VERTEX2003, Low Hall, Cum bria The PHOBOS Detector “Design, Experience and Analysis” RUSSELL BETTS for The PHOBOS Collaboration
Jan 19, 2018
VERTEX2003, Low Hall, Cumbria
The PHOBOS Detector“Design, Experience and Analysis”
RUSSELL BETTS
for
The PHOBOS Collaboration
VERTEX2003, Low Hall, Cumbria
Collaboration (May 2003)
Birger Back, Mark Baker, Maarten Ballintijn, Donald Barton, Bruce Becker, Russell Betts, Abigail Bickley, Richard Bindel, Andrzej Budzanowski, Wit Busza (Spokesperson), Alan Carroll,
Patrick Decowski, Edmundo Garcia, Tomasz Gburek, Nigel George, Kristjan Gulbrandsen, Stephen Gushue, Clive Halliwell, Joshua Hamblen, Adam Harrington, Conor Henderson,
David Hofman, Richard Hollis, Roman Holynski, Burt Holzman, Aneta Iordanova, Erik Johnson, Jay Kane, Nazim Khan, Piotr Kulinich, Chia Ming Kuo, Jang Woo Lee, Willis Lin, Steven Manly,
Alice Mignerey, Gerrit van Nieuwenhuizen, Aaron Noell, Rachid Nouicer, Andrzej Olszewski, Robert Pak, Inkyu Park, Heinz Pernegger, Corey Reed, Louis Remsberg, Christof Roland, Gunther Roland, Joe Sagerer, Pradeep Sarin, Pawel Sawicki, Iouri Sedykh, Wojtek Skulski,
Chadd Smith, Peter Steinberg, George Stephans, Andrei Sukhanov, Ray Teng, Marguerite Belt Tonjes, Adam Trzupek, Carla Vale, Robin Verdier, Gábor Veres, Bernard Wadsworth, Frank Wolfs,
Barbara Wosiek, Krzysztof Wozniak, Alan Wuosmaa, Bolek Wyslouch, Jinlong Zhang
ARGONNE NATIONAL LABORATORY BROOKHAVEN NATIONAL LABORATORYINSTITUTE OF NUCLEAR PHYSICS, KRAKOW MASSACHUSETTS INSTITUTE OF TECHNOLOGYNATIONAL CENTRAL UNIVERSITY, TAIWAN UNIVERSITY OF ILLINOIS AT CHICAGO
UNIVERSITY OF MARYLAND UNIVERSITY OF ROCHESTER
VERTEX2003, Low Hall, Cumbria
The PHOBOS Detector (2001)
137000 Silicon Pad Channels
1m
12m Be Beampipe
Spectrometer
Octagon
Vertex
Ring CountersPaddle Trigger Counter
Cerenkov Counter
DX magnet DX MagnetZDC ZDC
VERTEX2003, Low Hall, Cumbria
Bias Bus
p+ Implant
n+
Polysilicon Drain Resistor
Signal Lines
vias
300µm 5k nSi
0.2um ONO1.2um ONO
Double Metal, Single Sided, AC Coupled, Polysilicon Biased Produced by ERSO, Taiwan
Conservative Design, but
9 TypesCommon Readout with IDEAS VA HDR 64/128 Channel Chip
Silicon Sensors
VERTEX2003, Low Hall, Cumbria
Silicon Detector Modules Used in the Octagon Module
8.5c
m
6.5 cm
120 pads / sensor~0.05 - 0.1=/16
64 pads / sensor~0.05=/32
Ring Module
Multiplicity Array
VERTEX2003, Low Hall, Cumbria
Assembled Elements of the Multiplicity Array
Partially assembled Octagon
Ring arrays
Inner Vertex
Outer Vertex
VERTEX2003, Low Hall, Cumbria
Ring Counter
Octagon Detector
Vertex Detector
Octagon and Vertex
Prior to Insertion in Magnet Gap
Ring Counter
around
1mm Be Beampipe
VERTEX2003, Low Hall, Cumbria
Spectrometer Modules
VERTEX2003, Low Hall, Cumbria
Spectrometer Arm
18 sensors x 500 ch.
28 sensors x 512 ch.
66 sensors x 256 ch
21 sensors x 256 ch.
8 sensors x 1536 ch.
