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Heinz Pernegger for
First performance results from Phobos at RHIC
First performance results from Phobos at RHIC
Heinz Pernegger for the PHOBOS collaborationVertex 2000
Heinz Pernegger for
PHOBOS CollaborationPHOBOS CollaborationARGONNE NATIONAL LABORATORY
Birger Back, Nigel George, Alan Wuosmaa
BROOKHAVEN NATIONAL LABORATORYMark Baker, Donald Barton, Mathew Ceglia, Alan Carroll, Stephen Gushue, George Heintzelman, Hobie Kraner ,Robert Pak,Louis
Remsberg, Joseph Scaduto, Peter Steinberg, Andrei Sukhanov
INSTITUTE OF NUCLEAR PHYSICS, KRAKOWWojciech Bogucki, Andrzej Budzanowski, Tomir Coghen, Bojdan Dabrowski, Marian Despet, Kazimierz Galuszka, Jan Godlewski , Jerzy
Halik, Roman Holynski, W. Kita, Jerzy Kotula, Marian Lemler, Jozef Ligocki, Jerzy Michalowski, Andrzej Olszewski, Pawel Sawicki , Andrzej Straczek, Marek Stodulski, Mieczylsaw Strek, Z. Stopa, Adam Trzupek, Barbara Wosiek, Krzysztof Wozniak,
Pawel Zychowski
JAGELLONIAN UNIVERSITY, KRAKOWAndrzej Bialas, Wieslaw Czyz, Kacper Zalewski
MASSACHUSETTS INSTITUTE OF TECHNOLOGYWit Busza*, Patrick Decowski, Piotr Fita, J. Fitch, C. Gomes, Kristjan Gulbrandsen, P. Haridas, Conor Henderson, Jay Kane , Judith
Katzy , Piotr Kulinich, Clyde Law, Johannes Muelmenstaedt, Marjory Neal, P. Patel, Heinz Pernegger, Miro Plesko, Corey Reed, Christof Roland, Gunther Roland, Dale Ross, Leslie Rosenberg, John Ryan, Pradeep Sarin, Stephen Steadman, George Stephans,
Katarzyna Surowiecka, Gerrit van Nieuwenhuizen, Carla Vale, Robin Verdier, Bernard Wadsworth, Bolek Wyslouch
NATIONAL CENTRAL UNIVERSITY, TAIWANYuan-Hann Chang, Augustine Chen, Willis Lin, JawLuen Tang
UNIVERSITY OF ROCHESTERA. Hayes, Erik Johnson, Steven Manly, Robert Pak, Inkyu Park, Wojtech Skulski, Teng, Frank Wolfs
UNIVERSITY OF ILLINOIS AT CHICAGORussell Betts, Christopher Conner, Clive Halliwell, Rudi Ganz, Dave Hofman, Richard Hollis, Burt Holzman,, Wojtek Kucewicz, Don
McLeod, Rachid Nouicer, Michael Reuter
UNIVERSITY OF MARYLANDRichard Baum, Richard Bindel, Jing Shea, Edmundo Garcia-Solis, Alice Mignerey
Heinz Pernegger for
Relativistic Heavy Ion ColliderRelativistic Heavy Ion Collider
RHIC environment:Highest energy density ever produced in labAu-Au collisions with total s= 25TeVAbout 4000 charged particle per central collision
12 June: 1st Collisions @ s = 56 AGeV24 June: 1st Collisions @ s = 130 AGeV5 Sept: end of first Au-Au physics run
Heinz Pernegger for
What does Phobos measure ?What does Phobos measure ?
