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Multiplicity distributions of charged particles produced in non single-diffractive collisions between protons and antiprotons at centre of mass energies of 200 and 900 GeV are presented. The data were recorded in the UA5 streamer chambers at the CERN Collider, which was operated in a pulsed mode between the two energies. A new method to correct for acceptance limitations and inefficiencies based on the principle of maximum entropy has been used. Multiplicity distributions in full phase space and in intervals of pseudorapidity are presented in tabular form. The violation of KNO scaling in full phase space found by the UA5 group at an energy of 546 GeV is confirmed also at 200 and 900 GeV. The shape of the 900 GeV distribution in full phase space is narrower in the peak region than at 200 GeV but exhibits a pronounced high multiplicity tail. The negative binomial distribution fits data at 200 GeV in all pseudorapidity intervals and in small intervals at 900 GeV. In large intervals at 900 GeV, however, the negative binomial distribution. Fits to the partially coherent laser distribution are also presented as well as comparisons with predictions of the Dual Parton, the Fritiof and the Pythia models.

New data are presented on charged particle multiplicity distributions for non single-diffractive events produced at CM energies s = 200 and 900 GeV. The data were obtained at the CERN antiproton-proton collider operated in a new pulsed mode. The multiplicity distributions are very well described by a negative binomial distribution. The highest energy data show no sign of approaching scaling, confirming our earlier results on the breaking of KNO scaling. The energy variation of the average charged multiplicity can be fitted to a quadratic in ln s or a s0.13 dependence.

The UA5 Monte Carlo program, consisting of a non-diffractive event generator GENCL, a diffractive event generator DIFFR and a tracking program are described. The inputs to the event generators are explained in detail. Their outputs are compared to available data from the SppS Collider, and the agreement is shown to be good. The importance of some features of the generators are discussed. It is shown that cluster production and leading baryons are necessary to describe non-diffractive phenomena.

Data on antiproton-proton cross sections at the c.m. energies 200 and 900 GeV are presented. The data were obtained at the CERN antiproton-proton Collider operated in a new pulsed mode in which the same beams were accelerated and decelerated between beam energies of 450 and 100 GeV. The properties of the machine determine the ratio of the luminosities at the two energies to about 1% and thus an accurate measurement of the ratioR of the inelastic cross sections could be made. We findR (=σ 900/σ 200)=1.20±0.01±0.02, where the first error is statistical and the second systematic. Interpolating existing data to estimateσ ine1(200 GeV) this measurement ofR leads toσ ine1(900 GeV)=50.3+0.4+1.0 mb. Using an extrapolated value ofσ e1/σ tot we estimate the total cross section at 900 GeV to be 65.3±0.7±1.5 mb. Both the inelastic and total cross sections are compatible with a ln2 s dependence. Comparisons are made with different fits to the total cross section energy dependence.

Cross-sections for diffractive particle production and pseudorapidity distributions of the decay products of diffractive states are presented. The data were obtained with the UA 5 streamer chamber detector at the CERNpp Collider operated in a new pulsed mode yieldingpp interactions at c.m. energies of 900 and 200 GeV. Data recorded with a special trigger designed to select a sample of events enriched in single-diffractive interactions clearly favour ap t -limited fragmentation of diffractive states. The cross-section for single-diffractive particle production ϊ was found to be 7.8±0.5±1.1 mb at 900 GeV and 4.8±0.5±0.8 mb at 200 GeV (first error statistical, second systematic). From the pseudorapidity distribution of diffractive states we deduce the average number of charged particles to be 6.5±1.0 at 900 GeV and 4.1±1.1 at 200 GeV. Furthermore we report on our estimates for the cross-section of double-diffractive particle production at both Collider energies.

The production of Λ's and Ξ−'s in proton-antiproton collisions at 200 and 900 GeV c.m. energy has been studied using decays observed in the UA5 streamer chambers. The results are compared to previously published 546 GeV data, to results from other experiments, and to four theoretical models. The Λ yield per inelastic event is estimated to be 0.42±0.11 at 200 GeV and 0.66±0.14 at 900 GeV. We find a mean number of Ξ−'s per inelastic collision of 0.03−0.02+0.04 at 200 GeV and 0.06−0.03+0.05 at 900 GeV. The average transverse momentum of Λ's in the rapidity region |y|⩽2 is found to be 0.80−0.14+0.20 GeV/c at 200 GeV and 0.74±0.09 GeV/c at 900 GeV. The average transverse momentum of Ξ−'s in the rapidity region |y|⩽3 is estimated to be 0.8−0.2+0.4 GeV/c at 200 GeV and 0.7−0.1+0.2 GeV/c at 900 GeV which is lower than the unexpectedly high value of 1.1±0.2 GeV/c measured at 546 GeV. The ratio of Ξ− production to Λ production in the region |y|⩽2, pt>1 GeV/c is 0.07−0.04+0.08 at 900 GeV. This value is consistent with the ratio found in e+e− collisions and lower energy pp collisions but lower than the value obtained at 546 GeV. The average particle composition of events at 200 and 900 GeV, estimated using UA5 data, is presented.

