Приведена краткая хронология создания ускорителей заряженных частиц и коллайдеров. Рассмотрены ускорительный комплекс, основные детекторные установки и системы Большого адронного коллайдера (БАК). Описаны обработка сигналов детекторов БАК и направления дальнейшего развития этого коллайдера

(EHS/NA22 Collaboration) 1 Institute of Physics, AM-375036 Yerevan, Armenia 2 Institute of Particle Physics, Hua-Zhong Normal University, Wuhan 430070, China 3 Department of Physics, University of Antwerp, B-2610 Wilrijk, Belgium 4 Centro Brasileiro de Pesquisas Fisicas, BR-22290 Rio de Janeiro, Brazil 5 Radboud University Nijmegen/NIKHEF, NL-6525 ED Nijmegen, The Netherlands 6 Institute for High Energy Physics of Tbilisi State University, GE-380086 Tbilisi, Georgia; now at Northwestern Univ., Evanston, U.S.A. 7 Scobeltsyn Institute of Nuclear Physics, Lomonosow Moscow State University, RU-119899 Moscow, Russia Now at DESY, Hamburg, Germany Boost invariance and multiplicity dependence of the charge balance function are studied in πp and Kp collisions at 250 GeV/c incident beam momentum. Charge balance, as well as charge fluctuations, are found to be boost invariant over the whole rapidity region, but both depend on the size of the rapidity window. It is also found that the balance function becomes narrower with increasing multiplicity, consistent with the narrowing of the balance function when centrality and/or system size increase, as observed in current relativistic heavy ion experiments.

An analysis is presented of the rapidity and transverse momentum distributions and of the nuclear stopping power in collisions of % + and K + mesons with A! and Au nuclei at 250 GeV/c. The experimental results are compared to predictions of the additive quark model and the dual parton model. The AQM offers an overall consistent description of the data in this experiment. The DPM reproduces reasonably well the rapidity spectra in the central and projectile fragmentation regions, but fails to describe the nuclear stopping power.

The NA22 data on 7r" 7r” correlations are ana­ lyzed in terms of a number of twoand three-dimensional parametrizations (Gaussian space-time, Goldhaber, Bowler string-like, Bertsch hydrodynamical, Kopylov-Podgoretskii, etc.). Contrary to the results obtained for e+e” and pp col­ lisions, the Goldhaber parametrization, as well as string-like models, fail in describing the hadron-hadron data. Better fits are obtained in the framework of surface-emitting fireball­ like models, both when including and excluding hydrody­ namical expansion of nuclear matter. Our results indicate that pion radiation occurs at earlier stages of matter evolu­ tion than in nuclear collisions.

Inclusive production o f direct soft photons is studied in K + p and n + p interactions at 250 GeV/c. To­ tal cross sections, Feynman-x and transverse momentum distributions of direct y 's are presented. The measured cross sections are several times larger than expected from QED inner bremsstrahlung, indicating the presence of an anomalous soft photon source. The model of Lichard and Van Hove, based on the “cold quark-gluon plasma” pic­ ture, agrees with the data.

The correlation of negative particles at small momentum difference and its dependence on multiplicity and on kinematical cuts is studied in n +/?-interactions at 250 GeV/c. In terms of the Kopylov-Podgoretskir parametrization, an average radius of the pion emitting region of rK — 1.59 ± 0.14 fm and a life-time (or emission depth) t = 0.83 ± 0.25 fm are found. The Lorentz invariant parametrization of Goldhaber gives rG= 0.85 ± 0.04 fm. As­ suming two different sources of pions, their radii are es­ timated as /■, = 1.75 ± 0.25 fm and r 2 = 0.60 ± 0.08 fm. An angular and multiplicity dependence of the space-time size of the source is observed. The source is elongated along the collision axis and has larger size rK at higher multiplicities. The radius rK decreases with increasing pion pair momentum. The size of the emitting region appears to be larger for low rapidity pions than for pions from the fragmentation region. No evidence is found for a unique reference frame, where the pion source is mo­ tionless for each n +p collision, i.e. where the space-time size of the source is definitely smaller than in any other frame.

