1. Status of the MaPMT o Status quo o Ongoing work o Issues – mechanics – electronics – schedule o Conclusions LHCb meeting Milano 26. 9. 2000 Franz Muheim University of Edinburgh

2. 2 Milano, 26. 9. 2000LHCb RICH meeting Status Quo o Successful test of 3x3 array of MaPMTs –Quartz lenses and close packing work –Measured photon yield as expected –Demonstrated 40 MHz read-out with APVm chip o MaPMT works in LHCb environment –charged particles traversing lens and photocathode –magnetic field o MaPMT fulfills LHCb RICH requirements o Front-end electronics needs to be optimised

3. 3 Milano, 26. 9. 2000LHCb RICH meeting Photo Detector Decision o Pixel HPD is baseline –must fulfill milestones assessed at the end of 2000 o MaPMT is backup o Keep the MaPMT viable until end 2000 o recommended work programme –F/E readout: SCT128A –gain matching Attenuators or reduced gain of MaPMT o final decision: end 2000

4. 4 Milano, 26. 9. 2000LHCb RICH meeting Improvements o Further improvements possible –3-5 % higher QE is possible (manufacturer)  14-23 % more photons –Incorporate lens into vessel window  8% more photons –Optical coupling between lens & MAPMT  8% more photons –Binary electronics  Cost savings –Use 4  threshold cut  Smaller signal loss

5. 5 Milano, 26. 9. 2000LHCb RICH meeting Laboratory Results Pixel scan with LED  Signal / pedestal  = 40:1  Signal loss below 5  cut: 11.5 % Single channel spectrum (LED) -900 V o Better focusing improves collection efficiency

6. 6 Milano, 26. 9. 2000LHCb RICH meeting Low Gain o Additional studies with better sensitivity needed o Looks promising

7. 7 Milano, 26. 9. 2000LHCb RICH meeting Mechanics o In good shape –for the photo detector decision 12/99 o MAPMT pitch: 26.7 mm o Module pitch: 108.8 mm o  -metal shield: 0.4 mm o Mounting frame: carbon fibre, G10 o Have enough time to finalise design

8. 8 Milano, 26. 9. 2000LHCb RICH meeting Front-end Electronics o Options: 4 x 2 (SCTA128 or BEETLE) all would probably work –preamplifier with lower gain –attenuator network, separate chip or passive –low gain o Preamplifier modification –preferred solution –needs design effort: J. Buytaert & N. Smale o Attenuator network –passiveXtalk? –activedecouples preamp, needs design effort o Low gain –increases signal loss, less flexibility

9. 9 Milano, 26. 9. 2000LHCb RICH meeting Status of ASICs o SCTA128A_VELO –modified backend - 32 MUX –submission delayedNov 2000 - with CMS –tested march 2001 o SCTA “2” used by vertex group and Pad HPD o SCTA “3” production problem, available end Nov o Beetle –arrived at Heidelberg 3 weeks ago –shortcut in buffers prevents programming with I2C try to fix with ion beam –test structures with low gain “The results look good and close to simulation” - N. Smale –next submission planned Jan 2001

10. 10 Milano, 26. 9. 2000LHCb RICH meeting Binary Readout o Only with Beetle, SCTA128 is analogue o Advantages –ODE design for Pixel HPD can be taken “asis” –Optical links and 80 m between F/E and ODE –Cost o Does it work? HERA-B RICH has MaPMTs with binary readout o Must be studied - before end 2000 Estimate signal loss, parameters: –measured signal shape –mean gain of tube –spread of gain from pixel to pixel –collection efficiency within pixel

11. 11 Milano, 26. 9. 2000LHCb RICH meeting New Schedule New Schedule

12. 12 Milano, 26. 9. 2000LHCb RICH meeting Discussion o Mechanicsok o Front-end chip and mother board on critical path o Mother board –can profit from design studies for the photo detector choice but lots of effort needed –need motherboard to test MaPMTs 1/2002 o Front-end chip –gain matching needs effort and time –binary read-out has many advantages –Prefer same choice as vertex detector –analogue read-out restricts ODE to 12 m, copper links, radiation - single event upsets, same for vertex detector –need a functional front-end electronics for 1/2002

13. 13 Milano, 26. 9. 2000LHCb RICH meeting Conclusion o Multianode Photomultiplier Tubes are an excellent backup solution –No primary worries left o Big effort needed for proper Front-end and Off-detector electronics o Front-end chip and mother board on critical path o Need a fully committed team and a final decision should be taken at 12/2000 o Backup solutionsare only taken serious once the baseline has failed o We cannot afford to delay a decision after 12/2000 without delaying the LHCb RICH project