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At least 19 records

Hadron production measurement in the NA61/SHINE experiment at the CERN SPS for neutrino and cosmic ray experiments

This paper is focused on one of the physics goals of the NA61/SHINE experiment: measurements of hadron production needed for neutrino (T2K) and cosmic-ray (Pierre Auger and KASKADE) experiments. Knowledge of pion and kaon production from proton-Carbon interactions at 31GeV/c is of key importance for improving the accuracy of neutrino flux simulations of the T2K experiment at J-PARC. This information also helps to improve the accuracy of Monte Carlo models used in cosmic-ray physics. Three different methods of pion spectra extraction and two approaches for the kaon case are presented. Final differential cross section in several intervals of emission angle of charged pions and preliminary results for kaons are shown for p+C interactions at 31GeV/c based on the sample of events registered in the 2007 pilot run.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

Laser-seeded modulation instability within LHC proton beams

A new method for seeding the modulation instability (MI) within an SPS-LHC proton beam using a laser pulse is presented. Using simulations, we show that a laser pulse placed ahead of a proton beam excites axially symmetric selfmodulation modes within the proton beam and leads to peak accelerating fields that are comparable to previously proposed seeding methods.

43 PARTICLE ACCELERATORS↗

Proposed method for high-speed plasma density measurement in proton-driven plasma wakefield acceleration

Recently a proton-bunch-driven plasma wakefield acceleration experiment using the CERN-SPS beam was proposed. Different types of plasma cells are under study, especially laser ionization, plasma discharge, and helicon sources. One of the key parameters is the spatial uniformity of the plasma density profile along the cell that has to be within < 1% of the nominal density (6 Multiplication-Sign 10{sup 14} cm{sup -3}). Here a setup based on a photomixing concept is proposed to measure the plasma cut-off frequency and determine the plasma density.

43 PARTICLE ACCELERATORS↗

The exploration of the phase diagram of strongly interacting matter at the CERN SPS

The study of central collisions of heavy nuclei at CERN SPS energies revealed rapid changes in the energy dependence of hadron production properties in a narrow range around 30A GeV. The results indicate the onset of deconfinement in the early stage of the produced system and motivates the ongoing search for the predicted critical point. NA49 data on event-by-event fluctuations of transverse momentum, multiplicity, particle ratios as well as low mass pion pairs and proton number fluctuations are shown as a function of beam energy and system size.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

CERN and 60 years of science for peace

This paper presents CERN as it celebrates its 60{sup th} Anniversary since its founding. The presentation first discusses the mission of CERN and its role as an inter-governmental Organization. The paper also reviews aspects of the particle physics research programme, looking at both current and future accelerator-based facilities at the high-energy and intensity frontiers. Finally, the paper considers issues beyond fundamental research, such as capacity-building and the interface between Art and Science.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

Current and future liquid argon neutrino experiments

The liquid argon time projection chamber (LArTPC) detector technology provides an opportunity for precision neutrino oscillation measurements, neutrino cross section measurements, and searches for rare processes, such as SuperNova neutrino detection. These proceedings review current and future LArTPC neutrino experiments. Particular focus is paid to the ICARUS, MicroBooNE, LAr1, 2-LArTPC at CERN-SPS, LBNE, and 100 kton at Okinoshima experiments.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Multifractal moments in heavy ion Pb-Pb collisions at 158 A GeV

In present work, we use the method of scaled factorial moments to search for intermittent behavior in Pb-Pb interactions at 158 A GeV. The analysis is done on photon distributions obtained using preshower photon multiplicity detector. Scaled factorial moments are used to study short range fluctuations in pseudorapidity distributions of photons. Scaled factorial moments are calculated using horizontal corrected and vertical analysis. The results are compared with simulation analysis using VENUS event generator.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

Rad-hard readout system for Timepix3 Hybrid Pixel Detectors

The Beam Gas Ionisation (BGI) profile monitor, located in the Proton Synchrotron (PS) and Super Proton Synchrotron (SPS) at CERN, requires a radiation-tolerant readout system to transfer data from the challenging accelerator surroundings to the back-end for processing. The system needs to control and acquire data from four Timepix3 Hybrid Pixel Detectors (HPDs) located directly inside the beam pipe, a highly radioactive environment. It must ensure reliability given limited hardware access and preserve signal integrity for the high-speed data (32 channels at 320 MHz). However, due to the unavailability of a suitable rad-hard Timepix3 readout, the Beam Instrumentation PiXeL (BIPXL) readout system was designed to meet these requirements. This system employs radiation-hardened components such as the GBTx and the FEASTMP, both developed at CERN. It will be compatible with forthcoming hybrid pixel detector initiatives in similarly harsh radiation conditions.

