Accelerator Neutrinos

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Space charge in ionization detectors and the NA48 electromagnetic calorimeter

Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 421:1-2 (1999) 75-89

Authors:

S Palestini, GD Barr, C Biino, P Calafiura, A Ceccucci, C Cerri, JC Chollet, M Cirilli, J Cogan, F Costantini, S Crépé, D Cundy, R Fantechi, L Fayard, G Fischer, A Formica, PL Frabetti, W Funk, A Gianoli, S Giudici, A Gonidec, B Gorini, G Govi, L Iconomidou-Fayard, V Kekelidze, W Kubischta, S Luitz, I Mannelli, M Martini, I Mikulec, A Norton, J Ocariz, D Schinzel, M Sozzi, G Tatishvili, A Tkatchev, G Unal, M Velasco, O Vossnack, H Wahl

Abstract:

The subject of space charge due to positive ions slowly moving in parallel plate ionization chambers is considered. A model for the degradation of the detector response is developed, with particular emphasis on electromagnetic calorimeters .The topics discussed include: (a) the stationary; (b) the time dependent cases; (c) the limit of very large space charge; (d) the electric field dependence of the electron drift velocity; (e) the effect of longitudinal development of showers; (f ) the behaviour of the average reductions of response; and (g) the non-uniformity of response for different positions of the shower axis inside the cell defined by the electrodes. The NA48 calorimeter is used as application and for comparison of results. © 1999 Elsevier Science B.V. All rights reserved.
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Evaluation of the LEP Centre-of-Mass Energy Above the W-Pair Production Threshold

ArXiv hep-ex/9901002 (1999)
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Searches for scalar top and scalar bottom quarks in e+e- interactions at 161 GeV ≤ √s ≤ 183 GeV

Physics Letters Section B Nuclear Elementary Particle and High Energy Physics 445:3-4 (1999) 428-438

Authors:

M Acciarri, O Adriani, M Aguilar-Benitez, S Ahlen, J Alcaraz, G Alemanni, J Allaby, A Aloisio, MG Alviggi, G Ambrosi, H Anderhub, VP Andreev, T Angelescu, F Anselmo, A Arefiev, T Azemoon, T Aziz, P Bagnaia, L Baksay, S Banerjee, SW Banerjee, K Banicz, A Barczyk, R Barillère, L Barone, P Bartalini, A Baschirotto, M Basile, R Battiston, A Bay, F Becattini, U Becker, F Behner, J Berdugo, P Berges, B Bertucci, BL Betev, S Bhattacharya, M Biasini, A Biland, GM Bilei, JJ Blaising, SC Blyth, GJ Bobbink, R Bock, A Böhm, L Boldizsar, B Borgia, D Bourilkov, M Bourquin, S Braccini, JG Branson, V Brigljevic, IC Brock, A Buffini, A Buijs, JD Burger, WJ Burger, J Busenitz, A Button, XD Cai, M Campanelli, M Capell, G Cara Romeo, G Carlino, AM Cartacci, J Casaus, G Castellini, F Cavallari, N Cavallo, C Cecchi, M Cerrada, F Cesaroni, M Chamizo, YH Chang, UK Chaturvedi, M Chemarin, A Chen, G Chen, GM Chen, HF Chen, HS Chen, X Chereau, G Chiefari, CY Chien, L Cifarelli, F Cindolo, C Civinini, I Clare, R Clare, G Coignet, AP Colijn, N Colino, S Costantini, F Cotorobai, B de la Cruz, A Csilling, TS Dai, R D'Alessandro, R de Asmundis

Abstract:

Searches for scalar top and scalar bottom quarks have been performed at center-of-mass energies between 161 GeV and 183 GeV using the L3 detector at LEP. No signal is observed. Model-independent limits on production cross sections are determined for the two decay channels t̃1 → cχ̃0 1 and b̃1 → b χ̃0 1. Within the framework of the Minimal Supersymmetric extension of the Standard Model mass limits are derived. For mass differences between t̃1 and χ̃0 1 greater than 10 GeV a 95% C.L. limit of 81.5 GeV is set on the mass of the Supersymmetric partner of the left-handed top. A supersymmetric partner of the left-handed bottom with a mass below 80 GeV is excluded at 95% C.L. if the mass difference between b̃1 and χ̃1 is greater than 20 GeV. © 1999 Published by Elsevier Science B.V. All rights reserved.
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Dijet mass spectrum and a search for quark compositeness in (p)p collisions at sqrt(s) = 1.8 TeV

Physical Review Letters 82:12 (1999) 2457-2462

Authors:

