m. bonesini - 22/10/05 ral1 m. bonesini infn milano mice tof stations construction & planning

M. Bonesini - 22/10/05 RAL 1

M. Bonesini INFN Milano

MICE TOF stations construction & planning


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


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


TRD SEPT04 Layout

TOF0 TOF1

Ckov1

IronShield

TOF2Ckov2

Cal

ISISBeam

DiffuserProtonAbsorber

IronShield


…MICET

oF0

Che

renk

ov

Cal

orim

eter

FocusCoils

CouplingCoils

LiquidHydrogenAbsorbers

RFCavities

Tracking Spectrometers

MatchingCoils

Beam Diffuser

Tof1

Tof2


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


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+.


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


Some simulation studies: TOF0

TRDSize

480x480

SEPT04


TOF0 X/Y singles projection

SEP04 beamline (TRD) has fixed counter size to L=48 cm, W= 4cm (T= 1”)


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


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


Mechanics for TOF0

View of X/Y plane: 12 vertical counters , 12 horizontal counters


TOF0 support structure

No major changes foreseen up now


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)


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


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


Solenoid test magnet (B up to 50 gauss)

Test solenoid, PMT inside

Avtech pulser

Laser diode


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


Gain in magnetic field for R4998

90 degs 0

degs50 gauss

90 degs

50 Gauss


Timimg properties of R4998 in B field


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


Timing resolution vs rate for R4998

Npe is estimated via absolute gain measure (at SER peak)


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


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


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


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


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


News from AUG05 from T. Roberts

Beam envelope seems smaller

Reduce TOF1/TOF2 size ?


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


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


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


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


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)


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


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


Time resolution


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


Rate effect as function of B field


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


Timing resolution vs rate

Conventional R4998 PMT with active divider 2” fine-mesh PMT


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


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)


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)


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 …


Remaining … INFN funding :

1. Electronics, cal. System, HV for TOF0

2. All TOF1/TOF2 (aside some modest R&D for defining design)

This mainly drives the TOF1/TOF2 timescale

m. bonesini - 22/10/05 ral1 m. bonesini infn milano mice tof stations construction & planning

Documents

tof0 b

aug05 tof0

ral6 tof0 design

tof0 new point

ral27 tof0 planning

tof0 pmts choice tests

check tof0 performances

cosmics testbench slide