Proton-nucleus Interactions Research Articles

Search for nonextensivity in electron-proton interactions at s=300 GeV

Study of canonical entropy in electron-proton interactions at s=300 GeV is presented. The precision data collected by the H1 experiment at the HERA in different ranges of invariant hadronic mass W and the squared four-momentum exchange Q2 in electron-proton (ep) interactions have been analyzed in the ensemble theory approach. The canonical partition function relates to the multiplicity distribution which is often studied in collider experiments. We use the canonical ensemble partition function to explore the dynamics of hadron production in ep interactions by devising different methods to find the entropic parameter and the collision temperature. The inverse slope of the transverse momentum spectrum of produced hadrons also relates to the temperature. In the recent past, the CMS, ATLAS, and ALICE experiments at the LHC have studied the charged hadron transverse momentum and particle distributions in proton-proton and proton-nucleus interactions by using the Tsallis function within this approach. A detailed investigation into the role of the system volume and relation amongst different dynamical parameters reveals interesting results. Published by the American Physical Society 2024

Large rapidity gaps in proton–nucleus interaction

We analyse the cross-section of events with Large Rapidity Gaps observed in proton–lead collisions by the CMS Collaboration (arXiv:2301.07630). The role of the transverse size of elementary pN amplitude is discussed. We emphasize that the cross-section of incoming proton dissociation caused by the photon radiated off the lead ion is close to the value of dσ/dΔηF\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$d\\sigma /d\\Delta \\eta ^F$$\\end{document} measured by the CMS, and it is not clear why there is no room in the data for the Pomeron-induced contribution

Description of temperature effects on proton radioactivity

Role of thermal effects of hot parent nuclei in the characteristics of proton emission process has been studied for the first time by analyzing the surface energy coefficient γ entering in the calculation of proximity potential for 15 experimentally detected proton emitters (67≤Z≤83) in the isomeric states. In the present work, the proton-nucleus interaction potentials are obtained by using one of the latest versions of proximity potential formalism proposed by Zhang et al. in 2013. In addition, the quantum mechanical tunneling probability and consequently the proton radioactivity half-lives are calculated within the framework of the semiclassical WKB method. We present a new temperature-dependent (TD) form of the coefficient γ based on thermal properties of hot proton emitters in the framework of the finite-temperature generalized liquid-drop model. By integrating temperature dependence into the surface energy coefficient of proximity potential Zhang 2013, a reasonable description of the experimental half-lives of proton radioactivity is achieved. We extend the modified form of the Zhang 2013 model to predict the proton radioactivity half-lives of 6 proton emitters in the isomeric states, whose proton radioactivity is energetically allowed or observed, but has not been quantified yet. The obtained results reveal that the predictions by our model are in good agreement with the other theoretical methods, namely UDLP proposed by Qi et al. (2012) [19] and NGNL proposed by Chen et al. (2019) [49]. In this work, we also attempt to introduce an empirical formula for estimating the half-lives of one-proton emission process from the excited states by taking into account both the thermal effects of all the available 15 hot proton emitters and the contribution of centrifugal potential. Our results indicate that the calculated proton radioactivity half-lives by the current formula are in good agreement with experimental data. This means that the correlation between the half-lives of proton decay processes and the nuclear temperature T of proton emitters can be suitable to deal with the proton radioactivity one-proton transition from isomeric states.

Highlights from the NA61/SHINE

NA61/SHINE is a multipurpose fixed-target facility at the CERN Super Proton Synchrotron. The main goals of the NA61/SHINE stronginteractions program are to discover the critical point of strongly interacting matter as well as to determine the properties of produced particles relevant for the study of the onset of deconfinement - the transition between the state of hadronic matter and the quark-gluon plasma. An analysis of hadron production properties is performed in nucleus-nucleus, proton-proton, and proton-nucleus interactions as a function of collision energy and size of the colliding nuclei to achieve these goals. The selected NA61/SHINE results from this program are presented. In particular, the latest results from different reactions p+p, Be+Be, Ar+Sc, and Pb+Pb on hadron spectra and fluctuations are discussed. The NA61/SHINE results are compared with worldwide experiments and predictions from various theoretical models, like EPOS, PHSD, UrQMD, and others.

