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1. Production of hyperons and anti-hyperons in heavy-ion collisions at SPS: Experiments at the CERN Omega spectrometer

Author

G. Romano, A. Volte, Leonardo Paolo Rossi, Håvard Helstrup, R. Lietava, G. Vassiliadis, M. Morando, N. Carrer, P. Middelkamp, Anton Jusko, J.A. Lien, B. Sopko, T. Storås, Gunnar Løvhøiden, K.L. Norman, F. Posa, I. Králik, A. Di Mauro, Petr Zavada, J. Šťastný, M. Luptak, Vito Manzari, Paolo Martinengo, O. Villalobos Baillie, R. A. Ricci, V. Lenti, G.F. Segato, M. Vaníčková, J.B. Kinson, Rocco Caliandro, C. Salvo, Giovanni Darbo, J. Ftacnik, Jean-Charles Fontaine, E. Quercigh, A. Kirk, J. Bohm, G. Grella, E. Chesi, Bianca Osculati, T. Virgili, A. Diaczek, M. Venables, H. Rotscheidt, S. Simone, W. Beusch, C. Voltolini, M.E. Michalon-Mentzer, S. Saladino, J. P. Davies, K. Šafařík, V.A. Kachanov, K. Knudson, A.K. Holme, Alberto Andrighetto, D. Huss, P. Sennels, R. A. Fini, T. Kachelhoffer, A. Michalon, F. Pellegrini, S. Szafran, A. Jacholkowski, M. T. Muciaccia, N. Armenise, Michele Guida, K. Piska, J. C. Lassalle, Gianfranca De Rosa, W. Geist, P. Sené, K. Fanebust, L. Sandor, T.F. Thorsteinsen, D. Elia, J. Bán, P. Jovanovic, E. Nappi, David H. Evans, M. G. Catanesi, I. Mácha, Dario Barberis, A. Singovski, M. Dameri, Franco Meddi, T. Scognetti, Federico Antinori, Erik H.M. Heijne, D. Di Bari, Eugenio Cantatore, M. A. Mazzoni, B. Ghidini, E. Andersen, F. Navach, M. Sené, M. Campbell, G. Tomasicchio, J. Urban, M.F. Votruba, W. Klempt, H. Beker, V. Mack, Pavel Staroba, R. A. Loconsole, S. Di Liberto, B. Pastirčák, Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), WA97, and Heyd, Yvette

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, Strange quark, Large Hadron Collider, Spectrometer, [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Theory, Hyperon, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Omega, Atomic and Molecular Physics, and Optics, Nuclear physics, Heavy ion, Nuclear Experiment
Abstract

Recent results from the CERN Omega spectrometer on the enhancement of strange and multiply strange particle production in nucleus-nucleus with respect to proton-nucleus collisions are summarized. In particular, the new data from the WA97 experiment on Ω, Ξ and Λ production in PbPb and p-Pb collisions are presented and discussed.

Published
1999
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2. A, Ξ and Ω enhancement at central rapidity in Pb-Pb collisions at 158A GeV/ c

Author

Rocco Caliandro, A. Diaczek, K. Fanebust, J. Urban, B.T.H. Knudsen, A. Singovski, Federico Antinori, Michael A. Thompson, S. Saladino, A.K. Holme, G. Tomasicchio, N. Carrer, Eugenio Cantatore, M. A. Mazzoni, Leonardo Paolo Rossi, B. Ghidini, G. Rosa, Erik H.M. Heijne, G. Vassiliadis, G. Romano, J. C. Lassalle, J.B. Kinson, T.F. Thorsteinsen, D. Di Bari, V. Lenti, Giovanni Darbo, E. Chesi, Bianca Osculati, M. Morando, C. Salvo, M. Dameri, Pavel Staroba, M.F. Votruba, F. Navach, N. Armenise, Anton Jusko, K. Piska, E. Andersen, W. Klempt, Eugenio Nappi, H. Bakke, Michele Guida, F. Posa, Petr Zavada, K. Šafařík, Franco Meddi, D. Elia, A. Jacholkowski, I. Králik, Haavard Helstrup, Paolo Martinengo, T. Scognetti, W. Snoeys, M. Sené, M. Campbell, J. Bán, Dario Barberis, T. Virgili, A. Kirk, B.C. Earl, S. Simone, W. Beusch, A. Volte, R. Lietava, R. Sené, K. Knudson, O. Villalobos Baillie, R. A. Ricci, I. J. Bloodworth, H. Beker, D. Huss, V. Mack, P. Middelkamp, Vito Manzari, David H. Evans, M. G. Catanesi, S. Di Liberto, B. Pastirčák, R. A. Loconsole, J. Ftacnik, Giorgio Torrieri, M. T. Muciaccia, Trine Spedstad Tveter, V.A. Kachanov, P.I. Norman, G. T. Jones, P. Jovanovic, Gunnar Løvhøiden, L. Šándor, F. Pellegrini, R. A. Fini, A. Michalon, J. Bohm, M. Venables, M. Luptak, G.F. Segato, E. Quercigh, M.E. Michalon-Mentzer, Jean-Charles Fontaine, S. Szafran, H. Rotscheidt, T. Kachelhoffer, and G. Grella

Subjects
Nuclear physics, Physics, Particle physics, Nuclear Theory, Quark–gluon plasma, Hyperon, Transverse mass, Rapidity, Strangeness, Nuclear Experiment, Omega, Spectral line
Abstract

A, Ξ and Ω yields and transverse mass spectra have been measured in Pb-Pb and p-Pb collisions at 158A GeV/c. The yields in Pb-Pb interactions are presented as a function of the collision centrality and compared with those obtained from p-Pb collisions. Strangeness enhancement is observed which increases with centrality and with the strangeness content of the hyperon.

