ELEMENTARY PARTICLE PHYSICS PROFESSORS Gianpaolo Bellini Enrico Bellotti Maria di Corato Ettore Fiorini Luciano Mandelli Pietro Negri Giuliano Preparata Antonino Pullia Guido Vegni ASSOCIATE PROFESSORS Silvia Bonetti Daniel Victor Camin Emanuela Meroni Fernando Palombo Laura Perini Stefano Ragazzi Francesco Ragusa Luigi Zanotti RESEARCH ASSOCIATES Chiara Brofferio Massimo Caccia Marta Calvi Claudio Furetta Fabiola Gianotti Andrea Giuliani Simonetta Pensotti RESEARCH FELLOWS Mario Rosario Aleppo Attilio Andreazza Barbara Caccianiga Nicola Ferrari Nicola Labanca Barbara Maggi Angelo Nucciotti Maura Pavan Massimiliano Pindo Monica Rattaggi Francesco Tartarelli Alessandra Tonazzo ADMINISTRATIVE STAFF Lorella Branzoni TECHNICAL STAFF Roberto Campagnolo Ciro Venditti INFN STAFF RESEARCH DIRECTOR Giuseppe Costa Clara Matteuzzi RESEARCH ASSOCIATES Angelo Alessandrello Gianluca Alimonti Giuseppe Battistoni Maurizio Bonesini Carla Cattadori Donatella Cavalli Oliviero Cremonesi Nicolai Fedyakin Alfredo Ferrari Marco Giulio Giammarchi Alexey Golubchikov Serghei Goumeniouk Frank Hartmann Stefano Magni Sandra Malvezzi Marcello Mazzanti Chiara Meroni Dario Menasce Luigi Moroni Daniele Pedrini Laura Perasso Gianluigi Pessina Pier Giorgio Rancoita Gioacchino Ranucci Nicola Redaelli Angela Sala Paola Sala Silvano Sala Tommaso Tabarelli Clara Troncon RESEARCH FELLOWS Maurizio Acciari Walter Bonivento Daniele Brambilla Paola Caspani Pierre Colling Andrea D’Avella Pamela Ferrari Lothar Oberauer Ezio Previtali Marco Redaelli Silvia Resconi Schoenert Stephan ADMINISTRATIVE STAFF Luciana Brogiato Silvia Rognoni TECHNICAL STAFF Gianni Bacchiocchi Augusto Brigatti Romano Cavaletti Renato Cavallini Francesco Chignoli Mario Cighetti Pasquale D’Angelo Andrea Garagiola Silvano Grabar Stefano Latorre Roberto Leoni Roberto Mazza Bruno Monticelli Sergio Parmeggiano Fabrizio Sabatini Giorgio Sala Introduction The section of the Physics Department “Elementary Particles” is a large group of physicists, engineers, technicians, devoted to the experimental research in the field of the Elementary Particle Physics. The main topics covered by the activity of this group concern: Physics of the Heavy Flavours; study of the electroweak properties; lepton; Solar Neutrinos; Double beta decays. The research is carried out in experiments with accelerators both at fixed target (Fermilab: E687; E831) and at e+e- machines (LEP: Delphi, L3, Aleph) and at the Gran Sasso Underground Laboratory (Gallex, Borexino, Bolometers). Technical activities are also very important; they concern: the development of a calorimeter and of a microvertex in view of the experiment ATLAS at LHC (ATLAS calorimetry and ATLAS microvertex); preparation and test of a prototype of liquid Kripton calorimeter (Liquid Kripton Calorimeter); study of calorimetry with Si detectors (SICA5); development of cryogenic microelectronics. In some of the actrivities mentioned above the physicists of the section have a prominent role, sometimes they are spokesmen or coordinators of the collaborations. Some aspects of the thechnical developments have characteristics which are unique in the frame of the world research in this field. Study of charm properties - E687/E831 photoproduction experiments at Fermilab: Heavy Flavour Physics, Charm, Microvertex The E687 experiment takes place at the Tevatron of the Fermi National Laboratory (Fermilab) Batavia-Illinois-USA. The goal of the experiment is the study of the charm particles that allows to test the Standard Model describing the interactions of the elementary particles. The E687 detector is a large aperture magnetic spectrometer with vertex measurement, particle identification and calorimetric capabilities; the charm particles are produced by a photon beam impinging on a Beryllium target. During 1996 the group has carried on the analysis of the data collected during the 1990- 1991 fixed target run at Fermilab. The most important results are published on international journals (see publications). Among the several results deserve to be underscored the studies of the lifetimes of the charmed mesons and baryons (in particular the first measurement of the lifetime) that allowed to determine the lifetime hierarchy, the studies of the semileptonic decays with the consequent determination of the form factors, the amplitude analysis of the decay modes and , the search for CP violation in the charm meson decays, an extensive study of the hadronic decays of the charmed mesons and finally the study of the photoproduction dynamics using the completely reconstructed double D events. The goal of the new experiment, E831 (upgrade of E687), now in the data taking phase, is to complete the physics picture of the charm particles by collecting a statistics ten times bigger than our previous sample. In particular our group is responsible of the Silicon Microvertex Detector. The co-spokesman of E831 is L. Moroni. The responsibles of the Italian Collaboration is: G. Bellini for E687, D. Pedrini for E831. Responsibles: Gianpaolo Bellini, Luigi Moroni Recent Publications: 1. P.L. Frabetti, G. Alimonti, G. Bellini, B. Caccianiga, M. Di Corato, M. Giammarchi, P. Inzani, F. Leveraro, S. Malvezzi, D. Menasce, E. Meroni, L. Moroni, D. Pedrini, L. Perasso, A. Sala, S. Sala et al., "Analysis of the Dalitz plots", Phys. Lett. B351 (1995) 591. 2. P.L. Frabetti, G. Alimonti, G. Bellini, B. Caccianiga, M. Di Corato, M. Giammarchi, P. Inzani, F. Leveraro, S. Malvezzi, D. Menasce, E. Meroni, L. Moroni, D. Pedrini, L. Perasso, A. Sala, S. Sala et al., “Study of charged hadronic four body decays of the meson”, Phys. Lett. B 354 (1995) 486. 3. P.L. Frabetti, G. Alimonti, G. Bellini, B. Caccianiga, M. Di Corato, M. Giammarchi, P. Inzani, F. Leveraro, S. Malvezzi, D. Menasce, E. Meroni, L. Moroni, D. Pedrini, L. Perasso, A. Sala, S. Sala et al., “First measurement of the lifetime of the ”, Phys. Lett. B 357 (1995) 678. 4. P.L. Frabetti, G. Alimonti, G. Bellini, B. Caccianiga, M. Di Corato, M. Giammarchi, P. Inzani, F. Leveraro, S. Malvezzi, D. Menasce, E. Meroni, L. Moroni, D. Pedrini, L. Perasso, A. Sala, S. Sala et al., “Doubly and singly Cabibbo suppressed charm decays into the final state”, Phys. Lett. B 359 (1995) 403. 5. P.L. Frabetti, G. Alimonti, G. Bellini, B. Caccianiga, M. Di Corato, M. Giammarchi, P. Inzani, F. Leveraro, S. Malvezzi, D. Menasce, E. Meroni, L. Moroni, D. Pedrini, L. Perasso, A. Sala, S. Sala et al., "Search for the decay of and mesons to three charged kaons”, Phys. Lett. B363 (1995) 259. 6. P.L. Frabetti, G. Alimonti, G. Bellini, B. Caccianiga, M. Di Corato, M. Giammarchi, P. Inzani, F. Leveraro, S. Malvezzi, D. Menasce, E. Meroni, L. Moroni, D. Pedrini, L. Perasso, A. Sala, S. Sala et al., "Analysis of the decay mode muon neutrino”, Phys. Lett. B364 (1995) 127. 7. P.L. Frabetti, G. Alimonti, G. Bellini, B. Caccianiga, M. Di Corato, M. Giammarchi, P. Inzani, F. Leveraro, S. Malvezzi, D. Menasce, E. Meroni, L. Moroni, D. Pedrini, L. Perasso, A. Sala, S. Sala et al., "Study of higher mass charm baryons decaying to ”, Phys. Lett. B365 (1996) 461. 8. P.L. Frabetti, G. Alimonti, G. Bellini, B. Caccianiga, M. Di Corato, M. Giammarchi, P. Inzani, F. Leveraro, S. Malvezzi, D. Menasce, E. Meroni, L. Moroni, D. Pedrini, L. Perasso, A. Sala, S. Sala et al., "Fermilab E687 results and future high statistics charm experiment FOCUS/E831”, Nucl. Phys. (Proc. suppl.) 50 (1996) 154. 9. P.L. Frabetti, G. Alimonti, G. Bellini, B. Caccianiga, M. Di Corato, M. Giammarchi, P. Inzani, F. Leveraro, S. Malvezzi, D. Menasce, E. Meroni, L. Moroni, D. Pedrini, L. Perasso, A. Sala, S. Sala et al., "Charm - anti-charm asymmetries in high energy photoproduction”, Phys. Lett. B370 (1996) 222. 10. P.L. Frabetti, G. Alimonti, G. Bellini, B. Caccianiga, M. Di Corato, M. Giammarchi, P. Inzani, F. Leveraro, S. Malvezzi, D. Menasce, E. Meroni, L. Moroni, D. Pedrini, L. Perasso, A. Sala, S. Sala et al., "Analysis of the Cabibbo suppressed decay ”, Phys. Lett. B382 (1996) 312. 