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Timing Counter status @ Sept. 2004. Timing Counter Activities. Timing resolution: 100 ps FWHM have been achieved. PM’s characterised in the COBRA magnet for gain and timing. Full characterisation of single TC’s counter is started Final design and integration with DC is started - PowerPoint PPT Presentation
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CSN I, Assisi 2004 Giorgio Cecchet 1
Genova/Pavia/Roma
Timing Counterstatus @ Sept. 2004
CSN I, Assisi 2004 Giorgio Cecchet 2
Genova/Pavia/Roma
Timing Counter Activities
• Timing resolution: 100 ps FWHM have been achieved.• PM’s characterised in the COBRA magnet for gain and timing.• Full characterisation of single TC’s counter is started• Final design and integration with DC is started• Ф-detector : APD directly from Hamamatsu
CSN I, Assisi 2004 Giorgio Cecchet 3
Genova/Pavia/Roma
Timing resolution measurements
• First test(PSI-E5)- may 03: -BC404 (1X5x80 cm3) – light guides and 1”1/2 and 2” Hamamatsu
Fine Mesh PMs-passive beam collimation (6mm diameter) -5 cm positron path length.-Analogic electronics - Double Threshold Discriminator-MCA
2.35x (tL- tR)]/2= 124 ps FWHM
Scintillator
Light guide
248 ps FWHM(tL- tR)
Low Thr.
High Thr.
Delaycoinc
PM
CSN I, Assisi 2004 Giorgio Cecchet 4
Genova/Pavia/Roma
Timing resolution measurements
• Last test (LNF-Frascati-Beam Test Facility) January 04:Energy Range 25-800 MeV e- 25-550 MeV e+ Max. Repetition Rate 50 Hz Pulse Duration 1-10 ns Current/pulse 1 to 1010 particles (Allowed Current 103 particles/second)Beam spot : x=2mm y=4mm (in the focus)• Further geometrical selection of 5mmx5mm spot by two scintillating fibers
with APD read-out. Time spread due to the spot size ~25ps.• Coincidence with “APD cross” and the LINAC trigger allow to reject most
of the bck. Events.
beam
APD
APD
Scint. Fiber Spot SizeTime spread ~25ps
CSN I, Assisi 2004 Giorgio Cecchet 5
Genova/Pavia/Roma
Timing resolution measurements
1. 1,2,3 electron events are resolved in the charge spectrum2. (tL- tR) is selected in the 1e peak Our Best Results :
2.35x (tL- tR)]/2= 1042ps FWHM
1e2e
3e
CSN I, Assisi 2004 Giorgio Cecchet 6
Genova/Pavia/Roma
Characterisation in MagField
CSN I, Assisi 2004 Giorgio Cecchet 7
Genova/Pavia/Roma
CSN I, Assisi 2004 Giorgio Cecchet 8
Genova/Pavia/Roma
CSN I, Assisi 2004 Giorgio Cecchet 9
Genova/Pavia/Roma
Gain vs Rate
Zero field
1.05 T27.5º
The Gain vs Rate at 1500 V in zero field is fully recovered at 1.05 T and 27.5º at 2100 V. Unallowable increase of biasing voltage are needed at 0º.
CSN I, Assisi 2004 Giorgio Cecchet 10
Genova/Pavia/Roma
Gain Vs Bias at several angles
Same gain
Max gain curvein magn. field
+10º
+10º
CSN I, Assisi 2004 Giorgio Cecchet 11
Genova/Pavia/Roma
RMS timing resolution vs p.e.
60ps pulsedblue Laser
attenuator
100um Fiber
PM
Laser beam illuminates thewhole photocatode
CSN I, Assisi 2004 Giorgio Cecchet 12
Genova/Pavia/Roma
CSN I, Assisi 2004 Giorgio Cecchet 13
Genova/Pavia/Roma
ExpectedReduction
factor
Ext. PM Int. PM
Gain 12 @ 8.5º
5 @ 20º
35 @ 10º
15 @ 20º
TTS 1.2* @ 8.5º
1.2* @ 20º
1.8* @ 10º
1.6* @ 20º
☺ Increase Positron Path-Length ~ 5 cm
☺ Improve Geom. Matching Scint.-PMT
☺ Tilt the PM @ ~ 30º respect Magn. Field
→ Rotated Scint. Slab improves response uniformity and timing performance due to coincidences.
