Cross Section Measurements Research Articles

The neutrophil to lymphocyte ratio associates with markers of Alzheimer's disease pathology in cognitively unimpaired elderly people.

An elevated neutrophil-lymphocyte ratio (NLR) in blood has been associated with Alzheimer's disease (AD). However, an elevated NLR has also been implicated in many other conditions that are risk factors for AD, prompting investigation into whether the NLR is directly linked with AD pathology or a result of underlying comorbidities. Herein, we explored the relationship between the NLR and AD biomarkers in the cerebrospinal fluid (CSF) of cognitively unimpaired (CU) subjects. Adjusting for sociodemographics, APOE4, and common comorbidities, we investigated these associations in two cohorts: the Alzheimer's Disease Neuroimaging Initiative (ADNI) and the M.J. de Leon CSF repository at NYU. Specifically, we examined associations between the NLR and cross-sectional measures of amyloid-β42 (Aβ42), total tau (t-tau), and phosphorylated tau181 (p-tau), as well as the trajectories of these CSF measures obtained longitudinally. A total of 111 ADNI and 190 NYU participants classified as CU with available NLR, CSF, and covariate data were included. Compared to NYU, ADNI participants were older (73.79 vs. 61.53, p < 0.001), had a higher proportion of males (49.5% vs. 36.8%, p = 0.042), higher BMIs (27.94 vs. 25.79, p < 0.001), higher prevalence of hypertensive history (47.7% vs. 16.3%, p < 0.001), and a greater percentage of Aβ-positivity (34.2% vs. 20.0%, p = 0.009). In the ADNI cohort, we found cross-sectional associations between the NLR and CSF Aβ42 (β = -12.193, p = 0.021), but not t-tau or p-tau. In the NYU cohort, we found cross-sectional associations between the NLR and CSF t-tau (β = 26.812, p = 0.019) and p-tau (β = 3.441, p = 0.015), but not Aβ42. In the NYU cohort alone, subjects classified as Aβ + (n = 38) displayed a stronger association between the NLR and t-tau (β = 100.476, p = 0.037) compared to Aβ- subjects or the non-stratified cohort. In both cohorts, the same associations observed in the cross-sectional analyses were observed after incorporating longitudinal CSF data. We report associations between the NLR and Aβ42 in the older ADNI cohort, and between the NLR and t-tau and p-tau in the younger NYU cohort. Associations persisted after adjusting for comorbidities, suggesting a direct link between the NLR and AD. However, changes in associations between the NLR and specific AD biomarkers may occur as part of immunosenescence.

Measurement of 144Sm(p, γ) cross-section at Gamow energies

Abstract The cross-section measurement of 144Sm(p, γ)145Eu (T1/2 = 5.93(4) days) reaction has been performed at proton energies around 2.6-6.8 MeV using the activation technique. Molecular deposition technique was used to prepare the 144Sm targets having thickness between 100-350 μg/cm2 on Al backing. The astrophysical S-factor of this reaction has been measured for the first time at Ecm p=2.57±0.13 MeV, S-factor=2.542±1.152(×1010) MeV-b. Cross-section data were compared with the previously measured experimental data (2.8-7.5 MeV) from literature and the theoretical predictions obtained using Hauser-Feshbach statistical model. Obtained results were utilised to predict the reaction rates for 144Sm (p, γ) and 145Eu (γ, p) reactions.

Measurement of the neutron total cross section of 9Be at the Back-n white neutron source of CSNS

Abstract The neutron total cross section data of 9Be play an important role in nuclear structure model research of light nuclei and nuclear power installations. A measurement of the neutron total cross section of 9Be in the 0.3 eV-120 MeV energy region has been carried out by using time-of-flight method and transmission method with the Neutron Total Cross Sectional Spectrometer (NTOX) based on the multi-cell fast fission chamber at the China Spallation Neutron Source (CSNS)- Back-n white neutron source (Back-n). The fission count-neutron energy distributions of 235U and 238U without sample and with Be samples in three thicknesses were measured in the double-bunch operation mode during beam power of 100 kW. The Bayesian method is used to eliminate the influence of the double-bunch problem on neutron measurement in the energy region above 10 keV. The neutron total cross section of 9Be results is well consistent with ENDF/B-VIII.0 evaluation library data in 0.3 eV-20 MeV energy region. In the energy range of 0.3 eV to 10 keV, the deviation between our results and the evaluation results of ENDF/B-VIII.0 is within 2.5%, which is within 15% from 0.01-20 MeV. In the resonance energy region, the measured resonance energies in our experiment are 0.63 MeV, 0.82 MeV and 2.8 MeV respectively. The results show that the total cross section uncertainties of three thicknesses Be samples are within 2.2% in the energy region below 1 MeV. The total cross section uncertainty of 30 mm Be from 235U is the smallest and less than 5% in the energy region 0.3 eV-120 MeV. The results of this experiment can provide technical support for further data analysis and related nuclear data evaluation.

