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Fast Timing Counters for FP420/CMS and Test Beam Particle ID

Fast Timing Counters for FP420/CMS and Test Beam Particle ID. Mike Albrow, September 14 th 2006. FP420 (Forward Protons at 420m from CMS/ATLAS) R&D project. p. p. H. Measure p’s very well  M(H), J=0?, CP = ++, Hgg coupling... Difficulty: SM-H(120-160) ~ 1-10 fb.

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Fast Timing Counters for FP420/CMS and Test Beam Particle ID

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  1. Fast Timing Counters for FP420/CMS and Test Beam Particle ID Mike Albrow, September 14th 2006 FP420 (Forward Protons at 420m from CMS/ATLAS) R&D project p p H Measure p’s very well  M(H), J=0?, CP = ++, Hgg coupling... Difficulty: SM-H(120-160) ~ 1-10 fb. Need high luminosity (~ 30/fb) with multiple interactions. Pile-up: p’s from different events. Precision timing on p’s can reduce this: iff from same interaction.  Factor 20 – 30 reduction in pile-up B/G, + kinematic constraints.

  2. For FP420 we have tested two prototype designs. Both use Cerenkov light – prompt – GASTOF and QUARTIC. 1 atm. C4F8O 45-MIRROR GAS-Time-Of-Flight p MCP- PMT Aperture ~ 10 x 25 mm THIN WINDOW 1 m. All light arrives within 3 ps This is what I am suggesting to use for TOF ID in MTEST. QUARTIC (QUARtz TIming Cerenkov) Quartz bars 6mm x (6 – 1.5)mm x 20mm with air light guides to MCPMT pixels. 8 measurements on a track. Can measure 2 separate tracks >3mm in y. Used area 10mm x 25mm ~ 60mm quartz so thick for MTEST.

  3. GASTOF for prototype tests t958 For MTest: 1m. long Thin mirror/windows Univ. Louvain

  4. In Mtest (until this evening!): GASTOF 2 QUARTIC 1 GASTOF 1 QUARTIC 2

  5. It’s (10ps) been done! The challenges are the electronics and geometry for FP420. SLAC group (Va’vra) got 30ps for single p.e.

  6. Photodetector We concentrate on Burle 2” x 2” MCP PMT (Micro-channel plate PMT) Hamamatsu have higher performance with 10 um channels, but area smaller. Burle has 25 um channels (makes it slower) but are developing 10 um. Burle have given us tubes to test. 25um pores and one 10 um pore tube. Univ. Louvain bought 2 tubes for GASTOFs  M Test. These have an 8 x 8 array of 6mm pixels (  48mm x 48mm (2”)) For GASTOFs one output ... couple pixels “isochronously”

  7. Cerenkov light in C4F8O(Octafluorotetrahydrofuran, 2.5) non-flammable and non-toxic ... at atmospheric pressure. At 2 atm. K/p threshold is 6.5/12.5 GeV/c. Asymptotic #pe = 54

  8. e

  9. We must have a good reference signal free of jitter between stations. This is as important as the detectors themselves. Temperature control? Return path control? • Need to discuss with RF/clock experts. Sophie Baron is contact at CERN for LHC timing issues. Assuming jitter problem solved, calibrate with (p-independent). I have not compared abilities with conventional (P.H. or RICH or DIRC etc) Cerenkovs. This is a new approach which (a) meshes well with CMS application (b) Could be developed (Henry!) to 1 ps

  10. A possible reference time scheme (LHC): E W CMS or ATLAS p p QUARTIC/ GASTOF QUARTIC/ GASTOF CENTIME ? LHC-RF (400 MHz)  sharp regular pulse STOP STOP Single mode? “TDC” “TDC” FO START Optical Fiber Optical Fiber START Comparator (control) (250 ps) May not be necessary, but can test for L-R propagation time differential changes BPM (optimized for timing) BPM (optimized for timing) Tell where p is w.r.t. bunch centroid. (few mm/70mm) Fine correction on p_incident. Compare with sum time from

  11. Electronics, Set-up for MTest Three Gastof’s : redundancy, cross-checks, improved resolution (3-point fit to “timetrack”) ADC TDC <=25ps/bin MCPPMT light AMPLIFIER? A T T E N U A T O R ? CONSTANT FRACTION (?)DISCRIMINATOR OPTICAL REFERENCETIME HV v.stable no ripple OPTICAL to ELECTRICAL TDC bin/4 differences LOCAL CENTRAL Temperature controlled Stabilized Power Supplies Faraday cage? Short straight SMX cables, minimize connectors Only optical fibers

  12. This is ambitious, not for LHC Day 1, but P/U worse in 2010! L R t z z from central tracks This can identify (in principle) interactions that have particles in both L and R detectors. All are background for p+H+p!

  13. Fast Timing Layer Detectors ~ Existence proof: Burle 48mm x 48mm MCP PMT (Micro-channel plate PMT) as for QUARTIC Developing 10 micron channels, approaching 10 ps. Tile the plane with these MCP-PMT QUARTZ PLATE PARTICLES Approximate numbers: ~ 250 each side, perhaps 1000 1cm x 1cm pads Expensive solution (~1M$?) but cost could drop. Questions: Simulation, acceptance, background crap and especially RADIATION HARDNESS. Another solution?

  14. SUMMARY • High precision timing (<~ 10-20 ps) has important future roles: • It is essential for pile-up rejection in pp  p+H+p. p+WW+p at LHC • A very similar set-up can do particle I.D in beams (MTest Upgrade) • <2 ps, large areas open up new possibilities (I.D., Gaps in spacetime) • MCP-PMT is probably best fast photo-detector for now. Later??

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