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M. Bonesini INFN Milano

MICE TOF stations construction & planning. M. Bonesini INFN Milano. Outline. Introduction Present design for TOF0 PMTs studies Current problems Funding & timescale Present design for TOF1/TOF2 PMTs studies Open questions (TOF0/TOF1/TOF2) Conclusions.

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M. Bonesini INFN Milano

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  1. MICE TOF stations construction & planning M. Bonesini INFN Milano M. Bonesini - 22/10/05 RAL

  2. Outline • Introduction • Present design for TOF0 • PMTs studies • Current problems • Funding & timescale • Present design for TOF1/TOF2 • PMTs studies • Open questions (TOF0/TOF1/TOF2) • Conclusions M. Bonesini - 22/10/05 RAL

  3. Aims of TOF stations • TOF0 experiment trigger • TOF0/TOF1 PID on incoming muons • TOF1/TOF2 PID on particle traversing the cooling channel • TOF1/TOF2 contribute (t) to emittance measurement (st~60 ps has been questioned by INFN referees for TOF2) • Detector requirements: • Single detector resolution s~60 ps • High rate capability • Sustain nearby not-uniform B fringe fields M. Bonesini - 22/10/05 RAL

  4. TRD SEPT04 Layout ISIS Beam Iron Shield TOF0 TOF1 Diffuser Iron Shield TOF2 Ckov2Cal Proton Absorber Ckov1 M. Bonesini - 22/10/05 RAL

  5. Focus Coils …MICE Calorimeter Cherenkov ToF0 Tof2 Tracking Spectrometers Coupling Coils Tof1 Beam Diffuser Matching Coils RFCavities Liquid Hydrogen Absorbers M. Bonesini - 22/10/05 RAL

  6. TOF0 design is presently based on SEP04 beamline (mods may be foreseen for AUG05) • Particle rates was around 2.4-2.8 MHz for TOF0, it seems that new beamline AUG05 will reduce it to ~ 1.6 MHz -> better if beam profile will not shrink in AUG05 • TOF0 in the fringe field of quadrupoles for TOF0 B << 50 gauss (mail from Kevin). Conventional fast PMTs Hamamatsu R4998 with booster or active divider+mu-metal shielding M. Bonesini - 22/10/05 RAL

  7. Summary of Rates (Sept04 from Tom Roberts) Values are events per millisecond of Good Target; absorbers empty, no RF. Good μ+ = TOF0 & TOF1 & Tracker1 & Tracker2 & TOF2 & TOF1(μ+) & TOF2(μ+) Major changes from before:2 in. total thickness of TOF0 and TOF1  ~20% reduction in Good μ+~50% larger target acceptance  ~10% increase in TOF0 singles, ~1% in Good μ+. M. Bonesini - 22/10/05 RAL

  8. Rates (Singles per ms) target insertion reduced to get 600 good mu+/sec (AUG05) M. Bonesini - 22/10/05 RAL

  9. Some simulation studies: TOF0 TRD Size 480x480 SEPT04 M. Bonesini - 22/10/05 RAL

  10. TOF0 X/Y singles projection SEP04 beamline (TRD) has fixed counter size to L=48 cm, W= 4cm (T= 1”) M. Bonesini - 22/10/05 RAL

  11. TOF0 AUG05 beamline:news from 21/10/05 from T. Roberts “Maybe” (?) we may think to reduce detector size L,W We cannot go much lower for W : PMT assembly outer size is ~ 3.2 cm, only realistic possibility is L We keep design as it is now for the present time M. Bonesini - 22/10/05 RAL

  12. Scintillator counter layout • based on present beamline assumptions for all TOF stations L=480 mm, T=1”, W=40 mm for TOF0, 600 mm for TOF1/2. Choice between BC404/420 scintillator or ELJEN Technology 230 (~same quality) • To be revised with AUG05 beamline design: but soon, orders must be placed now for scintillator. Mainly I must fix L,W for TOF0 Seems a better choice M. Bonesini - 22/10/05 RAL

  13. Mechanics for TOF0 View of X/Y plane: 12 vertical counters , 12 horizontal counters M. Bonesini - 22/10/05 RAL

  14. TOF0 support structure No major changes foreseen up now M. Bonesini - 22/10/05 RAL

  15. Considerations for TOF0 PMT choice • Rate capability (up to some MHz) • Good timing properties (TTS) • Sustain magnetic field (we now assume <<50 gauss for TOF0) M. Bonesini - 22/10/05 RAL

  16. Conventional PMT test setup • Laser source to simulate MIP signal (about 300 p.e.) : • fast AVTECH pulser AVO-9A-C (risetime 200 ps, width 0.4-4 ns, repetition rate 1KHz-1MHz) with NDHV310APC Nichia violet laser diode(~400 nm, 60 mW) NEW!! • fast PLP-10 laser on loan from Hamamatsu Italia • Laser sync out triggers VME based acquisition (TDC + QADC) // MCA SILENA system • Home made solenoid test magnet (B up to 50 gauss, d~20 cm, L~50 cm) see later for details M. Bonesini - 22/10/05 RAL

