclear environment and both modify the initial scattering and change the fate of the particles produced from in neutrino-nucleus interactions. Study of nuclear effects will help to understand the structure of the atomic nucleus and its impact on neutrino interactions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Including 238 U(n,f)/ 235 U(n,f) and 239 Pu(n,f)/ 235 U(n,f) NIFFTE fission TPC Cross-sections into the Neutron Data Standards Database

The primary purpose of this report is to document how the 238 U/ 235 U and 239 Pu/ 235 U neutron induced fission cross-section ratios, 238 U(n,f)/ 235 U(n,f) and 239 Pu(n,f)/ 235 U(n,f), respectively, measured by the NIFFTE fission Time Projection Chamber (fissionTPC) were included in the most recent database (termed GMA) underlying Neutron Data Standards (NDS) evaluations. This report shows and discusses NDS input files, and underlying assumptions regarding the uncertainty estimate and necessary for including these data. This uncertainty estimate and the resulting files were based on information provided by fissionTPC experimentalists, R.J.Casperson, N.S. Bowden, L. Snyder and K.T. Schmitt for the 238 U ratio, and by L. Snyder for the 239 Pu ratio. The fissionTPC data were included twice, by D. Neudecker and V. Pronyaev, to counter-check results and exclude possible mistakes in their inclusion. It is shown in both evaluations that including fissionTPC 239 Pu(n,f)/ 235 U(n,f) data points to a lower evaluated 239 Pu(n,f) cross section above 10 MeV than the currently released NDS data. This raises the question whether a part of a previous dataset by Tovesson et al., that was previously rejected above 13 MeV for having low values, should be included in the NDS evaluation after all. The evaluated 238 U(n,f) cross section only changes significantly close to the threshold. The impact on the 235 U(n,f) cross section is minimal. fissionTPC data reduce evaluated uncertainties on both observables by 0–12% of the GMA evaluated uncertainties. However, the currently released NDS data contain in addition to these GMA evaluated uncertainties “Unrecognized Sources of Uncertainties” (USU) of 1.2%. It needs to be further discussed within the NDS project, whether the new fissionTPC data should also reduce USU.

238U(n,f)/235U(n,f)↗
DOE OSTI2021

A consistent, Bayesian, approach to the cross section probability distribution in the unresolved resonance region

The cross sections of neutron-induced reactions can be divided into three energy ranges: the resolved resonance region (RRR), the unresolved resonance region (URR), and the fast region. In general, the cross sections in the URR show significant fluctuations that cannot be predicted and cannot be experimentally resolved, thus, it is commonly assumed that the cross section at a specific energy is given by a probability distribution function (PDF) over a range of values that can span several orders of magnitude. The current methodology used to describe such behavior is to construct the PDF by stochastically generating resonance ladders and numerically measuring the PDF. The resonance ladders are sampled using known resonance statistical properties and average resonance widths and spacings extrapolated from the RRR. Although this is a standard and widely used technique, it is computationally very expensive, therefore, an alternative, analytical, approach would be preferable due to the considerable speed up of the computational time in real life applications. Moreover, the current methodology does not take into account existing experimental data, such for total and capture cross sections, that are available for many nuclei. Finally, this approach was developed to be used in reactor-scale applications and it is not suited for use in single-event applications. In this work we will rethink the entire approach to the PDF construction using a Bayesian mindset. This will allow us to provide a different definition of the PDF that allows a much faster calculation of the higher-temperature PDFs and a proper combination of theoretical and experimental PDFs following the probability theory. We will also show that our definition is well suited for single-event applications and we will make an explicit connection between our method and the standard approach. We do this by showing that the central limit theorem applies and our method leads to the same PDF obtained with the standard methodology, for a large number of events per history.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2021

Draft ASME Boiler and Pressure Vessel Code Cases and Technical Bases for Use of Alloy 617 for Constructions of Nuclear Component Under Section III, Division 5

