High Energy Nuclear Interactions Research Articles

Particle Identification in High Energy Collisions at RHIC

This article provides a technical introduction to the study of collider physics by focusing on the concept of particle identification (PID). Through a general overview of the Relativistic Heavy Ion Collider (RHIC) and the Pioneering High Energy Nuclear Interaction Experiment (PHENIX), the author discusses the role of Vanderbilt University researchers in collaborative work at the Brookhaven National Laboratory. After explaining the concept of event reconstruction and centrality with graphical images of experimental results, the author outlines the time-of-flight method of particle identification in high energy physics. A final presentation of the design concept for the Multi-Gap Resistive Plate Chamber (MRPC) integrates the more traditional foundations of theoretical physics with the next generation of physics experimentation in the field.

NATURE OF ANTIPROTON PRODUCTION IN HIGH ENERGY NUCLEAR COLLISIONS: ASSORTED DATA VERSUS SPECIFIC MODELS

We attempt here to deal with some of the important characteristics of secondary antiproton production in various high energy nuclear interactions on the basis of a model for production of particles in PP collisions. The results have, thereafter, been converted to those for AA collisions through an appropriate mechanism. The effect of rescattering and cascading in the production processes and on the chosen models has also been incorporated in a phenomenological manner. Comparison of the calculated results with data on the relevant observables leads to a striking agreement and this fair success is claimed here to obviously signal the strength of the basic models that are applied in the present work.

Study of high energy cosmic ray interactions at chacaltaya laboratory

Cosmic rays physics is currently studied with rather sophisticated detectors operating in a variety of either experimental conditions or atmospheric depths in the world. In this paper we present the main properties of the observed features of high-energy nuclear interaction phenomena of cosmic rays, with particular emphasis on some experimental observations made by the emulsion chamber technique at Chacaltaya Laboratory (Bolivia, 5230 m a.s.l.). A discussion on the past and present achievements as well as the future prospects of high altitude mountain laboratories for cosmic ray physics is presented.

Showers with large zenith angles observed in emulsion chambers

Showers with large zenith angles are observed in emulsion chambers exposed at Mt.Kanbala.The intensity of high energy muons is given and the multicore showers with large zenith angles are found.It is indicated that a new phenomenon may exist in the high energy nuclear interactions of cosmic rays.

Final state interactions in the (nuclear) FRITIOF string interaction scenario

We consider the final state reinteraction of the produced hadrons in a scenario with the initial high energy nuclear interaction provided by the FRITIOF Model. The basic idea is that any produced hadron is able to reinteract in accordance with the known cross sections (using classical trajectories for the motion and an impact parameter description of the interaction) from the Landau- Pomeranchuk formation time and onwards. This is treated as a rescattering transport process included in a Monte Carlo simulation subroutine, LUCIAE, to be connected to the FRITI0F, the ARIADNE, PYTHIA and the JETSET programs. We include a set of predictions, in particular on strangeness production, from the ensuing model.

Nonstatistical fluctuations in fragmentation of target nuclei in high energy nuclear interactions

Analysis of target fragmented 'black' particles in nuclear emulsion from high energy relativistic interactions initiated by 16O at 2.1 GeV/nucleon and 12C and 24Mg at 4.5 GeV/nucleon reveal the existence of nonstatistical fluctuations in the azimuthal plane of interaction. The asymmetry or the non-statistical fluctuations, while found to be independent of projectile mass or incident energy, are dependent on the excitation energy of the target nucleus.

Intermittency and fragmentation of target residue in high-energy nuclear interactions.

We analyze the angular distribution of target-associated slow particles in high-energy nuclear interactions, in terms of scaled factorial moments (SFMs). A power-law type behavior of SFMs, popularly known as ``intermittency,'' is a diagnostic indicator of possible dynamical phenomenon in multiparticle production and multifragmentation processes in high-energy physics. Our data of target associated slow particles reveal similar type of increase in SFMs with decreasing bin width of the angular distribution. The new observation thus contradicts the existing concept of evaporation model that the ``statistical equilibrium'' is reached before the emission of fragmented particles from residual target nuclei at high-energy nuclear interactions.