11. P.L. Frabetti, G. Alimonti, G. Bellini, B. Caccianiga, M. Di Corato, M. Giammarchi, P. Inzani, F. Leveraro, S. Malvezzi, D. Menasce, E. Meroni, L. Moroni, D. Pedrini, L. Perasso, A. Sala, S. Sala et al., "Observation of the vector meson Cabibbo suppressed decay ”, submitted to Phys. Lett. B. DELPHI High energy electron-positron collisions (LEP): Electroweak Interactions, Calorimetry, Microvertex Hardware : a) setting-up and calibrations of a small calorimeter (STIC) for the measurement of the Luminosity at the precision level of 0.1% , in DELPHI (one of the four experiments at LEP). The calorimeter is of Shashlik type and it is constituted by a sandwich of lead sheets and plastic scintillators with fibres readout. b) installation, calibration and tests of the new high precision vertex detector of DELPHI. The detector layout foresees two shells of double sided Si microstrips and one shell of single sided detectors. An extension in the forward region, made out of two layers of ministrip and two layers of digital pixels have been added. The overall number of 1.2 M pixels makes it the largest ever installed pixel detector. Preliminary results confirm the achievement of the design performances. Software and Physics Analysis : more than one million of Z decays were collected during '95 and the analysis was concentrated on the following items: a) High precision measurements of electroweak parameters b) Oscillation phenomena of the system c) Measurement of the lifetime of B particles and lepton d) Measurements of the decay width and through the analysis of the radiative events. The energy of LEP was gradually increased and during '96 the threshold for the productions of W+W- ( the charged weak interactions bosons) was reached. The analysis was concentrated on: e) measurement of the W mass f) measurement of the trilinear bosons coupling (ZWW). Responsibles: Antonino Pullia and Guido Vegni Recent Publications: 1. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”A study of radiative muon-pair events at energies and limits on an additional Z' gauge boson", Z. Phys. C65 (1995) 603. 2. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Production characteristics of and light meson resonances in hadronic decays of the ", Z. Phys. C65 (1995) 587. 3. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Measurement of the branching ratio of the Z by double hemisphere tagging", Z. Phys. C65 (1995) 555. 4. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Measurement of the forward-backward asymmetry of using prompt leptons and a lifetime tag", Z. Phys. C65 (1995) 569. 5. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”First evidence of hard scattering processes in single tagged collisions", Phys. Lett. B342 (1995) 402. 6. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Measurement of the forward-backward asymmetry of charm and bottom quarks at the Z pole using mesons", Z. Phys. C66 (1995) 341. 7. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Observation of orbitally excited B mesons", Phys. Lett. B345 (1995) 598. 8. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Search for heavy neutral Higgs bosons in two- doublet models", Z. Phys. C67 (1995) 69. 9. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”First measurement of the strange quark asymmetry at the peak", Z. Phys. C67 (1995) 1. 10. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Production of charged particles, and events and the decay of b hadrons", Phys. Lett. B347 (1995) 447. 11. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Measurement of using impact parameter measurement and lepton identification", Z. Phys. C66 (1995) 323. 12. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Inclusive measurements of the and production in hadronic decays", Nucl. Phys. B444 (1995) 3. 13. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Measurements of the polarization in the decays", Z. Phys. C67 (1995) 183. 14. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Strange baryon production in Z hadronic decays", Z. Phys. C67 (1995) 543. 15. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Production of strange B-baryons decaying into pairs at LEP", Z. Phys. C68 (1995) 541. 16. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ” production in Z decays", Z. Phys. C68 (1995) 353. 17. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Lifetime and production rate of beauty baryons from Z decays", Z. Phys. C68 (1995) 375. 18. W. Adam, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Lifetimes of charged and neutral B hadrons using event topology", Z. Phys. C68 (1995) 363. 19. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”A measurement of and lifetimes using events", Z. Phys. C68 (1995) 13. 20. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Observation of short range three-particle correlations in annihilation at LEP energies", Phys. Lett. B355 (1995) 415. 21. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”A measurement of the photon structure function at an average of 12 GeV2/c4”, Z. Phys. C69 (1995) 223. 22. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Search for exclusive charmless B meson decays with the DELPHI detector at LEP”, Phys. Lett. B357 (1995) 255. 23. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Study of prompt photon production in hadronic decays", Z. Phys. C69 (1995) 1. 24. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Observation of short range three particle correlations in annihilation at LEP energies”, Phys. Lett. B355 (1995) 415. 25. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”A measurement of the leptonic branching fractions”, Phys. Lett. B357 (1995) 715. 26. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Upper limits on the branching ratio and ”, Phys. Lett. B359 (1995) 411. 27. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Measurement of (1232) production in hadronic Z decays”, Phys. Lett. B361 (1995) 207. 28. W. Adam, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Measurement of inclusive production in hadronic decays”, Z. Phys. C69 (1995) 561. 29. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Search for promptly produced heavy quarkonium states in hadronic Z decays”, Z. Phys. C69 (1995) 575. 30. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”A precise measurement of the lepton lifetime”, Phys. Lett. B365 (1996) 448. 31. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Energy dependence of the differences between the quark and the gluon jet fragmentation”, Z. Phys. C70 (1996) 179. 32. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Performance of the DELPHI detector”, Nulc. Instr. and Methods A378 (1996) 57. 33. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Search for new phenomena using single photon events in the DELPHI detector at LEP”, submitted to Z. Phys. C. 34. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Charged particle multiplicity in interactions at 130 GeV”, Phys. Lett. B372 (1996) 172. 35. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Search for exclusive decay of the barion and measurements of its mass”, Phys. Lett. B374 (1996) 351. 36. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Updated precision measurement of the average lifetime of B hadrons”, Phys. Lett. B377 (1996) 195. 37. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”First measurement of (1525) production in hadronic decays", Phys. Lett. B379 (1996) 309. 38. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Kaon interference in the hadronic decays of the ”, Phys. Lett. B379 (1996) 330. 39. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Search for anomalous production of single photons at 130 and 136 GeV”, Phys. Lett. B380 (1996) 471. 40. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Study of radiative leptonic events with hard photons and search for excited chearged leptons at 130-136 GeV”, Phys. Lett. B380 (1996) 480. 41. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Search for the lightest chergino at 130 and136 GeV”, Phys. Lett. B382 (1996) 323. 42. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Production of and in Z decays", Z. Phys. C70 (1996) 371. 43. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Measurement of the partial decay width of the Z with the DELPHI detector at LEP", Z. Phys. C70 (1996) 531. 44. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Mean lifetime of the meson", Z. Phys. C71 (1996) 11. 45. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Determination of the average lifetime of b- baryons", Z. Phys. C71 (1996) 199. 46. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Determination of from the semileptonic decay ", Z. Phys. C71 (1996) 539. 47. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Measurement of the oscillation frequency using kaons, leptons and jet charge", Z. Phys. C72 (1996) 17. 48. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”First study of the interference between initial and final state radiation at the Z resonance", Z. Phys. C72 (1996) 31. 49. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Search for high mass resonances in e+e- and at LEP I", Z. Phys. C72 (1996) 179. 50. W. Adam, P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Study of rare b decays with the DELPHI detector at LEP", Z. Phys. C72 (1996) 207. 51. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Measurement of inclusive (892), (1020) and (1430) production in hadronic Z decays”, Z. Phys. C73 (1996) 61. 52. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Search for neutralinos, scalar leptons in interactions at GeV and 136 GeV”, Phys. Lett. B387 (1996) 651. 53. W. Adam, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Search for pair production of heavy objects in 4-jet events at GeV”, Z. Phys. C73 (1996) 1. 54. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”Tuning and test of fragmentation models based on identified particles and precision event shape data”, Z. Phys. C73 (1996) 11. 55. P. Abreu, A. Andreazza, M. Bonesini, W. Bonivento, M. Caccia, M. Calvi, C. Matteuzzi, C. Meroni, P. Negri, M. Paganoni, A. Pullia, S. Ragazzi, N.G. Redaelli, T. Tabarelli De Fatis, A. Tonazzo, C. Troncon, G. Vegni et al., ”An upper limit for Br from symmetric 3-jet hadronic decays”, Phys. Lett. B389 (1996) 405. 56. C. Troncon,"Measurement of spatial resolution and charge collection mechanism in double sided silicon microstrip detectors", Nucl. Phys. B44 (Proc. suppl.) (1995) 287. 57. V. Bonvicini, M. Caccia, N. Redaelli, M. Pindo, G. Vegni et al., "Screen printing and chip flipping techniques for large area hybrid pixel detectors bonding”, Nucl. Phys. B44 (Proc. suppl.) (1995) 409. 58. A. Andreazza, M. Caccia, C. Meroni, N. Redaelli, M. Pindo, C. Troncon, G. Vegni, et al., "The DELPHI Very Forward Tracker for LEP200", Nucl. Instr. and Methods A367 (1995) 198. 59. M. Pindo, "Radiation Hardness and resistance to electromigration effects of conductive glue bonds for hybrid pixel detectors realization", Proc. Workshop on Electronics for LHC, CERN/LHCC/95-96. 60. C. Meroni," The Forward extension of the DELPHI Silicon Tracker”, Proc. Workshop Vertex '95 WIS-96/18/june 1995-PH, p. 29. 61. M. Caccia, "Progress in the construction of the DELPHI Pixel detector", Workshop Semiconductor pixel detectors for particles and X rays, 24-26 March 1996. To be published in Nucl. Instr. and Methods A. 62. V. Chabaud, A. Andreazza, M. Caccia, C. Meroni, N. Redaelli, M. Pindo, C. Troncon, G. Vegni, et al., “The DELPHI silicon strip microvertex detector with double sided readout”, Nucl. Instr. and Methods A368 (1996) 314. 63. C. Troncon, "A new generation of vertex detectors for experiments at colliders”, Proc. of EPS Inter. Conference on High Energy Physics,Brussels, 27 July-3 August 1995. 64. C. Troncon “The DELPHI Microvertex Detector with Double Sided Readout”. Nuclear Physics B (Proc. Suppl.) 44 (1995), p.282 65. C. Troncon “Tagging Heavy Flavours with vertex detectors at e+e- colliders”. Proceedings of Vth Internations Workshop on Vertex Detectors, Chia, Cagliari, 16-21 june, 1996 L3 experiment at LEP collider: optoelectronics, semiconductor, detector, short-lived particle, vector boson The group has continued its scientific activity in the framework of the L3 experiment at e+e- LEP collider at CERN. During 94, it has contributed to set into operation the Silicon Microvertex Detector (SMD), and, in particular, the optoelectronic readout system (which is under Milan group responsability). SMD, which was fully operational in 94, enables to tag secondary vertices generated by short-lived particles. The group has continued the data analysis of the BR (Branching Ratio) of the decay channel Z-> J/ + X. The J/ particles have been reconstructed in their e+e- and m+m- decay channels. The found value of the BR has confirmed the ones of the other LEP experiments and the limited validity of the spectator-quark model. Responsible: Pier Giorgio Rancoita Recent Publications: 1. M. Acciarri, A. Baschirotto, R. Castello, S. Pensotti, P.G. Rancoita, M. Rattaggi, M. Redaelli et al., ”1994 running experience with the L3 Silicon Microvertex Detector", Nucl. Phys. B (Proc. Suppl.) 44 (1995) 296. 2. M. Acciarri, S. Pensotti, P.G. Rancoita, M. Redaelli et al., ”P-I-N like behaviour of detectors under high fluence neutron irradiation”, Nucl. Phys. B (Proc. Suppl.) 44 (1995) 480. 3. M. Acciarri, A. Baschirotto, R. Castello, S. Pensotti, P.G. Rancoita, M. Rattaggi, M. Redaelli et al., ”Measurement of exclusive branching fractions of hadronic one-pron tau decays”, Phys. Lett. B345 (1995) 93. 4. M. Acciarri, A. Baschirotto, R. Castello, S. Pensotti, P.G. Rancoita, M. Rattaggi, M. Redaelli et al., “Energy and particle flow in three-jet and radiative two-jet events from hadronic Z decays” , Phys. Lett.B345 (1995) 74. 5. M. Acciarri, A. Baschirotto, R. Castello, S. Pensotti, P.G. Rancoita, M. Rattaggi, M. Redaelli et al., “B* production in Z decays at LEP”, Phys. Lett. B345 (1995) 589. 6. M. Acciarri, A. Baschirotto, R. Castello, S. Pensotti, P.G. Rancoita, M. Rattaggi, M. Redaelli et al., ”Search for anomalous events at LEP”, Phys. Lett. B345 (1995) 609. 7. M. Acciarri, A. Baschirotto, M. Bosetti, S. Pensotti, P.G. Rancoita, M. Rattaggi et al., ”The L3 Silicon Microvertex Detector: installation and results on 1993 < Ãs < 140 GeV at LEP”, Phys. Lett. B370 (1996) 195. 18. M. Acciarri, A. Baschirotto, R. Castello, S. Pensotti, P.G. Rancoita, M. Rattaggi, M. Redaelli et al., “Search for excited leptons in e+e- annihilation at Ãs = 130-140 GeV”, Phys. Lett. B370 (1996) 211. 19. M. Acciarri, A. Baschirotto, R. Castello, S. Pensotti, P.G. Rancoita, M. Rattaggi, M. Redaelli et al., “Measurement of h production in two and three-jet events from hadronic Z decays at LEP”, Phys. Lett. 371 (1996) 126. 20. M. Acciarri, A. Baschirotto, R. Castello, S. Pensotti, P..G. Rancoita, M. Rattaggi, M. Redaelli et al., “Study of the structure of hadronic events and determination of as at Ãs = 130 GeV and 140 GeV”, Phys. Lett. B371 (1996) 137. 21. M. Acciarri, A. Baschirotto, R. Castello, S. Pensotti, P.G. Rancoita, M. Rattaggi, M. Redaelli et al., “Measurement of muon-pair production at 50< Ãs <86 GeV at LEP”, Phys. Lett. B374 (1996) 331. 22. M. Acciarri, A. Baschirotto, R. Castello, S. Pensotti, P.G. Rancoita, M. Rattaggi, M. Redaelli et al., “Search for supersymmetric particles at 130 GeV < Ãs < 140 GeV at LEP”, Phys. Lett. B377 (1996) 289. 23. M. Acciarri, A. Baschirotto, R. Castello, S. Pensotti, P.G. Rancoita, M. Rattaggi, M. Redaelli et al., “Measurement of the Michel parameters and the average t neutrino helicity from t decays in e+e- -> t+t-”, Phys. Lett. B377 (1996) 313. 24. M. Acciarri, A. Baschirotto, R. Castello, S. Pensotti, P.G. Rancoita, M. Rattaggi, M. Redaelli et al., “Search for unstable sequential neutral and charged heavy leptons in e+e- annihilation at Ãs=130 and 136 GeV”, Phys. Lett. B377 (1996) 304. 25. M. Acciarri, A. Baschirotto, R. Castello, S. Pensotti, P.G. Rancoita, M. Rattaggi, M. Redaelli et al., “Measurement of the Bd0 meson oscillation frequency”, Phys. Lett. B383 (1996) 487. 26. M. Acciarri, A. Baschirotto, R. Castello, S. Pensotti, P.G. Rancoita, M. Rattaggi, M. Redaelli et al., “Observation of multiple hard photon final states at Ãs =130-140 GeV at LEP”, Phys. Lett. B384 (1996) 323. 