Measurement Of Double-differential Cross Sections Research Articles

Measurements of jet cross-section ratios in 13 TeV proton-proton collisions with ATLAS

Measurements of jet cross-section ratios between inclusive bins of jet multiplicity are performed in 140 fb−1 of proton-proton collisions with s=13 TeV center-of-mass energy, recorded with the ATLAS detector at CERN’s Large Hadron Collider. These ratios are constructed from double-differential cross-section measurements that are made in bins of jet multiplicity and other observables that are sensitive the energy scale and angular distribution of radiation due to the strong interaction in the final state. Additionally, the scalar sum of the two leading jets’ transverse momenta is measured triple differentially, in bins of the third jet’s transverse momentum and of jet multiplicity. These measurements are unfolded to account for acceptance and detector-related effects. The measured distributions are used to construct ratios of the inclusive jet-multiplicity bins, which have been shown to be sensitive to the strong coupling αS while being less sensitive than other observables to systematic uncertainties and parton distribution functions. The measured distributions are compared with state-of-the-art QCD calculations, including next-to-next-to-leading-order predictions for two- and three-jet events. These predictions are generally found to model the data well and perform best in bins with a modest requirement on the third jet’s transverse momentum. Significant differences between data and Monte Carlo predictions are observed in events with large rapidity gaps and invariant masses of the leading jet pair. Studies leading to reduced jet energy scale uncertainties significantly improve the precision of this work and are documented herein. © 2024 CERN, for the ATLAS Collaboration 2024 CERN

Double-differential cross section measurement with low threshold detector for proton production induced by several tens of MeV protons

We have developed a low threshold detector consisting of Bragg curve counter (BCC), two siliconsurface barrier detectors (SSDs) and BGO scintillator to obtain experimental double-differential cross section (DDX) data for low energy proton production. Since the BCC offers advantage of self particle identification capability and a few μm-thick entrance window, protons produced by nuclear reactions down to 1 MeV have been identified. The capability of the detector is demonstrated in measurements using 70-MeV protons. Measured spectra are compared with calculation results of intra-nuclear cascade (INC) plus evaporation models and nuclear data library.

Measurements of top-quark pair differential and double-differential cross-sections in the ell +jets channel with pp collisions at sqrt{s}=13 TeV using the ATLAS detector

Single- and double-differential cross-section measurements are presented for the production of top-quark pairs, in the lepton + jets channel at particle and parton level. Two topologies, resolved and boosted, are considered and the results are presented as a function of several kinematic variables characterising the top and tbar{t} system and jet multiplicities. The study was performed using data from pp collisions at centre-of-mass energy of 13 TeV collected in 2015 and 2016 by the ATLAS detector at the CERN Large Hadron Collider (LHC), corresponding to an integrated luminosity of 36~mathrm {fb}^{-1}. Due to the large tbar{t} cross-section at the LHC, such measurements allow a detailed study of the properties of top-quark production and decay, enabling precision tests of several Monte Carlo generators and fixed-order Standard Model predictions. Overall, there is good agreement between the theoretical predictions and the data.

Measurement of double-differential cross sections for top quark pair production in pp collisions at sqrt{s} = 8,text {TeV} and impact on parton distribution functions

Normalized double-differential cross sections for top quark pair (mathrm{t}overline{mathrm{t}}) production are measured in pp collisions at a centre-of-mass energy of 8,text {TeV} with the CMS experiment at the LHC. The analyzed data correspond to an integrated luminosity of 19.7,text {fb}^{-1}. The measurement is performed in the dilepton mathrm {e}^{pm }mu ^{mp } final state. The mathrm{t}overline{mathrm{t}} cross section is determined as a function of various pairs of observables characterizing the kinematics of the top quark and mathrm{t}overline{mathrm{t}} system. The data are compared to calculations using perturbative quantum chromodynamics at next-to-leading and approximate next-to-next-to-leading orders. They are also compared to predictions of Monte Carlo event generators that complement fixed-order computations with parton showers, hadronization, and multiple-parton interactions. Overall agreement is observed with the predictions, which is improved when the latest global sets of proton parton distribution functions are used. The inclusion of the measured mathrm{t}overline{mathrm{t}} cross sections in a fit of parametrized parton distribution functions is shown to have significant impact on the gluon distribution.