PHENIX experiment at RHIC

The purpose of my talk is to present an overview of the PHENIX experiment (Pioneering High Energy Nuclear Interaction experiment) at RHIC. Physics issues related to the quark-gluon plasma, in particular, in relation to this experiment, are listed in Table 1. Two important aspects exist for the quark-gluon plasma. One is “deconfinement”, which is closely related to the Debye screening of the QCD potential. The basic mechanism of J/$ suppression is that, if the J/1c, ra d ius is longer than the screening length, then cz would not be able to find a bound state due to a Debye suppression of the long-range term of the CC potential and, thus, J/+ production is suppressed’). The degree of suppression depends strongly on the relative size difference between the meson radius and the screening length. Since r($‘) = 0.51 fm > r(J/$) = 0.25 fm > r(T) = 0.13 fm, we expect that 4’ must melt first, then J/$, and finally T. A stronger suppression of $J’ than Jill, reported by NA38 at this conference2) is, therefore, very impressive, and this result compels us to study these vector mesons systematically at RHIC. We plan to measure J/?c, in the mid-rapidity region by dielectrons, and J/+, +’ and ‘I at forward angles by dimuons. The other important element is “chiral symmetry restoration”. Because the mass of the d-meson is close to twice the kaon mass, and because both 4 and K could be distorted in the quark-gluon plasma, it was predicted3) that a change would occur in: (a) the branching ratio between leptonic and hadronic channels, (b) the mass of the 4, and (c) the width of the 4. Here, high-resolution &spectroscopy is required to study these points. We plan to measure &mesons by both electron and hadron channels. Thermal radiation of a hot gas has been a very topical subject for many years4). There was a confusing period, at least to me, in which it was debated whether or not the radiation was enhanced or suppressed when the phase transition occurred. Recently, a consensus among theorists seems to be that the gluon content is high at an early stage of the quark-gluon plasma and an enhancement must be expected in the region of mr (or, pT for photons) greater th an 2-3 GeV’). We plan to investigate this topic using the photon measurement. The nature of the phase transition is a very interesting point to study. If the phase transition is first-order, then, an entropy jump would be expected at Tc, because internal degrees of freedom of the constituents increase by a factor of about 12 from the pionic gas to the quark-gluon gas. If one plots T as a function of the energy density (E) of the system, the value of T increases with & in the phase of a pionic gas until it reaches Tc. The system stays at this temperature, even as E increases, until a sufficient energy density

Particle identification in a liquid argon calorimeter

This paper discusses a longitudinally segmented allene doped liquid argon detector used as a range telescope for identification of stopping particles. The detector is capable of isotopic identification at energies from < 0.2 to > 1 GeV/nucleon for atomic mass less than 150. It is meant to be flown on a long duration balloon flight for observation of heavy cosmic rays and high energy gamma rays, and for use at accelerators in identification of fragmentation products from high energy nuclear interactions.

Track-registration-and-development characteristics of CR-39 plastic track detector

CR-39 plastic track detector (Homalite) has been tested for its response to light particles (protons, alpha particles) and heavy ions ( 238U, 32S, 252Cf fission fragments, 19F, 16O and 12C) having a wide spectrum of energies. Perpendicular and oblique geometries were employed, and the exposed detectors were etched in stages in 6N NaOH at 70 ± 1°C. The track parameters like etch pit diameter, etched track length, and etching velocity along the track ( V t ) were obtained at the end of every etching stage. Both, Optical-Microscope (O.M.) and Scanning-Electron-Microscope (SEM) were utilized in these measurements. It has been found that the Etch-Rate Ratio (ERR = V t / V g ) for CR-39 is related to REL, the Restricted Energy Loss (in units of MeV cm 2g -1) of charged particles through the relation, ERR = 7.51 × 10 -8 ( REL) 2.36 for REL values exceeding 2 × 10 3 MeV cm 2 g -1. Similarly, the results show that ERR = 7.24 × 10 -7 ( Z 2 eff / β 2) 1.92 for Z 2 eff/β 2 values exceeding 3 × 10 3. The Restricted Energy Loss (REL) has been found to be related to Z 2 eff/β 2 through the relation (REL) ωo = 200 eV = 2.62 (Z 2 eff/β 2) 0.81 It has also been observed that the prolonged etching of CR-39 in stages (short intervals) enables us to make a rough classification between ‘light’ and ‘heavy’ reaction products such as those emitted in high energy nuclear interactions. The rate of track etching is significantly enhanced when the etchant becomes saturated with the etched products.

Some Observations on Deuterons Emitted in High Energy Nuclear Interactions

Production of deuterons in 24 GeV/c proton and 50 GeV/c pion interactions with emulsion nuclei has been investigated. Some characteristics of stars in which deuterons have been observed have been compared with the average characteristics of stars. It has been found that (i) for any given value of ng the average excitation of deuteron producing stars is higher than the total sample and (ii) the average shower multiplicity in stars with less energetic deuterons is higher than of the events with energetic deuterons or of the ordinary sample. None of the existing models for deuteron production seems to be capable of explaining the observed features.

