The results of E-190 experiment (project Thermalization) with 50 GeV proton beam irradiation of SVD-2 setup are presented. MC simulation has shown the linear dependence of number of photons detected ...in electromagnetic calorimeter and the average number of neutral pions. Multiplicity distribution of neutral pion, N0, for total number of particles in the event, Ntot = Nch + N0, are obtained with corrections on the setup acceptance, triggering and efficiency of the event reconstruction. The scaled variance of neutral pion fluctuations, ω = D/ < N0 >, versus total multiplicity is measured. The fluctuations increase at Ntot > 18. According to quantum statistics models this behavior can indicate a pion condensate formation in the high pion multiplicity system. This effect has been observed for the first time.
High-multiplicity study Kokoulina, E. S.; Kutov, A. Ya
Physics of atomic nuclei,
09/2008, Letnik:
71, Številka:
9
Journal Article
Recenzirano
Theoretical and experimental problems of multiparticle production are analyzed in the high-multiplicity region. Interesting collective phenomena may be revealed in this region. Preliminary results of ...the Thermalization Project are being reported.
Proton interactions with high multiplicity Kokoulina, E. S.; Nikitin, V. A.; Petukhov, Y. P. ...
Physics of atomic nuclei,
06/2012, Letnik:
75, Številka:
6
Journal Article
Recenzirano
Odprti dostop
Project Thermalization is aimed to study the proton-proton interaction with high multiplicity of secondary particles. The region of high multiplicity is especially actual at present. We expect the ...manifestation of the secondary particle collective behavior at this region. The experimentally measured topological cross section was corrected for apparatus acceptance and detection efficiency. These data are in good agreement with gluon dominance model. The comparison with other models is also done and shows no essential deviations. There is evidence that Bose-Einstein condensation can formed at high total multiplicity region.
New results of the search for collective phenomena have been obtained and analyzed in the present report. The experimental studies are carried out on U-70 accelerator of IHEP in Protvino. It is ...suggested that these phenomena can be discovered at the energy range of 50–70 GeV in the extreme multiplicity region since the high-density matter can form in this very region. The collective behavior of secondary particles is considered to manifest itself in the Bose-Einstein condensation of pions, Vavilov-Cherenkov gluon radiation, excess of soft-photon yield, and other unique phenomena. The perceptible peak in the angular distribution has been revealed. It was interpreted as the gluon radiation and so the parton matter refraction index was determined. The new software was designed for the track reconstruction based on Kalman Filter technique. This algorithm allows one to estimate more precisely the track parameters (especially momentum). The search for Bose-Einstein condensation can be continued by using the selected events with the multiplicity of more than eight charged particles. The gluon dominance model predictions have shown good agreement with the multiplicity distribution at high multiplicity and confirmed the guark-gluon medium formation under these conditions.
Hadron and nuclear interactions at high energies in the region of extreme multiplicities (much higher than mean multiplicities) are reviewed. Collective phenomena such as Bose-Einstein condensation, ...Cherenkov gluon radiation, clustering, and an excess yield of soft photons may manifest themselves in this region. The phenomenological gluon-dominance model developed for describing extreme multiplicities predicts the restrictions on their values and the type of hadronization mechanism and makes it possible to estimate thee size of the hadronization region. The status of the research within the Thermalization project at the U-70 accelerator of the Institute for High Energy Physics (IHEP, Protvino) is reported, and information about searches for new collective phenomena and about studies of known ones in the region of extreme multiplicities is given.
Analysis of high multiplicity events Kokoulina, E. S.; Kutov, A. Ya; Nikitin, V. A. ...
Physics of particles and nuclei letters,
12/2011, Letnik:
8, Številka:
8
Journal Article
Recenzirano
The experimental studies of the high multiplicity events in proton interactions are carried out on U-70 accelerator in Protvino. It is suggested that the collective phenomena can be discovered since ...the high density matter can be formed in this very region. The collective behavior of secondary particles can manifest in the Bose-Einstein condensation of pions, Vavilov-Cherenkov gluon radiation, excess of soft photon yield and other unique phenomena.
The stages of development and the current status of the versatile “Spectrometer with a Vertex Detector” setup designed for physics experiments at the U-70 accelerator of the Institute for High Energy ...Physics (Protvino) is described. The main detectors of the setup are the vertex detector based on silicon microstrip detectors, the wide-aperture magnetic spectrometer based on multiwire proportional chambers, and the lead-glass hodoscope γ detector. In the setup, there is a fast two-level trigger system for selecting required particle interactions. The key characteristics of the setup systems are presented, and the physical results obtained on it are briefly listed.
Theoretical and experimental studies of high multiplicity events are analyzed. Some interesting phenomena can be revealed at high multiplicities. Preliminary results of project "Thermalization" are ...reported.
The Thermalization project is currently under way on the extracted proton beam of the U-70 accelerator at the Institute for High Energy Physics. The main goal of this experiment is to study the ...collective behavior of secondary particles produced in a multiparticle
pp
interaction at beam energy
E
= 50–70 GeV. The region of high charged-particle multiplicities
n
ch
≥ 10 is investigated. In this region, a significant portion of energy in the center-of-mass system is dissipated on production of secondary particles, which results in formation of a hadronic system. At the initial instant of evolution, the density of this system is high, which may be responsible for the collective behavior of the secondary particles. The investigations are performed at the SVD-2 wide-aperture magnetic spectrometer. A multichannel trigger scintillation hodoscope used to select rare events with a large number of charged particles exceeding the predetermined value is described. The main flow of low-multiplicity events is suppressed by the trigger system by a factor of ∼10
2
.
Neutral pion number N0 distributions for each total number of particles in event Ntot=Nch+N0 are obtained. The scaled variance of neutral pion fluctuations, omega=D/, is measured. The fluctuations ...increase at Ntot >22. According to quantum statistics models it may indicate for the approaching to pion condensate conditions for high pion multiplicity in the system.
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