Probing the CP structure of the top quark Yukawa at the future muon collider

We study the top-Higgs coupling with a CP violating phase ξ at a future multi-TeV muon collider. We focus on processes that are directly sensitive to the top quark Yukawa coupling: tt¯h\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ t\\overline{t}h $$\\end{document}, tbhμν, and tt¯hνν¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ t\\overline{t} h\ u \\overline{\ u} $$\\end{document} with h→bb¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ h\ o b\\overline{b} $$\\end{document} and semileptonic top decays. At different energies, different processes dominate the cross section, providing complementary information. At and above an energy of O10\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\mathcal{O}(10) $$\\end{document} TeV, vector boson fusion processes dominate. As we show, in the Standard Model there is destructive interference in the vector boson fusion processes tt¯hνν¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ t\\overline{t} h\ u \\overline{\ u} $$\\end{document} and tbhμν between the top quark Yukawa and Higgs-gauge boson couplings. A CP-violating phase changes this interference, and the cross section measurement is very sensitive to the size of the CP-violating angle. Although we find that the cross sections are measured to O50%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\mathcal{O}\\left(50\\%\\right) $$\\end{document} statistical uncertainty at 1σ, a 10 and 30 TeV muon collider can bound the CP-violating angle |ξ| ≲ 9.0° and |ξ| ≲ 5.4°, respectively. However, cross section measurements are insensitive to the sign of the CP-violating angle. To determine that the coupling is truly CP violating, observables sensitive to CP-violation must be measured. We find in the tt¯h\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ t\\overline{t}h $$\\end{document} process the azimuthal angle between the t+t¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ t+\\overline{t} $$\\end{document} plane and the initial state muon+Higgs plane shows good discrimination for ξ = ±0.1π. For the tbhμν and tt¯hνν¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ t\\overline{t} h\ u \\overline{\ u} $$\\end{document} processes, the operator proportional to p→μ×p→h\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\left({\\overrightarrow{p}}_{\\mu}\ imes {\\overrightarrow{p}}_h\\right) $$\\end{document} · p→t\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\overrightarrow{p}}_t $$\\end{document} is sensitive to the sign of CP phase ξ. From these observables, we construct asymmetry parameters that show good distinction between different values and signs of the CP violating angle.

Cognitive Trajectories and Alzheimer Disease Biomarkers: From Successful Cognitive Aging to Clinical Impairment.

Cross-sectional definitions of successful cognitive aging have been widely utilized, but longitudinal measurements can identify people who do not decline. We performed this study to contrast maintenance with declining trajectories, including clinical conversion. We included baseline cognitively unimpaired Alzheimer's Disease Neuroimaging Initiative participants with 3 or more cognitive testing sessions (n = 539, follow-up 6.1 ± 3.5 years) and calculated slopes of an episodic memory composite (MEM) to classify them into two groups: maintainers (slope ≥ 0) and decliners (slope < 0). Within decliners, we examined a subgroup of individuals who became clinically impaired during follow-up. These groups were compared on baseline characteristics and cognitive performance, as well as both cross-sectional and longitudinal Alzheimer disease (AD) biomarker measures (beta-amyloid [Aβ], tau, and hippocampal volume). Forty-one percent (n = 221) of the cohort were MEM maintainers, and 33% (n = 105) of decliners converted to clinical impairment during follow-up. Compared to those with superior baseline scores, maintainers had lower education and were more likely to be male. Maintainers and decliners did not differ on baseline MEM scores, but maintainers did have higher non-MEM cognitive scores. Maintainers had lower baseline global Aβ, lower tau pathology, and larger hippocampal volumes than decliners, even after removing converters. There were no differences in rates of change of any AD biomarkers between any cognitive trajectory groups except for a higher rate of hippocampal atrophy in clinical converters compared to maintainers. Using longitudinal data to define cognitive trajectory groups reduces education and sex bias and reveals the prognostic importance of early onset of accumulation of AD pathology. ANN NEUROL 2024.

