Total Cross Section Measurements Research Articles

Measurement of Total Electronic Cross-Section, Total Atomic Cross-Section, Effective Atomic Numbers, Effective Electron Densities and Kerma for Some Br Compounds

The aim of this study is to calculate the experimental and theoretical the mass attenuation coefficient some Br compounds by using transmission method. Also using these values were determined the total electronic section, total atomic section, effective atomic number, effective electron density and Kerma. We performed the calculations of these values in attenuation by using direct excitation experimental geometry. The total attenuation cross sections of some halogene Br compounds were measured in a narrow beam good geometry using a high resolution Si(Li) detector in the energy with γ photons at 59.543 keV from Am-241 annular source. Theoretical mass attenuation coefficient values were computed from the XCOM data programme, based on mixture rule method. This study provide new insight into the literature since the values of effective atomic number, electron density and Kerma for some Br compounds have not been determined before. According to the results shown in mass attenuation coefficient, Zeff and Neff of Br compounds are closely associated with chemical structure. This research were undertaken to explore how Bromine compounds is gamma ray shielding material.

Elastic positron-uracil scattering cross sections

We report elastic integral and differential cross sections for positron collisions with uracil (${\mathrm{C}}_{4}{\mathrm{H}}_{4}{\mathrm{N}}_{2}{\mathrm{O}}_{2}$) for impact energies up to 10 eV. The cross sections were calculated employing the Schwinger multichannel (SMC) method in the static plus polarization approximation. The Born-closure procedure was applied to account for the long-range potential due to the permanent dipole moment of uracil. The present results are compared with experimental and theoretical data available in the literature, showing an overall good agreement with previously reported results. We also applied our differential cross sections to provide a correction to the total cross-section measurements by Anderson et al. [J. Chem. Phys. 141, 034306 (2014)] in order to account for the lack of angular resolution in the apparatus used by these authors. Besides, we applied a simple model employed by Franz and Gianturco [Phys. Rev. A 88, 042711 (2013)] to estimate the temperature effects on the uracil cross section. In particular, the level of agreement of the SMC differential cross sections as compared with the experimental findings is encouraging.

Proton Electromagnetic Form Factors Data Are in Disagreement with New Electron-Positron Annihilation into Proton-Antiproton Pair Total Cross Section Measurements

In this paper a consistency of new very precise data on electron-positron annihilation into proton-antiproton pair total cross section with existing proton and neutron electromagnetic form factors data is investigated. First, the result is represented by a theoretically predicted dashed line for the total cross section obtained in the simultaneous analysis of the proton and neutron form factors data by the advanced nucleon electromagnetic structure Unitary and Analytic model, and then, as the neutron data are always less precise from objective reasons than the proton data, the result is also represented by a theoretically predicted full line for the total cross section obtained in the analysis of only the proton form factors data in space-like and time-like regions by the advanced proton electromagnetic structure Unitary and Analytic model. In both cases one finds disagreement between the electron-positron annihilation into proton-antiproton pair total cross section data and the corresponding form factors data, which is demonstrated by a disagreement of the dashed and full curves representing theoretically predicted electron-positron annihilation into proton-antiproton pair total cross sections behaviors.

Evidence for electroweak production of four charged leptons and two jets in proton-proton collisions at [formula omitted

Evidence is presented for the electroweak (EW) production of two jets (jj) in association with two Z bosons and constraints on anomalous quartic gauge couplings are set. The analysis is based on a data sample of proton-proton collisions at s=13TeV collected with the CMS detector in 2016–2018, and corresponding to an integrated luminosity of 137fb−1. The search is performed in the fully leptonic final state ZZ→ℓℓℓ′ℓ′, where ℓ,ℓ′=e,μ. The EW production of two jets in association with two Z bosons is measured with an observed (expected) significance of 4.0 (3.5) standard deviations. The cross sections for the EW production are measured in three fiducial volumes and the result is σEW(pp→ZZjj→ℓℓℓ′ℓ′jj)=0.33−0.10+0.11(stat)−0.03+0.04(syst)fb in the most inclusive volume, in agreement with the standard model prediction of 0.275±0.021fb. Measurements of total cross sections for jj production in association with two Z bosons are also reported. Limits on anomalous quartic gauge couplings are derived in terms of the effective field theory operators T0, T1, T2, T8, and T9.

