The polarized proton and antiproton beam channel is currently under development at the U-70 accelerator of IHEP, Protvino, Russia. An availability of the both, polarized protons and antiprotons ...provides an exciting opportunity for the comparative studies of spin effects induced by polarized protons and antiprotons in a variety of hadronic reactions. While the proton and antiproton beams are formed by essentially the same method, there is the specific in the antiproton beam shaping and properties compared to protons. In this report, we address some technical details of forming the polarized antiproton beam and describe its main properties.
The absolute polarimeter based on the elastic p̄p-scattering in the diffraction kinematic regions with the total momentum transfer squared coverage of 0.1 < − t < 0.3 (GeV c)2 is proposed for the ...polarized antiproton beam at the U-70 proton synchrotron of IHEP. It is shown that it would take ∼200-400 hours for measuring the beam polarization at the statistical errors of ΔPB PB 10-15%. These time estimates include also the time which is necessary for the measurements of an analyzing power AN, using a polarized target. Besides the measurements of beam polarizations, the proposed polarimeter provides an opportunity for carrying out the experimental studies of the small momentum transfers physics which would be a valuable enrichment of the SPASCHARM experiment capabilities and its physics program.
The new SPASCHARM experiment for systematic studies of polarization phenomena in strong interactions is under construction now at IHEP, Protvino. The technical beam runs for the experiment first ...stage are planned for the Fall 2016 and Spring 2017. At this stage, the polarization measurements will be carried out with unpolarized hadronic beams of various compositions (π±, K±, p, antiprotons), using the polarized target. The universal large acceptance experimental set-up is capable detecting and identification most charged and neutral particles and reconstructing a large number of resonances produced in beam interactions at polarized proton target, and later on at the second stage, in collisions of polarized proton and antiproton beams with fixed targets of various materials. The large acceptance and wide data acquisition bandwidth would provide the capabilities for simultaneous data accumulation for a number of physics analyses from the measurements of single-spin asymmetries in inclusive and exclusive reactions to reconstructions of final state hyperon polarizations and spin density matrix elements for vector mesons in a wide range of kinematic variables (pT, xF).
A new experiment SPASCHARM for systematic study of polarization phenomena in inclusive and exclusive hadronic reactions is currently under commissioning at IHEP. The universal experimental setup will ...detect dozens of various resonances and stable particles produced in collisions of unpolarized beams with the polarized target, and at the next stage, using polarized beams. At the first stage with polarized target, the final states composed of light quarks (u, d, s) will be reconstructed. Hyperon polarization and spin density matrix elements of the vector mesons will be measured along with the single-spin asymmetries. The 2π-acceptance in azimuth, which is extremely useful for reduction of systematic errors in measurements of spin observables, will be implemented in the experiment. The solid angle acceptance of the setup, Δθ≈250 mrad vertically and 350 mrad horizontally in the beam fragmentation region, covers a wide range of kinematic variables pT and xF. This provides the opportunity for separating dependences on these two variables which is usually not possible in the setups with a small solid angle acceptance. Unlike some previous polarization experiments, the SPASCHARM will be able to simultaneously accumulate and record data on the both, charged and neutral particle production.
The electromagnetic calorimeter of PANDA at the FAIR facility will rely on the operation of lead tungstate (PbWO
4, PWO) scintillating crystals at temperatures near
-
25
∘
C
to provide sufficient ...resolution for photons in the energy range from 8
GeV down to 10
MeV. The radiation hardness of PWO crystals was studied at the IHEP (Protvino) irradiation facility in the temperature range from
+
20
∘
C
(room temperature) down to
-
23
∘
C
. These studies have indicated significantly different behavior in the time evolution of the damaging processes well below room temperature. Different signal loss levels at the same dose rate but at different temperatures were observed. The effect of a deep suppression of the crystal recovery process at temperatures below
0
∘
C
has been seen.
Identified charged pion, kaon, and proton spectra are used to explore the system size dependence of bulk freeze-out properties in Cu+Cu collisions at {radical}s{sub NN} = 200 and 62.4 GeV. The data ...are studied with hydrodynamically motivated blast-wave and statistical model frameworks in order to characterize the freeze-out properties of the system. The dependence of freeze-out parameters on beam energy and collision centrality is discussed. Using the existing results from Au + Au and pp collisions, the dependence of freeze-out parameters on the system size is also explored. This multidimensional systematic study furthers our understanding of the QCD phase diagram revealing the importance of the initial geometrical overlap of the colliding ions. The analysis of Cu+Cu collisions expands the system size dependence studies from Au+Au data with detailed measurements in the smaller system. The systematic trends of the bulk freeze-out properties of charged particles is studied with respect to the total charged particle multiplicity at midrapidity, exploring the influence of initial state effects.
Future of low-x forward physics at RHIC Bland, L. C.; Bieser, F.; Brown, R. L. ...
The European physical journal. C, Particles and fields,
08/2005, Letnik:
43, Številka:
1-4
Journal Article
Recenzirano
Odprti dostop
Comparisons of particle production from high-energy ion collisions with next-to-leading order perturbative QCD calculations show good agreement down to moderate transverse momentum values. ...Distributions of azimuthal angle differences between coincident hadrons in these collisions support a partonic origin to the particle production, again down to moderate transverse momentum values. The rapidity dependence of inclusive and coincident particle production can therefore be used to probe parton distribution functions down to small momentum fractions where theory anticipates that parton saturation could be present. This paper describes how such experiments could be completed.
Azimuthal anisotropy (v(2)) and two-particle angular correlations of high p(T) charged hadrons have been measured in Au+Au collisions at sqrts(NN)=130 GeV for transverse momenta up to 6 GeV/c, where ...hard processes are expected to contribute significantly. The two-particle angular correlations exhibit elliptic flow and a structure suggestive of fragmentation of high p(T) partons. The monotonic rise of v(2)(p(T)) for p(T)<2 GeV/c is consistent with collective hydrodynamical flow calculations. At p(T)>3 GeV/c, a saturation of v(2) is observed which persists up to p(T)=6 GeV/c.
PANDA electromagnetic calorimeters Semenov, P.A.; Kharlov, Yu.V.; Uzunian, A.V. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2009, 2009-1-00, Letnik:
598, Številka:
1
Journal Article
Recenzirano
PANDA is a challenging experimental setup to be implemented at the high-energy storage ring (HESR) at the international facility FAIR, GSI (Germany). PANDA physics program relies heavily on the ...capability to measure photons with excellent energy, position and timing resolution. For this purpose PANDA proposed to employ electromagnetic calorimeters using two different technologies: compact crystal calorimeter cooled to
-
25
∘
C
around target and lead–scintillator sandwich calorimeter with optical fibers light collection (so-called shashlyk calorimeter) in the forward region.
Institute for High Energy Physics (IHEP) PANDA group reports on two types of measurements performed at IHEP, Protvino: radiation hardness of the PWO crystals at
-
25
∘
C
and testbeam studies of the energy and position resolution of the shashlyk calorimeter prototype in the energy range up to 19
GeV.
Parity-odd domains, corresponding to nontrivial topological solutions of the QCD vacuum, might be created during relativistic heavy-ion collisions. These domains are predicted to lead to charge ...separation of quarks along the system's orbital momentum axis. We investigate a three-particle azimuthal correlator which is a P even observable, but directly sensitive to the charge separation effect. We report measurements of charged hadrons near center-of-mass rapidity with this observable in Au + Au and Cu + Cu collisions at square root of s(NN) = 200 GeV using the STAR detector. A signal consistent with several expectations from the theory is detected. We discuss possible contributions from other effects that are not related to parity violation.
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