Published
1998
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3. Λ, Ξ and Ω production in PbPb collisions at 158 A GeV/c

Author

Michael A. Thompson, S. Saladino, A.K. Holme, Dario Barberis, J. C. Lassalle, Petr Zavada, D. Di Bari, Gunnar Løvhøiden, M. T. Muciaccia, M. Morando, S. Simone, R. A. Fini, L. Šándor, F. Pellegrini, Anton Jusko, G. Grella, K. Knudson, W. Beusch, R. A. Loconsole, N. Carrer, V.A. Kachanov, A. Michalon, S. Szafran, A. Di Mauro, D. Huss, M.E. Michalon-Mentzer, I. Králik, P. Middelkamp, Giovanni Darbo, Paolo Martinengo, M. Luptak, G.F. Segato, F. Posa, E. Quercigh, J. Ftacnik, E. Chesi, Rocco Caliandro, P. Jovanovic, A. Kirk, Trine Spedstad Tveter, G. Romano, A. Singovski, E. Andersen, N. Armenise, W. Snoeys, B. Ghidini, H. Beker, T.F. Thorsteinsen, G. Rosa, H. Rotscheidt, David H. Evans, Jean-Charles Fontaine, P.I. Norman, G. T. Jones, M. Dameri, M. G. Catanesi, Vito Manzari, J. Bohm, V. Mack, J. Bán, Franco Meddi, M. Sené, A. Diaczek, F. Navach, M. Campbell, S. Di Liberto, A. Jacholkowski, M. Venables, T. Kachelhoffer, G. Tomasicchio, Leonardo Paolo Rossi, O. Villalobos Baillie, R. A. Ricci, B. Pastirčák, T. Scognetti, Pavel Staroba, M.F. Votruba, W. Klempt, Eugenio Nappi, Federico Antinori, Erik H.M. Heijne, J. Urban, K. Fanebust, B. Osculati, M.A. Mazzoni, E. Cantatore, J.B. Kinson, A. Volte, R. Lietava, R. Sené, K. Piska, D. Elia, T. Virgili, I.G. Bloodworth, V. Lenti, Michele Guida, C. Salvo, Håvard Helstrup, G. Vassiliadis, and K. Šafařík

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, Large Hadron Collider, Silicon pixel detectors, Hyperon, Spectral line, Baryon, Nuclear physics, Particle, Transverse mass, Rapidity, Quark Gluon Plasma, Nuclear Experiment
Abstract

Enhanced production of strange baryons and anti-baryons at central rapidity in S-W and S-z.sbnd;S with respect to p-A reactions has been reported by the CERN experiments WA85 and WA94. The WA97 experiment is extending such a study to Pb Pb collisions making use of the newly developed silicon pixel detectors. Results on Λ, Ξ − and Ω − production in Pb Pb collisions at 158 A GeV/ c at central rapidity are presented. Transverse mass spectra and particle ratios are presented. Hyperon yields are given as a function of the collision centrality and compared with those obtained from p-Pb collisions using the same experimental setup.

Published
1998
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4. Electronic detection of focused Cherenkov rings from aerogel

Author

Roger Forty, Salvatore Frullani, M. Iodice, L. Lagamba, R. De Leo, E. Cisbani, E. Nappi, A. Leone, C. Matteuzzi, G. M. Urciuoli, H. Becker, R. Suda, T. Ypsilantis, Roberto Perrino, M. Alemi, T. Sumiyoshi, J. Seguinot, Franco Garibaldi, Vito Manzari, I. Adachi, and T. Scognetti

Subjects
Physics, Nuclear and High Energy Physics, Condensed Matter::Other, Physics::Instrumentation and Detectors, Cherenkov detector, business.industry, Astrophysics::High Energy Astrophysical Phenomena, Aerogel, law.invention, Condensed Matter::Soft Condensed Matter, Optics, law, Radiator (engine cooling), Optoelectronics, High Energy Physics::Experiment, business, Instrumentation, Cherenkov radiation
Abstract

The recent development of highly transparent aerogel has permitted its use as a Cherenkov radiator in a focused (non-Rayleigh-scattered) mode. We report on the optical properties of this aerogel obtained by observation of Cherenkov rings with single-electron-sensitive phototubes. The dependence on aerogel radiator thickness of the number of Cherenkov ring hit points and background is shown and compared to expectations. A 5 cm thick radiator of this aerogel will permit π K identification up to 20 GeV/c.

