Recently, multiparticle-correlation measurements of relativistic p/d/^{3}He+Au, p+Pb, and even p+p collisions show surprising collective signatures. Here, we present beam-energy-scan measurements of ...two-, four-, and six-particle angular correlations in d+Au collisions at sqrts_{NN}=200, 62.4, 39, and 19.6 GeV. We also present measurements of two- and four-particle angular correlations in p+Au collisions at sqrts_{NN}=200 GeV. We find the four-particle cumulant to be real valued for d+Au collisions at all four energies. We also find that the four-particle cumulant in p+Au has the opposite sign as that in d+Au. Further, we find that the six-particle cumulant agrees with the four-particle cumulant in d+Au collisions at 200 GeV, indicating that nonflow effects are subdominant. These observations provide strong evidence that the correlations originate from the initial geometric configuration, which is then translated into the momentum distribution for all particles, commonly referred to as collectivity.
The generation of beams of secondary particles (π and
K
mesons) at proton accelerators is a difficult scientific and engineering problem. To obtain narrow directional particle beams for experiments, ...intense extracted proton beams are used, secondary particles (π and
K
mesons) are generated at an external target, and they are focused and transferred through long magneto-optical channels. In this work, a surprisingly simple method based on a crystal focusing device has been proposed to obtain secondary beams. An experiment on the production of a secondary beam using a crystal has been performed at the U-70 accelerator. Schemes for the formation of beams with energies
E
~ 1 TeV have been proposed for large colliders such as the Large Hadron Collider.
Inclusive transverse momentum spectra of eta mesons have been measured within p(T)=2-10 GeV/c at midrapidity by the PHENIX experiment in Au+Au collisions at root s(NN) = 200 GeV. In central Au+Au the ...eta yields are significantly suppressed compared to peripheral Au+Au, d+Au, and p+p yields scaled by the corresponding number of nucleon-nucleon collisions. The magnitude, centrality, and p(T) dependence of the suppression is common, within errors, for eta and pi(0). The ratio of eta to pi(0) spectra at high p(T) amounts to 0.40 < R-eta/pi(0)< 0.48 for the three systems, in agreement with the world average measured in hadronic and nuclear reactions and, at large scaled momentum, in e(+)e(-) collisions.
The Multi-Purpose Detector (MPD) is constructing to study the properties of the hot and dense matter created in heavy-ion collisions in the energy range of 4-11 A*GeV where the maximum baryonic ...density is expected. The crucial detector in the new experimental setup is a large-sized barrel electromagnetic calorimeter (ECal), designed for precise spatial and energy measurements for photons and electrons. Taking into account the requirements of high energy resolution, dense active medium with the small Moliere radius, and high segmentation of ECal, the Shashlyk-type electromagnetic calorimeter with projective geometry has been selected. The mass production of ECal modules has been started. In this talk, we report about methods and technologies for the quality control of ECal modules and their components.
Channeling efficiency in a target-crystal assembly Scandale, W.; Cerutti, F.; Esposito, L.S. ...
Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms,
03/2020, Volume:
467
Journal Article
Peer reviewed
In view of possible future fixed target experiments requiring precisely steered charged particle beams, the UA9 Collaboration has undertaken experimental studies of the use of bent silicon crystals ...for this purpose. The channeling efficiency of positively charged particles inside the crystalline lattice has been investigated in detail for a setup with a tungsten target installed in front of the crystal. Due to multiple Coulomb scattering inside the target, the channeling efficiency was observed to be reduced by a factor of about 6.1 for a 180 GeV/c quasi-parallel hadron beam. The yield of nuclear interaction secondaries as an estimation of the additional machine background is also discussed.
The UA9 setup for the double-crystal experiment in CERN-SPS Scandale, W.; Cerutti, F.; Esposito, L.S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2020, Volume:
975
Journal Article
Peer reviewed
Experiments to measure the electric and the magnetic moments of short-lived baryons using an internal target and two bent crystals in the vicinity of one of the existing LHC detectors were recently ...proposed, in the frame of the Physics Beyond Colliders Working Group at CERN. Investigating fixed-target physics in the LHC with in-vacuum solid targets is an unprecedented challenge. As a preparatory step, the layout of the UA9 experiment, installed in the CERN SPS to explore beam manipulations assisted by bent crystals, has been modified to study the feasibility of the double-crystal scenario in a circular accelerator. Ideally, the first crystal should capture halo protons in channeling states directing them onto the internal target to produce rare baryons, whilst the second crystal, located just downstream of the target, should channel the baryons, rotate their polarization vector and deflect them towards the detector area. The upgraded UA9 layout is presented. Preliminary measurements providing an insight of the beam behavior are reported.
Recently studies are started on the application of volume reflection of particles in crystals for the steering beams (for extraction and collimation of a circulating beam in accelerators). Volume ...reflection is more efficient than channeling, but requires amplification of the deflection angle by applying multicrystals. The report discusses two new applications of multicrystals made like multistrip structures: (i) the property of effective deflection of particle beam was used to protect the septum magnets of the U-70 in the process of extraction of the proton beam with energy of 50 GeV; (ii) the possibility of generation of gamma radiation was studied in the secondary electron beam with energy of 7 GeV. In both cases, promising preliminary data were obtained.
This paper describes an experiment on focusing a proton beam with an energy of 50 GeV on the U‑70 accelerator using a crystal device. The focusing device is based on the use of bending a ...plane-parallel silicon wafer in which the side faces are rotated relative to the crystallographic planes by a small angle. The beam is focused at a distance of 10 cm into a narrow line with a width of FWHM ~7 μm. The prospects for using such a short-focus device on modern accelerators are described.
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