Relativistic Heavy Ion Beams Research Articles

The BM@N spectrometer at the NICA accelerator complex

BM@N (Baryonic Matter at Nuclotron) is the first experiment operating and taking data at the Nuclotron/NICA ion-accelerating complex. The aim of the BM@N experiment is to study interactions of relativistic heavy-ion beams with fixed targets. We present a technical description of the BM@N spectrometer including all its subsystems.

Photon-photon fusion and tau g-2 measurement in ATLAS

Relativistic heavy-ion beams at the LHC are accompanied by a large flux of equivalent photons. New measurements of exclusive dilepton production (electron, muon, and tau pairs) performed by the ATLAS experiment are discussed. We present the photon-induced production of tau pairs and constraints on the tau lepton’s anomalous magnetic dipole moment. In addition, measurements of photon-induced electron and muon pair production are presented, which provide strong constraints on the nuclear photon flux and its dependence on the impact parameter and photon energy. Forward neutrons are utilised to provide an experimental handle on the impact parameter range sampled in the events.

Looking for QGP signatures in ultraperipheral PbPb collisions

Ultraperipheral collisions of relativistic heavy ion beams lead to a diverse set of photon-nucleus (photonuclear) interactions. The measurements of particles and their interaction produced in photonuclear reactions can shed light on the QCD dynamics of these novel, extremely asymmetric colliding systems, with energies between those available at RHIC and the LHC. Previous studies by ATLAS indicate significant elliptic and triangular flow coefficients in these events [1]. Thus, it is imperative to check these events for other potential QGP signatures including radial flow, strangeness enhancement, and enhanced baryon/meson production. This proceeding presents the measurement of charged hadron yields in photonuclear collisions using 5.02 TeV Pb+Pb data collected in 2018 by ATLAS, with a dedicated photo-nuclear event trigger. The charged hadron yields are presented as a function of pseudorapidity and transverse momentum in different categories of event multiplicity. The results are compared with 5.02 TeV p+Pb data collected in 2016 by ATLAS, at the same event multiplicities. The results are also compared with calculations from DPMJET and hydrodynamic-based models. These comparisons enable detailed characterizations of photonuclear collision properties, including the photon energy distribution, and whether small QGP droplets may be formed.

Multi-tile zinc-oxide-based radiation-hard fast scintillation counter for relativistic heavy-ion beam diagnostics: prototype design and test

This contribution summarizes the design and performance test of a prototype radiation-hard fast scintillation detector based on the indium-doped zinc oxide ceramic scintillator, ZnO(In). The prototype detector has been developed for use as a beam diagnostics tool for high-energy beam lines of the SIS18 synchrotron at the GSI Helmholtz Center for Heavy Ion Research GmbH. The new detector consists of multiple ZnO(In) scintillating ceramics tiles stacked on the front and back sides of a borosilicate light guide. The performance of the detector was tested in comparison to a standard plastic scintillation detector with 300 MeV/u energy 40Ar, 197Au, 208Pb, and 238U ion beams. The investigated prototype exhibits 100% counting efficiency and radiation hardness of a few orders of magnitude higher than the standard plastic scintillation counter. Therefore, it provides an improved beam diagnostics tool for relativistic heavy-ion beam measurements.

Ionoacoustic monitoring of relativistic heavy ion beams

The performance of ionoacoustic detectors is investigated with respect to application of high-precision range and energy loss measurements for relativistic heavy ions. The technique is based on the generation of a pressure wave when a microsecond-pulsed relativistic ion beam is stopped in a water container. The acoustic signal from individual ion pulses is registered by a piezoelectric detector and analyzed in the time/frequency domain to identify the location of pressure wave generation. The experiments were performed at the SIS18 synchrotron at GSI Helmholtzzentrum (Darmstadt, Germany) with Xe, Pb and U ions of energies between 200 MeV/u and 1 GeV/u. We show that the signal amplitude of the acoustic pressure pulse has a linear correlation with the beam intensity within a range of at least 104 to 109 particles/spill.By determining the delay time of the primary and reflected acoustic signal in the water reservoir, the ionoacoustic technique provides information on ion ranges of 1 % accuracy. By an energy-range calibration in combination with a simulation code such as FLUKA, the range data can be used to determine the beam energy. As demonstrated, inserting targets of known thickness in front of the detector is a simple approach for measuring the energy loss of relativistic ions. The advantage of the ionoacoustic technique is the rather simple experimental setup, the huge dynamic range, the information available online by means of only a single pulse and its radiation hardness. Ionoacoustic detectors have great potential as intensity and energy monitor for short-pulsed light and heavy ion beams at existing or future high-energy ion facilities.