27. M. Acciarri, A. Baschirotto, R. Castello, S. Pensotti, P.G. Rancoita, M. Rattaggi, M. Redaelli et al., “Search for neutral Higgs boson production through the process e+e- -> Z*H0” , Phys. Lett. B385 (1996) 454. 28. M. Acciarri, A. Baschirotto, R. Castello, S. Pensotti, P.G. Rancoita, M. Rattaggi, M. Redaelli et al., “Search for new particles in hadronic events with isoleted photons”, Phys. Lett. B388 (1996) 409. 29. M. Acciarri, A. Baschirotto, R. Castello, S. Pensotti, P.G. Rancoita, M. Rattaggi, M. Redaelli et al., “Measurement of the lifetime of the tau lepton”, Phys. Lett. B 389 (1996) 187. ALEPH: LEP, Particle Physics, Higgs, W boson, supersimmetry. ALEPH is an experiment running at the LEP accelerator, at CERN. During 1996 about 20 pb^-1 have been collected at energies of 161 and 172 GeV. The collected data are being used to measure cross sections to perform standard model studies, to search for Higgs boson and new particles, to measure the W boson mass. In the meantime the data collected at the Z0 peak are being used to produce final results on many topics: Standard Model precision measurements, B physics, QCD, tau lepton physics. Responsible: Francesco Ragusa Recent Publications: 1. D. Buskulic, F. Ragusa et al., “Measurement of the Branching Ratio and an Upper Limit on ”, Phys. Lett. B343 (1995) 444. 2. D. Buskulic, F. Ragusa et al., “Study of the four-fermion final state at the Z resonance” Z. Phys. C66 (1995) 3. 3. D. Buskulic, F. Ragusa et al., “Performance of the ALEPH detector at LEP”, Nucl. Instr. and Methods A360 (1995) 481. 4. D. Buskulic, F. Ragusa et al., “A Study of Production in Semileptonic B Decay”, Phys. Lett. B345 (1995) 103. 5. D. Buskulic, F. Ragusa et al., “Search for CP violation in the decay ”, Phys. Lett. B346 (1995) 371. 6. D. Buskulic, F. Ragusa et al., “Inclusive and Differential Cross-sections at the Z Resonance”, Z. Phys. C66 (1995) 355. 7. D. Buskulic, F. Ragusa et al., “Study of the Subjet Structure of Quark and Gluon Jets”, Phys. Lett. B346 (1995) 389. 8. D. Buskulic, F. Ragusa et al., “Michel Parameters and Neutrino Helicity from Decay Correlations in ”, Phys. Lett. B346 (1995) 379. 9. D. Buskulic, F. Ragusa et al., “An upper limit for the neutrino mass from decays”, Phys. Lett. B349 (1995) 585. 10. D. Buskulic, F. Ragusa et al., “Search for supersymmetric particles with R-parity violation in Z decays” Phys. Lett. B349 (1995) 238. 11. D. Buskulic, F. Ragusa et al., “Test of the Flavour Independence of ”, Phys. Lett. B355 (1995) 381. 12. D. Buskulic, F. Ragusa et al., “Improved Polarisation Measurement”, Z. Phys. C69 (1996) 183. 13. D. Buskulic, F. Ragusa et al., “Measurement of the Cross Section in Two Photon Collisions at LEP”, Phys. Lett. B355 (1995) 595. 14. D. Buskulic, F. Ragusa et al., “The Forward-Backward Asymmetry for Charm Quarks at the Z Pole”, Phys. Lett. B352 (1995) 479. 15. D. Buskulic, F. Ragusa et al., “Measurements of the b Baryon Lifetime”, Phys. Lett. B357 (1995) 685. 16. D. Buskulic, F. Ragusa et al., “Measurements of the Charged Particle Multiplicity Distribution in Restricted Rapidity Intervals”, Z. Phys. C69 (1995) 15. 17. D. Buskulic, F. Ragusa et al., “Limit on Oscillation Using a Jet Charge Method”, Phys. Lett. B356 (1995) 409. 18. D. Buskulic, F. Ragusa et al., “Combining Heavy Flavour Electroweak Measurements at LEP. The LEP Experiments: ALEPH, DELPHI, L3 and OPAL”, Nucl. Instr. and Methods A378 (1996) 101. 19. D. Buskulic, F. Ragusa et al., “First Measurement of the Quark-to-Photon fragmentation function”, Zeit Phys. C69 (1996) 365. 20. D. Buskulic, F. Ragusa et al., “Measurement of meson production in Z decays and of the lifetime”, Zeit Phys. C69 (1996) 585. 21. D. Buskulic, F. Ragusa et al., “A measurement of from ”, Phys. Lett. B359 (1995) 236. 22. D. Buskulic, F. Ragusa et al., “Measurement of from Scaling Violations in Fragmentation Functions in e+e- Annihilation”, Phys. Lett. B357 (1995) 487. 23. D. Buskulic, F. Ragusa et al., “Inclusive Production of Neutral Vector Mesons in Hadronic Z Decays”, Zeit Phys. C69 (1996) 379. 24. D. Buskulic, F. Ragusa et al., “Production of excited beauty states in Z decays”, Zeit Phys. C69 (1996) 393. 25. D. Buskulic, F. Ragusa et al., “Measurement of the effective b quark fragmentation function at the Z resonance”, Phys. Lett. B357 (1995) 699. 26. D. Buskulic, F. Ragusa et al., “A Precise Measurement of the Average b Hadron Lifetime”, Phys. Lett. B369 (1996) 151. 27. D. Buskulic, F. Ragusa et al., “A Measurement of the lifetime and production rate with combinations in Z decays”, Phys. Lett. B361 (1995) 221. 28. D. Buskulic, F. Ragusa et al., “Tau leptonic branching ratios”, Z. Phys. C70 (1996) 561. 29. D. Buskulic, F. Ragusa et al., “A Measurement of the lepton lifetime”, Zeit Phys. C70 (1996) 549. 30. D. Buskulic, F. Ragusa et al., “Tau hadronic branching ratios”, Z. Phys. C70 (1996) 579. 31. D. Buskulic, F. Ragusa et al., “A Measurement of the polarization in Z decays”, Phys. Lett. B365 (1996) 437. 32. D. Buskulic, F. Ragusa et al., “Quark and Gluon Jet Properties in Symmetric Three-Jet Events”, Phys. Lett. B384 (1996) 353. 33. D. Buskulic, M. Aleppo, F. Ragusa et al. “A Measurement of polarization from Z decays”, Phys. Lett. B374 (1996) 319. 34. D. Buskulic, M. Aleppo, F. Ragusa et al., “Determination of Using Jet Charge Measurements in Hadronic Z Decays”, Z. Phys. C71 (1996) 357. 35. D. Buskulic, M. Aleppo, F. Ragusa et al., “Search for supersymmetric particles in collisions at centre-of-mass energies of 130 and 136 GeV”, Phys. Lett. B373 (1996) 246. 36. D. Buskulic, M. Aleppo, F. Ragusa et al., “Improved measurement of the and meson lifetimes”, Z. Phys. C71 (1996) 31. 37. D. Buskulic, M. Aleppo, F. Ragusa et al., “Measurement of the Mass of the Baryon”, Phys. Lett. B380 (1996) 442. 38. D. Buskulic, M. Aleppo, F. Ragusa et al., “Study of the oscillation frequency using combinations in Z decays”, Phys. Lett. B377 (1996) 205. 39. D. Buskulic, M. Aleppo, F. Ragusa et al., Studies of QCD in Hadrons at = 130 and 136 GeV”, Accepted by Phys. Lett. B (1996). 40. D. Buskulic, M. Aleppo, F. Ragusa et al., “Measurement of hadron and lepton-pair production from e+e- annihilation at centre-of-mass energies of 130 and 136 GeV”, Phys. Lett. B378 (1996) 373. 41. D. Buskulic, M. Aleppo, F. Ragusa et al., “Four-jet final state production in e+e- collisions at centre-of-mass energies of 130 and 136 GeV”, Z. Phys. C71 (1996) 179. 42. D. Buskulic, M. Aleppo, F. Ragusa et al., “A study of single and multi-photon production in e+e- collisions at centre-of-mass energies of 130 and 136 GeV”, Phys. Lett. B384 (1996) 333. 43. D. Buskulic, M. Aleppo, F. Ragusa et al., “Search for CP violation in the decay ”, Phys. Lett. B384 (1996) 365. 44. D. Buskulic, M. Aleppo, F. Ragusa et al., “Measurement of the b forward-backward asymmetry and mixing using high- leptons”, Phys. Lett. B384 (1996) 414. 45. D. Buskulic, M. Aleppo, F. Ragusa et al., “Mass Limit for the Standard Model Higgs Boson with the full LEP I ALEPH Data Sample”, Phys. Lett. B384 (1996) 427. 46. D. Buskulic, M. Aleppo, F. Ragusa et al., “Search for heavy lepton pair production in e+e- collisions at centre-of-mass energies of 130 and 136 GeV”, Phys. Lett. B384 (1996) 439. 47. D. Buskulic, M. Aleppo, F. Ragusa et al., “Strange b baryon production and lifetime in Z decays”, Phys. Lett. B384 (1996) 449. 48. D. Buskulic, M. Aleppo, F. Ragusa et al., “Mass Limit for the Lightest Neutralino” , Accepted by Z. Phys. C (1996). 49. D. Buskulic, M. Aleppo, F. Ragusa et al. ,“Transverse Momentum Correlations in Hadronic Z Decays”, To be published on Z. Phys. C (1996). 50. D. Buskulic, M. Aleppo, F. Ragusa et al., “Search for charginos and neutralinos with R- parity violation at = 130 and 136 GeV”, Phys. Lett. B384 (1996) 461. 51. D. Buskulic, M. Aleppo, F. Ragusa et al., “Search for Excited Leptons at 130-140 GeV”, Phys. Lett. B385 (1996) 445. 52. D. Buskulic, M. Aleppo, F. Ragusa et al., “Four-fermion production in e+e- collisions at centre-of-mass energies of 130 and 136 GeV”, Phys. Lett. B388 (1996) 419. 53. D. Buskulic, M. Aleppo, F. Ragusa et al., “Production of Orbitally Excited Charm Mesons in Semileptonic B Decays”, To be published on Z. Phys. C. (1996). 