Measurement of double differential cross-section of light water at high temperature and pressure to generate S(α,β)

A series of double differential inelastic scattering cross-section measurements were performed on light water at several temperatures and pressures using high resolution time-of-flight inelastic spectrometers, namely the IN4c and the IN6 at the Institut Laue-Langevin (ILL), Grenoble, France to investigate the impact of temperature and pressure on S( q ,ω) and thus on the S(α, β) thermal scattering kernel. The present work aims at extending previous measurements with light water at room temperature and pressure to more realistic operating conditions in connection with nuclear power reactors.

Double Differential Cross Section Measurements for Electron Impact Ionization of Atmospheric Gases

SynopsisWe present comprehensive experimental measurements of double differential cross sections (DDCS) for atmospheric gases, Ar, N2, CO2 and CH4. DDCSs were obtained by measuring the energy and angular distributions of one of the two outgoing electrons which are indistinguishable by use traditional electron spectrometer with an electron analyzer.

Measurements of 12 C ion fragmentation on thin carbon target from the FIRST collaboration at GSI

The FIRST (Fragmentation of Ions Relevant for Space and Therapy) experiment at GSI laboratory took data in summer 2011, studying the collisions of a 12C ion beam with Carbon and Au thin targets. The experiment main purpose is the double differential cross section measurement of the carbon ion fragmentation at energies that are relevant both for tumor therapy and space radiation protection applications (100-1000 MeV/u). The FIRST dataset contains carbon ions collisions on a 3.43 g·Cin−2 carbon target (about 24 M events) and on a 0.96 g·cm−2 Au target (about 4.5 M events). The SIS (heavy ion synchrotron) was used to accelerate the 12C ions at the energy of 400 MeV/u. The preliminary results of differential cross sections measurements as a function of angle and energy for carbon target, in the small angle region (θ ≤ 5°), are presented.

Measurement of Double Differential Cross-Section for Electron Impact Ionization of Argon at 348 eV

Renewed interest in measuring cross-sections for scattering electrons or positrons by noble gas atoms at intermediate energies has recently led to test various theoretical approximations. Ionization of the noble gases such as He, Ne, Ar, Kr, and Xe by electron impact is an important process in collision physics. Argon has been studied from the discharge point of view for more than 100 years and interest in this gas is due to several important fundamental and technical considerations. Cross-sections for electron-impact ionization have been measured and calculated since the early days of collision physics because of their importance to the kinetics and dynamics of collisions in relevance to many practical applications. Previous experimental measurements of double di erential cross-sections (DDCS) by electron impact for targets rather than helium are very few. The most itemized study is that of Opal et al. [1]. They presented DDCS data for several gases at di erent incident energies of a wide angular range. The literature contains the results from several experimental measurements on the double di erential cross-section studies of Ar. The elastic scattering of electrons by noble gases has been extensively studied and a large number of either theoretically or experimentally obtained relative and absolute di erential cross-sections are available at various incident electron energies and scattering angles. The critical minima appearing in Ar DCS spectra are the most sensitive test for comparison of experimental and theoretical results and, hence, give good possibilities for testing di erent theoretical models. DuBois and Rudd [2] measured DDCS for 100 500 eV electron impact of Ar including Ne, N2, and H2 data. Hippler et al. [3] and Chaudhry et al. [4] reported energy distributions of ejected electrons in double or (multiple) ionization of rare gases 300 eV to 10 keV electron impact. Another work is done by Santos et al. [5] at 500 750 and 1000 eV electron impact single or multiple ionization DDCSs of Ar. Yates and Khakoo [6] have presented DDCSs of Ar for near threshold electron impact single ionization of Ar at 17, 18, 20, and 30 eV. In this work, we used Ar target as a typical that is reasonable to expect to understand ionization mechanism of atomic systems. We have measured DDCS for asymmetric geometry for di erent kinematical conditions.

