V0L Hardware Status

ALICE WEEK

CERN, MARCH 2003

Ana Delia Becerril IFUNAM, México.

Outline

• V0 Detector.

• V0L Proposed Detector Assembly.

• Megatile Technique.

• V0L Prototype.

• Experimental Setup.

• Results from Tests.

• Conclusion

V0 Detector

•Zero level trigger system for ALICE.

•Made of two arrays of scintillating counters, V0R (IPNL) and V0L (Mexico).

•Two centrality triggers (Pb-Pb reaction) .

•Multiplicity indicator.

•Control of the luminosity.

•Validation signal for the dimuon trigger.

V0L. Proposed Detector Assembly

• Axially simetric thin plastic scintillator.

• R min=43 mm. R max=445 mm.

• Located at 3500 mm to the left of vertex position.

• Covers = -5.1 to = -2.8.

• 72 pixels in 5 rings.

The Megatile Techique

• One single piece of scintillator.

• Half way machined grooves, filled with white epoxy.

• Both faces of scint.

• Radial grooves for WLS fibers.

Embedded WLS fiber

V0L prototype

• Made with the Megatile technique.

• BC408 plastic scintillator.• Y11 and BCF92 WLS

fibers tested.• Teflon and Aluminum

wrappings tested.• Prototype tested in

September 2002 at the PS accelerator at CERN.

• PMT Philips XP2020.

• 7 GeV/c pions beam.

Experimental Setup

Results from Tests

Single photoelectron calibration.

Light collection from MIP´s

Element of ring 2, with 3 Y11 WLS fibers and Al reflector.

Co

un

ts

Channel

Channel

Co

un

ts

Light yield

V0L sector Area ofscintillator

(cm2)

BC408scintillatorWrapping

Numberof WLSfibers

Y11p.e. p.e.

BCF92p.e. p.e.

Al 2 16.00 5.21 7.16 2.66Ring 1 7.99 Teflon 2 22.86 6.18 ---

Al 3 19.01 5.36 9.16 4.69Ring 2 18.85 Teflon 3 29.61 6.84 ---

Number of p.e. vs number of fibers per ring

16.04

22.86

19.01

29.61

0

5

10

15

20

25

30

35

0 1 2 3 4 5 6 7 8 9

Number of fibers

Ring 1 Fr Ring 3 Fr Ring 4 Fr Ring 5 Fr

Ring 1 Mx Al Ring 1Mx Tef Ring 2 Mx Al Ring 2 Mx Tef

Nu

mb

er o

f p

.e.

Time resolution as a function of the light yield

0.6

0.8

1

1.2

1.4

1.6

1.8

2

2.2

2.4

0 5 10 15 20 25 30 35 40 45 50

Number of photoelectrons

sig

ma

of

sc

inti

lla

tor

(ns

ec

)

Fr R1 Fr R3 Mex R1* Mex R2*

Conclusion• A prototype of V0L was built using the Megatile technique.

• A reasonable light collection can be achieved with this design.

• In order to increase the light collection, we need to improve our design.

•On the basis of this test, we consider that a design based on this technique can fullfil the requirements for the V0 system.

What´s next?•Increase the scintillator thickness (probably 2 cm.)

•Increase the number of WLS fibers by reading both faces of the scintillator.