54. D. Buskulic, M. Aleppo, F. Ragusa et al., “Improved measurement of the oscillation frequency”, To be published on Z. Phys. C. (1996). 55. D. Buskulic, M. Aleppo, F. Ragusa et al., “A study of decays involving and mesons”, To be published on Z. Phys. C. (1996). 56. D. Buskulic, M. Aleppo, F. Ragusa et al., “Observation of charmless hadronic B decays”, To be published on Phys. Lett. B. (1996). 57. D. Buskulic, M. Aleppo, F. Ragusa et al., “Charm counting in b decays”, to be published on Phys. Lett. B. (1996). 58. D. Buskulic, M. Aleppo, F. Ragusa et al., “Measurements of , form factors and branching fractions in the decays and ”, to be published on Phys. Lett. B. (1996). 59. R. Barate, F. Ragusa, M.Aleppo et al., “Inclusive production of neutral pions in hadronic Z decays”, to be published on Z. Phys. C. (1996). 60. R. Barate, F. Ragusa, M.Aleppo et al., “Studies of Quantum Chromodynamics with the ALEPH Detector”, to be published on Physics Reports (1996). ATLAS Calorimetry - LHC: LHC, Calorimetry, ATLAS, Higgs boson A group of physicists of the University and INFN, under the leadership of Prof. L. Mandelli, has collaborated in the preparation of the proposal of the ATLAS experiment at LHC (pp at =14 Tev). The CERN Director approved the experiment in 1996. The items on which the Milan group has contributed are: 1) Design and development of a LAr electromagnetic calorimetry. This activity has implied the construction and test of prototypes and their tests to hadrons at the CERN beams. The group developed, constructed and tested cryogenic preamplifiers and Kapton electrodes testing machines. 2) Optimization of the ATLAS detector and study of its potential in the discovery of the Higgs boson in the framework of the Standard Model and of SupersimmetricModels. 3) Implementation of a Montecarlo (Fluka) to compute electromagnetic and hadronic shower development. Application to calorimetry and computation of doses in various subdetectors and in the experimental hall. Responsible: Luciano Mandelli Recent Publications: 1. D.M. Gingrich, G. Battistoni, D.V. Camin, D. Cavalli,G. Costa,L. Cozzi, A. Cravero, N. Fedyakin, A. Ferrari, L. Mandelli, M. Mazzanti, L. Perini, P. Sala et al., ”Performance of a Liquid Argon Accordion Hadronic Calorimeter Prototype”, Nucl. Instr. and Methods A355 (1995) 295. 2. D.M. Gingrich, G. Battistoni, D.V. Camin, D. Cavalli,G. Costa,L. Cozzi, A. Cravero, N. Fedyakin, A. Ferrari, L. Mandelli, M. Mazzanti, L. Perini, P. Sala et al., ”Performance of a Large Scale Prototype of the ATLAS Accordion Electromagnetic Calorimeter”, Nucl. Instr. and Methods A364 (1995) 290. 3. R.A. Davis, G. Battistoni, D.V. Camin, D. Cavalli,G. Costa,L. Cozzi, N. Fedyakin, A. Ferrari, L. Mandelli, M. Mazzanti, L. Perini, S. Resconi, P. Sala et al., ”Construction and Test of a Fine-grained Liquid Argon Preshower Prototype”, CERN-PPE/96-123. Accepted by Nucl. Instr. and Methods. 4. D.M. Gingrich, G. Battistoni, D.V. Camin, D. Cavalli, G. Costa,L. Cozzi, N. Fedyakin, A. Ferrari, L. Mandelli, M. Mazzanti, L. Perini, S. Resconi, P. Sala et al., ”Performance of an Endcap Prototype of the ATLAS Accordion Electromagnetic Calorimeter”, CERN-PPE/96- 175. Accepted by Nucl. Instr. and Methods. 5. Z. Ajaltouni, G. Battistoni, D.V. Camin, D. Cavalli,G. Costa,L. Cozzi, N. Fedyakin, A. Ferrari, L. Mandelli, M. Mazzanti, L. Perini, S. Resconi, P. Sala et al., ”Results from combined test of an electromagnetic liquid argon calorimeter with a hadronic scintillating-tile calorimeter”, CERN-PPE/96-178. Accepted by Nucl. Instr. and Methods. ATLAS-AEP2 - Development and tests of pixel detectors and relative front-end electronics for the experiment ATLAS at LHC (CERN): pixels, front-end electronics, VLSI The group will take part in the Higgs search at the Large Hadron Collider at CERN, where the highest possible energy (16 Tev) will be available. In particular we are partecipating at the development of a pixel detector to be used as inner tracker in the ATLAS experiment. Because of the high multeplicity foreseen at this energy, the very high resolution offered by such detector will be very useful in the pattern recognition. No detector exists, so far, with the required characteristics: radiation hardness, compactness, low power consumption and capability to operate at 40 MHz. More R&D is then still needed, both for the detector and the front-end electronics. For this purpose a laser test has been setup in our laboratory in Milano; the same setup can be used also with radioactive sources. These tests are in fact complementary to the beam tests at CERN, which are usually done once the major problems have been solved or at least understood. Once debugged, the final version will be built in radiation hard technique. In the next year a full scale module prototype will be built and tested, before going to the final production, foreseen by 1998. Responsible: Laura Perasso BABAR experiment at PEP II: CP violation, silicon vertex tracker, electronic readout The group participates to the BaBar experiment on the asymmetric b-factory PEP II at SLAC (Stanford,USA). The aim of the experiment is the study of CP asymmetry in the B sector, rare decays of the B meson, charm, tau and gamma-gamma physics. Milan partecipates to the construction of the Silicon Vertex Tracker (SVT), having in particular the responsibility of the project and realization of all High Density Interconnets ( HDI ) and tails. The HDI's function is to provide the physical support, cooling and electrical interconnections for the readout IC's, and the connections to other components. The size of the HDIs is extremely constrained by the small physical region at disposal. The electrical requirements are stringent in order to minimize crosstalk and noise, especially on the analog and ground planes. The Milan design has 6 conductive layer on both sides of an alunimun nitride (AlN) substrate. During 1995-96 the project has been developed and prototypes have been realized in Milan in order to test the feasibility of such a multilayer. Milan is also responsible of the project and realization of the tails. The tail provides the electrical connections between the HDI and the matching card. It must be a flexible multi-layer circuit which carries both power and signals with minimum coupling between the digital and analog sections.DC resistance and impedance must be minimized. Our project has 5 conductive layers for a total tail thickness of 410 micrometer. The tail ends have to fit into a Berg connector and their thickness have to be 170 micrometer. Tail prototypes have been realized in Milan. HDI and tails prototypes have been used in a test bench in november '96. Responsible: Fernando Palombo Recent Publications 1. F. Palombo et al., “Hybrid design of the BaBar Silicon vertex”, Nucl. Instr. and Methods A379 (1996) 399. 2. P. Cantoni, B. Maggi, F. Palombo, A. Sala et al., “Particle identification in a LKr ionization chamber by multiple induced current measurements using the shape analysis of the signal”, Nucl. Instr. and Methods A368 (1996) 339. 3. P. Cantoni, S. Parmeggiano, B. Maggi, F. Palombo, A. Sala et al., “Experimental study of particle separation in a LKr ionization chamber by multiple measuring de/dx using the shape analysis of signal”, Nucl. Instr. and Methods A364 (1995) 258. 4. P. Cantoni, B. Maggi, F. Palombo, A. Sala et al., “Particle identification in a LKr ionization chamber by multiple induced current measurements using the shape analysis of the signal”, Nucl. Instr. and Methods A360 (1995) 427. 