E. Vlasov

A partial-wave analysis of the ηπ− and η′π− systems produced in the reactions π−N→η(η′)π−N on a berylium target at a beam momentum of pπ− = 37 GeV/c is performed. It is shown that (1) all the waves with negative exchange naturality are negligibly small for both systems; (2) the matrix element squared of the P+ wave with JPC = 1−+ for the η′π− system significantly exceeds that for the ηπ− system, which could testify to the dominance of systems with a valence gluon (qq̄g) in the JPC = 1−+ wave formation; (3) the ratio R = Br(a2−→η′π−)/BR(a−2→ηπ−) = (4.7±1.0(stat.) ±0.4(syst.)) × 10−2 has been obtained.

Topological cross sections are presented for K+p, K−p and pp interations at 32 GeV/c and for π+p and π−p interactions at 50 GeV/c observed in the 4.5 m Mirabelle hydrogen bubble chamber at Serpukhov. Parameters characterizing the behaviour of the multiplicity distributions, namely 〈nc〉, D and f2 and the normalized moments are given. The dependence of these parameters on the energy and the nature of the beam particle is discussed. The multiplicity distributions obtained cannot be described by a single function in the KNO variables.

The results of the partial wave analysis of the diffractive reaction π−A → π+π−π−A at the momentum 36 GeV/c on the scintillator target are presented. A resonance at m = 1.8 GeV with JPC = 0−+ (π(1800)) is clearly seen in this reaction. The characteristics of π(1800) point to the possible exotic nature of this object.

Charm D-meson production in 360 GeV π−p interactions has been studied using the high-resolution hydrogen bubble chamber LEBC and the European Hybrid Spectrometer. The data show evidence for leading quark effects both in the number of D-meson types and in the Feynman x distributions. The production cross section is of the form d2δdxdpT2∞(1-x)nexp(-apT2) with n = 2.8±0.8 and a = 1.1±0.3 (GeV/c)−2. The x distribution is, however, compatible with the presence of both central (n = 6) and leading (n = 1) D/Dproduction. The fraction of D-messons in the leading component is estimated to be ≈30%. The rapidity gap between members of reconstructed charm pairs is small compared to the available rapidity range. The inclusive cross section for single D-messons in the forward direction is: δ(D/D)=(408+15)μb (forx>0).

The final version of the European hybrid spectrometer (EHS) is described. EHS was used in the NA27 experiment to study charm particles produced in 360 GeV c π-p and 400 GeV c pp interactions. A rapid cycling, high resolution bubble chamber (LEBC) produced bubbles of 17 μm diameter which were measured with a precision of 2.5 μm. Short-lived charm particles are observed with an efficiency up to 90% (D±). The spectrometer accepts 70% of all particles produced, including approximately 100% of those in the forward hemisphere and the momenta of charged particles are measured to better than 1% over the whole momentum range. The charged particle identification detectors give information on 84% of the spectrometer tracks, half of which obtain unique identification. Two lead glass detectors measure the energy of electromagnetic showers such that the π0 mass distribution has a fwhm of 20 MeV c2. Hadronic showers are measured with two iron/scintillator calorimeters. The mass resolutions are 3.0, 0.9 and 11 MeV c2 for K0, Λ0 and D- charged particles respectively. The D0 mass is measured to be (1865.1 ± 1.8 ± 0.8) MeV c2. © 1987.

Longitudinal invariant structure functions Edσdx for a number oflow pt hadronic fragments produced in K+- interactions at 32 GeV/c are presented. Data were obtained in the Mirabelle bubble chamber. The fragmentation modes investigated are K± → K0, K̄0, K∗0,+(890), K̄∗0,−(890), ϕ, ϱ0, π+-, Λ, ḡL, and p → pinel, Δ++(1236), Λ, ḡL, π±, K0, ϱ0. These various fragmentation spectra clearly fall into a definite hierarchy, the invariant cross sections being more suppressed at large |x| the bigger the difference between initial and final state hadron quantum numbers. Invariant cross sections in the fragmentation regions are adequately fitted by a power law Edσ/dx ∝ (1 − |x|)n as suggested by dimensional or Regge counting The values of n are in general consistent with values obtained at FNAL and ISR energies for comparable data. They are in good overall agreement with the quark counting rules as recently reformulated, and the deviations observed suggest corrections due to strange (s) and light (u, d) quark mass differences. The power laws governing the kaon valence quark structure functions behave at large x as sKV(x)x→+1 ∼ (1 − x)0.5 and ūKV(x)x→+1 ∼ (1 − x) 1.5.