CSN I, Assisi 2004 Giorgio Cecchet 14
Genova/Pavia/Roma
TC key featuresScintillator CrossSection 39x39 mm 70º
PM section
PM activediameter
30º 30º8.5º
From COBRA center
105 cm
10º
25 cm
BB
0.75 T 1.05 T
CSN I, Assisi 2004 Giorgio Cecchet 15
Genova/Pavia/Roma
• Conclusions:– 2” PMs allow to obtain the target resolution– At first order, the resolution is limited by the number
of photoelectrons (light output from scintillator, quantum efficiency of PM, coupling scintillator-PM[2”], which has 39 mm dia. active area)
– At second order, the slew rate could be used to improve the resolution in small signal regime: we have demonstrated that amplification recovers the timing resolution.
– 2” PMs can supply 100uA -maximum- current ( 10uA for 1.5” PMs)
– 2” PMs lifetime correspond to 2.3 years at the event rate of 50kHz @ gain of 6x105. An increase of a factor 2 can be easily obtained.
• To be done:- First systematic tests of single element of TC started
in the run (May, 31 – June, 12) and will continue in the Frascati BTF
– Finalize the design of TC and integration with DC
50x39 mm
39x39 mm
CSN I, Assisi 2004 Giorgio Cecchet 16
Genova/Pavia/Roma
CSN I, Assisi 2004 Giorgio Cecchet 17
Genova/Pavia/RomaSingle Counter Response Study
CSN I, Assisi 2004 Giorgio Cecchet 18
Genova/Pavia/RomaSingle Counter Response Study
• 39x39 slab in rotated configuration simulating a positron trajectory @ 40.5° along z and 70°in radial plane
Very Preliminary
Position (mm)
Tim
e R
esol
utio
n F
WH
M (
ps)
BC408
BC404
CSN I, Assisi 2004 Giorgio Cecchet 19
Genova/Pavia/Roma
Mechanical design
CSN I, Assisi 2004 Giorgio Cecchet 20
Genova/Pavia/Roma
30º 30º8.5º
From COBRA center
105 cm
10º
25 cm
BB
CSN I, Assisi 2004 Giorgio Cecchet 21
Genova/Pavia/Roma
CSN I, Assisi 2004 Giorgio Cecchet 22
Genova/Pavia/Roma
3D view of TC
CSN I, Assisi 2004 Giorgio Cecchet 23
Genova/Pavia/Roma
Transverse Timing Counter
CSN I, Assisi 2004 Giorgio Cecchet 24
Genova/Pavia/Roma
Curved detector (triggering)• The design of the curved detectors has been modified in
order to match the budget limits for procurement of virgin APD form Hamamatsu (159 Euro/each).
• ~ 80 scintillating fibers and 160 APD per each TC.• Procurement preliminary procedure started
APD
Scint. Fibers5 x 10 mm
CSN I, Assisi 2004 Giorgio Cecchet 25
Genova/Pavia/Roma
Timing Counter Schedule
Test MilestoneAssemblyDesign Manufactoring
Fullinstallation
2002 2003 2004 2005
COBRA Test
Beam Test
Design
Assembly
PMT Evaluation PMT procur.
Procur & Manuf.
APD Evaluation APD test APD procur.
Beam Test
Design
PMT Evaluation PMT procur.
Procur & Manuf.
APD Evaluation APD test APD procur.
Mechanicalmatching
BGtest
APD procur.
New APDs
CSN I, Assisi 2004 Giorgio Cecchet 26
Genova/Pavia/Roma
- detector (triggering)• We found good APDs with high S/N ratio that we tested at PSI and LNF
(Frascati)
e- beam Pure e-beam
CSN I, Assisi 2004 Giorgio Cecchet 27
Genova/Pavia/Roma
- detector (triggering)• But, only about 10% of the selected APDs are good enough• Huge spread in dynamic parameters not predictable from static parameters [left
figure]• The CMS selection and conditioning of the first batch of APDs is not applicable to
MEG (we are working at few Volts from Vbkd – high gain- and we are interested to high slew rate and high S/N for timing purpose)
• For comparison new APDs from Hamamatsu have similar response[right figure] • More work is needed to better understand the correlation between static and dynamic
parameters of CMS APDs.
FromHamamatsu
from CMSselection
CSN I, Assisi 2004 Giorgio Cecchet 28
Genova/Pavia/Roma
Status of test and procurements of APD
Pulsed Laser
Integrating CalibratedPhotometer
Fast Photodiode
Photomultiplier
1/1000 attenuator
Splitters
APDCopper block
Peltier Cell
peak-to-noise ratio @ 250 photons signal
0.00
10.00
20.00
30.00
1 11 21 31 41 51 61 71 81 91
S/N ratioAbout 10% can be accepted
APD test bench in Genoa