5. Yu.M. Antipov, F. Palombo et al., “Yields of prompt protons and anti-protons in 40-GeV/c pi- be interactions involving the production of a cumulative particle”, Phys. At. Nucl. 58 (1995) 798, (Yad. Fiz. 58 (1995) 863). GALLEX: Solar Neutrinos. The group is actively involved in the Gallex experiment on solar neutrinos presently running in the Gran Sasso National Laboratory. This experiment was the first to detect neutrinos from the p-p reaction which is responsible for most of the energy produced in the sun. In 1995 the group took considerable responsability in the preparation of a second source of artifically produced neutrinos from electron capture of 51Cr with which the Gallex detector was efficiently tested. Various activation analysis of materials of Gallex using the neutron activation technique was also performed. The group is also partecipating the an extention and improvement of the Gallex experiment with the name of GNO, for Gallex Neutrino Observatory, where different detection techniques are being investigated Responsible: Enrico Bellotti Recent Publications: 1. P. Anselmann, E. Bellotti, C. Cattadori, O. Cremonesi, N. Ferrari, E. Fiorini, L. Zanotti et al., ”First results from the 51Cr neutrino source experiment with the GALLEX detector”, Phys. Lett. B342 (1995) 440. 2. E. Bellotti, C. Cattadori, O. Cremonesi, N. Ferrari, E. Fiorini, S. Latorre, ”Measurement of the gamma activity induced by neutron activation in the GALLEX neutrino source”, Nucl. Instr. and Methods B100 (1995) 199. 3. P. Anselmann, C. Cattadori, O. Cremonesi, E. Fiorini, S. Pezzoni, L. Zanotti et al., ”First observation of solar neutrinos from the p-p fusion with the Gallex experiment at Gran Sasso”, Secondo congresso nazionale di cosmologia. Asiago 21-22 Ottobre 1993, Proc. of S.A.It., 66 (1995). 4. P. Anselmann, E. Bellotti, C. Cattadori, O. Cremonesi, N. Ferrari, E. Fiorini, L. Zanotti et al., ”GALLEX solar neutrino observations: complete results for GALLEX II”, Phys. Lett. B357 (1995) 237. 5. E. Bellotti, C. Cattadori, O. Cremonesi, N. Ferrari, E. Fiorini, L. Zanotti et al., "GALLEX solar neutrino observations: results for GALLEX III", Phys. Lett. B388, (1996) 384. BOREXINO: a liquid scintillator solar neutrino detection experiment: solar neutrino, liquid scintillator technique, radon measurements Borexino experiment is carried out at the Gran Sasso underground laboratory. The goal of the experiment is to measure the flux of the neutrinos produced in the 7Be electron capture reaction occuring in the solar core. The major implications of the results of the experiment will cover a broad range of physics aspects, both in elementary particles and astrophysics fields. The detector consists of a large mass (300 tons) ultrapure liquid scintillator and of about 2000 photomultipliers to collect the light produced by the interacting particles. Because of the very low energy threshold (200 KeV), the control of background events, due to natural radioactivity, is crucial. In the last two years a small scale prototype CTF (Counting Test Facility) has been carried out and established the feasibility of Borexino. An intense research program has been developed to understand the scintillation mechanism and the light propagation in a large scale detector. The information of a photon propagation model has allowed us to reconstruct the events with good spatial resolution and calibrate the light yield in the detector. Spatial and energy information were both used to characterize the events and to put limits on the scintillation contamination: U, Th at about 5x10-16 g/g and 14C/12C ratio at about 10-18, matching the Borexino requirements. A long CFT phase has been dedicated to test the effectiveness of the scintillator purification system, which will be used "on-line" in the Borexino experiment to maintain for a long time the required ultra-high radiopurity. Spokesman of the experiment: G. Bellini Responsibles: E. Meroni, G. Ranucci Recent Publications: 1. G. Ranucci, ”An analytical approach to the evaluation of the pulse shape discrimination properties of scintillators”, Nucl. Instr. and Methods A354 (1995) 389. 2. G. Ranucci, A. Preda, ”Evaluation of time measurement precision in the Counting Test Facility of the Borexino experiment”, Nucl. Instr. and Methods A370 (1995) 597. 3. M. Balata, L. Cadonati, M. Laubenstein, G. Heusser, M.G. Giammarchi, R. Scardaoni, V. Torri, G. Cecchet, A. de Bari, A. Perotti, ”The water purification system for the low background counting test facility of the Borexino experiment at Gran Sasso”, Nucl. Instr. and Methods A370 (1995) 605. 4. E. Meroni et al., “Preliminary results of the CTF, test of Borexino experiment”, Presented at the Four Seas Conference Jun. 25-Jul. 1 1995 5. M. Giammarchi et al., “Borexino test results”, Proc. XV Workshop on Weak Interactions and Neutrinos (WIN 95). Talloires (France) Sept. 1995. 6. G. Bellini, “The Borexino experiment and the results of the Counting Test Facility”, Nucl. Phys. B (Proc. Suppl.) 48 (1996) 363. 7. M. Giammarchi et al., “High purity water in the nuclear physics experiment”, Ultrapure Water Journal, vol. 13, n.8 (1996) 59. 8. M. Giammarchi et al., “Results from the Borexino Counting Test Facility”, Presented at the VII Int. Workshop on Neutrino Telescopes, Venezia Feb. 1996. 9. M. Giammarchi et al., “High purity water in a nuclear physics experiment”, Presented at the Ultrapure Water Conference, Amsterdam Sept. 1996. 10. M. Giammarchi et al., “Borexino CTF results in view of the Borexino experiment”, Presented at the Workshop: Present and future of neutrino physics in Europe (NuPECC 1996), Frascati Nov. 1996. 11. E. Meroni et al., “Performances of the CTF experiment in prospect of Borexino”, Presented at the V Int. Conference of Advanced Technology and Particle Physics, Villa Olmo Oct. 7- 11 1996. BOLOMETERS: Cryogenic detectors in Physics and Astrophysics An array of four thermal telluride detectors was successfully operated for more than one year in the Gran Sasso National Laboratory to search for neutrinoless double beta decay of 130Te, reaching a sensitivity four orders of magnitude larger than reported previously in the literature. The detectors have a mass of 340 g each and are the larger ever fabricated. With this array, the first with thermal detectors, important limits were also obtained on the existence of the misterious Dark Matter which should account for most of the mass of the Universe. In this field the group was also able to measure for the first time the thermal detection efficiency of a nuclear recoil as a function of the energy. Another important result obtained with the above mentioned array is the discovery of the decay by electron capture of 123Te with an unprecedented value of the lifetime exceeding by nine orders of magnitude the life of the Universe. In the frame of the collaboration with the IRST Institute in Trento the group has prepared in Milano a series of microcalorimeters of implanted silicon capable to detect X rays with a resolution exceeding by one order of magnitude that of the best semiconductor detectors. The spectrum of Rherium and, for the first time, of Ammonium Perrhenate has been obtained in view of the measurement of the antineutrino mass. Responsible: Ettore Fiorini Recent Publications: 1. A. Alessandrello, E. Bellotti, C. Brofferio, D.V. Camin, C. Cattadori, O. Cremonesi, N. Ferrari, E. Fiorini, A. Giuliani, M. Pavan, G. Pessina, E. Previtali, L. Zanotti, ”A bromine cryogenic detector for solar and non solar neutrino spectroscopy”, Astroparticle Physics 3 (1995) 239. 2. A. Alessandrello, C. Brofferio, D.V. Camin, O. Cremonesi, E. Fiorini, E. Garcia, A. Giuliani, A. Nucciotti, M. Pavan, G. Pessina, E. Previtali, L. Zanotti et al., ”Underground low temperature calorimeters to search for rare events”, Nucl. Phys. B (Proc. Suppl.) 44 (1995) 181. 3. A. Alessandrello, C. Brofferio, O. Cremonesi, E. Garcia, A. Giuliani, A. Nucciotti, S. Parmeggiano, M. Pavan, G. Pessina, E. Previtali et al., ”First tests on a large mass, low temperature array detector”, Nucl. Instr. and Methods A360 (1995) 363. 4. A. Alessandrello, C. Brofferio, D.V. Camin, O. Cremonesi, E. Fiorini, A. Giuliani, A. Nucciotti, M. Pavan, G. Pessina, E. Previtali, L. Zanotti et al., ”Milano 130Te neutrinoless double beta decay search with thermal detectors”, XVth Moriond Workshop on Dark Matter in Cosmology, Ed. Frontieres 219, 1996. 5. A. Alessandrello, C. Brofferio, D.V. Camin, C. Cattadori, O. Cremonesi, E. Fiorini, A. Giuliani, A. Nucciotti, M. Pavan, G. Pessina, E. Previtali, L. Zanotti et al., ”Thermal detectors for neutrino physics: results and developments”, IV Int. Symp. on Weak and Electrom. Inter. in Nuclei, Japan 1995, World Sci. Pub. (1995) 583. 