Published
1997
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5. Hyperon production in Pb+Pb collisions at 158 A GeV/c

Author

S. Szafran, Anton Jusko, N. Armenise, Michele Guida, I. Králik, P. Jovanovic, S. Simone, K. Šafařík, Ph. Leruste, H. Helstrup, J. Ftacnik, P. Middelkamp, J. Bán, Paolo Martinengo, E. Nappi, N. Carrer, Leonardo Paolo Rossi, C. Voltolini, Federico Antinori, Håvard Helstrup, Pavel Staroba, Vito Manzari, J.A. Lien, G. Vassiliadis, V. Lenti, K. Fanebust, M. Luptak, G.F. Segato, Eugenio Cantatore, J. Šťastný, K. Knudson, M. Vaníčková, M. A. Mazzoni, S. Di Liberto, L. Lopez, B. Ghidini, A. Singovski, W. Geist, Erik H.M. Heijne, M. Morando, A. Jacholkowski, J.M. Brom, E. Quercigh, R. Blaes, P. Sennels, F. Posa, G. Romano, A. Volte, R. Lietava, R. Sené, B. Pastirčák, A.K. Holme, Alberto Andrighetto, G. Grella, K. Piska, J. L. Narjoux, T.F. Thorsteinsen, E. Andersen, Jean-Charles Fontaine, H. Rotscheidt, F. Navach, M. Dameri, D. Elia, L. Šándor, F. Pellegrini, M. T. Muciaccia, J. P. Davies, O. Villalobos Baillie, R. A. Ricci, David H. Evans, J. C. Lassalle, Petr Zavada, C. Salvo, I. Mácha, Dario Barberis, A. Di Mauro, K.L. Norman, G. Tomasicchio, Giovanni Darbo, V.A. Kachanov, T. Kachelhoffer, E. Chesi, Bianca Osculati, T. Storås, A. Kirk, M. G. Catanesi, B. R. French, M. Sené, B. Sopko, M. Campbell, A. Diaczek, M.E. Michalon-Mentzer, M.F. Votruba, W. Klempt, Franco Meddi, P. Farthouat, J. Bohm, T. Scognetti, J. Urban, H. Beker, J.B. Kinson, M. Venables, Gunnar Løvhøiden, V. Mack, R. A. Fini, A. Michalon, T. Virgili, W. Beusch, D. Huss, M. Benayoun, G. Rosa, and D. Di Bari

Subjects
Nuclear physics, Physics, Nuclear and High Energy Physics, Particle physics, Strange quark, Proton, Hadron, Hyperon, General Physics and Astronomy
Abstract

Preliminary results from WA97 measurements on Λ, Ξ and Ω production in lead-lead and proton-lead collisions are presented, along with a comparison of WA97 proton-lead data with previous WA85 proton-tungsten results. The ratio Ω/Ξ seems to be enhanced in lead initiated reactions compared to proton initiated reactions.

Published
1996
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6. Timing measurements in long rods of BC408 scintillators with small cross-sectional sizes

Author

L. Lagamba, T. Scognetti, A. Leone, Mauro Iodice, E. Cisbani, Roberto Perrino, R. De Leo, F. Garibaldi, S. Frullani, E. Nappi, and G. M. Urciuoli

Subjects
Physics, Nuclear and High Energy Physics, Scintillation, genetic structures, business.industry, Resolution (electron density), Ionizing particles, Scintillator, Rod, Phototube, Optics, sense organs, business, Instrumentation
Abstract

We have investigated the timing properties of BC408 scintillator rods with a length of 2 m, a width of 4 cm, and thicknesses of 0.5, 1, 2, and 4 cm, for scintillation light produced by minimum ionizing particles crossing the thickness of the rods. A deterioration of the timing properties, inversely related to the rod thickness, has been observed for scintillation light produced far from the read-out phototube. The timing resolution worsens by nearly 2 ns/m for the thinnest rod.

Published
1996
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7. Design of a large area fast RICH detector with CsI photocathode for particle identification at ALICE-LHC

Author

V. Valentino, A. Grimaldi, A. Ljubicic, R. Potenza, F. Posa, E. Nappi, T. Tustonic, F. Piuc, D. Williams, T. Scognetti, P. Sartori, G. Paic, A. Di Mauro, A. Tricomi, and Luigi Maria Galantucci

Subjects
Physics, Nuclear and High Energy Physics, Large Hadron Collider, Physics::Instrumentation and Detectors, Cherenkov detector, Detector, Atomic and Molecular Physics, and Optics, Particle detector, Particle identification, Ring-imaging Cherenkov detector, law.invention, Nuclear physics, law, High Energy Physics::Experiment, Collider, Cherenkov radiation
Abstract

ALICE, A Large Ion Collider Experiment, at the LHC collider operated with heavy-ion beams, envisages a Ring Imaging Cherenkov detector (RICH) system to identify particles in the momentum range: .7 GeV/c ÷ 2.5 GeV/c, as an alternative to a time of flight (TOF). In 1992 an extensive R&D programm was started to design and optimize a fast RICH detector based on proximity focusing of the Cherenkov radiation on a wire chamber with a Cesium Iodide solid photocathode. The implementation of an analog pad read-out scheme provides two dimensional information and efficient discrimination between ionizing particle and Cherenkov photoelectron impact points. After a discussion on the requirements, a description of the first large area prototype follows. Results of a beam test and detector performances are finally reported together with future developments and engineering issues.