Characteristics of nuclear interactions around 20 TeV

Features of high-energy nuclear interactions around 20 TeV are studied by means of a balloon-borne emulsion chamber with jet producer. Experimental results are compared with the Monte Carlo simulation by assuming the inclusive distributions of the parent π0(η) mesons and the observation condition of secondary γ-rays detected with the chamber. The quantities concerning the mean multiplicity, the angular distribution, the transverse-momentum spectrum and the fractional-energy spectrum of the produced particles were derived through the Monte Carlo simulation. The results were compared with those of accelerator experiments. They show that the mean transverse momentum of π0-mesons grows slowly with incident energy. They also indicate the appreciable increase of multiplicity and the scaling breakdown faster than logS in the central region, resulting in the gradual steepening of the fractional-energy spectrum in the same region. The distribution of the invariant mass of two γ-rays,Mγγ, indicates the appreciable production of ν-mesons compared with the simulation. It is also consistent with the angular correlation between charged particles and γ-rays.

Characteristics of high energy interactions II. Production spectra of Gamma-rays in graphite

Twenty high energy nuclear interactions produced in the graphite units of an emulsion chamber were recorded. The emulsion chamber was exposed to cosmic rays at an atmospheric depth of 10 g cm−2 for about 7 hr over Hyderabad, India. Fourteen interactions which radiated energyΣ Er⩾1000 GeV in the form ofγ-rays were analysed in detail. The median energy 〈Σ Er〉 of the interactions was 1600 GeV. Results concerning the multiplicity, the transverse and longitudinal momentum distributions, and the fractional energy distribution ofγ-rays in these interactions are presented. The average transverse momentum ofπ0—mesons is found to increase very slowly with the primary energyE0 and it can be approximated by the function =0·238E00.06.

Characteristics of high energy interactions I. High energy gamma-ray spectra near the top of the atmosphere

An emulsion chamber was used to study the characteristics of high energy nuclear interactions from the production spectra ofγ-rays. The emulsion chamber, which comprised of two parts, namely the detector and the graphite producer unit, was exposed to cosmic rays for about 7 hr at an atmospheric depth of 10 g cm−2 at Hyderabad (geomagnetic latitude 7·6°N). 720 electromagnetic cascades due toγ-rays were recorded in the detector. These cascades were classified into three groups; (a)γ-rays from nuclear interactions in the detector (b)γ-rays from nuclear interactions in the producer unit and (c)γ-rays of atmospheric origin. The energies of the cascades were determined using photometric method. The spectra ofγ-rays from groups (a) and (c) were determined and compared with similar spectra obtained at greater atmospheric depths. The spectra were found to obey a power law. The spectrum ofγ-rays of atmospheric origin was found to steepen at high energies,Er>2200 GeV.

Theoretical Studies of the Longitudinal Development of Extensive Air Showers. II: Average Behaviour of the Electron Component

The longitudinal development of the electron component of the air shower is investigated in connection with high energy nuclear interaction. The method of calculations and analyses developed for the study of the nuclear active component in a previous paper are used again. The transition curves of the electrons are considered. First, the transition curves are represented by four numerical constants. Next, model dependent features of the transition curves are discussed by investigating systematically the relationship between the four constants and parameters in the model of high energy nuclear interaction. From the results of the present work, a model of the longitudinal development of the electron component is presented, and is compared with other models ancl other simulations of air showers. § ] . lntrod ueLion The purpose of the present work is to provide a systematic view of the relationship between the basic properties of high energy nuclear interaction and the characteristic features of the longitudinal development of the air shower. In this paper, following the investigation of the nuclear active component of the air shower grven m a previous paper (hereafter referred to as PJ), we deal with the electron ,·ornponent in a similar way. The transition curves of the electnms, under consideration in the present paper, would be of great use in understanding the experimental data such as the size spectra at various altitudes, the angular distribution of the air showers 21 and the direct measurement of the transition curves by air scintillation light. 31 In the present and the previous paper, however, our investigations are restricted to the average transition curves of the fixed primary energy. For precise comparison of the theoretical results with experimental data, the fluctuations of the transition curves haYe to be taken into account. Stochastic properties of the transition curves due to fluctuations in the nuclear collisions vvill be discussed in detail in a following paper. In the coun>e of the present work, \Ve have found that the transition curves

