Cherenkov Detectors for b Physics Sacha Kopp University of Texas at Austin cos C = 1/(n ) CC...
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Transcript of Cherenkov Detectors for b Physics Sacha Kopp University of Texas at Austin cos C = 1/(n ) CC...
Cherenkov Detectors for b Physics
Sacha Kopp
University of Texas at Austin
cosC = 1/(n)
C“radiator”
“photo-detector”
2/30
Good Ol’ Days of Cherenkov Counters
ThresholdCounter
Velocity Selector
“Fitch Counter”
3/30
Ring-Imaging Cherenkov Detectors (RICH)
• First detectors: DELPHI “RICH” at LEP SLD “CRID” at SLC
• Both TMAE-based TPC’s, dual radiator
Original proposal in J. Séguinot & T. Ypsilantis, Nucl. Instr. Meth. 142, 377 (1977)
figures from J. Séguinot CERN-89-12
4/30
BaBar “Detector of Internally-Reflected Cherenkov-light (DIRC)”
5/30
DIRC Principle ee
t ~ 300 nsabout collision time
t ~ 8 nsabout collision timefigures from J. Schwiening, Nucl. Instr. Meth. A502, 67 (2003)
6/30
BaBar DIRC Performance
figures from B. Ratcliff, RICH2004 Conference
7/30
Belle DetectorSC solenoid 1.5T
CsI(Tl) 16X0
TOF counter
8GeV e -
Si vtx. det.3 lyr. DSSD
μ/KL detection14/15 lyr. RPC+Fe
Tracking + dE/dxsmall cell + He/C2H5
3.5GeV e +
Aerogel Cherenkov cnt.n=1.015~1.030
AK=0.101±0.025±0.005
3.9
8/30
Particle Identification at Belle
slide taken from Blair Ratcliff, RICH 2004 Conference
p/K/π separation is based on Likelihood ratio:
LR(K)=L(K)+L(π)
L(K)
9/30
CLEO-IIIRICH
Detector
• Fit inside existing CsI calorimeter (102 cm ID)
• Limit to 13% X0
• Needed <20 cm depth 0.0
0.2
0.4
0.6
0.8
1.0
0.0 0.5 1.0 1.5 2.0 2.5 3.0
eKp
Che
renk
ov A
ngle
(ra
d)
Momentum (GeV/c)
C = 12.8 mrad in LiF
• Coverage for daughters of B mesons produced at rest: pmax ~ 2.65 GeV/c
10/30
Photon Detectors
Charged Particle
Cherenkov Photon
Nitrogen Expansion Volume
Carbon Fiber Support Tube
LiF Crystal
LiF + TEA Detector
11/30
0
20
40
60
80
100
2 4 6 8 10 12
Wavelength (nm)
Tra
nsm
issi
on
orQ
uant
um E
ffic
ienc
y (%
)
Photon Energy (eV)
LiF
CaF2
He+TEA
CH4+TEA
C* (6.42)C* (7.48)
C*(7.94)
N* (8.30)
620 310 207 155 124 103
ROYGBIV
O2
H2O
• Alkali-halide crystals low dispersion (n/ = 0.0023 nm-1): cosC = 1/n() Can fabricate with good transparency, large sizes (after many yrs’ effort)
• Sole example in world: previous effort by Sauli @ FNAL E605, npe ~ 1-2
12/30
• Images are conic intersections distorted and truncated by refractive effects.
• Total internal reflection for trk < 6° sawtooth radiatorAlso reduces chromatic aberrations
Radiator Optics
Image in photon detectors:
charged track
Sawtooth image in detectors:
primary arcssecondary arcs (+1 reflection)
charged track
emerging
internally reflected radiator
photon detector
charged track charged track
reflected emerging
4mm
Planar radiator Sawtooth radiator
A. Efimov and S. Stone, Nucl. Instr. Meth. A371, 79 (1996)
13/30
14/30
Anode Wires
1 mm
e-CH +TEA gas4CaF Window2
4.5 mm
Window Frame
Cathode Pads
• Multiwire chamber 20246 cm2
• CH4 + TEA gas (no blinds/cloisons)
• Total 15 m2 of chambers
• <8% “dead area”
• No observed aging of components from corrosive TEA
• Cathode pad readout (80% coupling)
• Achieve effective gain ~ 105
Photon Detector MWPCs
S.K. & Georg Viehhauser
15/30
Single Photo-electron Detection• Assume:
electronics = 400 e
chamber gain ~ 40,000
• Charged ptcles ionize ~ 62 e-/cm in CH4
• Single ’s: large statistical fluctuations.• Gain limit g~105 due to feedback
(R.Arnold et al, Nucl. Instr. Meth. A270, 255 (1980).