B Abbott, M Abolins, V Abramov, BS Acharya, I Adam, DL Adams, M Adams, S Ahn, H Aihara, GA Alves, N Amos, EW Anderson, R Astur, MM Baarmand, VV Babintsev, L Babukhadia, A Baden, V Balamurali, B Baldin, S Banerjee, J Bantly, E Barberis, P Baringer, JF Bartlett, A Belyaev, SB Beri, I Bertram, VA Bezzubov, PC Bhat, V Bhatnagar, M Bhattacharjee, N Biswas, G Blazey, S Blessing, P Bloom, A Boehnlein, NI Bojko, F Borcherding, C Boswell, A Brandt, R Breedon, R Brock, A Bross, D Buchholz, VS Burtovoi, JM Butler, W Carvalho, D Casey, Z Casilum, H Castilla-Valdez, D Chakraborty, SM Chang, SV Chekulaev, LP Chen, W Chen, S Choi, S Chopra, BC Choudhary, JH Christenson, M Chung, D Claes, AR Clark, WG Cobau, J Cochran, L Coney, WE Cooper, C Cretsinger, D Cullen-Vidal, MAC Cummings, D Cutts, OI Dahl, K Davis, K De, K Del Signore, M Demarteau, D Denisov, SP Denisov, HT Diehl, M Diesburg, G Di Loreto, P Draper, Y Ducros, LV Dudko, SR Dugad, A Dyshkant, D Edmunds, J Ellison, VD Elvira, R Engelmann, S Eno, G Eppley, P Ermolov, OV Eroshin, VN Evdokimov, T Fahland, MK Fatyga, S Feher, D Fein, T Ferbel, G Finocchiaro

Abstract:

Using the DZero detector at the 1.8 TeV pbarp Fermilab Tevatron collider, we have measured the inclusive dijet mass spectrum in the central pseudorapidity region |eta_jet| < 1.0 for dijet masses greater than 200 Gev/c^2. We have also measured the ratio of spectra sigma(|eta_jet| < 0.5)/sigma(0.5 < |eta_jet| < 1.0). The order alpha_s^3 QCD predictions are in good agreement with the data and we rule out models of quark compositeness with a contact interaction scale < 2.4 TeV at the 95% confidence level. © 1999 The American Physical Society.
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Direct search for light gluinos

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 446:2 (1999) 117-124

Authors:

V Fanti, A Lai, L Musa, D Marras, A Nappi, B Hay, RW Moore, KN Moore, DJ Munday, MD Needham, MA Parker, TO White, SA Wotton, J Andersen, G Barr, G Bocquet, J Bremer, A Ceccucci, D Cundy, N Doble, G Fischer, W Funk, L Gatignon, A Gianoli, A Gonidec, G Govi, P Grafström, W Kubischta, S Luitz, G Kesseler, JP Matheys, A Norton, S Palestini, B Panzer-Steindel, D Schinzel, H Taureg, M Velasco, O Vossnack, H Wahl, G Wirrer, V Kekelidze, A Mestvirishvili, I Potrebenikov, G Tatichvili, A Tkatchev, A Zinchenko, O Boyle, VJ Martin, IG Knowles, HLC Parsons, P Dalpiaz, J Duclos, PL Frabetti, M Martini, F Petrucci, M Porcu, M Savrie, A Bizzeti, M Calvetti, G Graziani, E Iacopini, M Lenti, A Michetti, HG Becker, H Blümer, P Buchholz, D Coward, C Ebersberger, H Fox, A Kalter, K Kleinknecht, U Koch, L Köpke, B Renk, J Scheidt, J Schmidt, V Schönharting, I Schue, R Wilhelm, A Winharting, M Wittgen, JC Chollet, S Crépé, L Iconomidou-Fayard, L Fayard, J Ocariz, G Unal, D Vattolo, I Wingerter, G Anzivino, P Cenci, P Lubrano, M Pepe, B Gorini, P Calafiura, R Carosi, C Cerri, M Cirilli, F Costantini, R Fantechi

Abstract:

We present the results for a direct search for light gluinos through the appearance of η→3π0 with high transverse momentum in the vacuum tank of the NA48 experiment at CERN. We find one event within a lifetime range of 10-9-10-3 s and another one between 10-10-10-9 s. Both events are consistent with the expected background from neutrons in the beam, produced by 450 GeV protons impinging on the Be targets, which interact with the residual air in the tank. From these data we give limits on the production of the hypothetical gg̃ bound state, the R0 hadron, and its R0→ηγ + ̃ decay in the R0 mass range between 1 and 5 GeV. © 1999 Elsevier Science B.V. All rights reserved.
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