A search for the Centauro phenomenon has been made at s = 900 GeV using the UA5 detector at the SPS pp collider operated in a pulsed mode. Possible interpretations of the cosmic ray data are discussed leading to various analyses of our data which exploit the distinctive features of the Centauro events: high multiplicity, high pT and absence of produced photons. No indication of Centauro production is observed. Upper limits on the production of Centauros at the level of a few per thousand inelastic events are obtained.

Results on inclusive kaon production at 200 and 900 GeV centre of mass (CM) energy obtained with the UA5 detector at the pulsed CERN SPS antiproton-proton Collider are presented and compared with our earlier data at 546 GeV. The average transverse momentum 〈pt〉 of kaons has been estimated to be (0.50±0.04) GeV/c at 200 GeV and (0.63±0.03) GeV/c at 900 GeV in the central region and shows an increase with CM energy that is smore rapid than that expected from previous ISR data. The yield of kaons per inelastic pp event is found to be (0.72±0.12) at 200 GeV and (1.31±0.14) at 900 GeV. Finally, the K/π ratio has been found to exhibit a very slow increase with CM energy.

The CP-violation parameter η00 is determined through the eigentime-dependent asymmetry in the rates of initially tagged K0 and K0 decaying to π0 π0. From the analysis of the complete data set we obtain the values |η00|=[2.47±0.31stat.±0.24syst.]×10−3 and φ00=42.00±5.6stat.0±1.9syst.0.

A search for the decay KS → e+e− was performed within the framework of the CPLEAR experiment. Full event reconstruction together with e/π separation allowed powerful background rejection and high signal acceptance. The analysis of the complete set of data yields the result: BR(KS → e+e−) < 1.4 × 10−7 (90% CL), an improvement on the current experimental limit by a factor of 20.

Abstract An ATCA processor was designed to instrument the first layer of the CMS Barrel Muon Trigger. The processor receives and processes DT and RPC data and produces muon track segments. Furthermore, it provides readout for the DT detector. The ATCA processor is based on a Xilinx XCVU13P FPGA, receives data via 10 Gbps optical links and transmits track segments via 25 Gbps optical links. The processor is instrumented with a Zynq Ultrascale+ SoM connected with an SSD which provides the necessary resources for enhanced monitoring and control information. The design of the board as well as results on its performance are presented.

The design and performance of the upgraded CMS Level-1 Trigger Barrel Muon Track Finder (BMTF) is presented. Monte Carlo simulation data as well as cosmic ray data from a CMS muon detector slice test have been used to study in detail the performance of the new track finder. The design architecture is based on twelve MP7 cards each of which uses a Xilinx Virtex-7 FPGA and can receive and transmit data at 10 Gbps from 72 input and 72 output fibers. According to the CMS Trigger Upgrade TDR the BMTF receives trigger primitive data which are computed using both RPC and DT data and transmits data from a number of muon candidates to the upgraded Global Muon Trigger. Results from detailed studies of comparisons between the BMTF algorithm results and the results of a C++ emulator are also presented. The new BMTF will be commissioned for data taking in 2016.

The analysis of 150 GeV/c muon data collected during a test of a CMS Preshower prototype is presented. The test took place in 2004 in the H4 beam at CERN. The muon signal extraction is possible after pedestal subtraction and common mode correction. The results of a Geant-4-based simulation, developed for the Preshower prototype test, are also presented. The results of the simulation are found to be in excellent agreement with the data. It is also demonstrated that by combining the results of the data analysis and simulation an absolute calibration of the CMS Preshower detector system can be performed.

The CMS Preshower is a fine grain detector that comprises 4288 silicon sensors, each containing 32 strips. The data are transferred from the detector to the counting room via 1208 optical fibres running at 800 Mbps. This enormous total data flow of about 1 Tbps necessitates a significant reduction in the data volume. For the readout of the Preshower, a VME-based system is currently under development. The main objective of each readout board is to acquire on-detector data from up to 36 optical links, perform online data reduction and pass the concentrated data to the CMS event builder. The principle modules that the system is based on are being developed in collaboration with the TOTEM experiment.

