1. LHCC, V0, Sept. 20041 The V0 detector (Mexico Lyon collaboration)  Segmentation  Simulated performances secondaries / beam-gas  Counters design 1 / design 2  Electronics pulse treatment / FEE  Milestones mechanics / electronics V0A V0C

2. LHCC, V0, Sept. 20042 Segmentation of the arrays  Two arrays V0A and V0C 2 x 32 channels segmentation: 8 sectors x 4 rings  Pseudo-rapidity windows:  = 0.5-0.6/ring  V0AV0C Ring 15.1/4.5-3.7/-3.2 Ring 24.5/3.9-3.2/-2.7 Ring 33.9/3.4-2.7/-2.2 Ring 43.4/2.8-2.2/-1.7

3. LHCC, V0, Sept. 20043 Secondaries  Performances very degraded by secondaries produced in materials  No optimalization of the V0 for multiplicity measurement  Pb-Pb Hijing events (b < 11 fm) correlations M ch of events / M ch detected by V0 rings increase of hits by a factor two: 4000 MIP across each ring (8000 across the ring 1 of V0C)  Nevertheles, central and/or semi-central collisions can be selected by the FEE on the base of the total integrated charge provided by the counters  Efficiency of triggering: 83% in pp (inelastic) V0A V0C

4. LHCC, V0, Sept. 20044 p-gas background  The V0 should be able to filter a large part of the p-gas effect  ‘close p-gas’: Hijing (198 kHz) ‘halo’: file used by LHCb (47 kHz) pp physics: Pythia (200 kHz)  Gaussian vertex (5.3 cm) and time resolution (1 ns)  A cut at 11 ns: rejection depends on the relative rates of the two components 99% of rejected beam gas in the present case

5. LHCC, V0, Sept. 20045 Counters  Counters made of 2 cm BC404/BC408 scintillator 1 mm BCF9929A(s.c.)/BCF9929A(d.c.) WLS fibres 1.1 mm BCF98(d.c.) optical fibres Teflon foil as envelope Design 1 PM Teflon foil connector WLS fibres optical fibres Design 2 connector PM Teflon foil WLS fibres optical fibres

6. 6 Results  Design 1 applied to V0A elements 2 cm BC404 scintillator 1 mm BCF9929A(d.c.) WLS fibres 3 m of BCF98(d.c.) optical fibres  Present performances (MIP):  Design 1 provides a similar network of fibres to any scintillating track, whatever its location on the counter is time fluctuation minimized, better σ time  Adapted for large tiles  Adopted for V0A at RB24 side  Design 2 applied to V0C elements 2 cm BC408 scintillator 1 mm BCF9929A(s.c.) WLS fibres 5 m of BCF98(d.c.) optical fibres  Present performances (MIP): 500 – 600 ps 28 – 34 – 42 p.e.  For the RB26 side, the integration requires short transition from edge of counter to clear fibres  Only possible with design 2  Improvement with BC404/BCF(d.c.)? measures in progress 800 20 optical fibre

7. LHCC, V0, Sept. 20047 V0A array connector bar PM all fibres from a sector fibres gathered in 4 bundles fiber length 3 m

8. 8 V0C array box in carbon-fibre fiber length 5 m 24 bundles in a duct for 2 sectors rings 3 and 4 in 2 pieces to minimize time fluctuations 12 connectors

9. LHCC, V0, Sept. 20049 Electronics  Requirements MIP dynamic range: 1 to 500 with 98% of acceptance for the MIP signal dynamic range: close to 1000 (minimum of 3 mV achieved) charge information (0.6 < Q < 600 pC), time (σ time < 1 ns)  Mesh PMT with amplification (‘shoebox’) of the signal before its transmission (25 m of Cu-cables) to FEE  FEE 100% of life time made of three PCBs: CIU: charge and time digitization, pre-process of triggers CCIU: final trigger signal, collection of the data TTCIU: interface FEE/TTC  Concept finalized by the end of 2004

10. LHCC, V0, Sept. 200410 CIU board

11. LHCC, V0, Sept. 200411 Minimum-bias triggers  Starting from the discriminator signal  BB signal detected in time windows centered at +11 ns (V0A) and +3 ns (V0C)  BGA signal detected in time windows centered at -11 ns (V0A) and +3 ns (V0C)  BGC signal detected in time windows centered at +11 ns (V0A) and -3 ns (V0C)

12. 12 V0 mechanics milestones End 2004: March 2005: sector ‘0’ of V0A (Mexico) and V0C (Lyon) (construction and test) PRR submission October 2005: V0C commissioning, PMT characterization (Lyon) End 2005: V0A commissioning, PMT characterization (Mexico) April 2006: June 2006: V0C installation in ALICE End 2006: V0A installation in ALICE  Responsibles: Mechanics: J.Y. Grossiord (Lyon), XXXX (Mexico) p.e./MIP PMTgain arrays, fibre bundles, PMT mechanics

13. 13 V0 electronics milestones End 2004: electronics concept finalization (PMT, ‘shoebox’, FEE) CIU design prototype test March 2005: October 2005: CCIU and TTCIU design prototype test PRR submission End 2005: CIU, CCIU, TTCIU electronic scheme April 2006: electronics design ready for realization June 2006: electronics construction End 2006: electronics test, calibration, connection to CTP electronics ready for installation in ALICE  Responsibles: Electronics: Y. Zoccarato

14. 14 V0 milestones End 2004: electronics concept finalization (PMT, ‘shoebox’, FEE) CIU design prototype test March 2005: sector ‘0’ of V0A (Mexico) and V0C (Lyon) PRR submission October 2005: V0C commissioning, PMT characterization (Lyon) CCIU and TTCIU design prototype test PRR submission End 2005: V0A commissioning, PMT characterization (Mexico) CIU, CCIU, TTCIU electronic scheme April 2006: electronics design ready for realization June 2006: V0C installation in ALICE electronics construction End 2006: V0A installation in ALICE electronics test, calibration, connection to CTP electronics ready for installation in ALICE  Responsibles: Electronics: Y. Zoccarato Mechanics: J.Y. Grossiord (Lyon), XXXX (Mexico)

15. 15 labeltotal price PM R5946 + HV200000 Electronics + VME120000 V0A + V0C + cabling45000 Total in SF365000 V0 cost