Measuring tau g-2 using ATLAS Pb+Pb collisions

Relativistic heavy-ion beams at the LHC are accompanied by a large flux of equivalent photons, leading to photon-induced processes. Measurements of photon-induced production of tau lepton pairs can be used to constrain the tau lepton's anomalous magnetic dipole moment (g-2). A recent ATLAS measurement using muonic decays of tau leptons in association with electrons and tracks is presented. This provides one of the most stringent limits on g-2 of the tau lepton to date.

Studies of three-and four-body hypernuclei with heavy-ion beams, nuclear emulsions and machine learning

Interests on few-body hypernuclei have been increased by recent results of experiments employing relativistic heavy ion beams. Some of the experiments have revealed that the lifetime of the lightest hypernucleus, hypertriton, is significantly shorter than 263 ps which is expected by considering the hypertriton to be a weakly-bound system. The STAR collaboration has also measured the hypertriton binding energy, and the deduced value is contradicting to its formerly known small binding energy. These measurements have indicated that the fundamental physics quantities of the hypertriton such as its lifetime and binding energy have not been understood, therefore, they have to be measured very precisely. Furthermore, an unprecedented Λnn bound state observed by the HypHI collaboration has to be studied in order to draw a conclusion whether or not such a bound state exists. These three-body hypernuclear states are studied by the heavy-ion beam data in the WASA-FRS experiment and by analysing J-PARC E07 nuclear emulsion data with machine learning.

Elastic Photon Scattering on Hydrogenic Atoms near Resonances

Scattering of light on relativistic heavy ion beams is widely used for characterizing and tuning the properties of both the light and the ion beam. Its elastic component—Rayleigh scattering—is investigated in this work for photon energies close to certain electronic transitions because of its potential usage in the Gamma Factory initiative at CERN. The angle-differential cross-section, as well as the degree of polarization of the scattered light are investigated for the cases of 1 s − 2 p 1 / 2 and 1 s − 2 p 3 / 2 resonance transitions in H-like lead ions. In order to gauge the validity and uncertainty of frequently used approximations, we compare different methods. In particular, rigorous quantum electrodynamics calculations are compared with the resonant electric-dipole approximation evaluated within the relativistic and nonrelativistic formalisms. For better understanding of the origin of the approximation, the commonly used theoretical approach is explained here in detail. We find that in most cases, the nonrelativistic resonant electric-dipole approximation fails to describe the properties of the scattered light. At the same time, its relativistic variant agrees with the rigorous treatment within a level of 10% to 20%. These findings are essential for the design of an experimental setup exploiting the scattering process, as well as for the determination of the scattered light properties.

Charge state tailoring of relativistic heavy ion beams for the Gamma Factory project at CERN

We present charge‐state evolution studies for Pb54+ ion beams passing through stripper foils at relativistic energies of 5.9 GeV/u. The purpose of this investigation is to determine the optimum target material and non‐equilibrium thickness for the efficient production of few‐electron lead ions, that is, Pb80+ and Pb81+, at the present European Organization for Nuclear Research, CERN, accelerator facility at energies as high as 5.9 GeV/u. Based on these predictions, an Al stripper foil has been selected for a proof‐of‐principle measurement in the frame of the Gamma Factory study group. The experimental data confirms a substantial yield of non‐bare Pb ions. In addition, a charge‐state evolution study for the production of Li‐like lead ions Pb79+ is presented, which will be subject of a follow‐up experiment in the near future.