originally seen by H. Schlumbohm, Z. Phys. 151, 563 (1958)
• Analog readout of signal accurate clustering in RICH identification of charged
particles
4
/1dze
ggz
= e4/g
= 96%
16/30
Readout Electronics
• VA_RICH chip variation of chip used for Si tracking detectors (input Cdet)
daisy-chain multiple chips into one VME controller input protection (protect against chamber sparking) dynamic range 650,000 e
Marina Artuso
17/30
Electronics Performance
• 230,400 channels in CLEO RICH onboard sparsification.
• Coherent noise subtraction was an improvement, also adopted for CsI incoh ~ 2.6 ADC counts ~ 400e
Marina Artuso & Silvia Schuh
18/30
• Parasitic µ beam (> 100 GeV).
• 2 MWPCs as track reference
• Demonstrated npe~12 expected for CLEO-III
Sawtooth works as expected given clarity measurements.
RICH Beam Test
E866 beam dump
MWPC1MWPC2
Trigger counters
Vetocounter
1.5 m
RICHconcrete
N = 13.5N = 13.5
=4.8 mr =4.8 mr
CC
NN
19/30
photo of beam testBeamline
Elliot Lipeles
Ray Mountain
Silvia Schuh
Alex Efimov
20/30
Beam Test Events Planar
Sawtooth
M. Artuso et al Nucl. Instrum. Meth. A441, 374 (2000)
21/30Sheldon Stone
Yuri Maravin
Jeff Cherwinka
Rachid Ayad
Rachid Ayad
22/30
AlexSmith
RayMountain
GeorgViehhauser
SilviaShuh
23/30
Ray Mountain
Jeff Cherwinka
Georg Viehhauser
24/30
First CLEO-III Data
ee ee taken from T. Skwarnicki, BCP Conference, Taipei, Dec. ‘99
25/30
CLEO-III RICH Performance
M. Artuso et al, Nucl. Instrum. Meth. A554: 147-194 (2005)
BDK
BD
Beam Constrained Mass (GeV/c)
A. Bornheim et al, Phys. Rev. D68:052002 (2003)
26/30
LHCb Layout
b Exp’ts at Hadron Machines
CERN LHC Proposed for FNAL Tevatron
• Purpose is to collect large samples to over-constrain Unitarity Triangle and search for New Physics.
27/30
Particle ID in Forward b Experiments
Gas
C4F8O
n=1.00138
LiquidC5F12
n=1.24
(proximity focused)(mirror-focused)
(mirror-focused)BTeV RICH
28/30
-20,000 V
-19,890 V
-15,800 V
ground
Vacuum-based Photodetectors
0pe 1pe
2pe
3pe
BTeV HPD readout with VA_RICH
87 mm
125 mm
e-
+60 VSilicondiode
HPD: DEP PP0380AT
figures from T. Skwarnicki, presentation at DOE review of BTeV
29/30
MAPMTs
Beam(120 GeV p)
Glassmirror
Gas tank:C4F8O
and Argon
Beam Test of BTeV RICH
figures from T. Skwarnicki, presentation at DOE review of BTeVJ.C. Wang
R. MountainS. Blusk
30/30
Looking Back• The CLEO-III/c RICH detector works well
• We all made it through a challenging project working beyond edge of demonstrated technology rising/falling of semiconductor industry learning curve in chambers, crystals, gas systems, electronics, … near-miss not choosing CsI or other photocathode
• I would like to express my gratitude and admiration for my coworkers at Syracuse, and those that followed to make the RICH a success.
• All of us grateful for the job Sheldon did supporting our research encouraging “discussion” spreading infectious enthusiasm maintaining focus providing “guidance” to young turks
• I wish Sheldon & Syracuse group many years of productive research