VERTEX2003, Low Hall, CumbriaSignal/Noise Distribution
Source Test : Ring Detector pa
d
pulse height
Cou
nts
Peak S/N = 16
keV) 380 and keV 360 , LK,e Tin, (Sn 113
MeV) 3.5maxE -
β ),(RutheniumRu 106
Acceptance criteria for Module : - bad channels < 5 % - S/N > 10
VERTEX2003, Low Hall, Cumbria
Running Experience at RHIC•Summer 2000 - Commissioning and First Collisions at sqrt(s) = 56 and 130 GeV/u Au+Au. Detector 98% Functioning.
•Summer 2001 - January 2002 – Long Au+Au run at 200 GeV/u. First pp data. 24 hr run at 19.6 GeV/u
•November 2002 – May 2003 – d+Au and pp at 200 GeV/u
Au+Au
d+Au130 GeV/u
200 GeV/u
200 GeV/u
VERTEX2003, Low Hall, Cumbria
Radiation Monitoring with Real Time Detectors and TLDs
VERTEX2003, Low Hall, Cumbria
Radiation Exposure•Chronic Radiation Dose not Troublesome – kRad.
•Acute Incidents a Significant Problem
•High Levels During Beam Tuning – Detector Turned Off
•“Blast” Events Due to Beam Misadventures with Detector On – Abort Kicker Malfunction. Damage to Readout Chips – Particularly Calibration Circuits. Partially Recovered by Adjustment of Control Voltages.
VERTEX2003, Low Hall, Cumbria
Dead Channels after Beam Blast
RingN
RingP
Octagon
Just after the beamblasted the detector
After readjustingthe VA chip operating
parameters
VERTEX2003, Low Hall, Cumbria
+5.40 +3-3-5.4
Multiplicity Measurement
•Hit Counting in Octagon and Rings plus Poisson Correction for High Occupancy.
•Energy Deposition to count MIPs.
•“Tracklets” in Vertex and Spectrometer
Octagon Rings
VERTEX2003, Low Hall, Cumbria
PHOBOS Data on dN/ddN
/d
19.6 GeV 130 GeV 200 GeVPreliminary
Extensive and Systematic Data Set
PHOBOS PHOBOS PHOBOS
Typical systematic error band (90%C.L.)
VERTEX2003, Low Hall, Cumbria
Energy Dependence of Central dN/d
Scale by Npart/2 & Shift to = - ybeam
The “Fragmentation Region” grows with sNN
19.6 GeV is preliminary19.6 GeV is preliminary Systematic errors not shown
PHOBOS Au+Au
PHOBOS Au+Au
dNch
/d
/<N
part/2
>
dNch
/d
6% central
beamy
VERTEX2003, Low Hall, Cumbria
Flow - v2 vs and s
Averaged over Centrality
PHOBOS Au+Au Preliminary v2200
Final v2130
200 GeV
130 GeV
nucl-ex/0205021
VERTEX2003, Low Hall, Cumbria
Total Multiplicity for AA and pp (pp)
19.6 GeV is preliminaryAA data is central
VERTEX2003, Low Hall, Cumbria
Remove the “Leading Proton” Effect
sseffBasile et al (1980-1984)
pQCD e+e- Calculation
)/exp( sBsch CAN
(A. Mueller, 1983)
VERTEX2003, Low Hall, Cumbria
Comparison of Nch vs. Energy
pQCD e+e- Calculation
)/exp( sBsch CAN
VERTEX2003, Low Hall, Cumbria
Comparison of Nch vs. Energy
Different Systems Converge at High Energy.
Universality of Nch?
PHOBOS Preliminary Central Au+Au
Central AA
pp (pp) data @ seff
e+e-
1 10 102 103 s (GeV)
VERTEX2003, Low Hall, Cumbria
Nch scales with Npart
Error bands due to high- extrapolation
Au+Au
(preliminary)
Total Charged Particle Production ~ Npart
VERTEX2003, Low Hall, Cumbria
Summary•PHOBOS Silicon has Proved Robust and Stable.
•Successfully Operated Through Three Runs and Largely Survived Several Incidents.
•Physics Results from Multiplicity Display Interesting Scaling Behavior.
•PHOBOS Spectrometer Results (not shown) Add New Information on Observed Phenomenon of Suppression of High pT Particles.