Reaction channel contributions to the proton +Pb208 optical potential at 40 MeV

Background: Reaction channel coupling substantially modifies the real and imaginary nucleon-nucleus interactions for nuclei of $Z=20$ or less in ways that cannot be represented as uniform renormalizations of folding model potentials. For such nuclei coupling to inelastic channels also contributes. This raises the question of the effect of these couplings for heavier target nuclei.Purpose: To establish and characterize the contribution to the proton-nucleus interaction generated by coupling to neutron pickup (outgoing deuteron) channels for 40 MeV protons on the heavy closed shell nucleus $^{208}\mathrm{Pb}$. To identify and evaluate the consequent dynamical non-locality.Methods: Coupled reaction channel (CRC) calculations provide the elastic channel $S$-matrix ${S}_{lj}$ due to the included processes. Inversion of ${S}_{lj}$ will produce the local potential that would yield, in a single channel calculation, the elastic scattering observables from the CRC calculation. Subtracting the bare potential of the CRC calculations gives a local and $l$-independent representation of the dynamical polarization potential (DPP). From the DPPs due to various combinations of channel couplings, the influence of dynamically generated nonlocality can be identified.Results: Coupling to deuteron channels generates a repulsive component for the real potential and an absorptive component for the imaginary term. The radial shapes of both terms were modified in ways that could not be represented by uniform renormalization; the rms radius of the real part was substantially altered. Evidence of the dynamical nonlocality of the DPP due to pickup is provided by the nonadditivity of contributions of different couplings and other effects. For the doubly closed shell $^{208}\mathrm{Pb}$ coupling to low-lying (nongiant) collective states has a very small effect on elastic scattering, making a negligible contribution compared with pickup, and was not included.Conclusions: The DPPs established here strongly challenge the notion that folding models, in particular local density models, provide a satisfactory description of elastic scattering of protons from heavy nuclei. Coupling to neutron pickup channels induces dynamical nonlocality in the proton optical model potential with implications for direct reactions.

Production of High-Transverse-Momentum Deuterons and Tritons at an Angle of 40{{}^{circ}} in Proton–Nucleus Interactions at a Beam Energy of 50 GeV

Data on the production of positively charged particles emitted at an angle of 40{}^{circ} (in the laboratory frame) with transverse momenta of up to 2.7 GeV/c in the interaction of 50-GeV/c protons with carbon, aluminum, copper, and tungsten nuclear targets are presented. Particular attention is given to studying the production of light nuclear fragments, such as deuterons (d) and tritons (t). An analysis of data on d and t particles gives grounds to state that these fragments arise via a local mechanism of their direct knockout from nuclei. The results were obtained in the SPIN experiment at the Institute for High Energy Physics (IHEP, Protvino).

Negatively Charged Pion Multiplicity Analysis in Hadron-Hadron and Hadron-Nucleus Collisions at Momenta of 1-400 GeV/c

Data on the mean multiplicity of negative pion produced in minimum bias proton-proton, proton-neutron and proton-nucleus interactions as well as central nucleus-nucleus interactions at momenta of I .4-400 GeV/c per nucleon have been compared within the framework of a modified I-RITIOF model [1]. [2].The results for neutron-neutron and nucleon-nucleon interactions were then constructed. The dependence of the mean pion multiplicity in proton-nucleus and central nuclear collisions are studied as a function of the collision energy and the nucleus mass number. The model shows good agreement for pi -mesons, as shown in several comparisons in refs

Highlights from the NA61/SHINE strong-interactions programme

NA61/SHINE is a multipurpose fixed-target facility at the CERN SPS. The main goals of the NA61/SHINE strong-interactions programme are to discover the critical point of strongly interacting matter as well as to study the properties of the onset of deconfinement. In order to reach these goals, a study of hadron production properties is performed in nucleus-nucleus, proton-proton and proton-nucleus interactions as a function of collision energy and size of the colliding nuclei. In this contribution, the NA61/SHINE results from a strong interaction measurement programme are presented. In particular, the latest results from different reactions p+p, Be+Be, Ar+Sc, and Pb+Pb on hadron spectra, as well as intermittency, higher-order moments of multiplicity fluctuations and spectator induced electromagnetic effects are discussed.

Proton radioactivity and α-decay of neutron-deficient nuclei

Proton radioactivity and α-decay half-lives of neutron-deficient nuclei have been systematically studied. The proton-nucleus interaction potential is developed by single folding the density distribution of the daughter nuclei with the effective M3Y-Paris nucleon-nucleon (NN) interaction. The penetrability is calculated with the Wentzel-Kramers-Brillouin approximation. The applicability of the universal decay law on the proton decay half-lives has been examined and a new set of parameters has been identified. The competition between α-decay and proton radioactivity of neutron-deficient nuclei has been investigated. The proton radioactivity is found to be the dominant mode of decay for nuclides located very close to the proton drip-line. The effect of using different microscopic proton and neutron density distributions on the half-lives for these two decay modes is studied. It is found that the calculated half-lives with the microscopic densities that obtained from the self-consistent Hartree–Fock-Bogoliubov method successfully reproduce the experimental data. The impact of nuclear deformation on the half-lives is investigated for these two decay modes. The influence of nonlocality through the finite-range exchange part of the NN interaction on the α-decay process is elucidated. Our theoretical calculations have been confirmed experimentally and satisfactory agreement has been achieved.