Published
1995
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8. Development of large area fast-RICH prototypes with pad readout and solid photocathodes

Author

A. Ljubicic, Helmuth Berger, F. Piuz, E. Nappi, R. Ribeiro, J. Almeida, C. Coluzza, T. Scognetti, A. Di Mauro, Guy Paic, David O. Williams, André Braem, Giorgio Margaritondo, and F. Posa

Subjects
Physics, Nuclear and High Energy Physics, Photon, Atmospheric pressure, Physics::Instrumentation and Detectors, business.industry, Detector, Photocathode, Secondary electrons, Optics, Radiator (engine cooling), Quantum efficiency, Detectors and Experimental Techniques, business, Instrumentation, Cherenkov radiation
Abstract

In the frame of the RD26 collaboration at CERN we have built and tested several prototypes of fast-RICH detectors suitable for the construction of large systems. The detectors used a solid photocathode consisting of a 500 nm CsI layer evaporated on a conventional pad readout board of a MWPC operated with a methane/isobutane mixture at atmospheric pressure. The results indicate that such a detector may be used for long periods of time in stable operating conditions provided the gas mixture is continuously flushed through the detector. Evidence is presented for a significant loss of transmission of Cherenkov photons in the NaF radiator due to internal anisotropy of the crystal. We present the results of the performance of the photocathodes, the quantum efficiency of the CsI we have extracted from the measured Cherenkov photons and the identification achievable in a high density environment such as the detector ALICE planned for the heavy ion LHC. The results of a study of primary and secondary electron photoemission of CsI layers indicate that the surface structure and electron yield depend on the source material and on the heat treatment of the layer.

Published
1994
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9. A fast RICH detector for particle identification in ALICE at LHC

Author

Guy Paic, F. Piuz, E. Nappi, R. Ribeiro, A. DiMauro, F. Posa, T. Scognetti, and A. Ljubicic

Subjects
Physics, Nuclear and High Energy Physics, Range (particle radiation), Particle physics, Large Hadron Collider, Physics::Instrumentation and Detectors, Detector, Particle identification, Charged particle, Nuclear physics, Time of flight, Hermetic detector, High Energy Physics::Experiment, Rapidity, Detectors and Experimental Techniques, Nuclear Experiment, Instrumentation
Abstract

The ALICE collaboration proposes to investigate central ion-ion collisions (PbPb) at the Large Hadron Collider operated in the ion mode. The core of the detector covers 1.8 units of rapidity centered at midrapidity. The maximum expected rapidity density is 8000 charged particles. The proposed detector is planned to measure the momentum, charge and mass of the majority of the particles in the range of transverse momentum of 0.05–2.0 GeVc. In the range of momenta where charged particle identification, by means of ionization losses, is not possible (by the TPC, and/or silicon detectors), i.e. above 0.8 GeV/c for pions and kaons, the ALICE detector envisages two alternatives currently actively investigated — a time of flight wall or a RICH detector. The RICH detector under study is of the proximity focusing type with a liquid C6F14 radiator, using a MWPC with pad readout equipped with a solid photocathode for UV light detection.

Published
1994
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10. An optical readout RICH detector for the NA35 heavy-ion experiment

Author

G. Roland, W. Heck, J. Baechler, T. Scognetti, G. Vasileiadis, Guy Paic, K. Runge, M. Le Vine, A. Ljubicic, R. K. Bock, A. Sandoval, F. Posa, G. Tomasicchio, D. Vranic, Apostolos Panagiotou, Predrag Buncic, E. Nappi, A. Di Mauro, E. Schmoetten, Maurice Hoffmann, and R. Stock

Subjects
Physics, Nuclear and High Energy Physics, Range (particle radiation), Large Hadron Collider, Physics::Instrumentation and Detectors, Detector, Tracking (particle physics), Particle identification, Nuclear physics, Momentum, High Energy Physics::Experiment, Heavy ion, Nuclear Experiment, Instrumentation
Abstract

A 50 × 50 cm2 RICH detector prototype with optical readout has been tested during the 1992 32S run period at the CERN SPS, to provide particle identification in the momentum range 1.5–4.0 GeV/c. Construction details and results of the analysis of the CCD images are discussed, taking reconstruction algorithms and tracking predictions into account.

Published
1994
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11. Fast RICH detector with a cesium iodide photocathode at atmospheric pressure

Author

E. Nappi, R. Ribeiro, F. Piuz, F. Posa, G. Paic, A. Ljubicic, André Braem, A. DiMauro, T.D. Williams, and T. Scognetti

Subjects
Physics, Nuclear and High Energy Physics, Wire chamber, Photon, Physics::Instrumentation and Detectors, business.industry, Detector, Photoelectric effect, Photocathode, Cathode, law.invention, Optics, law, Physics::Accelerator Physics, Angular resolution, Detectors and Experimental Techniques, business, Instrumentation, Cherenkov radiation
Abstract

CsI photocathodes of 30 × 30 cm 2 size have been operated in a fast RICH detector composed of a NaF radiator and a multiwire proportional chamber with a cathode pad readout. Results are presented from tests with a 3 GeV c proton beam. A Cherenkov angular resolution of 8 mrad is obtained by detecting a mean of 8 photoelectrons per ring. Methods are described for counting the Cherenkov photons and evaluating the differential quantum efficiency of the CsI photocathode. The results obtained with photons impinging at a large angle on the CsI layer are presented and discussed in comparison with higher quantum efficiencies observed under different experimental conditions.

