1. A. Di Mauro (CERN, Geneva, Switzerland) on behalf of the ALICE collaboration

2. Outline  Physics motivation for a Very High Momentum PID upgrade  Detector layout studies  Expected performance  Trigger issues  2009 beam test  Outlook 07/05/2010A. Di Mauro - RICH2010, Cassis2

3. Physics motivation  ALICE specifically designed to study Quark-Gluon Plasma in “heavy ion collisions” at LHC, but p+p studies relevant part of the physics program  PID capability with different techniques over a large momentum range (ITS, TPC: dE/dx; TOF; TRD; HMPID: RICH)  Baryon/meson enhancement in 2-8 GeV/c observed at RHIC and interest for PID with jets (predicted “jet quenching” at higher p t ): “High Momentum” range of pushed to larger values wrt HMPID design specifications (  1<p<3 GeV/c; K,p: 2<p<5 GeV/c) track-by-track  Very High Momentum PID detector proposed to extend charged hadron track-by-track PID capability up to 30 GeV/c, in particular addressing measurement of jets properties 07/05/2010A. Di Mauro - RICH2010, Cassis3

4. Design constraints  Charged hadrons ( , K, p) identification in 10 - 30 GeV/c  Focusing RICH with C 4 F 10 gaseous radiator  Limited available space in ALICE  Acceptance, radiator length  Large photosensitive area (~ 3 m 2 ), B=0.5 T, limited time for R&D and (possibly) detector construction  HMPID know-how: CsI, MWPC, FEE,… 07/05/2010A. Di Mauro - RICH2010, Cassis4

5. Detector principle scheme  Focusing RICH, C 4 F 10 gas radiator L~ 80 cm  HMPID-like photon detector as baseline option: MWPC with CsI pad (8x8 mm) segmented photocathode, CH 4 at atm. P; alternative: CsI-TGEM (see talk by V. Peskov)  Spherical (or parabolic) mirror, light C-fiber substrate, Al/MgF 2 coating  FEE based on HMPID Gassiplex chip, analogue readout for centroid measurement 5A. Di Mauro - RICH2010, Cassis CaF 2 07/05/2010

6. Integration in ALICE 07/05/2010A. Di Mauro - RICH2010, Cassis6 ITS TPC TRD TOF PHOS HMPID EMCAL

7. Integration in ALICE old layout  12 modules  “projective” geometry  8% acceptance 07/05/2010A. Di Mauro - RICH2010, Cassis7 PHOS

8. Integration in ALICE 2010 layout  in sectors 11 and 12, ~ 4/5 available for VHMPID  projective geometry abandoned, “supermodule” layout to maximize filling factor 07/05/2010A. Di Mauro – RICH2010, Cassis8 DCAL PHOS Free for VHMPID

9. 11 12 Integration in ALICE 07/05/2010A. Di Mauro – RICH2010, Cassis9 11 12 Free slot for prototype ~ ½ supermodule  7% acceptance wrt TPC  12% wrt TPC in |η | < 0.5 (jet fully contained)

10. Supermodule preliminary layout 07/05/2010A. Di Mauro – RICH2010, Cassis10 CsI PC Top view Pad MWPC 3.2 m 1.3 m 1.9 m Under study:  Mirror orientation (impact parameter, focal plane)  Pad size (close track separation, angle resolution) Some results in a poster by G. Volpe

11. Design studies 11A. Di Mauro - RICH2010, Cassis Photon detector adaptation/ optimization F. Piuz “contribution” Integration of photon-detector and MIP localization in same MWPC layer Mounting of CaF 2 window with cathode grid coating Chamber segmentation (handling, CsI PC mounting in glove-box) 07/05/2010

12.  N 0 ~ 90 cm -1  N pe ~ 22 10 photon clusters (photons geometrical overlap, 8x8 mm 2 pad) Detector figure of merit 07/05/2010A. Di Mauro - RICH2010, Cassis12

13. Angular resolution 07/05/2010A. Di Mauro - RICH2010, Cassis13   chromatic [mrad] 1.26   emission [mrad] 0.5   pixel [mrad] 2.0   total [mrad] 2.3 N rp ~ 10   track [mrad] ~ 0.8 Single  events 30 GeV/c Theoretical estimation (Unrealistic) conditions: perfect tracking, no background

14. Particle separation 07/05/2010A. Di Mauro - RICH2010, Cassis14 Theoretical estimation of needed Cherenkov ring angular resolution for 3  separation  m 2 2 – m 1 2 2 n  p 2 tan  √N rp =

15. PID performance 07/05/2010A. Di Mauro - RICH2010, Cassis15  PID performance studied using ALIROOT (ALICE simulation framework) events with single particle Cherenkov rings overlapped to HIJING background  Results for old layout with SiO 2 window