We present results of the performance of the second prototype of the CASTOR quartz–tungsten sampling calorimeter, to be installed in the very forward region of the CMS experiment at the LHC. The energy linearity and resolution, as well as the spatial resolution of the prototype to electromagnetic and hadronic showers are studied with E=20–200 GeV electrons, E=20–350 GeV pions, and E=50, 150 GeV muons from beam tests carried out at CERN/SPS in 2004. The responses of the calorimeter using two different types of photodetectors (avalanche photodiodes APDs, and photomultiplier tubes PMTs) are compared.

Inclusive spectra of π− production for pp interactions are discussed at 69 GeV/c both in the central and in the fragmentation region and are compared to data at lower and higher energies. The pT dependence of the invariant structure function is also analysed.

The Small angle TIle Calorimeter (STIC) provides calorimetric coverage in the very forward region of the DELPHI experiment at the CERN LEP collider. The structure of the calorimeters, built with a so-called “shashlik” technique, gives a perfectly hermetic calorimeter and still allows for the insertion of tracking detectors within the sampling structure to measure the direction of the showering particle. A charged-particle veto system, composed of two scintillator layers, makes it possible to trigger on single photon events and provides e–γ separation. Results are presented from the extensive studies of these detectors in the CERN testbeams prior of installation and of the detector performance at LEP.

Data from a high statistics Mirabelle bubble chamber K−p experiment at 32 GeV/c are used to study inclusive single and double diffraction dissociation. From the reaction K−p → K− + X we find a total proton single dissociation cross section of 1040 ± 120 μb, with comparable contributions from proton dissociations into 1 and 3 charged particles. There is evidence for double dissociation in K−p → (K−π+π−) + X+, with cross section of 64 ± 20 μb. Cross sections and dσdt′ distributions are in qualitative agreement with the factorization hypothesis. With the results from a companion K+p experiment, the total diffractive cross section (elastic + SD + DD) is estimated. It amounts to ≅4.75 mb, i.e., about 25% of the total KN cross section and about 50% of Pumplin's upper bound for the diffractive cross section. A comparison with ISR data suggests that the total DD cross section increases by ∼2 mb over the c.m. energy range from ∼10 to ∼50 GeV.

Results of a partial wave analysis of the ηπ+π− final state are presented using 4.2×104 events with |t|<0.2 GeV2, collected at the VES setup; the reaction is π−p→π−π+ηn from a beryllium target. The data reveal resonant structures, which are identified by phase motion as well as peaks in intensities of partial waves. The f2(1565) meson, also called the AX meson, is observed in decays to [a2(1302)π]L=1. The parameters obtained from a fit with a Breit–Wigner amplitude are M=1550±20 MeV with Γ=130±40 MeV. The higher mass f2 resonances are also discussed. For JP=3−, the well known ρ3(1690) is seen in decays to both a2(1320)π and ρη channels. The complex behaviour of 3−− amplitudes at higher masses is described best by introducing two additional resonant poles near 2.14 and 2.30 GeV. There is evidence for an f4(2300) meson, decaying dominantly to [f2η]L=3.

Results are presented on the inclusive π± production in K−p interactions at 32.1 GeV/c. The invariant longitudinal distributions have been calculated both for π+ and π− in the backward c.m. hemisphere and extrapolated in the forward hemisphere under some physical assumptions. The inclusive cross sections for π+ and π− amount to 32.9 ± 1.5 mb and 35.0 ± 0.7 mb respectively. The energy dependence of the inclusive pion production has been analyzed in the framework of Mueller-Regge phenomenology both in the proton fragmentation and in the central region.

The FEC-CCS is a custom made 9U VME64x card for the CMS Off-Detector electronics. The FEC-CCS card is responsible for distributing the fast timing signals and the slow control data, through optical links, to the Front-End system. Special effort has been invested in the design of the card in order to make it compatible with the operational requirements of multiple CMS detectors namely the Tracker, ECAL, Preshower, PIXELs, RPCs and TOTEM. This paper describes the design architecture of the FEC-CCS card focusing on the special design features that enable the common utilization by most of the CMS detectors. Results from the integration tests with the detector electronics subsystems and performance measurements will be reported. The design of a custom made testbench for the production testing of the 150 cards produced will be presented and the attained yield will be reported.