  17. Rate capabilities of PMTs • To have a linear signal the mean average anode current (100A for R4998 ) must not be exceeded -> damage to dynodes ... shorter PMT lifetime • This gives a theoretical rate capability of: 267 KHZ with R4998 BUT !!! Divider can be modified for R4998 (going up to 1.67 MHZ) with booster or active divider M. Bonesini - 22/10/05 RAL

  18. Solenoid test magnet (Bup to 50 gauss) Test solenoid, PMT inside Laser diode Avtech pulser M. Bonesini - 22/10/05 RAL

  19. R4998 with modified divider circuit: booster or active divider for last dynodes Nominal: up to 1.5 MHz R4998 PMT rate studies M. Bonesini - 22/10/05 RAL

  20. Gain in magnetic field for R4998 50 Gauss 90 degs 0 degs 50 gauss 90 degs M. Bonesini - 22/10/05 RAL

  21. Timimg properties of R4998 in B field M. Bonesini - 22/10/05 RAL

  22. Rate effects studies for R4998 • done with available R4998 with modified divider fromHamamatsu (booster on lastdynodes) • Light signal corresponds to ~ 300 p.e. 1 MHz 1 MHz M. Bonesini - 22/10/05 RAL

  23. Timing resolution vs rate for R4998 Npe is estimated via absolute gain measure (at SER peak) M. Bonesini - 22/10/05 RAL

  24. Continuos pulsing vs ISIS-cycle • Results for rate effects have been compared with a continuos pulsing rate R and simulating an ISIS-like cycle : 1 ms at rate R + 20 ms at no rate • Results (as expected) show no difference M. Bonesini - 22/10/05 RAL

  25. Final considerations for TOF0 PMTs choice • tests are under way, but active divider seems a good option • no problem for rate effects • ESSENTIAL POINT: to estimate for real final counters Npe (this determines rate behaviour) -> counters prototypes available // cosmic testbench available M. Bonesini - 22/10/05 RAL

  26. Back of the envelope calculation Concerns Intrinsic resolution 1) Light attenuation & Timing degradation with respect to distance from PMT. 2) Quality of scintillator 3) Ageing effect Needs evaluation with cosmics testbench M. Bonesini - 22/10/05 RAL

  27. TOF0 planning • Nov 05: decide L,W scintillator and place orders (EIJLEN vs BICRON) -> needs final AUG05 rate maps at TOF0 • End 05: define choice between booster/active divider for R4998 (tests+cosmic testbench for Npe)-> needs definitive B field maps at TOF0 • Parasitic testbeam with MEG friends at BTF: asap -> check TOF0 performances up to PMT output (st + rate behaviour with e-) • Mid 2006: combined testbeam with EMCAL at BTF -> define electronic readout (V1290 ? TDCs) • End 2006: define calibration scheme (cosmics+ laser) • End 2006/beg 2007: buy FE electronics, laser calibr. system, HV … • Items 1-6 funded (~120 KE); no funding yet for items 6 • But good news: Sofia group is interested in TOF business, so we can be more confident on this schedule. We will define actual division of work later, according to interests. A Pavia group (still working on PMT tests) is planning to join TOF effort M. Bonesini - 22/10/05 RAL

  28. TOF1/TOF2 design is still based on SEP04 beamline design • But timescale is less critical (as respect to TOF0) • New point: final B-field calculations after shielding of J. Cobb et al . Main result is that at PMT positions B//~200 G, B_|_ ~ 1000 G -> fine-mesh PMTs need additional m-metal shielding M. Bonesini - 22/10/05 RAL

  29. News from AUG05 from T. Roberts Beam envelope seems smaller Reduce TOF1/TOF2 size ? M. Bonesini - 22/10/05 RAL

  30. |B| at TOF for 7 configurations of Iron Discs & Gap Calculations from J. Cobb, maybe some work can be done to shape shielding to change the relative weight of B//, B_|_ M. Bonesini - 22/10/05 RAL

  31. Considerations for TOF1/TOF2 PMT choice • Rate capability (up .5 MHz on full detector) • Good timing properties (TTS) • Sustain magnetic field ( about .1-.2 T for TOF2) Tests at Lasa magnet test facility with Pavia MEG group to optimize choice (M.Bonesini, F.Strati INFN Milano, G.Baccaglioni,F.Broggi, G. Volpini INFN Milano –LASA, G. Cecchet, A. DeBari, R. Nardo’, R. Rossella INFN Pavia, S. Dussoni, F.Gatti, R. Valle INFN Genova). From MEG experiment M. Bonesini - 22/10/05 RAL

  32. Tests done at LASA • Laser source to simulate MIP signal (about 300 p.e.) : fast PLP-10 laser on loan from Hamamatsu Italia • Laser sync out triggers VME based acquisition (TDC + QADC) • 5000 events for each data point : different PMTs (fine-mesh vs mod R4998), different B-field, different inclination vs B field axis (), diff laser rate to simulate incoming particle rates M. Bonesini - 22/10/05 RAL

