Status of the mapmt
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Status of the MaPMT. Status quo Ongoing work Issues mechanics electronics schedule Conclusions. LHCb meeting Milano 26. 9. 2000. Franz Muheim University of Edinburgh. Status Quo. Successful test of 3x3 array of MaPMTs Quartz lenses and close packing work

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Status of the MaPMT

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Status of the mapmt

Status of the MaPMT

Status quo

Ongoing work

Issues

mechanics

electronics

schedule

Conclusions

LHCb meeting

Milano

26. 9. 2000

Franz Muheim

University of Edinburgh


Status quo

Status Quo

  • 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

  • MaPMT works in LHCb environment

    • charged particles traversing lens and photocathode

    • magnetic field

  • MaPMT fulfills LHCb RICH requirements

  • Front-end electronics needs to be optimised

LHCb RICH meeting


Photo detector decision

Pixel HPD is baseline

must fulfill milestonesassessed at the end of 2000

MaPMT is backup

Keep the MaPMT viable until end 2000

recommended work programme

F/E readout: SCT128A

gain matchingAttenuators or reduced gain of MaPMT

final decision: end 2000

Photo Detector Decision

LHCb RICH meeting


Improvements

Improvements

  • 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

LHCb RICH meeting


Laboratory results

Laboratory Results

Single channel spectrum (LED)

Pixel scan with LED

-900 V

  • Signal / pedestal s = 40:1

  • Signal loss below 5 s cut: 11.5 %

  • Better focusing improves collection efficiency

LHCb RICH meeting


Low gain

Low Gain

  • Additional studies with better sensitivity needed

  • Looks promising

LHCb RICH meeting


Mechanics

Mechanics

  • In good shape

    • for the photo detector decision 12/99

  • MAPMT pitch: 26.7 mm

  • Module pitch: 108.8 mm

  • -metal shield: 0.4 mm

  • Mounting frame: carbon fibre, G10

  • Have enough time to finalise design

LHCb RICH meeting


Front end electronics

Front-end Electronics

  • Options:4 x 2 (SCTA128 or BEETLE) all would probably work

    • preamplifier with lower gain

    • attenuator network, separate chip or passive

    • low gain

  • Preamplifier modification

    • preferred solution

    • needs design effort: J. Buytaert & N. Smale

  • Attenuator network

    • passiveXtalk?

    • activedecouples preamp, needs design effort

  • Low gain

    • increases signal loss, less flexibility

LHCb RICH meeting


Status of asics

Status of ASICs

  • SCTA128A_VELO

    • modified backend - 32 MUX

    • submission delayedNov 2000 - with CMS

    • tested march 2001

  • SCTA “2” used by vertex group and Pad HPD

  • SCTA “3”production problem, available end Nov

  • 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

LHCb RICH meeting


Binary readout

Binary Readout

  • Only with Beetle, SCTA128 is analogue

  • Advantages

    • ODE design for Pixel HPD can be taken “asis”

    • Optical links and 80 m between F/E and ODE

    • Cost

  • Does it work? HERA-B RICH has MaPMTs with binary readout

  • Must be studied - before end 2000Estimate signal loss, parameters:

    • measured signal shape

    • mean gain of tube

    • spread of gain from pixel to pixel

    • collection efficiency within pixel

LHCb RICH meeting


New schedule

New Schedule

LHCb RICH meeting


Discussion

Discussion

  • Mechanicsok

  • Front-end chip and mother board on critical path

  • Mother board

    • can profit from design studies for the photo detector choice but lots of effort needed

    • need motherboard to test MaPMTs 1/2002

  • 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

LHCb RICH meeting


Conclusion

Conclusion

  • Multianode Photomultiplier Tubes are an excellent backup solution

    • No primary worries left

  • Big effort needed for proper Front-end and Off-detector electronics

  • Front-end chip and mother board on critical path

  • Need a fully committed team and a final decision should be taken at 12/2000

  • Backup solutionsare only taken serious once the baseline has failed

  • We cannot afford to delay a decision after 12/2000 without delaying the LHCb RICH project

LHCb RICH meeting


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