Measurements of total reaction cross sections for 17Ne using a solid hydrogen target

We measured the energy dependence of the total reaction cross sections (σR) for the proton-drip-line nucleus,17Ne, using a solid hydrogen target. We compared the experimental data with theoretical calculations using the Glauber model. We found that the theoretical cross sections overestimate the experimental ones in the low-energy region (∼100A MeV), whereas they significantly underestimate the experimental data in the intermediate-energy region (∼300-500A MeV). These trends are the same as those for σR for carbon-proton collisions, which were measured previously. We discuss several possibilities for resolving this discrepancy. This work demonstrates the necessity of additional careful investigations of the energy dependence of σR for various nuclei on proton targets in order to determine nuclear size properties precisely.

Acceptance-angle effects on the charge transfer and energy-loss cross sections for collisions ofC4+with atomic hydrogen

The charge-transfer process for collisions of ${\mathrm{C}}^{4+}$ with atomic hydrogen is studied theoretically and experimentally in this work. Our theoretical study is based on an electron-nuclear dynamics approach applied here for the state-to-state and total contributions to the electron-capture cross sections. Our theoretical results are complemented by experimental measurements of the absolute total cross section for collisions of ${\mathrm{C}}^{4+}$ with atomic hydrogen, which were carried out using an ion-atom merged-beams technique at relative collision energies of $0.122--2.756$ keV/u and performed with an improved apparatus at Oak Ridge National Laboratory. We find that the structure observed around a collision energy of 0.5 keV/u in the experimental results is due to the combined contributions of the $3\ensuremath{\ell}$ capture cross sections, the coupling of the electronic and nuclear dynamics, and the acceptance angle in the experimental configuration. We also report the ${\mathrm{C}}^{4+}$ kinetic energy loss and stopping cross section. We find that the ${\mathrm{C}}^{4+}$ gains energy for relative collision energies between 0.1 and 10 keV/u, with a maximum at $\ensuremath{\sim}1$ keV/u. Our theoretical study shows that, to compare to the merged-beams experimental results, one has to account for effects produced by the merged path length of the apparatus.

Measurement of neutron total cross sections at the VESUVIO spectrometer

In this article we examine the procedures to determine total cross sections from neutron transmission experiments performed at the time-of-flight spectrometer VESUVIO (ISIS Pulsed Neutron and Muon Source, at the Rutherford Appleton Laboratory, UK). On the one hand we present a newly developed Python-based algorithm, running within the Mantid analysis environment, to obtain neutron total cross sections as a function of the incident neutron energy, employing the information recorded by the transmission monitor. We describe its basic operating principles and parameters, as well as its user interface, which is applied to a specific example of data processing on a set of graphite samples of different manufacturing processes. On the other hand, we discuss a series of features and recent upgrades that make VESUVIO the instrument of choice for accurate and broad-band thermal neutron cross section measurements.

Experimental techniques to study the [formula omitted] process for nuclear astrophysics at the Cologne accelerator laboratory

The nuclear astrophysics setup at the Institute for Nuclear Physics, University of Cologne, Germany is dedicated to measurements of total and partial cross sections of charged-particle induced reactions at astrophysically relevant energies. These observables are key ingredients for reaction network calculations of various stellar scenarios, and crucial for the understanding of the nucleosynthesis of elements. The experiments utilize the high-efficiency γ-ray spectrometer HORUS, and the 10 MV FN-Tandem accelerator. An updated target chamber as well as further experimental methods established in the last years will be presented which allow to measure cross sections down to the nb region. The reliability of the measured cross sections is proven by a 89Y(p, γ)90Zr commissioning experiment. Additionally, an application for nuclear astrophysics will be presented. The results of a 93Nb(p, γ)94Mo experiment will be discussed as well as their deviations compared to formerly reported results.

Total cross section measurements for electron scattering from tin(IV) chloride (SnCl4)

SynopsisTotal cross section for electron scattering from SnCl4 molecules has been measured for energies from 0.6 to 300 eV. Obtained results have been compared with total cross sections for electron scattering from other tetrachoride molecules: XCl4 where X=C, Si, Ge.

Neutron capture and total cross-section measurements of 155Gd and 157Gd at ANNRI in J-PARC

Neutron capture and total cross sections of 155Gd and 157Gd were measured with the neutron time-of-flight method in Accurate Neutron-Nucleus Reaction measurement Instrument at Material and Life Science Experimental Facility of the Japan Proton Accelerator Research Complex using the NaI (Tl) spectrometer and Li-glass detectors. Preliminary cross sections were obtained in the neutron energy region from 4 meV to 100 meV. The derived cross sections agree with evaluated values in JENDL 4.0 and the experimental results by Mastromarco but were not consistent with those by Leinweber.