47 OTHER INSTRUMENTATION↗

Transverse emittance growth due to rf noise in crab cavities: Theory, measurements, cure, and high luminosity LHC estimates

The High-Luminosity LHC (HL-LHC) upgrade with planned operation from 2029 onward has a goal of achieving a tenfold increase in the integrated number of recorded collisions thanks to a doubling of the intensity per bunch ( 2.2 × 10 11 protons) and a reduction of β * (the β value in the two high luminosity detectors, namely ATLAS and CMS) to 15 cm. Such an increase in recorded collisions would significantly expedite new discoveries and exploration. Crab cavities are an important component of the HL-LHC upgrade and will contribute strongly to achieving an increase in the number of recorded collisions. However, noise injected through the crab cavity radio frequency (rf) system could cause significant transverse emittance growth and limit luminosity lifetime. We presented a theoretical formalism relating transverse emittance growth to rf noise in an earlier work. In this follow-up paper, we summarize measurements in the super-proton synchrotron (SPS) at CERN that validate the theory, we present estimates of the emittance growth rates using state-of-the-art rf and low-level rf (LLRF) technologies, and we set the rf noise specifications to achieve acceptable performance. A novel dedicated feedback system acting through the crab cavities to mitigate emittance growth will be required. In this work, we develop a theoretical formalism to evaluate the performance of such a feedback system in any collider, identify limiting components, present simulation results to validate these studies, and derive key design parameters for an HL-LHC implementation of such a feedback system. Published by the American Physical Society 2024

43 PARTICLE ACCELERATORS↗

HiRadMat: A high-energy, pulsed beam, material irradiation facility

HiRadMat is a recently constructed facility designed to provide high-intensity pulsed beams to an irradiation area where different material samples or accelerator components can be tested. The facility, located at the CERN SPS accelerator complex, uses a 440 GeV proton beam with a pulse length up to 7.2 μs and a maximum intensity up to 10{sup 13} protons / pulse. The facility, a unique place for performing state-of-the art beam-to-material experiments, operates under transnational access and welcomes and financially supports, under certain conditions, experimental teams to perform their experiments. (authors)

43 PARTICLE ACCELERATORS↗

Searching for the QCD critical point in AA collisions at CERN SPS

We investigate the transverse momentum correlations of pairs of opposite charged pions near their production threshold. Through intermittency analysis, we search for power-law dependence on observation scale, as dictated by critical QCD. We analyze the data on the most central collisions in four A systems (A = p, C, Si, Pb) at maximum SPS energy. We find a significant effect for the SiSi system approaching in size the critical QCD predictions as measured by the intermittency index {phi}{sub 2}. Absence of this effect in the ({pi}{sup -}, {pi}{sup -}) sector of the SiSi system gives further support that the observed behavior in the isoscalar mode is of critical origin.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Identity method-a new tool for studying chemical fluctuations

Event-by-event fluctuations of the chemical composition of the hadronic system produced in nuclear collisions are believed to be sensitive to properties of the transition between confined and deconfined strongly interacting matter. In this paper a new technique for the study of chemical fluctuation, the identity method, is introduced and its features are discussed. The method is tested using data on central PbPb collisions at 40 A GeV registered by the NA49 experiment at the CERN SPS.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

A formula for charmonium suppression

In this work a formula for charmonium suppression obtained by Matsui in 1989 is analytically generalized for the case of complex cc-barpotential described by a 3-dimensional and isotropic time-dependent harmonic oscillator (THO). It is suggested that under certain scheme the formula can be applied to describe J/{psi} suppression in heavy-ion collisions at CERN-SPS, RHIC, and LHC with the advantage of analytical tractability.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Fission and fragmentation of {sup 208}Pb nuclei in collisions with gold nuclei at an energy of 158 GeV per nucleon