Published
1994
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12. Particle identification with a solid photocathode RICH in ALICE at LHC

Author

Guy Paic, E. Nappi, A. Di Mauro, R. Ribeiro, F. Posa, D. Vranic, F. Piuz, A. Ljubicic, and T. Scognetti

Subjects
Physics, Nuclear and High Energy Physics, Range (particle radiation), Large Hadron Collider, Photon, Physics::Instrumentation and Detectors, Cherenkov detector, Tracking (particle physics), Photocathode, Particle identification, law.invention, Nuclear physics, law, Instrumentation, Cherenkov radiation
Abstract

We present a simulation of the response of a solid photocathode (CsI) proximity focusing RICH detector for the future heavy ion ALICE experiment at the LHC accelerator at CERN. The UV detector is a pad chamber with fast analog readout, the pad size being 8 × 8 mm 2 . The radiator is envisaged to be 1 cm of liquid freon. The simulation includes full pad response and single particle and Cherenkov photon generation and tracking through various media. The input consists of a realistic particle density and momentum distribution as expected in a lead-lead collision at LHC energies. A novel analysis method is given which proves to be satisfactory for a 3σ separation between pions and kaons in the momentum range of interest at the expected particle densities of 50–70 particles/m 2 . The method is a “Hough-like” transform that maps the pad coordinate space directly to the Cherenkov angle parameter space. It proves to be robust enough to be able to handle the high particle densities with sufficient precision.

Published
1994
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13. A RICH detector as particle identification detector in ALICE

Author

R. Ribeiro, T. Scognetti, A. Ljubicic, F. Piuz, A. DiMauro, Eugenio Nappi, F. Posa, and Guy Paic

Subjects
Physics, Nuclear physics, Nuclear and High Energy Physics, Particle physics, Large Hadron Collider, Physics::Instrumentation and Detectors, Detector, ALICE (propellant), Particle density, Particle identification
Abstract

The novel developments in the solid photocathodes using CsI evaporated on a pad readout MWPC open a way to achieve large areas of RICH detector fulfilling the particle identification requirements in the high particle density environment of ALICE at LHC. The first prototypes have been tested and expected performance is presented.

Published
1994
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14. Reconstruction of Cherenkov rings in imaging detectors

Author

G. Roland, E. Nappi, G. Tomasicchio, A. Ljubicic, D. Vranic, T. Scognetti, E. Schmoetten, M. Wensveen, K. Runge, W. Heck, Predrag Buncic, R. Stock, A. Di Mauro, Maurice Hoffmann, Apostolos Panagiotou, M. Koncul, F. Posa, R. K. Bock, A. Sandoval, G. Vasileiadis, Guy Paic, J. Bächler, and M. LeVine

Subjects
Physics, Nuclear and High Energy Physics, Physics::Instrumentation and Detectors, Cherenkov detector, business.industry, Detector, ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION, Reconstruction method, Particle identification, Particle detector, law.invention, Nuclear physics, Optics, law, Particle, High Energy Physics::Experiment, Point (geometry), business, Instrumentation, Cherenkov radiation
Abstract

A simulation and reconstruction method is presented which enables particle identification in a multihit environment with a RICH detector even in the case where the particle hit point on the detector is not precisely determined. The method is demonstrated for the configuration of the NA35 experiment.

Published
1994
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15. Strange and multistrange baryon production in Pb-Pb collisions at 158 A GeV/c

Author

Leonardo Paolo Rossi, W. Beusch, K.L. Norman, Håvard Helstrup, S. Szafran, D. Huss, G. Vassiliadis, D. Di Bari, Pavel Staroba, P. Jovanovic, M. T. Muciaccia, F. Posa, J.B. Kinson, G. Tomasicchio, Federico Antinori, V.A. Kachanov, W. Geist, N. Armenise, G. Romano, S. Saladino, A.K. Holme, V. Lenti, J. C. Lassalle, E. Andersen, Alberto Andrighetto, N. Carrer, T.F. Thorsteinsen, G. Rosa, A. Kirk, Erik H.M. Heijne, M.F. Votruba, A. Jacholkowski, W. Klempt, Eugenio Nappi, C. Salvo, Gunnar Løvhøiden, G. Grella, P. Middelkamp, J. Bán, M. Sené, M. Campbell, S. Di Liberto, H. Beker, Eugenio Cantatore, Anton Jusko, B. Sopko, H. Rotscheidt, M. A. Mazzoni, B. Ghidini, J. P. Davies, R. A. Fini, A. Singovski, J. Urban, A. Michalon, B. Pastirčák, David H. Evans, V. Mack, Vito Manzari, J. Šťastný, A. Volte, J.A. Lien, Franco Meddi, K. Šafařík, Petr Zavada, F. Navach, T. Kachelhoffer, Michele Guida, R. Lietava, I. Králik, M. Luptak, G.F. Segato, M. G. Catanesi, Giovanni Darbo, L. Šándor, F. Pellegrini, R. Sené, M. Vaníčková, M. Morando, Paolo Martinengo, T. Scognetti, E. Quercigh, Jean-Charles Fontaine, E. Chesi, Bianca Osculati, T. Storås, Tiziano Virgili, M. Dameri, M.E. Michalon-Mentzer, K. Knudson, I. Mácha, Dario Barberis, P. Sennels, J. Bohm, S. Simone, A. Di Mauro, M. Venables, R. A. Loconsole, J. Ftacnik, Rocco Caliandro, A. Diaczek, K. Fanebust, K. Piska, D. Elia, C. Voltolini, O. Villalobos Baillie, R. A. Ricci, Physique Corpusculaire et Cosmologie - Collège de France (PCC), Collège de France (CdF (institution))-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Collège de France (CdF)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Heyd, Yvette