We study twoand three-particle correlations as a function of invariant mass. Using data on n +p and K +p collisions at 250 GeV/c, we compare correlation functions and normalised factorial cumulants for various charge combinations. Strong positive correlations are ob­ served only at small invariant masses. The normalised cumulants for “exotic” [(-----), ( + + ) ] and “non­ exotic” pairs (H— ) and triplets decrease in power­ like fashion with increasing invariant mass. The mass dependence is not incompatible with the power-law be­ haviour as expected in a Dual Mueller-Regge framework. Comparison with FRITIOF reveals strong disagree­ ments, which are due to too large production rates of resonances, such as p° and /ƒ, and the absence of a BoseEinstein low-mass enhancement in JETSET.

Cross-sections are obtained for coherent interac­ tions of 7r+ and K +-mesons with A1 and Au nuclei at 250 GeV/c, leading to three, five and seven charged mesons. The total coherent cross-section is (4.3 ± 0.5)% of the inelastic cross-section for each of the four meson-nucleus interac­ tions. In 85% of the coherent events, the charged meson pro­ duction is accompanied by neutral mesons. Effective mass distributions are presented for coherently produced particles, including charged mesons and photons, carrying total mea­ sured energy of more than 85% of the initial energy. Charged particle and 7 spectra are analysed. No charge asymmetry is observed within the coherently produced cluster.

Cross-sections are obtained for coherent interac­ tions of 7r+ and K +-mesons with A1 and Au nuclei at 250 GeV/c, leading to three, five and seven charged mesons. The total coherent cross-section is (4.3 ± 0.5)% of the inelastic cross-section for each of the four meson-nucleus interac­ tions. In 85% of the coherent events, the charged meson pro­ duction is accompanied by neutral mesons. Effective mass distributions are presented for coherently produced particles, including charged mesons and photons, carrying total mea­ sured energy of more than 85% of the initial energy. Charged particle and 7 spectra are analysed. No charge asymmetry is observed within the coherently produced cluster.

In 2010 detector ATLAS was completely functional with 3.5 TeV proton beam collisions. Brief detector description, operation c onditions and performance of the detector at the initial operation period are presen ted.

A multi-dimensional analysis of two-particle correlations in + p-interactions at 250 GeV/c shows interesting structure. Particularly strong positive short-range ra-pidity and azimuthal correlations are observed for low-p T like-sign pairs. This observation is not reproduced by models used for comparison (FRITIOF, DPM, quark gluon (multi) string model). A possible explanation is Bose-Einstein interference not included in these models.

A selected sample of 59200 +p and K+p non-single-di ractive interactions at ps = 22 GeV is used to investigate one-, twoand three-dimensional factorial moments, factorial cumulant moments, as well as correlation integrals. The rise of factorial moments and cumulants with decreasing phase-space volume is stronger when evaluated in three than in lower dimensions. Ratios of slopes are easier to obtain than the slopes themselves. Contrary to earlier ndings, they turn out to depend on the dimension. The order dependence of the averaged ratios is better described by a L evy stable law solution with = 1:6 than by the Gaussian approximation of the -model ( = 2) or a second order phase transition ( = 0), but values > 2 inconsistent with L evy-type uctuations are reached in a three-dimensional analysis. The multiparticle contributions to the factorial moments are calculated by means of factorial cumulant moments. A particular improvement of the method is that of correlation (or density) integrals. It leads to the conclusion that Bose-Einstein interference plays an important role in the intermittency e ect, but indication is found for an interpretation alternative to the conventional view of Bose-Einstein correlations. 2

An analysis o f the A-dependence of the targetdiffractive cross-section is presented. Data on the ¿-depen­ dence of the cross section are fitted in the usual exponential form. The mean multiplicity of negative particles produced diffractively is found not to be sensitive to the nuclear mass. The ^-dependence of the emitted proton multiplicity and the angular distributions of the produced charged particles suggest re-scattering of the emitted particles on other nu­ cleons of the nucleus. All these facts are compared with results obtained by Monte-Carlo simulation according to a two-component Dual Parton Model. on multiple-scattering theory have been compared with the HELIOS data. In this paper, for the first time an analysis is presented of diffraction dissociation of Au and A1 targets excited by a meson beam. This is performed in the NA22 experiment by means of a positive, meson enriched beam of 250 GeV/c. NA22 data have been collected both for hadron-hadron and hadron-nucieus collisions to allow a comparison under the same experimental conditions. The paper is organized as follows: The experimental pro­ cedure is described in Sect. 2. The model description is shortly presented in Sect. 3. The results are presented in Sect. 4 and discussed in Sect. 5.