The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code currently only allows five materials for use in construction of nuclear components for high temperature service. These are: 2.25Cr-1Mo and V-modified 9Cr-1Mo steels, Types 304 and 316 stainless steels and the high nickel Alloy 800H. Since 2005, the US high temperature gas-cooled reactor program has been characterizing elevated temperature mechanical properties of Alloy 617 as the leading candidate construction material for the intermediate heat exchanger. After analysis of these experimental results, along with historical data and additional results available through the Generation IV International Forum, Very High Temperature Reactor, Materials Program Management Board Materials Handbook, a draft ASME Code Case to allow nuclear construction with Alloy 617 for temperatures up to 1750°F (954°C) has been developed. This report contains the Code Case for Low Temperature Service Construction of Section III, Division 5, Subsection HB, Subpart A, Class A and Subsection HC, Subpart A, Class B components, which has been approved in Section II, Materials, and Section III, Rules for Construction of Nuclear Facility Components. Supporting technical justification for the low temperature Code Case is also included. This Code Case allows use of Alloy 617 up to 800°F (425°C). This report also contains an updated draft of a Section III, Division 5, Subsection HB, Subpart B, Class A Code Case for Alloy 617 to qualify it for use in construction of nuclear components up to 1750°F (954°C) for service life up to 100,000 hours. The draft contained in Appendix 4, subject to editorial revision and approval by the ASME Special Task Group on Alloy 617 Code Qualification, will be submitted for approval by letter ballot by the appropriate ASME Committees. The technical justification supporting the Code Case is presented in Appendix 5 of this report. This background document is part of the information package that will be submitted with the Code Case for ballot.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

Improving the probability tables of the cross section of near closed-shell nuclei [Slides]

The level density distribution of near closed-shell nuclei is much lower than the typical nucleus, therefore, the cross sections show significant fluctuations, and these fluctuations are not predictable. The current methodology used to describe such behavior and construct the probability table of the cross section is based on the extrapolation of the average resonance widths and average resonance spacings from the resonance region and use these parameters to construct the probability table. Although this is a standard and widely used technique, it does not take into account the existing experimental data, such for total and the elastic cross section. Our goal is to extend the current theory and provide a more general approach to compute the probability distribution function of the cross section combining the existing probability tables and the available experimental data. Results will be presented for 90 Zr.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2022

Evaluation and Validation of the n+ 63,65 Cu Cross Sections [Slides]

This presentation discusses the objective of the research which is to update n+ 63,65 Cu cross section evaluations with recently measured data to resolve discrepancies in benchmark performance. It also discusses the models used which are the R -matrix analysis and the analysis of angular distribution coefficients. Additionally, the validation methods that were used are discussed, including the Rez shielding benchmark and the ICSBEP criticality benchmarks. In conclusion, he n+ 63,65 Cu cross sections have been updated via R-matrix analysis up to 100 keV. An increased average capture cross section and the adoption of experimentally based Legendre coefficients lead to improved performance in reactivity benchmarks. In the fast region, the adoption of the JENDL-4.0 cross sections above 4.0 MeV improves the performance in shielding benchmarks. Ultimately, the n 63,65 Cu ENDF files will be submitted to ENDF/B-VIII.1.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2022

First Extraction of Single Differential Cross-Sections on Argon for CC1$\mu$2p0$\pi$ Event Topologies in the MicroBooNE Detector

The precise measurement of cross-sections for a variety of interactions is critical to the success of forthcoming flagship neutrino experiments. Of special interest are neutrino interactions that leave the nucleus in a 2-particle 2-hole state (2p2h). This note will present the first cross-section measurement for the production of 2p2h states on argon. Using MicroBooNE data collected from the first three years of operation, we select events corresponding to a charged-current $ν_µ$ interaction that left the argon nucleus in a 2p2h state. These interactions produce a topology with one muon and two protons in the final state (CC1$\mu$2p0$\pi$). This analysis targets a single differential cross-section measurement for CC1$\mu$2p0$\pi$ event topologies in a variety of kinematic variables. Comparisons are made to a set of theoretical models that explore different cross-section modeling configurations.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