fast timing counters for fp420/cms and test beam particle id
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
1Mike Albrow Sept 14th 2006Time-of-Flight with GASTOFs im Test Beam
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 pH
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.
( ) 10ps ( ) 2.1mmt z ( )[interactions] 55 80mmz
Factor 20 – 30 reduction in pile-up B/G, + kinematic constraints.
2Mike Albrow Sept 14th 2006Time-of-Flight with GASTOFs im Test Beam
For FP420 we have tested two prototype designs.Both use Cerenkov light – prompt – GASTOF and QUARTIC.
pMCP-PMT
45-MIRROR
THIN WINDOW
1 atm. C4F8O
1 m.
GAS-Time-Of-Flight
Aperture ~ 10 x 25 mm
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 20mmwith air light guides to MCPMT pixels.8 measurements on a track. Can measure2 separate tracks >3mm in y.
Used area 10mm x 25mm~ 60mm quartz so thick for MTEST.
All light arrives within 3 ps
3Mike Albrow Sept 14th 2006Time-of-Flight with GASTOFs im Test Beam
GASTOF for prototype tests t958
Univ. Louvain
For MTest: 1m. longThin mirror/windows
4Mike Albrow Sept 14th 2006Time-of-Flight with GASTOFs im Test Beam
In Mtest (until this evening!):
GASTOF 1 GASTOF 2 QUARTIC 1QUARTIC 2
5Mike Albrow Sept 14th 2006Time-of-Flight with GASTOFs im Test Beam
It’s (10ps) been done!The challenges arethe electronics and geometry for FP420.SLAC group (Va’vra)got 30ps for single p.e.
6Mike Albrow Sept 14th 2006Time-of-Flight with GASTOFs im Test Beam
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”
7Mike Albrow Sept 14th 2006Time-of-Flight with GASTOFs im Test Beam
Cerenkov light in C4F8O (Octafluorotetrahydrofuran, 2.5)
2ch 2 2
2pe
2pe
pe
1 1cosθ = ; sin θ 1.0
βn β n
n(λ) (C4F8O) = 1.001375 for λ 400nm - 650nm
N 490 ( . .) (cm) sin θ
For L = 1m., Q.E. = 20% N 9800 sin θ
N ( 1) 27
Q E L
... at atmospheric pressure.
At 2 atm. K/p threshold is 6.5/12.5 GeV/c.Asymptotic #pe = 54
non-flammable and non-toxic
8Mike Albrow Sept 14th 2006Time-of-Flight with GASTOFs im Test Beam
e
1
2.( /100 )t ns
9Mike Albrow Sept 14th 2006Time-of-Flight with GASTOFs im Test Beam
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 CMSapplication (b) Could be developed (Henry!) to 1 ps
M(π), M(K), M(p)
2 2cm detectors before m ...π/μ at 10 GeV/c
and π/K at 50 GeV/c!
10Mike Albrow Sept 14th 2006Time-of-Flight with GASTOFs im Test Beam
CMSor
ATLAS
LHC-RF (400 MHz) sharp regular pulse
“TDC” “TDC”
QUARTIC/GASTOF
QUARTIC/GASTOF
START START
STOP STOP
Optical Fiber Optical Fiber
Comparator(control)
May not be necessary, but can testfor L-R propagation time
differential changes
E W
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 E Wt +t
p p
75.5 mmz 75.5 mmz
A possible reference time scheme (LHC):
(250 ps)
Single mode?
CENTIME
?
FO
11Mike Albrow Sept 14th 2006Time-of-Flight with GASTOFs im Test Beam
Three Gastof’s : redundancy, cross-checks, improved resolution(3-point fit to “timetrack”)
Electronics, Set-up for MTest
MCPPMT
HVv.stable
no ripple
ATTENUATOR?
AMPLIFIER?
CONSTANTFRACTION (?)
DISCRIMINATOR
ADC
TDC<=25ps/bin
OPTICALREFERENCE
TIMEOPTICAL
toELECTRICAL
LOCAL CENTRAL
Only optical fibers
TDC bin/4differences
Temperature controlledStabilized Power SuppliesFaraday cage?Short straight SMX cables, minimize connectors
, , , ,e K p
light
12Mike Albrow Sept 14th 2006Time-of-Flight with GASTOFs im Test Beam
,L it ,R itL R
,L it
,R it
tz
This is ambitious, not for LHC Day 1, but P/U worse in 2010!This is ambitious, not for LHC Day 1, but P/U worse in 2010!
This can identify (in principle) interactions that have particles
in both L and R detectors. All are background for p+H+p!
Pads 1cm ×1cm
with 10 20 ps
covering (e.g) 3.9 | | 4.9
at (5.0?)7.5m
t
z
z from centraltracks
13Mike Albrow Sept 14th 2006Time-of-Flight with GASTOFs im Test Beam
Fast Timing Layer Detectors
~ Existence proof:Burle 48mm x 48mm MCP PMT (Micro-channel plate PMT) as for QUARTICDeveloping 10 micron channels, approaching 10 ps.
Tile the plane with these
QUARTZPLATE
MCP-PMT
PARTICLES Approximate numbers:~ 250 each side, perhaps 1000 1cm x 1cm padsExpensive solution (~1M$?) but cost could drop.
Questions: Simulation, acceptance, background crapand especially RADIATION HARDNESS. Another solution?
14Mike Albrow Sept 14th 2006Time-of-Flight with GASTOFs im Test Beam
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??