Measurements of Double Differential Cross-Sections for He at Intermediate Energy

Detailed studies on ionization of atoms and molecules by electron impact have made numerous contributions to understanding of the structure of atoms and molecules including the interaction between particles. After a ionizing collision a scattered electron, an ejected electron and a recoil ion is formed. Doubly di erential cross-sections give detailed information for one of the outgoing electrons. In this study, we report the angular distribution of double di erential cross-sections of ejected electrons from He in intermediate energy region.

Measurements of Double Differential Cross-Sections for He at Intermediate Energy

Measurements of Double Differential Cross-Sections for He at Intermediate Energy

Measurement of Charged-Particle Emission Double-Differential Cross Section of Fluorine for 14.2MeV Neutrons

We carried out detailed measurement of the double-differential cross sections of fluorine for the emissions of protons, deuterons, tritons, and α-particles with 14.2MeV incident neutrons. An improved charged-particle spectrometer with a pencil DT-neutron beam furnished at the FNS facility of the Japan Atomic Energy Agency enabled us to obtain precise data with a fine energy resolution over a wide energy range and an angular range from 15 to 150°. The present experiment is the first simultaneous measurement of the four different kinds of charged particles and provides useful data to establish a nuclear reaction model of fluorine as well as to confirm previous experimental data. Angular-differential cross sections for several discrete peaks corresponding to excited states of residual nuclei were extracted to discuss the reaction mechanism of charged-particle emission. The obtained data suggest that the charged-particle emission reaction of fluorine has a complicated mechanism in which there are contributions from the direct reaction, pre-equilibrium, and equilibrium processes. The obtained data were compared with the nuclear data evaluated in JENDL-3.3 and ENDF/B-VII.0. The results show large differences in the energy and angular distributions of emitted particles and the charged-particle production cross sections between the measured and evaluated data.

A Bragg curve counter with an internal production target for the measurement of the double-differential cross-section of fragment production induced by neutrons at energies of tens of MeV

A Bragg curve counter equipped with an internal production target was developed for the measurements of double-differential cross-sections of fragment production induced by neutrons at energies of tens of MeV. The internal target permitted a large detection solid angle and thus the registration of processes at low production rates. In this specific geometry, the detection solid angle depends on the emission angle and the range of the particle. Therefore the energy, atomic number, and angle of trajectory of the particle have to be taken into account for the determination of the solid angle. For the selection of events with tracks confined within a defined cylindrical volume around the detector axis, a segmented anode was applied. The double-differential cross-sections for neutron-induced production of lithium, beryllium, and boron fragments from a carbon target were measured at 0° for 65 MeV neutrons. The results are in good agreement with theoretical calculation using PHITS code with GEM and ISOBAR model.

Doubly differential cross sections for ionization of xenon by spin-polarized electrons

Even though spin-dependent effects are naturally associated with relativistic effects, it has been known for some time that significant spin asymmetries for electron-impact ionization are possible in a completely non-relativistic model if the J-state of the residual ion can be experimentally resolved. In the lowest order implementation of the same model, the spin asymmetry would vanish if the J-states of the ion are not experimentally resolved (i.e., summed over). Consequently, it is perhaps possible to search for relativistic effects by looking at asymmetries for which the final ion J-state is not resolved. There is also some experimental evidence that relativistic effects might be important for large scattering angles which are inaccessible to current experimental set-ups. If this is the case, relativistic effects might be seen in a double differential cross section measurement which integrates over all angles. Very recently, some significant experimental spin asymmetries for electron–xenon scattering have been reported for a doubly differential spin-asymmetry measurement in which the final J-state was not resolved. The purpose of this paper is to investigate whether or not these experimental results indicate relativistic effects.

PISA – an experiment for fragment spectroscopy at the Internal Beam of COSY: application of an Axial Ionization Chamber

The Proton-Induced SpAllation (PISA) experiment performed at the internal beam facility of the COSY storage ring in Jülich, Germany, which is aimed at the precise measurement of double differential cross-sections over a broad range of energies and angles for spallation reactions induced by protons of 200– 2500 MeV energy in various targets, is presented. In this paper the emphasis is put on the design, principles of operation and performance of a Bragg Curve Detector (BCD) optimized for internal beam experiments at storage rings. Very clean and distinct product identification (with Z up to ∼14) from reactions, in which a Ni target was bombarded with a 1.9 GeV circulating proton beam, is obtained. The individual elements are resolved for emission energies higher than 0.5 MeV/ nucleon . Moreover, due to the detector read-out achieved by coupling a specially designed current sensitive preamplifier directly to a sampling ADC, the shape analysis of the signals from the BCD allows the isotope identification of light particles with A up to ∼11. It is also found that the BCD can be used efficiently as a thin Δ E detector for the telescope consisting of the BCD and a series of silicon detectors.