16. PID performance Signal (GeV/c) Absence of signal (GeV/c)  4-24 K11-24 p19-3811-17 07/05/201016A. Di Mauro - RICH2010, Cassis Lower limit: cut N rp >2 Upper limit: 3  separation

17. PID performance: contamination p  K p  K p  K 07/05/201017A. Di Mauro - RICH2010, Cassis  PID algorithm based on HMPID pattern recognition (Hough transform)  Further tuning/optimization needed for VHMPID ring patterns + p ID below threshold  Performance to be checked with final detector layout

18. High p trigger issues 18 A. Di Mauro - RICH2010, Cassis Expected quite low charged hadron yields Efficient high p trigger mandatory for sample enrichment Baseline solution as high momentum L1 trigger: ALICE TRD 5000 HIJING events, impact par.: 0-5 fm, B = 0.2 T 07/05/2010

19. High p trigger issues 07/05/2010A. Di Mauro - RICH2010, Cassis19  R&D on a dedicated HPTD (High-P Trigger Detector) based on track angle measurement with strip chambers for tracks crossing the VHMPID  Fast L0 trigger (mostly relevant for the p+p environment, ~100 KHz rate) to tag tracks at p > 2 GeV  L1 trigger to select tracks in the high- p range (tunable cut-off: 8-15 GeV) with suppression of combinatorial background in high multiplicity Pb+Pb environment  Impact on detector design, due to needed space before and after RICH (~ 30 cm in total)

20. Nov ‘09 beam test results 07/05/201020A. Di Mauro - RICH2010, Cassis Spherical mirror - HMPID prototype (60x40 cm) with spare CsI PC, equipped with gaseous radiator and spherical mirror - Spherical mirror R=200 cm: Al-MgF 2 coating on C-fiber substrate from CMA - Raw C 4 F 10 from F2

21. Nov ‘09 beam test results  Raw C 4 F 10 : cut-off at 174 nm measured by COMPASS  Mirror coating: low reflectivity, ~0.63 at 170 nm (too thick MgF 2 layer)  Poor angle resolution dominated by not well defined beam track + detector misalignment 21 N photon clusters ~ 2 (!) 07/05/2010A. Di Mauro - RICH2010, Cassis

22. 2010 beam test plans 22/03/10ALICE Upgrade Forum22 Prototype equipped with large vessel and ~ final size mirror (60x40, R=160 cm) with adjustable orientation, to test: - Radiator length - CaF 2 (and SiO 2 ) window with coated Cr grid as MWPC cathode - Mirror technology (e.g. reflective coating, fixation), aberrations, focal plane optimization - Radiator gas system parameters, C 4 F 10 after cleaning in COMPASS setup beam Beam chambers Mirror center

23. Outlook  R&D project for construction and installation of large prototype (~1.5x2.5 m 2 ) approved by the collaboration in Oct 09  Tight schedule for installation during 2012/13 LHC shutdown  New design started in 2010, preliminary layout studied by simulations, finalization and validation using beam tests in 2010 and 2011  If upgrade approved, aim at full detector installation in next long LHC shutdown (2016?) 07/05/2010A. Di Mauro - RICH2010, Cassis23

24. The VHMPID collaboration 07/05/2010A. Di Mauro – RICH2010, Cassis24 Instituto de Ciencias Nucleares Universidad Nacional Autonoma de Mexico, Mexico City, Mexico E. Cuautle,I. Dominguez, D. Mayani, A. Ortiz, G. Paic, V. Peskov Instituto de Fsica Universidad Nacional Autonoma de Mexico, Mexico City, Mexico R. Alfaro Benemerita Universidad Autonoma de Puebla, Puebla, Mexico M. Martinez, S. Vergara, A. Vargas Universita’ degli Studi di Bari and INFN Sezione di Bari, Bari, Italy G. De Cataldo, D. Di Bari, E. Nappi, C. Pastore, I. Sgura, G. Volpe CERN, Geneva, Switzerland A. Di Mauro, P. Martinengo, L.Molnar, D. Perini, F. Piuz, J. Van Beelen MTA KFKI RMKI, Research Institute for Particle and Nuclear Physics, Budapest, Hungary A. Agocs, G.G. Barnafoldi, G. Bencze, L. Boldizsar, E. Denes, Z. Fodor, E. Futo, G. Hamar, P. Levai, C. Lipusz, S. Pochybova Eotvos University, Budapest, Hungary D. Varga Chicago State University, Chicago, IL, USA E. Garcia Yale University, New Haven, USA J. Harris, N. Smirnov Pusan National University, Pusan, Korea In-Kwon Yoo, Changwook Son, Jungyu Yi