Deuterium and Tritium from Solar Flares at ~ 10 MeV Per Nucleon

view Abstract Citations (21) References (10) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Deuterium and Tritium from Solar Flares at ~ 10 MeV Per Nucleon Anglin, J. D. ; Dietrich, W. F. ; Simpson, J. A. Abstract High-resolution, solid-state charged-particle telescopes on the Earth satellites IMP-S and IMP-6 have made it possible to resolve all the hydrogen and helium isotopes of solar-flare origin in groups of solar flares within the period 1969 September-1972 Novemher. The average isotopic ratios, P, in equal energy per nucleon intervals are: P(2H/1H) = (8 2) x 10- P(3H/1H) = (2.1 1.0) x 10- and F(2H/4He) = (1.1 0.2) x 10-2, which can be compared with our previous result F(3He/4He) = 2 X 10-2. We conclude that the high yields of 2H, 3H (with a half-life of 12 years and, hence, of recent origin), and 3He can only be explained by high-energy nuclear interactions and that the acceleration process takes place in the chromosphere. Subject headings: abundances, solar - flares, solar Publication: The Astrophysical Journal Pub Date: November 1973 DOI: 10.1086/181353 Bibcode: 1973ApJ...186L..41A full text sources ADS |

Proton Interactions at High Energies

The background, the results, and the meaning of two recent experiments performed in the new CERN colliding-beam accelerator are described. The experiments, which involved collisions between oppositely directed beams of high- energy protons, have revealed a new and unexpected property of the strong interaction at extremely high energies. The results obtained so far have shown that above a certain energy the probability that two passing protons will interact increases with energy, a finding that may require a major revision in the accepted description of high-energy nuclear interactions.

Power-Law Energy Spectrum Deduced from the Angular Distribution of Nuclear Interactions of 20 to ∼103GeV

The ${log}_{10}F$ plots of the angular distribution for the forward-cone secondaries, observed in high-energy nuclear interactions produced in nuclear emulsion, are found to fit well to a linear function of $\ensuremath{\eta}(\ensuremath{\theta})$ [$\ensuremath{\cong}0.46\ensuremath{-}\mathrm{ln}tan\ensuremath{\theta}$], i.e., ${log}_{10}F=\ensuremath{\alpha}\ensuremath{\eta}(\ensuremath{\theta})+\ensuremath{\gamma}$. This fact is used to argue for the power-law differential energy spectrum in multiple production with the index of power $\ensuremath{\alpha}\mathrm{ln}10$, with the aid of already established experimental results. The values of $\ensuremath{\alpha}$, obtained from fitting procedures, are approximately equal to - 1 for nuclear interactions with a sufficient number of charged secondaries in a wide range of the primary energy ${E}_{p}$ between 20 and \ensuremath{\sim} ${10}^{3}$ GeV. It is also concluded, from the systematic study of the 1335 30-GeV/c proton jets, that the nature of the target nucleus in the hadron-nucleus collisions does not affect the shape of the angular distribution of the forward-cone secondaries.

Energy transfer to neutral pions in high energy nuclear interactions

The fraction of energy transferred to the neutral pions (\( K_{\pi ^ \circ } \) ), in an interaction of high energy (> 20 GeV) N-particles (nucleons and pions) with atomic nuclei, is estimated from the data collected, using a total absorption spectrometer (TAS) and a multiplate cloud chamber. The average value of\( K_{\pi ^ \circ } \) (\( \bar K_{\pi ^ \circ } \)) is found to be 0·12 ± 0·01 in the energy range 20–100 GeV (Ē0 = 35 GeV) and 0·19 ± 0·02 in the region of > 100 GeV (Ē0 = 206 GeV). The value of\( \bar K_{\pi ^ \circ } \) obtained in different experiments and its dependence on the primary energy are discussed. An increase in\( \bar K_{\pi ^ \circ } \) in pion-nucleus collisions with the energy of the pion or an increase in the ratio of pions to protons, at 800 gm./cm.2, in the energy range of a few tens of GeV to a few hundred GeV or both is to be invoked to explain the energy dependence of\( \bar K_{\pi ^ \circ } \) observed in this investigation.

Monte Carlo studies on the hadronic component of extensive air showers

Three-dimensional Monte Carlo calculations have been performed on the development of the hadronic component of extensive air showers using a semi-empirical model of high-energy nuclear interactions. Results include integral energy spectra and lateral distribution of nuclear active particles as well as total hadronic energy flux. The probability of multi-core showers is discussed. The contribution of pionization tends to mask the dependence of this probability on primary atomic number. Fluctuations of total and central hadronic energy flux are investigated. Maps of hadronic energy flux in the core region of individual showers are presented.