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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
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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 (t~60 ps has been questioned by INFN referees for TOF2)
• Detector requirements:
o Single detector resolution ~60 ps
o High rate capability
o Sustain nearby not-uniform B fringe fields
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TRD SEPT04 Layout
TOF0 TOF1
Ckov1
IronShield
TOF2Ckov2
Cal
ISISBeam
DiffuserProtonAbsorber
IronShield
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…MICET
oF0
Che
renk
ov
Cal
orim
eter
FocusCoils
CouplingCoils
LiquidHydrogenAbsorbers
RFCavities
Tracking Spectrometers
MatchingCoils
Beam Diffuser
Tof1
Tof2
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
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Summary of Rates (Sept04 from Tom Roberts)
Description LAHET Geant4
MARS
TOF0 2355 2693 2834
TOF1 462 529 557
Tracker1 422 482 507
Tracker2 284 324 342
TOF2 281 321 338
Good μ+ 277 316 333Values 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+.
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Rates (Singles per ms) target insertion reduced to get 600 good mu+/sec (AUG05)
LAHET Geant4 MARS Average
TOF0 1722 1762 1508 1664
TOF1 813 832 712 786
Tracker1
771 790 675 745
Tracker2
629 644 551 608
TOF2 627 641 549 606
Good
μ+ (Ev/sec)
621 635 544 600
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”)
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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
EJ230 BC420 BC404
Light output
64 % 64% 68%
max 391 nm 391 nm 408nm
Risetime 0.5 ns 0.5 ns 0.7 ns
Decay time
1.5 ns 1.5 ns 1.8 ns
Pukse FWHM
1.3 ns 1.3 ns 2.2 ns
Att length - 140 cm 140 cmSeems a better choice
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Mechanics for TOF0
View of X/Y plane: 12 vertical counters , 12 horizontal counters
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Considerations for TOF0 PMT choice
1. Rate capability (up to some MHz)2. Good timing properties (TTS)3. Sustain magnetic field (we now
assume <<50 gauss for TOF0)
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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
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Rate capabilities of PMTsTo have a linear signal the mean average anode current (100 A for R4998 ) must not be exceeded -> damage to dynodes ... shorter PMT lifetimeThis gives a theoretical rate capability of:
267 KHZ with R4998BUT !!! 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 (B up to 50 gauss)
Test solenoid, PMT inside
Avtech pulser
Laser diode
M. Bonesini - 22/10/05 RAL 19
R4998 PMT rate studies R4998 with modified
divider circuit: booster or active divider for
last dynodes
Nominal: up to 1.5 MHz
R 4998 R 5505 Structure Linear Focused Fine Mesh
Stages 10 15 Gain 5.7 106 5 105 B=0
1.8 104 B=1 T Rise Time 0.7 ns 1.5 ns
Transit Time 10 ns 5.6 ns Transit Time
Jitter 0.16 ns 0.35 ns
M. Bonesini - 22/10/05 RAL 20
Gain in magnetic field for R4998
90 degs 0
degs50 gauss
90 degs
50 Gauss
M. Bonesini - 22/10/05 RAL 22
Rate effects studies for R4998
• done with available R4998 with modified divider from Hamamatsu (booster on last dynodes)
• Light signal corresponds to ~ 300 p.e.
1 MHz
1 MHz
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Timing resolution vs rate for R4998
Npe is estimated via absolute gain measure (at SER peak)
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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
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Final considerations for TOF0 PMTs choice
tests are under way, but active divider seems a good option no problem for rate effectsESSENTIAL POINT: to estimate for real final counters Npe (this determines rate behaviour) -> counters prototypes available // cosmic testbench available
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Back of the envelope calculation
..300200.... ephv
En riseEQopticalscint.
losstimingep
ConcernsIntrinsic 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
1. Nov 05: decide L,W scintillator and place orders (EIJLEN vs BICRON) -> needs final AUG05 rate maps at TOF0
2. End 05: define choice between booster/active divider for R4998 (tests+cosmic testbench for Npe)-> needs definitive B field maps at TOF0
3. Parasitic testbeam with MEG friends at BTF: asap -> check TOF0 performances up to PMT output (t + rate behaviour with e-)
4. Mid 2006: combined testbeam with EMCAL at BTF -> define electronic readout (V1290 ? TDCs)
5. End 2006: define calibration scheme (cosmics+ laser) 6. End 2006/beg 2007: buy FE electronics, laser calibr.
system, HV …Items 1-6 funded (~120 KE); no funding yet for items 6But 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
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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, B1000 G -> fine-mesh PMTs need additional -metal shielding
M. Bonesini - 22/10/05 RAL 29
News from AUG05 from T. Roberts
Beam envelope seems smaller
Reduce TOF1/TOF2 size ?
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Calculations from J. Cobb, maybe some work can be done to shape shielding to change the relative weight of B//, B_|_
|B| at TOF for 7 configurations of Iron Discs & Gap
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Considerations for TOF1/TOF2 PMT choice
1. Rate capability (up .5 MHz on full detector)
2. Good timing properties (TTS)3. 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
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Tests done at LASA
Laser source to simulate MIP signal (about 300 p.e.) : fast PLP-10 laser on loan from Hamamatsu ItaliaLaser 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
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Used laser light sourceLight source: Hamamatsu fast laser ( 405 nm, FWHM 60 ps, 250 mW peak power) PLP-10Optical 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
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Test magnet at LASA (B up to 1.2T)
PMT under test
1. B field up to 1.2 T
2. 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 TTSManufactured by Hamamatsu Photonics
R5505 R7761 R5924
Tube diameter 1” 1.5” 2 “
No. Of stages 15 19 19
Q.E.at peak .23 .23 .22
Gain (B=0 T) 5.0 x 10 5 1.0 x 10 7 1.0 x 10 7
Gain (B= 1 T) 1.8 x 10 4 1.5 x 10 5
2.0 x 10 5
Risetime (ns) 1.5 2.1 2.5
TTS (ns) 0.35 0.35 0.44
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Gain in B field (various orientations)
G(T
)/G(0
)
2”
B(T)
G(B)/G(B=0T)
PMT axis
B
> critical angle: this points to mu-metal
shielding for TOF1/2
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 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
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Timing resolution vs rate
Conventional R4998 PMT with active divider 2” fine-mesh PMT
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Rate effectsQuestion: 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 delaysAfter 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 costsTOF0 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)
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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 detectorsFix beamline to define final geometry of scintillator counters, mainly L,W: for TOF0 an early answer is needed by November 05Be completely sure of B field at TOF0 well below 50 GDefine by simulation the need of t ~ 60 ps for TOF2Define by simulation is calibration is feasible with only through-going muons, exploiting detector redundancy (X+Y strips)and …