Phobos searches for signs of Quark-Gluon Plasma at RHICMeasures multiplicity of charged particles over full solid angleReconstruct tracks in mid-rapidity range with low Pt threshold and identifies themMeasures particle ratio/spectra, particle correlation
Phobos “lives” on analog signals of our silicon detectorsMultiplicity measurement use dE/dx as multiplicity estimatorSpectrometer uses dE/dx method for particle identificationAnalog information used to reject backgroundAnalog signals partially used in pattern recognition
Heinz Pernegger for
The Multiplicity detectorThe Multiplicity detector
1 layer of large silicon pad detectors “everywhere”Count single hits or sum of analog signals in a detector area as measure of particle multiplicityHas to deal with high occupancy (>80%)
Vertex
octagon
Heinz Pernegger for
The silicon spectrometerThe silicon spectrometer
16 layer of smaller silicon pad detectors near mid rapdityTracks and Identifies particles (dE/dx) in 2T magnetic fieldAll silicon readout with Viking VAHDR1 chips
Very high dynamic range (>100MIPs), peaking time 1.1s
1x1mm to 0.7x19mm
Heinz Pernegger for
Our silicon detectorsOur silicon detectorsDouble Metal, Single sided, AC coupled, polysilicon biased detectorsproduced by ERSO, Taiwan
p+ Implant
n+
Polysilicon Drain Resistor
bias bussignal lines
vias
300um 5kOhm nSi
0.2um ONO1.2um ONO
AC coupled Pad (p-implant + metal 1 pad)
polisilicon bias resistor
metal 2 readout line
contact hole metal 1- metal 2
Heinz Pernegger for
Before installationBefore installationThe full silicon detector in numbers:
500 wafers, 1600 Viking VAHDR1 readout chips9 different wafer layouts produced by Miracle/Erso, TaiwanAssembled to 240 modules with 140 000 channels
Commissioning setup (15% of full) March-JulyStudy environment and measure first collisions
Full installation for physics run on July 13• 200/200 modules functional • 1082/1084 chips functional = 99.8%• In channels: 98.8% channels fully functional• Peak Signal/Noise = 13:1 to 20:1 depending on sensor
layout• Original requirements : S/N>10 and full functional
channels >95%
Heinz Pernegger for
RHIC beams in PhobosRHIC beams in Phobos
Physics Run 2000
Luminosity estimated using coincidence of signals in the Zero Degree Calorimeters. =10.7barn used to convert counts to luminosity.
PR00 Start6 Bunches
Start 55 Bunches
Integrated Luminosity
B-1
Date
RHIC Integrated Luminosity 65+65 GeV RHIC Integrated Luminosity 65+65 GeV
Heinz Pernegger for Run 5332 Event 35225 08/31/00 06:59:24Run 5332 Event 35225 08/31/00 06:59:24PHOBOS Online Event DisplayPHOBOS Online Event Display
Spectrometer Arm N
Spectrometer Arm P
Octagon Multiplicity detector
Trigger Scintillators N
Trigger Scintillators P
Not to scale Not all sub-detectors shown
Au-A
u B
eam
Mom
entu
m =
65
.12
GeV
/c
Heinz Pernegger for
Performance of the Multiplicity Detector Performance of the
Multiplicity Detector
phi
Z (beam)
One high multiplicity event in the octagon
occupancy up to 80%
Color encodes pulse height
Opening to Vtx
Opening to Vtx
Opening to Spec
Opening to Spec
Heinz Pernegger for
Dealing with high occupancyDealing with high occupancy
Problems associated with high occupancy:
Few channels left to determine common-mode-noise correctionEvent-by-event baseline shift dependent on input signal
Base line before and after
correction
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Signal dependence on occupancy
Signal dependence on occupancy
Problems associated with high occupancy:
Gain dependence on occupancy can distort the multiplicity measurementMultiplicity measured =
dE(meas)/<dE(part)>Gain loss at highest occupancy: 20% NO baseline corr.6% WITH baseline corr.