Light Charged Particle Production Induced by Fast Neutrons (En = 25-65 MeV) on 209Bi

This paper presents the experimental set-up and data reduction procedures regarding the measurement of double-differential cross sections for light charged particle production in fast neutron induced reactions (n, px), (n, dx), (n, tx) and (n, αx) on bismuth in the incident neutron energy range 25-65 MeV and at laboratory angles from 20° to 160°. Preliminary double-differential and energy-differential cross sections for hydrogen isotopes are presented.

Measurements of Double-Differential Cross Sections of Charged-Particle Emission Reactions for Several Structural Elements of Fusion Power Reactors by 14.1-MeV Incident Neutrons

A two-dimensional energy and time-of-flight charged-particle spectrometer has been developed and used to measure the double-differential cross-section (DDX) data of (n, xp) and (n, xα) reactions for several elements with 14.1-MeV incident neutrons at OKTAVIAN, the Intense 14-MeV Neutron Source Facility of Osaka University. The DDX data of the 51V(n, xp), 51V(n, xα), natFe(n, xp), natFe(n, xα), 59Co(n, xp), 59Co(n, xα), natNi(n, xα), natCu(n, xα), 93Nb(n, xp), 93Nb(n, xα), and natMo(n, xp) reactions are measured. The angle-integrated energy differential cross-section (EDX) data were deduced from the measured DDX data and compared with other experimental results [except for the 59Co(n, xp) reaction] and evaluated nuclear data of JENDL fusion file (JENDL-FF). A comparison was also done with the ENDF/B-VI for the total reaction cross sections of all measured reactions except for the natMo(n, xp) reaction and the EDX of the natNi(n, xα) and natCu(n, xα) reactions. The theoretical calculations were done by using the SINCROS-II code. The measured data agreed fairly well with other data for almost all the reactions. The JENDL-FF and SINCROS-II data underestimate the measured EDX data for the reactions of 93Nb(n, xα) and natMo(n, xp). For the natFe(n, xp), natFe(n, xα), 59Co(n, xα), and natNi(n, xα) reactions, smaller data are given than other data, i.e, other experimental data, JENDL-FF, and ENDF/B-VI. The SINCROS-II code can reproduce well for both the proton and alpha-particle emission cross-section values.

Double Differential Cross Section Measurements of the (n,px), (n,dx), (n,tx) and (n,alphax) Reactions on 12C: Kerma Determination at Energies Between 30 and 75 MeV

The double-differential cross sections for the (n,px), (n,dx), (n,tx) and (n,alphax) reactions on carbon have been measured at 42.5, 62.7 and 72.8 MeV incident neutron energies at laboratory angles from 20o to 160o in 10o steps. The energy differential cross sections are deduced and consequently the partial and total kerma values. Experimental results are compared with existing data and theoretical calculations. Preliminary results on carbon are also shown concerning the light charged particle spectra induced by neutrons from the low energy tail of the incident neutron spectrum.

Large solid angle spectrometer for the measurements of differential (n, charged-particle) cross sections

A charged-particle spectrometer with a large solid angle close to 4 π has been developed for studies of fast neutron induced charged-particle emission reactions. On the basis of a high-pressure gridded ionization chamber employing high- Z structural elements, the spectrometer permits the measurements of energy-angular distribution of secondary charged-particles with very high geometrical efficiency and a good signal-to-noise ratio. It has been applied successfully for the measurements of double-differential cross sections of (n, xα) reactions for incident neutrons up to 14 MeV, and of (n, p) reactions up to 6 MeV by use of the data reduction and particle selection methods developed in this study. The present spectrometer proved to be an efficient means for studies of differential (n, charged-particle) cross sections.