Giant polarization in tetragonal-like BiFeO3 film via (Ba,Ca)TiO3 doping

BiFeO3 is a multiferroic material, its tetragonality (T) phase usually exhibits large tetragonality (c/a ratio) and strong ferroelectricity. Unlike the commonly used method of strain engineering via substrate, here we present a general and practical approach for obtaining T-like phase BiFeO3 films through (Ba,Ca)TiO3 doping (BF-BCT). The BF-BCT film coherently grows on the La0.7Sr0.3MnO3/(La0.18Sr0.82)(Al0.59Ta0.41)O3 (001) substrate even at 180 nm thick, implying a very large critical thickness, and shows a large tetragonality of 1.12. Impressively, the films exhibit a giant remanent polarization (2Pr) of 320 μC/cm2, which is higher than the corresponding values of any other lead-free ferroelectric films reported to date. Cross-sectional scanning transmission electron microscopy measurements confirm the presence of the T-like phase in BF-BCT films, where the giant polarization might be attributed to the off-center B-site atom. The BF-BCT films are structurally homogeneous without any precipitation of the second phase. The giant polarization observed in the BF-BCT films indicate their great potential for application in next-generation storage and information devices.

Measurement of the total and differential cross-sections of tt¯W\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ t\\overline{t}W $$\\end{document} production in pp collisions at s\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\sqrt{s} $$\\end{document} = 13 TeV with the ATLAS detector

Measurements of inclusive and differential production cross-sections of a top-quark-top-antiquark pair in association with a W boson (tt¯W\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ t\\overline{t}W $$\\end{document}) are presented. They are performed by targeting final states with two same-sign or three isolated leptons (electrons or muons) and are based on s\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\sqrt{s} $$\\end{document} = 13 TeV proton-proton collision data with an integrated luminosity of 140 fb−1, recorded from 2015 to 2018 with the ATLAS detector at the Large Hadron Collider. The inclusive tt¯W\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ t\\overline{t}W $$\\end{document} production cross-section is measured to be 880 ± 80 fb, compared to a reference theoretical prediction of 745 ± 50 (scale) ± 13 (2-loop approx.) ± 19 (PDF, αs) fb. Differential cross-section measurements characterise this process in detail for the first time. Several particle-level observables are compared with a variety of theoretical predictions, which generally agree well with the normalised differential cross-section results. Additionally, the relative charge asymmetry of tt¯W+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ t\\overline{t}{W}^{+} $$\\end{document} and tt¯W−\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ t\\overline{t}{W}^{-} $$\\end{document} is measured inclusively to be ACrel\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {A}_{\ extrm{C}}^{\ extrm{rel}} $$\\end{document} = 0.33 ± 0.05, in very good agreement with the theoretical prediction of 0.322 ± 0.003 (scale) ± 0.007 (PDF), as well as differentially.

First Observation of a Three-Resonance Structure in e+e−→Nonopen Charm Hadrons

We report the measurement of the inclusive cross sections for e+e−→nOCH (where nOCH denotes non-open charm hadrons) with improved precision at center-of-mass (c.m.) energies from 3.645 to 3.871 GeV. We observe three resonances: R(3760), R(3780), and R(3810) with significances of 8.1σ, 13.7σ, and 8.8σ, respectively. The R(3810) state is observed for the first time, while the R(3760) and R(3780) states are observed for the first time in the nOCH cross sections. Two sets of resonance parameters describe the energy-dependent line shape of the cross sections well. In set I [set II], the R(3810) state has mass (3805.7±1.1±2.7) [(3805.7±1.1±2.7)] MeV/c2, total width (11.6±2.9±1.9) [(11.5±2.8±1.9)] MeV, and an electronic width multiplied by the nOCH decay branching fraction of (10.9±3.8±2.5) [(11.0±3.4±2.5)] eV. In addition, we measure the branching fractions B[R(3760)→nOCH]=(25.2±16.1±30.4)%[(6.4±4.8±7.7)%] and B[R(3780)→nOCH]=(12.3±6.6±8.3)%[(10.4±4.8±7.0)%] for the first time. The R(3760) state can be interpreted as an open-charm (OC) molecular state, but containing a simple four-quark state component. The R(3810) state can be interpreted as a hadrocharmonium state. Published by the American Physical Society 2024