  33. Used laser light source • Light source: Hamamatsu fast laser ( 405 nm, FWHM 60 ps, 250 mW peak power) PLP-10 • Optical system: x,y,z flexure movement to inject light into a CERAM/OPTEC multimode fiber (spread 14 ps/m) • PMT under test Laser light Signal ~ 300 p.e. to reproduce a MIP as measured with an OPHIR Laser powermeter M. Bonesini - 22/10/05 RAL

  34. Test magnet at LASA (Bup to 1.2T) PMT under test • B field up to 1.2 T • Free space 12 cm in height • For other tests : shielded conventional PMTs, we will refurbish the magnet, enlarging the gap up to 18-20 cm (field will go down to ~ .4-.5 T) M. Bonesini - 22/10/05 RAL

  35. Fine Mesh Photomultiplier Tubes • Secondary electrons accelerated parallel to the B-field. • Gain with no field: 5 x 10 5– 10 7 • With B=1.0 Tesla: 2 x 104 - 2.5 x 10 5 • Prompt risetime and good TTS • Manufactured by Hamamatsu Photonics M. Bonesini - 22/10/05 RAL

  36. Gain in B field (various orientations) G(B)/G(B=0T) G(T)/G(0) B  PMT axis 2”  > critical angle: this points to mu-metal shielding for TOF1/2 B(T) M. Bonesini - 22/10/05 RAL

  37. Time resolution M. Bonesini - 22/10/05 RAL

  38. Rate effects (as a function of HV) • rate capability is limited by max anode mean current (tipically 0.1mA for a 2” R5924 PMT) • this is the ONLY relevant point, e.g. in B field if gain is lower by a factor F rate capability increases by 1/F • With very high particle rates: try to reduce mean current M. Bonesini - 22/10/05 RAL

  39. Rate effect as function of B field M. Bonesini - 22/10/05 RAL

  40. Timing resolution vs rate • Tests with MCA Ortec TRUMP 8K+ TAC Ortec 566 and CF discriminator • ORTEC CF8000 • Timing resolution is not affected by rate R • It depends as expected from Npe M. Bonesini - 22/10/05 RAL

  41. Timing resolution vs rate Conventional R4998 PMT with active divider 2” fine-mesh PMT M. Bonesini - 22/10/05 RAL

  42. Rate effects • Question: any difference between rate capability in continuos pulse mode or in accelerator-like pulsed mode ? • Answer: no, as clear from the fact that rate capability is driven only by max Ia bunched mode at rate R Continuos mode at rate R M. Bonesini - 22/10/05 RAL

  43. TOF1/TOF2 planning • Not yet funded from INFN: funds are up to now for TOF0 up to PMTs (no electronics, calibration system, HV). But design seems less challenging than TOF0 (similar, lower rates, even if with higher B field) • We will do some R&D/design work in parallel with TOF0, to avoid delays • After funding, delivery may be end 2007/beginning 2008: main bottlenecks (aside manpower) are delivery times for PMTS (4-5 months), scintillator (3-4 months) M. Bonesini - 22/10/05 RAL

  44. Estimate of costs TOF0 PMT assembly R4998 (1600 Euro x 40) 64K Euro scintillators 10K Euro Lightguides machining/supports/… i 5K Euro Electronics mountingsi/patch panels/dividers 5K Euro HV/signal cables 3K Euro 87K Euro TOF1 (or TOF2)PMT assembly 2” fine-mesh (2500 Euro x 35) 87.5KEuro scintillators 10K Euro Lightguides machining/supports/… 5K Euro Electronics mountingsi/patch panel/dividers 5K Euro HV/signal cables 3K Euro 110.5KEuro Laser cal syst Fast laser + fibers bundle 60K Euro laser diagnostics, electronics 5K Euro 65KEuro Cosmics cal syst scintillators, support, … 10K Euro Front-end QADC,TDC 40K Euro electronics Discriminators 10K Euro NIM electronics 5K Euro Crate VME 8K Euro 63KEuro HV supply 100 channels CAEN + mainframe 35K Euro Total 481 KEuro Got up to now ~110KE (+ ~ 50KE in-kind material) M. Bonesini - 22/10/05 RAL

  45. Main open points • FE electronics (V1290 TDC with TOT corrections instead of V775 TDC + V792 QADC)… but this rate problem is common to all MICE detectors • Fix beamline to define final geometry of scintillator counters, mainly L,W: for TOF0 an early answer is needed by November 05 • Be completely sure of B field at TOF0 well below 50 G • Define by simulation the need of st ~ 60 ps for TOF2 • Define by simulation is calibration is feasible with only through-going muons, exploiting detector redundancy (X+Y strips) • and … M. Bonesini - 22/10/05 RAL

  46. Remaining … INFN funding : • Electronics, cal. System, HV for TOF0 • All TOF1/TOF2 (aside some modest R&D for defining design) • This mainly drives the TOF1/TOF2 timescale M. Bonesini - 22/10/05 RAL

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