6. A. Alessandrello, C. Brofferio, D.V. Camin, O. Cremonesi, E. Fiorini, A. Giuliani, A. Nucciotti, M. Pavan, G. Pessina, E. Previtali, L. Zanotti et al., ”Array of bolometric detectors for measurements of double beta decay of 130Te”, Int. Europhys. Conference on High Energy Physics, 1995. 7. A. Alessandrello, C. Brofferio, D.V. Camin, O. Cremonesi, E. Fiorini, E. Garcia, A. Giuliani, A. Nucciotti, M. Pavan, G. Pessina, E. Previtali, L. Zanotti et al., ”The Milano-Gran Sasso experiment on double beta decay usign thermal detector array”, 27th International Conference on High Energy Physics, Glasgow, Proc. Inst. of Physics Publishing 943, 1995. 8. A. Alessandrello, C. Brofferio, D.V. Camin, O. Cremonesi, E. Fiorini, A. Giuliani, A. Nucciotti, M. Pavan, G. Pessina, E. Previtali, L. Zanotti et al., ”Preliminary results on direct detection of wimps with a TeO2 bolometer”, Int. Workshop on the dark side of the Universe: experimental efforts and theoretical framework, 1995. 9. A. Alessandrello, C. Brofferio, D.V. Camin, O. Cremonesi, E. Fiorini, A. Giuliani, A. Nucciotti, M. Pavan, G. Pessina, E. Previtali, L. Zanotti et al.,”The Milano-Gran Sasso double beta decay experiment: toward a 20-crystal array”, Nucl. Instr. and Methods A370 (1996) 241. 10. A. Alessandrello, C. Brofferio, D.V. Camin, C. Cattadori, R. Cavallini, O. Cremonesi, E. Fiorini, A. Giuliani, A. Nucciotti, S. Parmeggiano, M. Pavan, M. Perego, G. Pessina, E. Previtali, L. Zanotti et al., ”Development of Si microcalorimeters for a neutrino mass experiment”, Nucl. Instr. and Methods A370 (1996) 244. 11. A. Alessandrello, C. Brofferio, D.V. Camin, O. Cremonesi, E. Fiorini, A. Giuliani, A. Nucciotti, M. Pavan, G. Pessina, E. Previtali, L. Zanotti et al., ”Cryogenic thermal detectors as a powerful way to analyse internal activities”, Nucl. Instr. and Methods A370 (1996) 269. 12. C. Arpesella, E. Bellotti, P.P. Sverzellati et al., ”Gamma ray activity of neodimium samples”, Nucl. Instr. and Methods A372 (1996) 415. 13. E. Fiorini, ”Thermal detectors for neutrinos, dark matter and rare events”, Nucl. Phys. B (Proc. Suppl.) 48 (1996) 41. 14. A. Alessandrello, C. Brofferio, D.V. Camin, O. Cremonesi, E. Fiorini, A. Giuliani, A. Nucciotti, M. Pavan, G. Pessina, E. Previtali, L. Zanotti et al., ”Improvements in 130Te double beta decay search with cryogenic TeO2 array detectors”, Nucl. Phys. B (Proc. Suppl.) 48 (1996) 238. 15. A. Alessandrello, C. Brofferio, D.V. Camin, P. Caspani, P. Colling, O. Cremonesi, E. Fiorini, A. Giuliani, A. Nucciotti, M. Pavan, G. Pessina, E. Previtali, L. Zanotti et al., "Preliminary results on the performance of a TeO2 thermal detector in a search for direct interactions of WIMPs", Phys. Lett. B384 (1996) 316. 16. A. Alessandrello, C. Brofferio, D.V. Camin, P. Caspani, P. Colling, O. Cremonesi, E. Fiorini, A. Giuliani, A. Nucciotti, M. Pavan, G. Pessina, E. Previtali, L. Zanotti et al., "Development and optimization of a modular bolometer to search for rare decays", Czechoslovak Journal of Physics, Vol. 46 (1996) Suppl. S5. 17. A. Alessandrello, C. Brofferio, D.V. Camin, P. Caspani, C. Cattadori, P. Colling, O. Cremonesi, E. Fiorini, A. Giuliani, A. Nucciotti, M. Pavan, G. Pessina, E. Previtali, L. Zanotti et al., "Construction and characterization of Si thermistors for high resolution X-ray detectors", Czechoslovak Journal of Physics, Vol. 46 (1996) Suppl. S5. 18. E. Fiorini et al., ”Low-temperature particle detectors”, to be published in Annual Review of Nuclear Particle Science n. 46.” 19. A. Alessandrello, C. Brofferio, D.V. Camin, O. Cremonesi, E. Fiorini, A. Giuliani, A. Nucciotti, M. Pavan, G. Pessina, E. Previtali, L. Zanotti et al., ”Wimps search with TeO2 thermal detectors: first results of the Milano-Gran Sasso experiment”, to be published on Edition Frontieres. 20. M. Pavan, G. Pessina, E. Previtali, L. Zanotti et al., ”Evidence for naturally occurring electron capture of 123Te”, Submitted to Phys. Rev. Lett. 21. A. Alessandrello, C. Brofferio, D.V. Camin, O. Cremonesi, E. Fiorini, A. Giuliani, A. Nucciotti, M. Pavan, G. Pessina, E. Previtali, L. Zanotti et al., "Double and single beta decay with thermal detectors", Invited paper to the 17th Int. Conf. on Neutrino Physics and Astrophysics, Helsinki June 1996. 22. A. Alessandrello, C. Brofferio, D.V. Camin, C. Cattadori, O. Cremonesi, E. Fiorini, A. Giuliani, A. Nucciotti, M. Pavan, G. Pessina, E. Previtali, L. Zanotti et al., ”Low temperature microcalorimeter development for a neutrino mass experiment”, Int. Workshop on Neutrino Telescopes, Venezia, 1996. 23. A. Alessandrello, C. Brofferio, D.V. Camin, P. Caspani, O. Cremonesi, E. Fiorini, A. Giuliani, A. Nucciotti, M. Pavan, G. Pessina, E. Previtali, L. Zanotti et al., "A modular bolometric detector for decay and dark matter searches", VIII Rencontres de Blois, June 1996. LINUS, study of visible photon interactions with nuclear magnetic dipoles, oriented in a high magnetic field at T = 4 K: coherent interaction, magnetic dipoles, nuclear magnetic resonance, relaxation Observations made in past years by J. Weber seem to prove that absorption of visible photons by a system of nuclear magnetic dipoles, that could exhibit coherence properties, is possible at low (4 K) temperatures. The experiment, whose aim is to check J. Weber's observations, consists in studying the light transmission through LiF or Al2O3 crystals, when their nuclear magnetic dipoles are oriented in a strong magnetic field. Absorption should occur after times that are characteristic for spin-lattice relaxation. A NMR probe will be used to monitor the magnetization of crystals. Experiment is mainly funded by INFN. Preliminary negative results have been obtained, but will be further checked with an improved set-up. Responsible: Stefano Ragazzi ICARUS: neutrino oscillations, solar neutrinos, nucleon decay. The group is involved since the middle of 1995, in the software activity of the ICARUS collaboration, that is now constructing a 600 tons detectors to be installed at the Gran Sasso Laboratories. The main activities of the Milano group in 1996 were the calculation of atmospheric neutrino fluxes with a realistic and detailed modelling and the simulation of signals seen in the ICARUS detector from physics events. Responsible: Donatella Cavalli Recent publication: 1. D. Cavalli et al., “A search program of explicit -oscillations with the Icarus detector at long distances”, CERN/SPSLC 96-58. AMS: antimatter, space station, cosmic rays, transition radiation. The recently approved experiment AMS (Alpha Magnetic Spectrometer) has to take data on the International Space Station Alpha (ISSA). The aim of the experiment is to search for antimatter as a signal for a symmetric universe. Presently, a systematic study on predictions of antiproton spectra of local and, possibly, of extragalactic origin has been carried out in order to determine the characteristics of the final set of detectors to be put into operation on ISSA. Furthermore, the scientific Italian terminal, namely the experimental data center for Italian groups participating to AMS experiment, is under realization in Milan. Responsible: P.G.Rancoita OROS-SICA5: silicon detector, VLSI electronics, preamplifier, front-end, radiation damage. The group has completed the data analysis activity in the field of silicon calorimetry, radiation damage studies on both silicon detector and VLSI front-end electronics, and initiated the isotopic enrichment of bulk silicon with 29Si. During 95/96, a systematic analysis of the data collected with hadron Si/Fe and Si/Fe+Pb calorimeters have shown that, by adding Pb, a Si/Fe calorimeter becomes compensating. The term due to binding energy losses has been evaluated. Effects of irradiations with neutrons (with a kinetic energies of 1 MeV on average) on silicon detectors and VLSI preamplifiers up to a fluence of about 1016 n/cm2 have been studied. At the maximun fluence of irradiation the developed VLSI electronics is still operating. An anlysis of isotopic content on a small silicon ingot, after a preliminary thermic treatment, has shown it may be possible to increase the concentration of the 29Si isotope in part of the ingot by diffusion when a thermic gradient is applied. Responsible: P.G. Rancoita Recent Publications: 1. M.Bosetti, N.Croitoru, C.Furetta, C.Leroy, S.Pensotti, P.G.Rancoita, M.Rattaggi, M.Redaelli and A.Seidman, “Study of current voltage characteristics of irradiated silicon detectors”, Nucl. Instr. and Methods B95 (1995) 219. 