The DsTau Experiment: A Study for Tau-Neutrino Production

For clarifying the validity of the Lepton Universality hypothesis, one of the fundamental statements of the Standard Model, the interaction cross section for all three flavors of leptons have to be known with high precision. In neutrino sector, for electron and muon neutrinos, the interaction cross section is known fairly well, but for tau neutrino only poor estimations exist. In particular, the most direct measurement by the DONuT experiment was performed with rather poor accuracy due to low statistics and an uncertainty of the tau neutrino flux. The DsTau experiment proposes to study tau-neutrino production process and thus to improve significantly the accuracy of calculations of tau neutrino flux for neutrino accelerator experiments. To study reactions providing most of tau neutrinos, the experiment uses a setup based on high resolution nuclear emulsions, capable to register short lived particle decays created in proton-nucleus interactions. The present report is an overview of the DsTau experiment together with some of the preliminary results from the pilot run.

DsTau: study of tau neutrino production with 400 GeV protons from the CERN-SPS

In the DsTau experiment at the CERN SPS (NA65), an independent and direct way to measure tau neutrino production following high energy proton interactions was proposed. As the main source of tau neutrinos is a decay of Ds mesons, produced in proton-nucleus interactions, the project aims at measuring a differential cross section of this reaction. The experimental method is based on a use of high resolution emulsion detectors for effective registration of events with short lived particle decays. Here we present the motivation of the study, details of the experimental technique, and the first results of the analysis of the data collected during test runs, which prove feasibility of the full scale study of the process in future.

Study of tau neutrino production in proton-nucleus interactions

Tau neutrino properties are not so well known in comparison to those of muon or electron neutrinos. The tau neutrino interaction cross-section was directly measured by the DONUT experiment in 2008 on a basis of 9 registered tau neutrinos, and with a large systematical error of 50% due to a poor knowledge of the tau neutrino flux in this beam dump experiment. However, more accurate measurement of the cross section is needed for future neutrino experiments. It would also allow testing the Lepton Universality (LU) of Standard Model in neutrino interactions. Recently several results for B-meson decays (LHCb, Babar) demonstrated hints of possible LU violation. The tau neutrinos are produced in the Ds meson decays to tau, Ds → τ vT, and the cascade decay of the tau τ → vT X. DsTau experiment has been proposed to study the tau neutrino production at CERN SPS. It will measure the Ds production differential cross-section in the proton-tungsten interactions. This will allow reducing of the uncertainty due to the tau neutrino flux in the DONUT result from 50% to 10%. The peculiar Ds cascade decay topology ("double kink") in a few mm range will be detected by nuclear emulsion tracker thanks to its excellent spatial resolution (∼50nm).In 2016 and 2017, we made test beam exposures of nuclear emulsion modules at CERN SPS 400GeV/c proton beam followed by the pilot run in August 2018. A physics run in 2021 is scheduled. The status and prospects of the DsTau project as well as a review of the modern nuclear emulsion technique and the methods of its data analysis are presented.

New empirical formulae for the in-medium nucleon-nucleon cross-section

New empirical formulae for in-medium nucleon-nucleon cross-section are presented and used to study the proton-nucleus interaction in the framework of Glauber model. The total, absorption and elastic cross-sections are calculated for many target nuclei. The calculated total cross-sections using the in-medium effective factor,fm4, give a reasonable fit with the experimental data. In addition, the in-medium factorsfm1,fm2 and fm3 successfully reproduce the absorption cross-section at energies up to 600 MeV.

Light in the beam dump. Axion-Like Particle production from decay photons in proton beam-dumps

The exploration of long-lived particles in the MeV-GeV region is a formidable task but it may provide us a unique access to dark sectors. Fixed-target facilities with sufficiently energetic and intense proton beams are an ideal tool for this challenge. In this work we show that the production rate of Axion-Like-Particles (ALPs) coupled pre-dominantly to photons receives a significant contribution from daughter-photons of secondary π0 and η mesons created in the proton shower. We carefully compare the PYTHIA simulated spectra of such secondaries to experimental literature, compute the ALP flux from the Primakoff conversion of these photons, and finally revisit existing limits on ALPs and update the prospects for a set of existing and future searches. Our results show that taking this production mechanism into account significantly enhances the sensitivity compared to previous studies based on coherent ALP production in primary proton-nucleus interactions.