Studies of baryonic matter at the BM@N experiment (JINR)

BM@N (Baryonic Matter at Nuclotron) is the first experiment undertaken at the accelerator complex of NICA-Nuclotron. The aim of the BM@N experiment is to study interactions of relativistic heavy ion beams with fixed targets. The scientific program of the BM@N experiment comprises studies of nuclear matter in the intermediate energy range between experiments at the SIS and NICA/FAIR facilities. The BM@N experiment has recorded first experimental data in December 2016. The experimental runs were performed in the deuteron and carbon beams of kinetic energy per nucleon ranging from 3.5 to 4.5 GeV. The extended configuration of the BM@N set-up was realized in recent runs with the argon and krypton beams. The first measurement of short range correlations of nucleons in carbon nucleus was performed in inverse kinematics with the carbon beam and liquid hydrogen target. The experimental program covering physics of heavy ion collisions as well as first experimental results on the production of hyperons are presented.

Hyperons at the BM@N experiment: first results

BM@N (Baryonic Matter at Nuclotron) is the first experiment to be realized at the accelerator complex of NICA-Nuclotron at JINR (Dubna). The aim of the experiment is to study interactions of relativistic heavy ion beams of kinetic energy per nucleon ranging from 1 to 4.5 GeV with fixed targets. First results of the analysis of minimum bias interactions of the deuteron and carbon beams of 4 AGeV kinetic energy with different targets are discussed. Preliminary results from the data collected in the recent experimental run with the argon beam are also presented.

Design studies for the NeuLAND VETO detector

NeuLAND (New Large-Area Neutron Detector) is the neutron detector for the R3B-experiment (Reactions with Relativistic Radioactive Beams) at FAIR (Facility for Anti-proton and Ion Research). NeuLAND is a fully active detector composed of plastic scintillator bars. Neutrons are detected by the production of charged particles in the scintillators through hadronic scattering. These charged particles are then detected by their scintillation light. Due to the highly granular design of NeuLAND, the primary neutron interaction points can be accurately reconstructed. These reconstructed points contribute to a kinematically complete reconstruction of reactions with relativistic heavy-ion beams in the target, the goal of the R3B-experiment. However, charged particles produced by scattering on other parts of the R3B-setup may provide a significant background. To distinguish the target neutrons from the background, a VETO detector could be placed in front of NeuLAND. This VETO detector is a single plane of thin plastic scintillator bars. It, therefore, provides a high detection efficiency for background particles, but a low detection efficiency for neutrons. For every signal in the VETO, NeuLAND signals can be analyzed with respect to their correlation to the VETO signal and can be eliminated from the further neutron analysis. In this paper, the design of this VETO detector is discussed.

The BM@N Experiment at JINR: Status and Physics Program

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Lifetimes of relativistic heavy-ion beams in the High Energy Storage Ring of FAIR

Abstract The High Energy Storage Ring, HESR, will be constructed at the Facility for Antiproton and Ion Research, FAIR, Darmstadt. For the first time, it will be possible to perform experiments with cooled high-intensity stable and radioactive heavy ions at highly relativistic energies. To design experiments at the HESR, realistic estimations of beam lifetimes are indispensable. Here we report calculated cross sections and lifetimes for typical U 88 + , U 90 + , U 92 + , Sn 49 + and Sn 50 + ions in the energy range E = 400 MeV/u–5 GeV/u, relevant for the HESR. Interactions with the residual gas and with internal gas-jet targets are also considered.

First Results from BM@N Technical Run with Deuteron Beam

BM@N (Baryonic Matter at Nuclotron) is the first experiment to be realized at the accelerator complex of NICA-Nuclotron at JINR (Dubna). The aim of the experiment is to study interactions of relativistic heavy ion beams with a kinetic energy from 1 to 4.5 AGeV with fixed targets. The BM@N set-up at the starting phase of the experiment is introduced. First results of the analysis of minimum bias experimental data collected in the technical run in interactions of the deuteron beam of 4 AGeV with different targets are presented. The spacial, momentum and primary vertex resolution of the GEM tracker are studied. The signal of Lambda-hyperon is reconstructed in the proton-pion invariant mass spectrum. The data results are described by Monte Carlo simulations. The investigation has been performed at the Laboratory of High Energy Physics, JINR.

