VHMPD proto-collaboration Very High Momentum Particle Identification Detector for ALICE at the LHC Nikolai Smirnov, Yale University for the VHMPID proto-collaboration Abstract We propose the construction of a detector to extend the capabilities of ALICE in the high transverse momentum pT region. The proposed VHMPID detector performs charged hadron identification on a track-by-track basis in the 10 GeV/c < pT < 25 ( Option 1) or 35 ( Option 2) GeV/c momentum range and provides ALICE with new opportunities to study parton-medium interactions at LHC energies. The VHMPID covers 8% of the TPC acceptance and presents sufficient acceptance for triggered- and tagged-jet studies, allowing for the first time identified charged hadron measurements in jets. There are two special constrains on the VHMPID in ALICE: a 1.2 m maximum radial distance available, and the necessity to trigger on high pT charged particles. Detector Geometry and Components Double Cherenkov Radiator, Option 2 Focusing RICH, CF4 gas radiator ,spherical mirror and GEM Detector with CsI (windowless approach) Tracking Detector Threshold Cherenkov Detector (TIC mode), C4F10 gas radiator, quartz window and GEM Detector with CsI Each detector read-out – pads 0.5x0.5 cm2 This option provides its own “high pT” trigger Coverage ~ 8 % of TPC acceptance in phase space BACKFRAME PHOS VHMPID Identification momentum range Full scale simulation and reconstruction including CF4 scintillations π and p identification probability with Central Pb+Pb HJ as a background Possible position in ALICE with modules of 1.4x1.0x1.10 m3 signal Absence of signal π 3 - 35 K 9 - 35 p 18 - 42 9 - 18 Detector Geometry and Components ( Option 1 ) Radiator gas C4F10 (n ≈ 1.0014, gth ≈ 18.9). Quartz window Photon detectors Pad-segmented CsI photocathode is combined with a MWPC with the same structure and characteristic of that used in the HMPID detector. The gas used is CH4, the pad size is 0.8×0.84 cm2 (wire pitch 4.2 mm), or a GEM-like detector with a CsI photocathode (higher gain, feedback photons suppression). Focusing RICH - spherical mirror with the detector at R/2. This option needs 3-4 additional tracking detectors for a “high pT trigger” P, GeV/c P, GeV/c Particle was identified as π (Blue), k - Red, p – Green, No PID - black Detector response ( cluster charge) for UV photons and MIPs and High pT trigger possibility Cluster charge, pC Three reconstructed MIP hits were matched as a track, Line fit in (XY) and (RZ) DCA to (0., 0.) in (XY), cm DCA, cm With cuts selected to get 98% efficiency for “one high Pt track / event” for Central HIJING event the probability to get a false trigger ( “DCAxy < 15. cm”) is smaller than 4% / detector Simulations Full simulation in AliRoot (or/and “stand-alone” using GEANT-3 + reconstruction), Hough transform has been applied to separate signal from background. One pion track is embedded in a 5.5 TeV Pb+Pb HJ event with a charged particle multiplicity dNch/dy ~ 4000 at midrapidity. Pion trace is clearly detected in the MWPC above the background . Pt, GeV/c Blue – UV photons; Red – MIPs Green – No FEE Noise VHMPID There are two more topics to be discussed: I ) ALICE EMC as a trigger for VHMPID II ) ALICE TPC PiD performance on track-by-track basis The absolute scintillation light yield of CF4 was measured using a CsI photocathode GEM Identification momentum range 9 – 18 GeV/c 18 – 24 GeV/c p 9 – 14 GeV/c 3 -14 GeV/c Absence of signal signal k Scintillation Yield = 320.8 ± 9.8 g / MeV Preliminary results reported: B.Azmoun et.al., Conf. Rec. 2007 IEEE NSS/MIC A.Pansky et.al., Nucl. Inst. Meth. A354 (1995) 262-269 Y= 250 ± 50 g/MeV with PMT Variable distance between Am source and SBD Variable distance between light source and GEM 3s separation , 80 cm long radiator Conclusion: A VHMPID of about 9 square meters with identification of protons track by track up to 24-25 GeV/c is technically possible. Positioned opposite to the EMCAL in ALICE it would allow the study of jets with a gamma in the EMCAL and would give about 1000 events up to 30GeV. For dijets an annual yield of 10000 events would reach 120 GeV. π and p identification probability with Central Pb+Pb HJ as a background VHMPD proto-collaboration A.Agócs3, R. Alfaro4, G.Barnafoöldi, L. Boldizsár3, E. Cuautle1, G. De Cataldo2,6, D. Di Bari2, A. Di Mauro6, Z. Fodor3, F. Formenti6, E. Futó3, E. García5, J. W.Harris7, G. Hamar3, P. Lévai3, P. Martinengo6, A. Mastroserio2, L. Molnár2,3, E. Nappi3, A. Ortiz1, D. Perini6, V. Peskov1, F. Piuz6, P. Podesta1, L. Serkin2, O. Sokolov1, N. Smirnov7, D. Varga3, G. Volpe3 1Instituto de Ciencias Nucleares Universidad Nacional Autónoma de México 2Dipartimento di Fisica dell’Università degli Studi di Bari and INFN Sezione di Bari, Bari, Italy 3MTA KFKI RMKI Research Institute for Particle and Nuclear Physics 4Instituto de Física, Universidad Nacional Autónoma de México 5Chicago State University 6CERN 7Yale University P, GeV/c P, GeV/c This work has been supported by the projects Conacyt 44268F and 050166, DGAPA –UNAM IN-111205, OTKA No NK062044, IN71374, DoE DE-FG02-94ER40865 050166 Particle was identified as π (Blue), k - Red, p – Green, No PID - black