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The ALICE Cosmic Ray Trigger E. Casimiro + , A. Fernández * , E. Gámez * , R. López * , S. Román * , L. Villaseñor # , A

The ALICE Cosmic Ray Trigger E. Casimiro + , A. Fernández * , E. Gámez * , R. López * , S. Román * , L. Villaseñor # , A. Zepeda + + Depto. de Física CINVESTAV-IPN * Benemérita Universidad Autónoma de Puebla # Universidad Michoacana de San Nicolás de Hidalgo. Introduction

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The ALICE Cosmic Ray Trigger E. Casimiro + , A. Fernández * , E. Gámez * , R. López * , S. Román * , L. Villaseñor # , A

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  1. The ALICE Cosmic Ray Trigger E. Casimiro+, A. Fernández*, E. Gámez*, R. López*, S. Román*, L. Villaseñor#, A. Zepeda+ + Depto. de Física CINVESTAV-IPN * Benemérita Universidad Autónoma de Puebla # Universidad Michoacana de San Nicolás de Hidalgo Introduction In recent decades, cosmic ray air showers initiated by high-energy proton or nucleus collisions in the atmosphere have been studied with large area experiments on the surface or with muon measurements deep underground. In principle, these cosmic ray experiments explore two completely different realms of physics, particle astrophysics and particle interaction physics, which are, however, intimately related by the interpretation of the data. Several groups at CERN have proposed to use their detectors and underground area facilities to study cosmic rays, e.g. UA1[ua1] and more recently by the LEP experiments [2] (ALEPH, L3 and DELPHI). The ACORDE-ALICE group have proposed to install an array of scintillator counters on top of the ALICE magnet at P2-LHC cavern 40 m underground, together with a 150 x 150 m2 array of scintillation counters arranged on a 10 m grid on the surface above P2.The simultaneous and complementary measurement of the muonic and the electromagnetic component of a cosmic ray air shower with this apparatus could provide the determination of both shower core and primary energy by two independent methods. Large Hadron Collider CERN ALICE Detector ALICE at point 2 ACORDE HMPID TRD PMD TPC MUON SPEC. ITS TOF PHOS FMD The ALICE Collaboration is building a dedicated heavy-ion detector to exploit the unique physics potential of nucleus-nucleus interactions at LHC energies.The main purpose is to study the physics of strongly interacting matter at extreme energy densities, where the formation of a new phase of matter, the quark-gluon plasma, is expected. • Astroparticle physics: • Energy spectrum, chemical composition • Acceleration mechanism, anisotropy • Exotic events • (muon bundles, centauro, anti-centauro, etc.) • Particle interactions physics: • forward particle production • p-p, p-A interactions • Heavy quark production ALICE TPC (Time Projection chamber) The detector ACORDE: Acorde-1 + Acorde-2 Acorde-1: Array of scintillator counters on top of ALICE Magnet combined with Alice tracking detectors (TPC, TOF, HMPID) UNANIMOUSLY ACCEPTED (March 20th 2002) Acorde-2: Array of scintillator counters at the surface of the LCH Point 2: (Under consideration) The ALICE TPC is the main tracking detector of the central barrel and together with the inner tracking detectors has to provide charged particle momentum measurement, particle identification and vertex determination with sufficient momentum resolution two track separation and dE/dx resolution for studies of hadronic and leptonic signals in the region pt < 10 GeV/c and pseudorapidities -0.9 < η < 0.9. In addition we plan, to use the TPC to reconstruct cosmic ray events with a very high multiplicity p p Physics related to cosmic ray: at LHC central rapidity ACORDE scintillators modules Scintillator Array Cosmo-Aleph TPC (lateral view) Muon bundles ALEPH detected some (very intriguing) events with high multiplicity, up to 160 tracks reconstructed at their TPC central region Cosmic ray flux at the ALICE cavern. ALIROOT simulation To detect cosmic rays in ALICE a tool, named ACORDE (Alice Cosmic Ray Detector), has been proposed [4]. This device will provide a fast level-zero trigger signal to the central trigger processor, when cosmic ray particles impinge upon the ALICE detector. To implement this trigger we will locate panels of plastic scintillator counters above the three upper faces of the ALICE magnet. Each panel contains 16 counters arranged in 8 rows of doublets. Each doublet consists of two parallel (side by side) counters. We have arrived to a preliminary design of the geometrical arrangement of the scintillator panels covering the top magnet face in which will collocate four panels (covering the central part of the top face) arranged transversely (i.e. with the counters running transverse to the larger side of the face). The two magnet faces just on the sides of the top one can be covered similarly. Depending on physics issues we may decide to cover more area of the upper faces of the ALICE magnet. The cosmic ray trigger has to deliver (to the central trigger processor) a level-zero signal, indicating a cosmic ray event, within a 850 nsec window from the crossing of a particle through our detectors. A base line implementation shall require coincidences (within a certain time window) between two counters on a doublet. If any coincidence occurs, it will generate a short pulse and AND-it to the LHC Clock. The resulting output will be our trigger signal. L3+C Experiment By the end of LEP operation, L3 experiment made an special cosmic ray run. A high precision momentum and μ+/μ- ratio spectrum (30 GeV– 1 TeV range), was obtained [3]. • References: • O.C. Allkofer, K. Eggert, P. Erhard et al. The UA1 detector as a possible cosmic ray device, Proc. 17th Int. Cosmic Ray Conf.,Paris, 10 (1981) • CosmoLep, an underground cosmic ray muon experiment in the LEP ring, CERN/LEPC 99-5, LEPC/P9 • P. Le Coultre, L3C collaboration, Proceedings of the 27th Int. Cosmic Ray Conf., Hamburg, Germany, Vol. 7, p305. • http://elinares.home.cern.ch/ACORDE/index.html SRL AFT

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