2. M.Bosetti, N.Croitoru, C.Furetta, C.Leroy, S.Pensotti, P.G.Rancoita, M.Rattaggi, M.Redaelli, A.Seidman , “DLTS measurements of Energetic levels generated in silicon detectors”, Nucl.Instr. and Methods A361 (1995) 461. 3. C.Furetta, C.Leroy, S.Pensotti, A.Penzo and P.G.Rancoita, “Energy resolution of Si/Fe and Si/Pb electromagnetic calorimeters”, Nucl. Sci. Journal 32 (1995) 85. 4. C.Furetta, C.Leroy, S.Pensotti, A.Penzo and P.G.Rancoita, “Experimental determination of intrinsic fluctuations from binding energy losses in Si/U hadron calorimeters”, University of Montreal - Preprint: HEP-94/022, November 1994, Nucl.Instr. and Methods A361 (1995) 149. 5. P.D'Angelo, C.Leroy, S.Pensotti and P.G.Rancoita, Operation modes of SiCPICal detector for SPECT applications, University of Montreal - Preprint: HEP-94/024, November 1994, Nucl. Scie. Journal, 32 (1995) 413. 6. C.Furetta, A.Gambirasio, F.Lamarche, C.Leroy, S.Pensotti, A.Penzo, M.Rattaggi and P.G.Rancoita, “Determination of intrinsic fluctuations and energy response of Si/Fe and Si/Fe+Pb calorimeters up to 70 GeV of incoming hadron energy”, HEP-95/012, May 1995, Nucl. Instr. and Methods A 368 (1996) 378. 7. N.Croitoru, A.Gambirasio, P.G.Rancoita and A.Seidman, “Current-Voltage characteristics of irradiated silicon detectors at fluences up to 1016 n/cm2”, Nucl. Instr. and Methods B111 (1996) 297. 8. A.Baschirotto, R.Castello, A.Gola, C.Onado, G.Pessina, P.G.Rancoita, M.Redaelli, and A.Seidman, Radiation damage study of a fast bipolar monolithic charge sensitive preamplifier”, Nucl. Instr. and Methods B114 (1996), 327, Phys. Lett. B363 (1995) 118. 9. N.Croitoru, P.G.Rancoita, M.Rattaggi, G.Rossi and A.Seidman, “Electrical conduction at low temperatures in high energy silicon detectors before and after irradiation with neutrons”, Nucl.Instr. and Methods B114 (1996) 120. 10. P.D'Angelo, C.Leroy, S.Pensotti and P.G.Rancoita, “High resolution silicon collimated photon imaging calorimeter for diagnostic in nuclear medicine”, Nucl. Phys. B44 (Proc. Sup.) (1995) 719. 11. A.Baschirotto, R.Castello, A.Gola, G.Pessina, P.G.Rancoita, M.Redaelli and A.Seidman, “Design and implementation of a monolithic bipolar readout system”, Nucl. Phys. B44 (Proc. Sup.)(1995) 617. 12. A.Baschirotto, R.Castello, A.Gola, G.Pessina, P.G.Rancoita, M.Rattaggi, M.Redaelli and A.Seidman, “Radiation damage investigation for the design of a hardened fast bipolar monolithic charge sensitive preamplifier”, Nucl. Instr. and Methods A362 (1995) 466. 13. A.Baschirotto, R.Castello, G.Pessina, P.G.Rancoita, M.Rattaggi, M.Redaelli and A.Seidman, “Design of a hardened fast bipolar monolithic charge sensitive preamplifier”, Proc. of the 18th Convention of Electrical and Electronics Engineers in Israel (Tel-Aviv 7-8 March, 1995), IEEE 95TH (1995), p 2.5.5/1. 14. M.Acciarri, N.Croitoru, C.Leroy, S.Pensotti, P.G.Rancoita, M.Redaelli and A.Seidman, “Influence of neutron irradiation on forward current of semiconductor detectors”, Proc. of the 18th Convention of Electrical and Electronics Engineers in Israel (Tel-Aviv 7-8 March, 1995), IEEE 95TH (1995), p 3.5.5/1. 15. A.Baschirotto, R.Castello, A.Gola, G.Pessina, P.G.Rancoita, M.Redaelli, A.Seidman and A.Volpi, “Realization of a versatile high-speed bipolar charge sensitive preamplifier for calorimeter applications”, Proceedings of the ESSCIRC'95 Twenty-first European Solid- State Circuits Conference (Lille 19-21 September 1995), edited by P.Garda (Edition Frontiers 1995), p 310. Cryogenic Microelectronics: cryogenics, particle detectors, electronics, low noise, GaAs, MESFET, preamplifiers This research activity aims at understanding the mechanisms that limit the performance of electronic devices and monolithic structures at very low temperatures. The scope is to acquire the knowledge that would allow the realization of optimized low noise preamplifiers to satisfy stringent requirements of cryogenic particle detectors in terms of noise, speed and power dissipation. Different monolíthic process have been studied, while a complete characterization and modelling have been performed on a GaAs ion-implanted MESFET process. Field-effect transistors and low noise preamplifiers chips have been designed and operated at 4 K in conjunction with bolometers used in double-beta decay experiments at the Gran Sasso Laboratory. Most recently, monolithic preamplifiers optimized for LAr calorimetry have been designed and fabricated. Tests with a prototype detector at CERN has demonstrated superior noise and speed performance of those chips immersed in LAr, at 87 K. The correlation of noise with process parameters has also been studied, as well as the uniformity of a large number of chips distributed in four wafers. Responsible:Daniel Victor Camin Recent publications: 1. D.V.Camin, "Noise in Readout Systems for Cryogenic Detectors", invited paper, in "Superconductivity and Particle Detection". ed: T.A.Girard, A.Morales and G.Waysand, World Scientific, (1995) p. 223. 2. D.V.Camin, N.Fedyakin and G.Pessina, "Monolithic Current-sensitive Preamplifier for the Accordion LAr Calorimeter", Nucl. Instr. and Methods, A 360 (1995) 153. 3. A.Alessandrello, C.Brofferio, D.V.Camin, O.Cremonesi, A.Giuliani, A.Nucciotti, M.Pavan, G.Pessina, and E.Previtali, "Cryogenic, Monolithic, Differential GaAs Preamplifier for Bolometric Detectors", Nucl. Instr. and Methods, A 360 (1995) 186. 4. D.V.Camin, G.Pessina and E.Previtali, "Monolithic Cryogenic Preamplifiers Based on Large Gate Area GaAs MESFETs", IEEE Trans. on Nucl.Sci., vol.42 (1995)p. 758. 5. D.V.Camin, and RD3 Collaboration "Performance of Monolithic Current-Sensitive Preamplifiers with an Accordion LAr Calorimeter", in Proc. of the V International Conference in High Energy Physics, Brookhaven National Laboratory, September 15 to October 1, 1994.Ed: H.A.Gordon and D. Rueger, World Scientific (1995) p. 401. 6. D.V.Camin, "Front-End Electronics: An overview", presented at the 3rd International Workshop on GaAs and Related Compounds, San Miniato, 20-23 March , 1995. Report INFN AE 95-23, 22 Dec. 1995. 7. D.V.Camin, N.Fedyakin and G.Pessina, "Monolithic GaAs Preamplifiers for Cryogenic Particle Detectors", invited talk at the Third Symposium on Low temperature Electronics of the Electrochemical Society, Reno, Nevada, May 21-26, 1995. Vol 95-9 (1995) p. 401. 8. D.V.Camin, N.Fedyakin, G.Pessina, F.Sabatini and M.Sironi, "Cryogenic Front-End Electronics in III-V Technology for Liquid Argon Calorimetry", Proc. of the First Workshop on Electronics for LHC Experiments, Lisbon, 11-15 September 1995, CERN/LHCC/95-96 (1995)p. 257. 9. D.V.Camin, N.Fedyakin, G.Pessina, E.Previtali and M.Sironi, "Improvements in Dynamic and Noise Performance of Cryogenic GaAs Monolithic ASIC's", IEEE Transactions on Nuclear Science, vol.43, No.3, (1996) 1649. 10. A.Alessandrello, C.Brofferio, D.V.Camin, O.Cremonesi, A.Giuliani, A.Nucciotti, M.Pavan, G.Pessina, E.Previtali et al., "Differential, Voltage-Sensitive Preamplifiers for Bolometric Detectors", Nucl. Instr. and Methods A370 (1996) 220. 11. D.V.Camin, and G.Pessina, "Cryogenic ASIC’s in GaAs for Applications with Particle Detectors”, Nucl. Instr. and Methods A370 (1996) 269. Journal de Physique IV, Colloque C3 Supplement au Journal de Physique III, vol 6, (1996) p.225. 12. G. Battistoni, D.V. Camin, N. Fedyakin, G. Pessina, F.Sabatini and P. Sala, "Realisation of Reliable Cryogenic ASIC's Using GaAs Ion-implanted MESFET Technology", Proc. of the Second Workshop on Electronics for LHC Experiments, Balatonfured, 23-27 September 1996, CERN/LHCC/96-39 (1996)p. 53. 13. G.Meneghesso, D.V.Camin, G.Pessina, N.Fedyakin et al. "Experimental Study of Deep Levels in MESFETs", in : ESSDERC'96 Proc. of the 26th European Solid State Device Research Conference, Bologna, Italy, 9-11 September 1996. Ed: G.Baccarani and M.Rudan. Editions Frontieres. (1996) p.563.