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, Large Hadron Collider, Spectrometer, Quark-gluon plasma, nucleon, WA97, [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], Detector, Strangeness, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Tracking (particle physics), Omega, Baryon, Nuclear physics, Particle
Abstract

The series of experiments (WA85, WA94 and WA97) at the Omega spectrometer at CERN SPS have systematically studied the production of different strange particles. Strangeness enhancements at central rapidities have been reported by WA85 and WA94 in S-W and SS with respect to p-A collisions. For the investigation of PbPb interactions in the WA97 experiment a new detector suitable for high particle densities, the Pixel Tracking Chamber, has been developed based on silicon pixel detectors. The results on production ratios and cross sections of Λ, Λ , Ξ − , Ξ + , Ω − and Ω + detected by this experiment are presented. A significant enhancement of the Ω over Ξ ratio is observed when comparing p-Pb to PbPb data (a factor of about 3).

Published
1998

16. Enhancement of central Λ, Ξ and yields in Pb-Pb collisions at 158 A GeV/c

Author

A. Kirk, M.T. Muciaccia, Giorgio Torrieri, A. Singovski, G. Grella, F. Navach, J.B. Kinson, F. Posa, Jean-Charles Fontaine, David H. Evans, S. Szafran, B.T.H. Knudsen, Michele Guida, S. Simone, E. Andersen, Eugenio Cantatore, Federico Antinori, Trine Spedstad Tveter, R.A. Loconsole, M. G. Catanesi, M. Morando, Petr Zavada, B. Ghidini, M. Dameri, Rocco Caliandro, P.I. Norman, Michael A. Thompson, Erik H.M. Heijne, S. Saladino, N. Carrer, G. T. Jones, H. Bakke, W. Beusch, H. Rotscheidt, K. Piska, Gunnar Løvhøiden, A.K. Holme, Anton Jusko, M. Sené, M. Campbell, A. Diaczek, M.E. Michalon-Mentzer, I. J. Bloodworth, V. Lenti, D. Huss, P. Jovanovic, R. A. Fini, Dario Barberis, T. Virgili, H. Beker, P. Middelkamp, O. Villalobos Baillie, R. A. Ricci, K. Fanebust, E. Nappi, J. Urban, A. Michalon, T. Kachelhoffer, J. Bohm, A. Volte, B.C. Earl, I. Králik, N. Armenise, M.A. Mazzoni, Walter Snoeys, Davide Elia, M. Venables, V. Mack, Vito Manzari, R. Lietava, R. Sené, M. Luptak, G.F. Segato, Domenico Di Bari, Paolo Martinengo, K. Knudson, G. Tomasicchio, L. Šándor, A. Jacholkowski, F. Pellegrini, E. Quercigh, Franco Meddi, V.A. Kachanov, G. Romano, M.F. Votruba, T. Scognetti, W. Klempt, G. Rosa, Pavel Staroba, T.F. Thorsteinsen, Haavard Helstrup, J. Bán, Giovanni Darbo, E. Chesi, Bianca Osculati, K. Šafařík, Leonardo Paolo Rossi, G. Vassiliadis, C. Salvo, J. C. Lassalle, S. Di Liberto, B. Pastirčák, and J. Ftacnik

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, 010308 nuclear & particles physics, Nuclear Theory, Hyperon, Hyperons, Strangeness, 01 natural sciences, Spectral line, Nuclear physics, 0103 physical sciences, Quark–gluon plasma, Transverse mass, Quark Gluon Plasma, Nuclear Experiment, 010306 general physics
Abstract

Λ, Ξ and Ω yields and transverse mass spectra have been measured in Pb-Pb and p-Pb collisions at 158 A GeV/c. The yields in Pb-Pb interactions are presented as a function of the collision centrality and compared with those obtained from p-Pb collisions. Strangeness enhancement is observed which increases with centrality and with the strangeness content of the hyperon.

