VERTEX2003, Low Hall, Cumbria The PHOBOS Detector “Design, Experience and Analysis” RUSSELL...

VERTEX2003, Low Hall, Cumbria

The PHOBOS Detector“Design, Experience and Analysis”

RUSSELL BETTS

for

The PHOBOS Collaboration


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


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


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


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


Assembled Elements of the Multiplicity Array

Partially assembled Octagon

Ring arrays

Inner Vertex

Outer Vertex


Ring Counter

Octagon Detector

Vertex Detector

Octagon and Vertex

Prior to Insertion in Magnet Gap

Ring Counter

around

1mm Be Beampipe


Spectrometer Modules


Spectrometer Arm

18 sensors x 500 ch.


66 sensors x 256 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


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


Radiation Monitoring with Real Time Detectors and TLDs


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.


Dead Channels after Beam Blast

RingN

RingP

Octagon

Just after the beamblasted the detector

After readjustingthe VA chip operating

parameters


+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


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.)


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


Flow - v2 vs and s

Averaged over Centrality

PHOBOS Au+Au Preliminary v2200

Final v2130

200 GeV

130 GeV

nucl-ex/0205021


Total Multiplicity for AA and pp (pp)

19.6 GeV is preliminaryAA data is central


Remove the “Leading Proton” Effect

sseffBasile et al (1980-1984)

pQCD e+e- Calculation

)/exp( sBsch CAN

(A. Mueller, 1983)


Comparison of Nch vs. Energy

pQCD e+e- Calculation

)/exp( sBsch CAN


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)


Nch scales with Npart

Error bands due to high- extrapolation

Au+Au

(preliminary)

Total Charged Particle Production ~ Npart


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.

VERTEX2003, Low Hall, Cumbria The PHOBOS Detector “Design, Experience and Analysis” RUSSELL...

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Transcript of VERTEX2003, Low Hall, Cumbria The PHOBOS Detector “Design, Experience and Analysis” RUSSELL...