1. V0L Hardware Status ALICE WEEK CERN, MARCH 2003 Ana Delia Becerril IFUNAM, México.

2. Outline V0 Detector. V0L Proposed Detector Assembly. Megatile Technique. V0L Prototype. Experimental Setup. Results from Tests. Conclusion

3. 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.

4. 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.

5. 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.

6. Embedded WLS fiber

7. 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.

8. PMT Philips XP2020. 7 GeV/c pions beam. Experimental Setup

9. Results from Tests Single photoelectron calibration. Light collection from MIP´s Element of ring 2, with 3 Y11 WLS fibers and Al reflector. Counts Channel Counts

10. Light yield

11. Number of p.e.

13. 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.