Test of CP-invariance of the Higgs boson in vector-boson fusion production and in its decay into four leptons

A search for CP violation in the decay kinematics and vector-boson fusion production of the Higgs boson is performed in the H → ZZ* → 4ℓ (ℓ = e, μ) decay channel. The results are based on proton-proton collision data produced at the LHC at a centre-of-mass energy of 13 TeV and recorded by the ATLAS detector from 2015 to 2018, corresponding to an integrated luminosity of 139 fb−1. Matrix element-based optimal observables are used to constrain CP-odd couplings beyond the Standard Model in the framework of Standard Model effective field theory expressed in the Warsaw and Higgs bases. Differential fiducial cross-section measurements of the optimal observables are also performed, and a new fiducial cross-section measurement for vector-boson-fusion production is provided. All measurements are in agreement with the Standard Model prediction of a CP-even Higgs boson.

Cross-Sectional Melt Pool Geometry of Laser Scanned Tracks and Pads on Nickel Alloy 718 for the 2022 Additive Manufacturing Benchmark Challenges

AbstractThe Additive Manufacturing Benchmark Series (AM Bench) is a NIST-led organization that provides a continuing series of additive manufacturing benchmark measurements, challenge problems, and conferences with the primary goal of enabling modelers to test their simulations against rigorous, highly controlled additive manufacturing benchmark measurement data. To this end, single-track (1D) and pad (2D) scans on bare plate nickel alloy 718 were completed with thermography, cross-sectional grain orientation and local chemical composition maps, and cross-sectional melt pool size measurements. The laser power, scan speed, and laser spot size were varied for single tracks, and the scan direction was varied for pads. This article focuses on the cross-sectional melt pool size measurements and presents the predictions from challenge problems. Single-track depth correlated with volumetric energy density while width did not (within the studied parameters). The melt pool size for pad scans was greater than single tracks due to heat buildup. Pad scan melt pool depth was reduced when the laser scan direction and gas flow direction were parallel. The melt pool size in pad scans showed little to no trend against position within the pads. Uncertainty budgets for cross-sectional melt pool size from optical micrographs are provided for the purpose of model validation.

Measurements of neutron capture cross-sections for nuclides of interest in decommissioning: 45Sc, 63Cu, 64Zn, 109Ag, and 113In

ABSTRACT As nuclear facilities are dismantled in decommissioning, various and large amounts of waste are generated. Even more inconveniently, they are radioactive waste due to neutron activation. Thus, the neutron capture cross-sections of nuclides targeted for decommissioning are required to evaluate the radioactivity produced. The present study selected 45Sc, 63Cu, 64Zn, 109Ag and 113In among targeted nuclides, and performed the measurements of thermal-neutron capture cross-sections by an activation method at the Kyoto University Research Reactor. The thermal-neutron capture cross-sections were derived on the basis of Westcott’s convention. The present results were obtained as follows: 27.18 ± 0.28 barn for 45Sc(n,γ)46Sc, 4.34 ± 0.06 barn for 63Cu(n,γ)64Cu, 0.719 ± 0.011 barn for 64Zn(n,γ)65Zn, 4.05 ± 0.05 barn for 109Ag(n,γ)110mAg and 8.53 ± 0.27 barn for 113In(n,γ)114Inm1+m2 reactions. The results for 45Sc and 64Zn support evaluated cross-section data within the limits of uncertainties, while those for the other nuclides were slightly different from evaluated ones. The obtained results are useful not only for the evaluation of isotope production, but also for the consideration of those nuclides as flux monitors, as an alternative to Au and Co.

