LHCC, V0, Sept. 2004 1

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

LHCC, V0, Sept. 2004 2

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

V0A V0CRing

1 5.1/4.5 -3.7/-3.2

Ring 2 4.5/3.9 -3.2/-2.7

Ring 3 3.9/3.4 -2.7/-2.2

Ring 4 3.4/2.8 -2.2/-1.7

LHCC, V0, Sept. 2004 3

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 Mch of events / Mch 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

LHCC, V0, Sept. 2004 4

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

LHCC, V0, Sept. 2004 5

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

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 σtime 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

80020

optical fibre

LHCC, V0, Sept. 2004 7

V0A array

connector bar

PM

all fibres from a sector

fibres gathered in 4 bundlesfiber length 3 m

8

V0C array

box in carbon-fibre

fiber length 5 m24 bundles in a duct for 2 sectors

rings 3 and 4in 2 pieces to minimize timefluctuations

12 connectors

LHCC, V0, Sept. 2004 9

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 (σtime < 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

LHCC, V0, Sept. 2004 10

CIU board data from V0C

V0A

BBA (BBC)

BGA (BBC)BBA (BGC)

X 4 HPTDC (8 ch/chip)

dataL1 buff

buffer

data from V0A

L2

DAQ

L0

hit

ADC

ADC

DISC.

DISC.

THR

buffer

buffer

bufferbuffer

individual offsetcompensation

adjustable windows(step of 20 ps, range of 10 ns)

adjustable windows (.5 to 12 ns, step of .5 ns)

programmableintegration gate width

(from 3 ns to 36 ns, 3 ns step)

+1 sum foreach ring

+

+

FPGA4

4

from V0C

1 sum for

each ring4

4from V0C

1 sum for

each ring4

4from V0C

programmable thresholds

BC

4

5 triggers, eg :- minimum bias- beam/gaz (right)- beam/gaz (left)- multiplicity- centrality

x 3

2 a

nodes

time

BB MB triggers

centrality triggers

THRcharge

THRmult

.

BGA BGC(V0C)

BG MB triggers

multiplicity triggers

chargelow M

DAQ

charge

L0

L0

LHCC, V0, Sept. 2004 11

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)

V0A

DISC.

DISC.

THR

buffer

buffer

adjustable windows(step of 20 ps, range of 10 ns)

adjustable windows (.5 to 12 ns, step of .5 ns)

BGA

BBA

+

+1 sum for

each ring4

1 sum for

each ring4

x 3

2 a

nodes

l t

BGC

BBC

+

+

-11 ns

+11 ns

V0C

-3 ns

+3 ns

ABGCBGA

C&

BB

bbc

bba

C&

Multiplicity trigger

A

THRmult

.

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

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

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

label total pricePM R5946 + HV 200000

Electronics + VME 120000V0A + V0C +

cabling 45000Total in SF 365000

V0 cost