Measurement of the differential Drell-Yan cross section in proton-proton collisions at sqrt{mathrm{s}} = 13 TeV

Measurements of the differential cross section for the Drell-Yan process, based on proton-proton collision data at a centre-of-mass energy of 13 TeV, collected by the CMS experiment, are presented. The data correspond to an integrated luminosity of 2.8 (2.3) fb−1 in the dimuon (dielectron) channel. The total and fiducial cross section measurements are presented as a function of dilepton invariant mass in the range 15 to 3000 GeV, and compared with the perturbative predictions of the standard model. The measured differential cross sections are in good agreement with the theoretical calculations.

59 POLYGENIC RISK SCORES ANALYSES IN ANTIPSYCHOTIC-INDUCED WEIGHT GAIN

The nuclear astrophysics setup at the Institute for Nuclear Physics, University of Cologne, Germany is dedicated to measurements of total and partial cross sections of charged-particle induced reactions at astrophysically relevant energies. These observables are key ingredients for reaction network calculations of various stellar scenarios, and crucial for the understanding of the nucleosynthesis of elements. The experiments utilize the high-efficiency γ-ray spectrometer HORUS, and the 10 MV FN-Tandem accelerator. An updated target chamber as well as further experimental methods established in the last years will be presented which allow to measure cross sections down to the nb region. The reliability of the measured cross sections is proven by a 89Y(p, γ)90Zr commissioning experiment. Additionally, an application for nuclear astrophysics will be presented. The results of a 93Nb(p, γ)94Mo experiment will be discussed as well as their deviations compared to formerly reported results.

First determination of the {rho } parameter at {sqrt{s} = 13} TeV: probing the existence of a colourless C-odd three-gluon compound state

The TOTEM experiment at the LHC has performed the first measurement at sqrt{s} = 13,mathrm{TeV} of the rho parameter, the real to imaginary ratio of the nuclear elastic scattering amplitude at t=0, obtaining the following results: rho = 0.09 pm 0.01 and rho = 0.10 pm 0.01, depending on different physics assumptions and mathematical modelling. The unprecedented precision of the rho measurement, combined with the TOTEM total cross-section measurements in an energy range larger than 10,mathrm{TeV} (from 2.76 to 13,mathrm{TeV}), has implied the exclusion of all the models classified and published by COMPETE. The rho results obtained by TOTEM are compatible with the predictions, from other theoretical models both in the Regge-like framework and in the QCD framework, of a crossing-odd colourless 3-gluon compound state exchange in the t-channel of the proton–proton elastic scattering. On the contrary, if shown that the crossing-odd 3-gluon compound state t-channel exchange is not of importance for the description of elastic scattering, the rho value determined by TOTEM would represent a first evidence of a slowing down of the total cross-section growth at higher energies. The very low-|t| reach allowed also to determine the absolute normalisation using the Coulomb amplitude for the first time at the LHC and obtain a new total proton–proton cross-section measurement sigma _{mathrm{tot}} = (110.3 pm 3.5),mathrm{mb}, completely independent from the previous TOTEM determination. Combining the two TOTEM results yields sigma _{mathrm{tot}} = (110.5 pm 2.4),mathrm{mb}.

Measurement of the neutron total cross section of carbon at the Back-n white neutron beam of CSNS

To verify the performance of the neutron total cross-sectional spectrometer, the neutron total cross section of carbon is initially measured in the energy range of 1 eV to 20 MeV using the time-of-flight method. The measurement is performed at the Back-n white neutron source with a 76-m time-of-flight path using the China Spallation Neutron Source. A multilayer fast fission chamber with 235U and 238U is employed as the neutron detector. The diameter and thickness of the natural graphite sample are 70 mm and 40 mm, respectively. Signal waveforms are collected using a data acquisition system. Off-line data processing was used to obtain the neutron time-of-flight spectra and transmissions. The uncertainty of the counting statistics is generally approximately 3% for each bin in the energy range of 1–20 MeV. It is determined that the results for the neutron total cross section of carbon obtained using 235U cells are in good agreement with the results obtained using 238U cells within limits of statistical uncertainty. Moreover, the measured total cross sections show good agreement with the broadening evaluated data.