ΜΕΛΕΤΑΤΑΙ Η ΠΕΡΙΕΚΤΙΚΗ ΠΑΡΑΓΩΓΗ ΤΩΝ ΚΑΟΝΙΩΝ ΚΑΙ ΤΩΝ ΒΑΡΥΟΝΙΩΝ Λ ΚΑΙ Ξ ΣΤΗΝ ΚΕΝΤΡΙΚΗ ΠΕΡΙΟΧΗ ΤΗΣ ΩΚΥΤΗΤΑΣ ΚΑΙ ΣΕ ΕΝΕΡΓΕΙΣ 200, 546 ΚΑΙ 900 GEV ΣΤΟ ΚΕΝΤΡΟ ΜΑΖΑΣΤΗΣ ΑΛΛΗΛΕΠΙΔΡΑΣΗΣ ΡΡ ΧΡΗΣΙΜΟΠΟΙΩΝΤΑΣ ΔΙΑΣΠΑΣΕΙΣ ΠΟΥ ΠΑΡΑΤΗΡΗΘΗΚΑΝ ΣΤΟΥΣ ΘΑΛΑΜΟΥΣ ΚΑΤΑΙΟΝΙΣΜΩΝ ΤΟΥ ΠΕΙΡΑΜΑΤΟΣ UA5. ΤΑ ΔΕΔΟΜΕΝΑ ΣΥΛΛΕΧΘΗΚΑΝ ΣΤΟ ΠΕΙΡΑΜΑ UA5 ΚΑΤΑ ΤΗ ΛΕΙΤΟΥΡΓΙΑ ΤΟΥ ΕΠΙΤΑΧΥΝΤΗ ΣΥΓΚΡΟΥΟΜΕΝΩΝ ΔΕΣΜΩΝ PP ΤΟΥ CERN ΣΥΜΦΩΝΑ ΜΕ ΤΟ ΣΥΝΕΧΗ ΚΑΙ ΤΟΝ ΠΑΛΜΙΚΟ ΤΡΟΠΟ ΛΕΙΤΟΥΡΓΙΑΣ ΤΟΥ. ΠΕΡΙΓΡΑΦΟΝΤΑΙ ΛΕΠΤΟΜΕΡΕΙΕΣ ΠΟΥ ΑΦΟΡΟΥΝ ΤΟΝ ΑΝΙΧΝΕΥΤΗ, ΤΙΣ ΣΥΝΘΗΚΕΣ ΚΑΤΑ ΤΗΝ ΛΕΙΤΟΥΡΓΙΑ ΤΟΥ ΠΕΙΡΑΜΑΤΟΣ ΚΑΙ ΤΗΝ ΔΙΑΔΙΚΑΣΙΑ ΑΝΑΛΥΣΗΣ, ΚΑΙ ΠΑΡΑΤΙΘΕΝΤΑΙ ΑΠΟΤΕΛΕΣΜΑΤΑ ΠΟΥ ΑΦΟΡΟΥΝ ΤΗΝ ΜΕΣΗ ΕΓΚΑΡΣΙΑ ΟΡΜΗ ΤΩΝ ΕΝ ΛΟΓΩ ΣΩΜΑΤΙΩΝ, ΤΗΝ ΜΕΣΗ ΠΟΛΛΑΠΛΟΤΗΤΑ ΚΑΙ ΤΟΝ ΠΑΡΑΓΟΝΤΑ ΚΑΤΑΣΤΟΛΗΣ ΤΗΣ ΙΔΙΟΤΥΠΙΑΣ. ΤΑ ΑΠΟΤΕΛΕΣΜΑΤΑ ΣΥΓΚΡΙΝΟΝΤΑΙ ΜΕ ΑΠΟΤΕΛΕΣΜΑΤΑ ΣΕ ΧΑΜΗΛΟΤΕΡΕΣ ΕΝΕΡΓΕΙΕΣ, ΜΕ ΑΠΟΤΕΛΕΣΜΑΤΑ ΣΕ ΑΛΛΗΛΕΠΙΔΡΑΣΕΙΣ Ε+Ε- ΚΑΙ ΜΕ ΤΙΣ ΤΙΜΕΣ ΠΟΥ ΠΡΟΒΛΕΠΟΝΤΑΙ ΑΠΟ ΤΡΙΑ ΘΕΩΡΗΤΙΚΑ ΠΡΟΤΥΠΑ. ΤΕΛΟΣ ΠΑΡΑΤΙΘΕΤΑΙ Η ΣΥΝΘΕΣΗ ΕΝΟΣ ΤΥΠΙΚΟΥ ΓΕΓΟΝΟΤΟΣ ΤΗΣ ΑΛΛΗΛΕΠΙΔΡΑΣΗΣ ΡΡ ΣΤΙΣ ΜΕΛΕΤΩΜΕΝΕΣ ΕΝΕΡΓΕΙΕΣ.

A measurement of the branching ratio for Ks → e+e− decay was performed with the CPLEAR detector at LEAR. Full event reconstruction together with calorimeter e/π separation allowed for powerful background rejection and high signal acceptance. Analysis of data taken up to 1994 yields the result: Br(Ks → e+e−) < 4.2 · 10−7 (90 % CL).