Heinz Pernegger for
Multiplicity sensor uniformityMultiplicity sensor uniformity
+/- 1%
+/- 3%
No substantial signal variation due to different layout
(double metal line routing/ varying pad size)
3.6 x 8.4 cm
8.3 cm x 6.5 cm
Smp= 93 keV
Smp= 85keV
Heinz Pernegger for
Performance of tracking detectors
Performance of tracking detectors
Hits in VTX
Hits in SPECTracks in SPEC
130 AGeV
56 AGeV
130 AGeV
Heinz Pernegger for
Signal uniformity in Spec/Vertex
Signal uniformity in Spec/Vertex
Signal distrbutions for different layouts:
All signal distribution after calibration (20% effect!)Small pads (type 1 & 2 , 1mm2)Larger pads (type 3,4,5 10 mm2)“strips” (vertex : 0.4x20 mm2)
Very uniform in shape and peak
T1 Smp= 90
T2 Smp=85
T3 Smp= 85
T4 Smp=85
T5 Smp=85
Inner Vtx Smp=87
Outer Vtx Smp=85
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Uniformity within sensorsUniformity within sensors
Pad row (along readout lines accros sensor)
Rela
tive s
ignal vari
ati
on
+/- 2%1 x 1 mm2 0.4 x 6 mm2 0.7 x 7.5 mm2
0.7 x 15 mm2 0.7 x 19 mm2 0.3 x 23 mm2
0.3 x 46 mm2
Typical variation <+/-1% within sensor over large range of pad size and readout line length
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Signal/Noise vs sensor layoutSignal/Noise vs sensor layoutSig
nal peak
[e-]
Nois
e [
e-]
Large pads
Longs readout
lines (high capacitance)
Chip dominated base offset
(ENC = 900 e-+5e-/pF @ 1.1s)
=24000e-
Closest to beam
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Focus on Si signal simulationFocus on Si signal simulationCritical test of detector understandingBoth distributions contain the same number of central eventsPoints are for VTX data
No correction for detector thickness
Histogram is for simulated VTX signals
GEANT
Response from test-beam
Electronics noise
Shulek correction
(CR setup)
Heinz Pernegger for Optimizing our signal simulation
Optimizing our signal simulation
Measured dE/dx in silicon in a testbeam and verified simulation:
Measure dE/dx and distribution shape, test PIDCover large momentum range (130MeV – 8GeV), measure & K
Data
Geant
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Measuring charged multiplicityMeasuring charged multiplicity
VTX TrackletsTwo hit combinations that point to the vertexd = 2 – 1
Good tracklets have d<.1
SPEC TrackletsTwo hit combinations that point to the vertexdR = (d2 + d2) Good tracklets have dR<.015
Heinz Pernegger for
Results :PHOBOS Measurement of Charged :PHOBOS Measurement of Charged Particle Multiplicitynear Mid-rapidity Particle Multiplicitynear Mid-rapidity
hep-ex/0007036hep-ex/0007036 Accepted for publication in PRL Oct 02 2000Accepted for publication in PRL Oct 02 2000
dNch/d (||<1) at sNN= 56 GeV: 408±12±30 dNch/d (||<1) at sNN=130 GeV: 555±12±35
Heinz Pernegger for
SummarySummaryThe good performance allowed a very fast physics analysis
Submitted within 5 week after first recorded collisionThe first publication of all RHIC experiment
Phobos successfully completed its first physics run:3.5 million Au-Au collisions on tape (collected mainly in 2 weeks)
Phobos silicon detector operated flawlessly98 % off al channels fully functionalNot a single module failure during installation and all runningOperates at S/N >15
Phobos is well equipped for future analysisVery uniform and well calibrated signal responseCan operate at high occupanciesDetector showed to be reliable and stable
Heinz Pernegger for
Readout & Calibration systemReadout & Calibration system
Readout with Viking VAHDR1 chipsVery high dynamic range (>100MIPs), peaking time 1.1s
Phobos “lives” on analog signalsMultiplicity measurement use dE/dx as multiplicity estimatorSpectrometer uses dE/dx method for particle identificationAnalog information used to reject backgroundAnalog signals partially used in pattern recognition
• Dedicated calibration systemMeasures full gain curve for each channel (1-2/day)Verifies functionality and normalizes gain of different detector modules and sensors
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Derivation of dN/dDerivation of dN/d
Extract from correlation of
Primaries in –1 < < 1Measured number of tracklets
dN/d
Nu
mb
er
of
Tra
ckle
ts
5<z<10
SPEC
VTX
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Measuring dN/d with tracklets
Measuring dN/d with tracklets
Number of reconstructed tracklets is proportional to dN/d | <1
To reconstruct trackletsReconstruct vertexDefine tracklets based on the vertex and hits in the front planes of SPEC and VTXRedundancy essentially eliminates feed-down, secondaries, random noise hits
To determine Run the same algorithm through the MCFolds in detector response and acceptance
1
d
dNZ
d
dN primarytracklets