Published
1998

17. WA97 results on strangeness production in lead-lead collisions at 158 A GeV/c

Author

S. Simone, V. Lenti, G. Tomasicchio, J. Urban, A. Di Mauro, R. A. Loconsole, L. Šándor, F. Pellegrini, J.A. Lien, M. T. Muciaccia, Ph. Leruste, N. Carrer, J. Ftacnik, N. Armenise, M. Morando, A. Diaczek, M.F. Votruba, W. Klempt, Eugenio Nappi, Leonardo Paolo Rossi, M.E. Michalon-Mentzer, C. Salvo, J. Bán, Pavel Staroba, J. C. Lassalle, H. Rotscheidt, P. Middelkamp, Giovanni Darbo, J. L. Narjoux, K. Knudson, J. P. Davies, H. Beker, E. Chesi, B. R. French, Franco Meddi, Håvard Helstrup, E. Andersen, J. Bohm, Michele Guida, K. Piska, G. Vassiliadis, A. Kirk, P. Farthouat, P. Jovanovic, A. Volte, T. Scognetti, M. Luptak, D. Elia, G.F. Segato, Vito Manzari, M. Sené, V. Mack, R. Lietava, R. Sené, Anton Jusko, I. Mácha, T. Storås, M. Vaníčková, A. Jacholkowski, K. Fanebust, W. Geist, F. Posa, T. Kachelhoffer, C. Voltolini, K. Šafařík, M.A. Mazzoni, B. Osculati, E. Quercigh, Federico Antinori, M. Venables, V.A. Kachanov, Erik H.M. Heijne, T.F. Thorsteinsen, T. Virgili, I. Králik, K.L. Norman, Petr Zavada, Paolo Martinengo, J.B. Kinson, G. Grella, S. Szafran, P. Sennels, A. Singovski, J.C. Fontaine, G. Romano, Michael Campbell, R. A. Fini, M. Dameri, A. Michalon, G. Rosa, Gunnar Løvhøiden, Dario Barberis, D. Di Bari, Eugenio Cantatore, B. Ghidini, F. Navach, W. Beusch, D. Huss, M. Benayoun, B. Sopko, David H. Evans, J. Šťastný, M. G. Catanesi, L. Lopez, S. Saladino, A.K. Holme, Alberto Andrighetto, S. Di Liberto, B. Pastirčák, O. Villalobos Baillie, and R. A. Ricci

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, Proton, Heavy Ion Collisions, Strangeness production, Strangeness, Nuclear physics, Lead (geology), Quark Gluon Plasma, Quark–gluon plasma, Mass spectrum
Abstract

Preliminary results from WA97 measurements on Λ, Ξ and Ω production in lead-lead and proton-lead collisions are presented, along with a comparison of WA97 proton-lead data with previous WA85 proton-tungsten results. The ratio Ω gX seems to be enhanced in lead initiated reactions compared to proton initiated reactions.

Published
1996

18. Microanalysis surface studies and photoemission properties of CsI photocathodes

Author

André Braem, Brian P. Tonner, T. Scognetti, Rachel Chechik, C. Coluzza, A. Buzulutskov, Giorgio Margaritondo, Amos Breskin, Sidney R. Cohen, E. Conforto, S. Sgobba, Guy Paic, Eugenio Nappi, Tiziana dell’Orto, F. Piuz, and J. Almeida

Subjects
Physics, Surface (mathematics), Nuclear and High Energy Physics, business.industry, Crystal structure, Microanalysis, Microscopic scale, law.invention, Optics, law, Electrode, Optoelectronics, Quantum efficiency, Detectors and Experimental Techniques, business, Instrumentation, Chemical composition, Monochromator, TMAE
Abstract

We present recent results of the study of surface properties and quantum efficiency (QE) of CsI photocathodes prepared on various substrates. Microanalysis methods provide laterally resolved surface morphology and chemical composition of the photoemissive film. Integral measurements of the QE of CsI were done with a monochromator system and a RICH device. It was shown that CsI films deposited on large area Ni- or Ni-Au-coated printed circuit electrodes have a uniform crystalline structure and an average QE close to that reached on polished stainless steel. The films have a good stability in air over periods of Ih. On a microscopic scale of 3-30 mu m, the films exhibit nonuniform emission properties correlated with variations in the chemical composition.