The PMTs of the CMS Hadron Forward calorimeter were found to generate a large size signal when their windows were traversed by energetic charged particles. This signal, which is due to Čerenkov light production at the PMT window, could interfere with the calorimeter signal and mislead the measurements. In order to find a viable solution to this problem, the response of four different types of PMTs to muons traversing their windows at different orientations is measured at the H2 beam-line at CERN. Certain kinds of PMTs with thinner windows show significantly lower response to direct muon incidence. For the four anode PMT, a simple and powerful algorithm to identify such events and recover the PMT signal using the signals of the quadrants without window hits is also presented. For the measurement of PMT responses to Čerenkov light, the Hadron Forward calorimeter signal was mimicked by two different setups in electron beams and the PMT performances were compared with each other. Superior performance of particular PMTs was observed.

The wave with exotic quantum numbers JPC=1−+ is studied in η’π−, ηπ−, f1π−, and ρ0π− systems produced in π−N interactions at pπ−=37 GeV/c in the high‐statistics experiment at IHEP VES setup. The magnitude of JPC=1−+ wave in η’π− system significantly exceeds that in ηπ− system. Resonance‐like structure with mass M=1.62±0.02 GeV and with Γ=0.24±0.05 GeV is observed in ρ0π− system.

The reaction π− A → K+K−π− A was studied at the momentum of 37 GeV/c on the beryllium target at the wide aperture VES spectrometer. The partial-wave analysis of the K+K−π− system produced at low |t′| < 0.08 GeV2 was performed. It is shown that in the wave with JP = 0− there exists an object withmass 1.79±0.014 GeV/c2 and width 0.21±0.07 GeV/c2 decaying into κK− and |0(975)π−.

The small angle tile Calorimeter (STIC) provides calorimetric coverage in the very forward region for the DELPHI experiment at the CERN LEP collider. A veto system composed of two scintillator layers allows one to trigger on single photon events and provides e-/spl gamma/ separation. We present here some results of extensive measurements performed on part of the calorimeter and the veto system in the CERN test beams prior to installation and report on the performance achieved during the 1994 LEP run.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Abstract A study of the length distribution of charged secondary interactions gives no evidence for the existence of charged anomalons in the products of the interactions of 360 GeV/ c π − and protons in hydrogen. Fits to the data yield 95% confidence level upper limits for anomalon production as a function of anomalon mean free path.

The structure of the calorimeters built with the "Shashlik" technique allows the insertion of tracking detectors within the sampling structure, in order to improve the accuracy in the determination of the showering particle direction and to enhance the e-/spl pi/ separation ability. The new luminosity monitor of the DELPHI detector at LEP was equipped with two planes of silicon pad detectors placed at a depth of 4 and 7.4 radiation lengths. A description of the silicon detectors is given, together with the results from the exposure to a test beam.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A novel technique for longitudinal segmentation of shashlik calorimeters has been tested in the CERN West Area beam facility. A 25 tower very fine samplings e.m. calorimeter has been built with vacuum photodiodes inserted in the first 8 radiation lengths to sample the initial development of the shower. Results concerning energy resolution, impact point reconstruction and electron/pion separation are reported.

Two techniques for longitudinal segmentation of shashlik calorimeters are proposed. Results concerning energy resolution and e/π separation are reported.

Several solutions to realize an Electromagnetic Calorimeter based on the Shashlik technique with longitudinal segmentation are considered. The possibility to build a barrel calorimeter at a Linear Collider experiment using the proposed techniques is exploited.

In a K−p experiment at 32 GeV/c with a sensitivity of 6 ev/≈b the inclusive reaction K−p → p + X was studied in the kinematical region x < −0.3. Most of the protons in this region were identified by ionization. Correcting for losses of the very slow as well as of the fast protons in this region we obtained σp(x < −0.3) = 5.9 ± 0.2 mb. The double invariant differential cross sections of protons were analysed in terms of the variables x, pT2, and M2/s, t, and the contributions from separate peripheral mechanisms were analysed. A triple-Regge analysis was performed on the inclusive proton d2σ/dtd(M2/s) distribution with |t| < 1.1 GeV2. The fit with an RRP term resulted in an effective trajectory for the exchanged reggeon lying somewhat lower than that for the leading meson trajectory. Inclusion in the fit of an additional ππp term showed that pion exchange is important in the triple-Regge region at small |t|.