The fission and fragmentation of ultrarelativistic {sup 208}Pb nuclei in collisionswith gold nuclei were studied by using a beam from the SPS accelerator at CERN at an energy of 158 GeV per nucleon. The detectors of the target area of the NA45/CERES spectrometer were used in respective measurements. The value obtained for the fission cross section is 301 {+-} 44 mb, where about 77% of events stem from the electromagnetic interaction of colliding nuclei, while the remaining part is the contribution of peripheral nuclear interactions. The spallation of lead nuclei that involves the formation of heavy fragments occurs only in collisions where the impact parameter satisfies the condition b > 10 fm. A complete disintegration of lead nuclei to intermediate-mass fragments and light particles is observed in some peripheral collisions.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

COMPASS results on collins and sivers asymmetries for charged hadrons

The study of transverse spin and transverse momentum effects is an important part of the scientific program of COMPASS, a fixed target experiment at the CERN SPS taking data since 2002. The studies are carried on by measuring the hadrons produced in deep inelastic scattering (DIS) of 160 GeV/ c muons off different targets. Among the possible asymmetries in the hadron azimuthal distributions, particularly interesting are the Collins and Sivers asymmetries which the COMPASS Collaboration has measured using transversely polarised deuteron and proton targets. Here new results for charged pions and kaons obtained from the 2010 run with a transversely polarised proton target are presented for the first time.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Spin filtering at COSY and perspectives for PAX

The high physics potential of experiments with stored polarized antiprotons led to the proposal of the PAX [1] experiment (Polarized Antiproton eXperiment) for the High Energy Storage Ring (HESR) of the new FAIR facility at GSI (Darmstadt/Germany). It is proposed to polarize a stored antiproton beam by means of spin filtering by a polarized hydrogen gas target. The feasibility of spin filtering with protons using a transversely polarized hydrogen gas target has been demonstrated in the FILTEX experiment [2] and recently confirmed at the COSY ring in Jülich. A spin filtering experiment using a longitudinally polarized hydrogen gas target is planned after the installation of a siberian snake in 2014. Further measurements including the investigation of pd-breakup reactions [3] and a test of the time reversal (TRIC) [4] are planned using the developed experimental setup. A proposal for a spin-filtering experiment with antiprotons at AD/CERN [5] has been submitted to the CERN SPS comitee to investigate the spin-dependence of the pbar-p and pbar-d interaction. This knowledge is necessary to properly design a dedicated Antiproton-Polarizer Ring.

43 PARTICLE ACCELERATORS↗

Unpolarized azimuthal asymmetries in SIDIS at COMPASS

The study of the spin structure of the nucleon and of the effects due to the quarks transverse momentum are part of the scientific program of COMPASS, a fixed target experiment at the CERN SPS. The azimuthal modulations which appear in the cross-section of SIDIS off unpolarised targets give insight on the intrinsic momentum structure of the nucleon and on the possible correlation between transverse spin and transverse momentum of the quarks. We present the results for the amplitudes of the cos(ϕ), cos(2ϕ), and sin(ϕ) modulatuions (where ϕ is the azimuthal hadron angle in the gamma-nucleon system) obtained from the COMPASS data collected with a 160 GeV/c positive muon beam impinging on a deuteron target. The amplitudes are measured for both positive and negative hadrons, and the results on the dependence of the relevant kinematical variables obtained after a multi dimensional analysis are also presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Testing sterile neutrinos with new fixed target experiment at CERN SPS

We discuss the recently proposed new fixed target experiment at CERN with SPS beam of 400 GeV protons aimed at searches for sterile neutrinos produced in charmed hadron decays. The three sterile neutrino introduced to the Standard Model can explain the active neutrino masses and mixings by means of seesaw type I mechanism, baryon asymmetry of the Universe by making use of leptogenesis via sterile-active neutrino oscillations in the primordial plasma, and dark matter phenomenon due to a relic component of the lightest sterile neutrino. The new beam-dump with detector placed as close to the target as possible will allow to test many other extensions of the Standard Model with new unstable yet long-lived particles at GeV mass scale.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