Published
1995

19. First results from the 1994 lead beam run of WA97

Author

J.A. Lien, K. Fanebust, M. Dameri, M.A. Mazzoni, Federico Antinori, Erik H.M. Heijne, Leonardo Paolo Rossi, Anton Jusko, Ivan Kralik, B. R. French, Franco Meddi, P. Farthouat, T. Scognetti, Håvard Helstrup, A. Di Mauro, L. Lopez, S. Saladino, G. Vassiliadis, N. Carrer, S. Sclmane, J. Stastny, Alberto Andrighetto, S. Di Liberto, T. Virgili, A.K. Holme, M.E. Michalon-Mentzer, P. Middelkamp, H. Beker, A. Kirk, A. Volte, Jozef Urban, Paolo Martinengo, A. Pallares, S. Szafran, B. Pastirčák, Giovanni Darbo, R. Lietava, R. Sené, S. Simone, A. C. Bayes, A. Singovski, R. A. Fini, N. Armenise, C. Gemme, E. Chesi, A. Diaczek, M. T. Muciaccia, B. Sopko, V. Khodyrev, F. Pellegrini, Eugenio Cantatore, G. Romano, A. Michalon, Vito Manzari, L. Sandor, K.L. Norman, O. Villalobos Baillie, R. Blaes, Petr Zavada, B. Ghidini, R. A. Ricci, T. Reitan, G. Alexeev, J. Bán, A. Jacholkowski, E. Andersen, F. Navach, J.B. Kinson, H. Vettunen, J L. Reister, M. Morando, Ph. Leruste, I. Mácha, J. Sahagun Pareja, Dario Barberis, David H. Evans, P. Jovanovic, R. Fang, P. Sennels, B. Osculati, J. C. Lassalle, W. Geist, M. G. Catanesi, M. Sené, J. P. Davies, K. Knudson, H. Rotscheidt, T.F. Thorsteinsen, V.A. Kachanov, J. N. Carney, Gunnar Løvhøiden, F. Posa, M. Luptak, G.F. Segato, M. Vaníčková, W. Beusch, T. Kachelhoffer, Pavel Staroba, E. Quercigh, A. Inyakin, M. Benayoun, M. Pairat, Michael Campbell, D. Di Bari, J. L. Narjoux, J. Bohm, G. Grella, Michele Guida, J. Kahane, V. Lenti, T. Storaas, P. Shagin, C. Voltolini, J.M. Brom, K. Piska, J. P. Dufey, D. Elia, G. Tomasicchio, M.F. Votruba, W. Klempt, G. Rosa, Eugenio Nappi, Karel Safarik, Physique Corpusculaire et Cosmologie - Collège de France (PCC), Collège de France (CdF (institution))-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Heyd, Yvette, and Collège de France (CdF)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Nuclear and High Energy Physics, Silicon pixel detectors, Silicon, Physics::Instrumentation and Detectors, 010308 nuclear & particles physics, Nuclear Theory, chemistry.chemical_element, 01 natural sciences, law.invention, Nuclear physics, Baryon, Telescope, Lead (geology), chemistry, law, 0103 physical sciences, Quark Gluon Plasma, Nuclear Experiment, 010306 general physics, Beam (structure)
Abstract

WA97 is designed to study strange and multi-strange baryon and anti-baryon production in 160 A GeV c PbPb collisions at the SPS with a telescope of silicon microdetectors. Four planes of silicon pixel detectors were successfully employed during the 1994 Pb run. A total of 60M central PbPb events were collected. We describe the experimental setup and report on some preliminary results from the off-line analysis.

Published
1995

20. A large area optical imaging uv detector operating with TMAE at 48 dregee C

Author

R. Ferorelli, E. Nappi, R. K. Bock, M. Bosteels, A. Sandoval, Jean-Paul Fabre, E. Schmoetten, M. Wensveen, J. Baechler, M. J. LeVine, A. Ljubicic, K. Runge, D. Vranic, A. Di Mauro, W. Heck, Apostolos Panagiotou, F. Posa, Guy Paic, G. Vasileiadis, Predrag Buncic, N. Facchini, T. Scognetti, M. Koncul, Maurice Hoffmann, R. Stock, G. Roland, and G. Tomasicchio

Subjects
Physics, Nuclear and High Energy Physics, Large Hadron Collider, Uv detector, Physics::Instrumentation and Detectors, business.industry, Photon detector, Detector, C region, Particle identification, Optics, Optical imaging, Detectors and Experimental Techniques, business, Instrumentation, Cherenkov radiation
Abstract

We describe the multistep avalanche chamber (MSAC) used in the experiment NA35 at CERN as photon detector of a ring imaging Cherenkov counter (RICH) that upgraded the experimental setup of a vertex streamer chamber by providing particle identification in the 1.5–3.5 GeV/c region. The chamber design contains some innovative technical solutions to limit the sparking rate and to allow the sensitive area to be larger than the present 50 × 50 cm2. The detector is read out optically using a CCD camera in conjunction with a system of light intensifiers, since the optical readout offers a convenient way to record events in a two-dimensional array. Construction details and test results are discussed.

Published
1992

21. Morphological Effects in the Quantum Yield of Cesium Iodide

Author

M. Bertolo, Anna Monica Bianco, J. Almeida, Eugenio Nappi, T. Scognetti, F. Piuz, R. Sanjines, S. Sgobba, S. Fontana, G. Paic, Giorgio Margaritondo, C. Coluzza, F. Barbo, S. Cerasari, Tiziana dell’Orto, and André Braem

Subjects
Physics, Diffraction, WAVELENGTH BAND 1-300, Nuclear and High Energy Physics, business.industry, INSULATORS, X-RAYS, MODELS, Analytical chemistry, Quantum yield, RAY PHOTO-CATHODES, Secondary electrons, law.invention, SECONDARY-ELECTRON EMISSION, Optics, law, CSI, Secondary emission, Microscopy, PHOTOCATHODES, Quantum efficiency, Crystallite, Scanning tunneling microscope, business, Instrumentation
Abstract

We demonstrated that polycrystalline cesium iodide (CsI) on large area Ni/Au coated printed board provides a quantum efficiency (QE) higher by a factor of 2 than the films deposited on the standard Cu/Au printed circuits. This is the most important result of the present systematic study of the QE lateral inhomogeneity for CsI on different substrates. We found a strong correlation between the QE lateral variation and the morphological homogeneity of the films. The QE was measured by UV photoelectron emission microscopy and spatially resolved X-ray photoemission, and the morphology studies were performed by secondary electron microscopy, X-ray diffraction and scanning tunneling microscopy.

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