Lower extremity woven and non-woven venous stent morphology and luminal changes

ObjectiveVenous stents are a common treatment modality for obstructive venous disease. Venous stents differentiate themselves by either a woven or braided structure, open or closed cell arrangement or based on material composition (elgiloy vs. nitinol). Changes in the morphology of venous stents over time may contribute to restenosis or thrombosis. Woven elgiloy stents are prone to proximal and distal edge deformation compared to dedicated venous stents which offer increased radial force at stent edges. The objective of this study is to describe luminal morphological changes among various venous stents and between woven to non-woven venous stent configuration, over time. MethodsA retrospective review at a single institution between January 2014-June 2021 identified patients treated with venous stents. Patients with iliac and/or femoral venous stents with intraoperative intravascular ultrasound (IVUS) and a post-operative computed tomography (CT) scan were included in the study. Cross-sectional diameters measurements were taken at proximal, middle, and distal portions of each stent from intravascular ultrasound (IVUS) at the time of initial stenting and compared to the cross-sectional diameter measurements taken from CT imaging at follow-up. A paired t-test was used to compare the luminal change with a D’Agostino-Pearson test used for normality. ResultsFifty-four stents distributed amongst thirty-eight patients were identified. Mean time to follow-up was 17.5 months. Stents were placed in the common iliac vein (n=37, 68.5%), external iliac vein (n=14, 25.9%), and common femoral vein (n=3, 5.6%). Implanted stents included the Boston Scientific Wallstent (n=23, 42.6%), Bard Venovo (n=3, 5.6%), Boston Scientific Vici (n=23, 42.6%), and Medtronic Abre (n=5, 9.3%). The mean luminal loss was measured at 2.12 mm proximally (95% confidence interval (CI), 1.64-2.60; p<0.001), 1.29 mm at the mid-stent (95% CI, 0.83-1.74, p<0.001) and 1.56 mm distally (95% CI, 0.99-2.12; p<0.001). There was no significant difference in luminal changes between woven and non-woven stents at proximal (p=0.374), middle (p=0.179), and distal (p=0.609) stent measurements. ConclusionThis study reports morphological changes within venous stents and between woven and non-woven venous stents. Our findings demonstrate that the edge-stent luminal reduction traditionally attributed to woven configurations also occurs with the newer non-woven stents. Additional factors such as anatomic location, pelvic curvature or other external forces may be accountable for this change rather than geometrical configuration of the stent.

Poly(dicarbon monofluoride) (C2F)n bridges the neutron reflectivity gap

Graphites covalently intercalated with fluorine to form (C2F)n structural type compounds shows a dramatic increase of the interlayer distance up to by a factor of almost 3 to reach ∼9 Å. Such graphite fluoride compounds containing only carbon and fluorine offer the rare opportunity to bridge the so-called gap in the reflectivity of neutron reflectors. Slow neutron reflectors are of great interest in designing neutron sources as well as in fundamental and applied science; they require synthesizing high thermal and chemical compound stability graphite fluorides. In this work, a new strategy is proposed for synthesizing (C2F)n compounds in a well-controlled method. Our results show that the outcome (C2F)n has a covalent character with only sp3 hybridized carbon atoms. Moreover, C-F bonds in the fluorocarbon sheets and CF2 groups on the sheet edges lead to the desired stability and hydrophobic character. A dedicated home-made neutron diffractometer was built for measurements of double-differential neutron cross sections of crystals with specific large interlayer distances found in (C2F)n compounds. We demonstrate that the synthesized fluorine intercalated graphites developed effectively cover the gap in the reflectivity for the new generation of neutron reflectors.

Measurement of spectral averaged cross sections of capture reactions in the LR-0 reference neutron field

Measurement of spectral averaged cross sections of capture reactions in the LR-0 reference neutron field

A high-intensity, low-energy heavy ion source for a neutron target proof-of-principle experiment at LANSCE

The capability to directly study neutron capture reactions on radionuclides with half-lives on the of order minutes would allow key cross section measurements in nuclear astrophysics and energy applications. However, such experiments with stationary targets are currently impossible because of signal detection and target sample fielding issues. To overcome these challenges, a neutron target facility is being developed to permit neutron capture experiments on unstable isotopes in inverse kinematics at the Los Alamos Neutron Science Center (LANSCE). This next-generation facility will consist of a heavily moderated, high-intensity spallation neutron target coupled with a radioactive ion beam storage ring. A proof-of-principle experiment is underway to demonstrate this neutron target concept at LANSCE in the near term with stable ions and without a storage ring. Here, mA-level beams of 10-50 keV heavy ions exhibiting large resonant neutron capture cross sections will be generated by a new ion source, transported through a large-volume neutron moderator surrounding an adjacent spallation target driven by the LANSCE accelerator, and collected downstream of the moderator for subsequent decay-counting measurements. The neutron density within the moderator will be obtained from these decay yields and compared with Monte Carlo N-Particle (MCNP) simulation results. The science application, operational requirements, and performance objectives for this heavy ion source will be presented.