Neutron total cross section measurements of polyethylene using time-of-flight method at KURNS-LINAC

ABSTRACTThe neutron total cross sections of polyethylene have been measured in the energy region from 0.001 eV to 40 keV by the time-of-flight (TOF) method using the Kyoto University Institute for Integrated Radiation and Nuclear Science – Linear Accelerator (KURNS-LINAC). A 6Li detector and a gas electron multiplier (GEM) detector have been used as a neutron detector, and the polyethylene plates of 0.31 and 0.20 cm thickness were employed for the neutron transmission measurement.The present results were compared with the previous results and the evaluated data in JENDL-4.0. In the energy region below 0.01 eV, the present results are in good agreement with the data measured by Herdade et al. (1973) and by Granada et al. (1987). On the other hand, the evaluated data in JENDL-4.0 are larger than all the measured data. In the energy region from 0.035 to 0.15 eV, the data measured by Granada et al. and the evaluated data in JENDL-4.0 are up to about 4 ~ 6% larger than the present results.

Bare-carbon-ion-impact electron emission from adenine molecules: Differential and total cross-section measurements

Bare-carbon-ion-impact electron emission from adenine molecules: Differential and total cross-section measurements

K‐K electron capture from adenine and CO2 molecule by fast carbon ions using KLL‐Auger electron technique

The experimental measurement of total electron transfer cross section in Bragg peak energy region is important to understand energy loss in the biomolecular system. In this study, we have measured state selective, K‐K electron capture and K‐ionization cross sections for adenine (C 5H 5N 5) in collisions with fast (2.5–5 MeV/u) C ions. These are compared with the data for smaller gas molecule, CO 2. These are derived from a study of the KLL‐Auger electron emission yields as a function projectile charge state. The K‐ionization cross‐section (σKI) data are compared with the ECUSAR (united and separated atom [USA] approximation with energy loss [E], Coulomb deflection [C], and relativistic [R] corrections) model calculation. The measured σKI data and the calculations are in good agreement. The K‐K transfer cross‐section (σK−K) data are compared with the CPSSR (perturbed stationary state [PSS] with Coulomb deflection [C] and relativistic corrections [R]) calculation that underestimates the measured data for such symmetric collision system. The energy dependence of σK−K for adenine is found to be flat in contrast to a sharp variation predicted by the model. The K‐transfer cross section is found to be substantial fraction of the K‐ionization.

Electron scattering from 1-butanol at intermediate impact energies: Total cross sections.

We report experimental measurements of the absolute total cross sections (TCSs) for electron scattering from 1-butanol at impact energies in the range 80-400 eV. Those measurements were conducted by considering the attenuation of a collimated electron beam, at a given energy, through a gas cell containing 1-butanol, at a given pressure, and through application of the Beer-Lambert law to derive the required TCS. We also report theoretical results using the Independent-Atom Model with Screening Corrected Additivity Rule and Interference approach. Those results include the TCS, the elastic integral cross section (ICS), the ionization total ICS, and the sum over all excitation process ICSs with agreement at the TCS level between our measured and calculated results being encouraging.

New physics from TOTEM’s recent measurements of elastic and total cross sections

We analyze the recently discovered phenomena in elastic proton–proton scattering at the LHC, challenging the standard Regge-pole theory: the low- ‘break’ (departure from the exponential behavior of the diffraction cone), the accelerating rise with energy of the forward slope B(s, t = 0), the absence of secondary dips and bumps on the cone and the role of the odderon in the forward phase of the amplitude, ρ(13 TeV) = 0.1 ± 0.01, and especially its contribution at the dip region, measured recently by TOTEM. Relative contributions from different components to the scattering amplitude are evaluated from the fitted model.

Study on background shielding for a compact photoneutron source

A compact photoneutron source (PNS), based on an electron LINAC was designed and constructed to provide required experimental nuclear data for Thorium Molten Salt Reactor (TMSR). All devices including the LINAC, the neutron production target and the detector systems were arranged in a shared hall, leading to a high background of neutron and γ-ray. The necessary shielding design was made to reduce the backgrounds. A series of preliminary measurements of total cross section in thermal neutron energy region for some key nuclides of TMSR, such as 232Th and 7Li, have been performed at this PNS. It was found, however, that additional shielding needs to be constructed to further reduce the neutron and γ-ray backgrounds. MCNP is a major tool for the background shielding design since it has the calculation capability for a coupled neutron-photon-electron transport problem. A two-step subsection simulation based on MCNP involving with variance reduction techniques (Sub-Var method) was performed to provide required flux and spectrum calculation for the new background shielding design. Based on the simulated results, a new local shielding was designed and constructed, which can reduce the thermal neutron background by three orders of magnitude and the γ-ray background by two orders of magnitude. The neutron flux and energy spectrum were measured under the new shielding condition and compared with the simulated ones, showing a good agreement with each other in the thermal energy region. Therefore, a significant improved shielding for the PNS is achieved, which is expected to provide a required assurance for the future measurements of neutron cross section at the PNS.