The fixed target experiment for studies of baryonic matter at the Nuclotron (BM@N)

BM@N (Baryonic Matter at Nuclotron) is the first experiment to be realized at the accelerator complex of NICA-Nuclotron. The aim of the BM@N experiment is to study interactions of relativistic heavy ion beams with fixed targets. The BM@N setup, results of Monte Carlo simulations, the BM@N experimental program and results of technical runs are presented.

The Fixed Target Experiment for Studies of Baryonic Matter at the Nuclotron (BM@N)

BM@N (Baryonic Matter at Nuclotron) is the first experiment to be realized at the NICA-Nuclotron accelerator complex. The aim of the BM@N experiment is to study relativistic heavy ion beam interactions with fixed targets. The BM@N setup, results of Monte Carlo simulations, and the BM@N experimental program are presented.

Simulation of longitudinal dynamics of laser-cooled and RF-bunched C3+ ion beams at heavy ion storage ring CSRe**Supported by National Natural Science Foundation of China (11405237, 11504388)

Laser cooling of Li-like C3+ and O4+ relativistic heavy ion beams is planned at the experimental Cooler Storage Ring (CSRe). Recently, a preparatory experiment to test important prerequisites for laser cooling of relativistic 12C3+ ion beams using a pulsed laser system has been performed at the CSRe. Unfortunately, the interaction between the ions and the pulsed laser cannot be detected. In order to study the laser cooling process and find the optimized parameters for future laser cooling experiments, a multi-particle tracking method has been developed to simulate the detailed longitudinal dynamics of laser-cooled ion beams at the CSRe. Simulations of laser cooling of the 12C3+ion beams by scanning the frequency of the RF-buncher or continuous wave (CW) laser wavelength have been performed. The simulation results indicate that ion beams with a large momentum spread could be laser-cooled by the combination of only one CW laser and the RF-buncher, and show the requirements of a successful laser cooling experiment. The optimized parameters for scanning the RF-buncher frequency or laser frequency have been obtained. Furthermore, the heating effects have been estimated for laser cooling at the CSRe. The Schottky noise spectra of longitudinally modulated and laser-cooled ion beams have been simulated to fully explain and anticipate the experimental results. The combination of Schottky spectra from the highly sensitive resonant Schottky pick-up and the simulation methods developed in this paper will be helpful to investigate the longitudinal dynamics of RF-bunched and ultra-cold ion beams in the upcoming laser cooling experiments at the CSRe.

Accurate isotopic fission yields of electromagnetically induced fission of U238 measured in inverse kinematics at relativistic energies

SOFIA (Studies On Fission with Aladin) is a novel experimental program, dedicated to accurate measurements of fission-fragment isotopic yields. The setup allows us to fully identify, in nuclear charge and mass, both fission fragments in coincidence for the whole fission-fragment range. It was installed at the GSI facility (Darmstadt), to benefit from the relativistic heavy-ion beams available there, and thus to use inverse kinematics. This paper reports on fission yields obtained in electromagnetically induced fission of U238.15 MoreReceived 14 February 2017DOI:https://doi.org/10.1103/PhysRevC.95.054603©2017 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasFissionLow & intermediate energy heavy-ion reactionsNuclear reactionsPhotonuclear reactionsTechniquesNuclear data analysis & compilationNuclear Physics

The fixed target experiment for studies of baryonic matter at the Nuclotron (BM@N)

BM@N (Baryonic Matter at Nuclotron) is the first experiment to be realized at the accelerator complex of NICA-Nuclotron. The aim of the BM@N experiment is to study interactions of relativistic heavy-ion beams with fixed targets. The BM@N setup, results of Monte Carlo simulations and the BM@N experimental program are presented.