The DELPHI STIC detector is a lead-scintillator sampling calorimeter with wavelength shifting optical fibers used for light collection. The main goal of the calorimeter at LEP100 is to measure the luminosity with an accuracy better than 0.1%. The detector has been in operation since the 1994 LEP run. Presented here is the performance measured during the 1994-1995 LEP runs, with the emphasis on the achieved energy and space resolution, the long-term stability and the efficiency of the detector. The new bunch-trains mode of LEP requires a rather sophisticated trigger and timing scheme which is also presented. To control the trigger efficiency and stability of the calorimeter channels, a LED-based monitoring system has been developed.

The new luminosity monitor of the DELPHI detector, STIC (Small angle TIle Calorimeter), was built using a Shashlik technique. This technique does not provide longitudinal sampling of the showers, which limits the measurement of the direction of the incident particles and the e — π separation. For these reasons STIC was equipped with a Silicon Pad Shower Maximum Detector (SPSMD). In order to match the silicon detectors to the Shashlik read out by wavelength shifter (WLS) fibers, the silicon wafers had to be drilled with a precision better than 10 μm without damaging the active area of the detectors. This paper describes the SPSMD with emphasis on the fabrication techniques and on the components used. Some preliminary results of the detector performance from data taken with a 45 GeV electron beam at CERN are presented.

Two techniques for longitudinal segmentation of shashlik calorimeters are proposed. Results concerning energy resolution, impact point reconstruction and e//spl pi/ separation are reported.

Two techniques for longitudinal segmentation of shashlik calorimeters are proposed. Results concerning energy resolution, impact point reconstruction and e/n separation are reported.

A search for the light pseudoscalar sgoldstino production in three-body K- decay K- --&gt; pi-pi0 P has been performed with the ISTRA+ detector exposed to the 25 GeV negative secondary of the U-70 proton synchrotron. No signal is seen. Upper limits for the branching ratio at 90% confidence level vary between 2.0 10**-5 and 0.5 10**-5 in the effective mass m(P) range from 0 up to 190 MeV. Our results improve the limits published by the E787 Collaboration in the mass interval between 0 and 120 MeV and are the first ones at higher masses.

The small angle tile calorimeter (STIC) provides calorimetric coverage in the very forward region of the DELPHI experiment at the CERN LEP collider. The structure of the calorimeters, built with so-called "shashlik" technique, allows the insertion of tracking detectors within the sampling structure, in order to make it possible to determine the direction of the showering particle. Presented here are some results demonstrating the performance of the calorimeter and of these tracking detectors at LEP.

The inclusive production of ..pi../sup +/, ..pi../sup -/, ..pi../sup 0/, and K/sup 0/ mesons in K/sup -/p interactions at 32 GeV/c is investigated. The data are presented in the form of structure functions depending on the longitudinal and transverse momentum components in the lab and c.m. systems. The neutral-pion distributions are derived from the moments of the ..gamma..-ray distributions. The structure functions for ..pi../sup +/ and ..pi../sup -/ production are compared with the neutral-pion and neutral-kaon data and with data obtained at lower energies. The inclusive K*/sup -/(890) production cross section is evaluated.

The Small Angle TIle Calorimeter (STIC) is a sampling lead-scintillator calorimeter, built with “shashlik’ technique. Results are presented from extensive studies of the detector performance at LEP.

The STIC calorimeter was installed in the DELPHI detector in 1994. The main goal is to measure the luminosity with an accuracy better than 0.1%. The calorimeter was built using the “Shashlik” technique. The light is collected by wavelength shifting fibers and readout by phototetrodes that can operate inside the magnetic field. The detector performance during the 1994–1995 data taking is presented. The different contributions to the systematic error on the luminosity measurement are discussed.

The light-monitoring system of the forward neutral-hadron calorimeter of the European hybrid spectrometer is described. A general block diagram of the system, the functional relationships of the modules, and the ideology of the mathematical support are presented. The calorimeter records neutral particles in momentum range of 10-400 MeV/c. The calorimeter consists of 200 identical counters in modules of four each in a 10 X 20 matrix. The counters are made from plastic scintillators interlayed by steel plates. Light is collected by means of a rod reemitter admitted along the counter axis.