Impact of JLab data on the determination of GPDs at zero skewness and new insights from transition form factors N→Δ

It is well-established now that the generalized parton distributions (GPDs) at zero skewness are playing important roles in some physical process such as elastic electron-nucleon scattering, elastic (anti)neutrino-nucleon scattering, and wide-angle Compton scattering (WACS) via various types of form factors (FFs). In this study, we are going to utilize the recent JLab measurements of the elastic electron-nucleon scattering reduced cross section, namely GMp12, as a touchstone to unravel the tension observed between the measurements of the WACS cross section and the data of the proton magnetic FF GMp. We also investigate the impact of GMp12 data on valence unpolarized GPDs Hvq and Evq at zero skewness by performing some χ2 analyses of the related experimental data. By calculating the electric and scalar quadrupole ratios, REM and RSM, and magnetic transition FF GM*/3GD related to the nucleon-to-delta (N→Δ) transition using the extracted GPDs and comparing the results with corresponding experimental measurements, we show that our results are in an excellent consistency with experiments, indicating the universality property of GPDs. We emphasize that the inclusion of these data in the future analysis of GPDs can significantly affect the extracted GPDs especially their uncertainties at smaller values of Q2. Published by the American Physical Society 2024

Photoionization cross sections measurements of the excited states of lutetium and ytterbium in the near threshold region.

In this work, the threshold photoionization cross sections from the excited states of lutetium and ytterbium atoms were investigated by the laser pump-probe scheme under the condition of saturated resonant excitation. We obtained the resonance enhanced multiphoton ionization spectra of the lutetium and ytterbium atoms of the lanthanide metals in the range of 307.50-312.50nm and 265.00-269.00nm, respectively; the photoionization cross sections of the 5d6s(1D)6p(2D05/2) and 5d6s(3D)6p(2P01/2) states of lutetium and the 4f13(2F0)5d6s2(J = 1) states of ytterbium above threshold regions (0.4-1.6eV) were measured, and measured values ranged from 2.3 ± 0.2 to 17.7 ± 1.5 Mb.

Pushing the high count rate limits of scintillation detectors for challenging neutron-capture experiments

One of the critical aspects for the accurate determination of neutron capture cross sections when combining time-of-flight and total energy detector techniques is the characterization and control of systematic uncertainties associated to the measuring devices. In this work we explore the most conspicuous effects associated to harsh count rate conditions: dead-time and pile-up effects. Both effects, when not properly treated, can lead to large systematic uncertainties and bias in the determination of neutron cross sections. In the majority of neutron capture measurements carried out at the CERN n_TOF facility, the detectors of choice are the C6D6 liquid-based either in form of large-volume cells or recently commissioned sTED detector array, consisting of much smaller-volume modules. To account for the aforementioned effects, we introduce a Monte Carlo model for these detectors mimicking harsh count rate conditions similar to those happening at the CERN n_TOF 20 m flight path vertical measuring station. The model parameters are extracted by comparison with the experimental data taken at the same facility during 2022 experimental campaign. We propose a novel methodology to consider both, dead-time and pile-up effects simultaneously for these fast detectors and check the applicability to experimental data from 197Au(n, γ), including the saturated 4.9 eV resonance which is an important component of normalization for neutron cross section measurements.

New experimental measurements of X-ray emissions induced by protons of several tens of MeV on elements with Z=22 to Z=79: Toward quantitative high-energy PIXE

K-shell X-ray production cross-sections measurement campaigns were carried out at the ARRONAX cyclotron with titanium, chromium, copper, molybdenum, silver and gold targets for different energies from 15 to 68 MeV. These measurements, carried out using three detectors (SDD, CdTe and HPGe), complete the database with 66 new values. Our different measurements agree with previously published data and are consistent for all three detectors, confirming the absence of experimental bias. The universal ionisation cross-section representation allows an optimisation of the data using a 3rd-order polynomial function. This function can be used for HE-PIXE quantification for elements with atomic numbers between 22 (Ti) and 79 (Au) in the studied energy region.

Proton-induced reactions for 47Sc (and 46Sc) production: new nuclear cross section measurements on enriched titanium targets

Proton-induced reactions for 47Sc (and 46Sc) production: new nuclear cross section measurements on enriched titanium targets