Cross Sections for K±N Scattering for Simulating Cumulative-Kaon Interactions in Nuclei

Reliable cross sections for kaon-nucleon scattering are required for quantitatively estimating the effect of secondary interactions of cumulative K+ and K− mesons on their yields from various nuclei in proton-nucleus (pA) interactions at proton energies between 9 and 10 GeV and between 15 and 70 GeV. The preparation of these cross sections for a simulation code was a priority task that was solved for the kaon-momentum range between 0.35 and 2.75 GeV/c.

N – N, PT – N and PT – PT Fluctuations in Nucleus–Nucleus Collisions at the NA61/SHINE Experiment

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Recent Results and the Future of the NA61/SHINE Strong Interactions Program

NA61/SHINE is a fixed target experiment at the CERN Super-Proton- Synchrotron. The main goals of the experiment are to discover the critical point of strongly interacting matter and study the properties of the onset of deconfnement. In order to reach these goals the collaboration studies hadron production properties in nucleus-nucleus, proton-proton and proton-nucleus interactions. In this talk, recent results on particle production in p+p interactions, as well as Be+Be and Ar+Sc collisions in the SPS energy range are reviewed. The results are compared with available world data. The future of the NA61/SHINE scientifc program is also presented.

On Strangeness in NA61/SHINE

NA61/SHINE is a fixed target experiment at the CERN Super-Proton- Synchrotron. The main goals of the experiment are to discover the critical point of strongly interacting matter and to study the properties of the onset of deconfinement. In order to reach these goals, a study of hadron production properties is performed in nucleus-nucleus, proton-proton and proton-nucleus interactions as a function of collision energy and size of the colliding nuclei. In this paper, I will review recent results on strangeness production in p+p, Be+Be and Ar+Sc collisions in the SPS energy range. Kinematic spectra and mean multiplicities of kaons obtained with various analysis methods will be shown. An overview of strangeness production and its dependence on system size in the vicinity of the phase transition will be presented as well.

News from the NA61/SHINE experiment

NA61/SHINE is a fixed target experiment operating at the CERN SPS. Its main goals are to search for the critical point of strongly interacting matter and to study the onset of deconfinement. For these goals a scan of the two dimensional phase diagram (T-μB) is being performed at the SPS by measurements of hadron production in proton-proton, proton-nucleus and nucleusnucleus interactions as a function of collision energy. In this paper the status of the NA61/SHINE strong interaction physics programme is presented including recent results on proton intermittency, strongly intensive fluctuation observables of multiplicity and transverse momentum fluctuations. These measurements are expected to be sensitive to the correlation length in the produced matter and, therefore, have the ability to reveal the existence of the critical point via possible non-monotonic behavior. The NA61/SHINE results are compared to the model predictions.

Modelled Excitation Functions of 112,114,116,118,120,122,124Sn Isotopes for an Incident Energy Range of 10-80 MeV

The data of the cross–section is required for understanding nuclear reaction mechanism, developing and testing validity of available nuclear reaction models as much as it has been used in the applied fields of nuclear physics. Reliable experimental data is importance of comparison with theoretical nuclear model calculations for testing predictive ability. In the event that experimental data failure appearance, theoretical models are filling this gab for supplying with calculated data. Because of these reasons, both of experimental and theoretical studies need of each other. For a long time, theoretically studies have been carried out for proton total reaction cross section calculation. At the end of these studies, several analytical equations have been proposed by their authors. Comparison of the suggested equations and rearrangement for different value of parameters are enormously important for reaching successfully results. In this study, proton total reaction cross sections have been calculated for 112,114,116,118,120,122,124Sn isotopes using proton-nucleus interaction analytic equation that was proposed by M.A. Alvi. Also, optical model calculations carried out for same reactions by TALYS code. Excitation functions have been plotted with collected experimental data up to 80 MeV proton incident energy. Coefficient comparisons have been made via determined excitation function curves. The obtained results have been discussed by way of the excitation function graphics and compared with the available experimental data. Satisfactory agreements have been seen between calculated data and its measured equivalents. A validation of used theoretical model has been confirmed and tested via obtained results for these Sn isotopes and these energy ranges.