加速器と実験装置

Bevalac•••••

今はもう無いLawrence Berkeley Laboratory (LBL)
Bevatron (反෩子の生成→ノーベルࡪ) + Hilac
Emax = 2.1 （2Z/A） A GeV
1970年代中頃~1980年代の終わり• ‫ژ‬エネルギー重イオン衝突実験の先駆け– 衝突のグローバルな様相– 基本的なアイデア– 測定方法

AGS
•
•
•
•

Brookhaven National Laboratory (BNL)
世界初の強収束（෩子）加速器 (三つのノーベルࡪ)
Emax = 15 （2Z/A） A GeV
1986年~• 主な結果– 大きなバリオン密度– ストレンジ粒子生成– フロー• RHICの前段加速器– 同時に෩子等の実験プログラム

SPS• CERN - European Organization for Nuclear Research• 固定標的用෩子加速器＋෩子・反෩子衝突型加速器• W、Z の発見
• Emax = 400 （2Z/A） A GeV• 1986年~• QGPを示唆する結果– J/y 収量の異常– 粒子収量とスペクトル– 低‫ޑ‬量レプトン対収量異常• 将来、LHCの前段加速器

The Relativistic Heavy Ion Collider at BNL••••

Two independent rings 3.83 k incircumference–120 bunches/ring–106 ns crossing time
Maximum Energy–s_ = 500 GeV p-p–
s_ = 200 GeV Au-Au
per N-N collision
Design Luminosity–
Au-Au 2x1026 cm-2s-1–
p - p 2x1032 cm-2s-1 ( polarized)
Capable of colliding any nuclearspecies on any other nuclear speciesRHIC

the lay of the land
12:00 o’clock

PHOBOS
10:00 o’clock

RHIC

PHENIX
8:00 o’clockSTAR
6:00 o’clock

U-lineHigh Int. Proton Source

BAF (NASA)

LINAC

BRAHMS
2:00 o’clockm g-2

4:00 o’clock
Design Parameters:
Beam Energy = 100 GeV/u
No. Bunches = 57
No. Ions /Bunch = 1 ¥ 109
Tstore = 10 hours
Lave = 2 ¥ 1026 cm-2 sec-1

9 GeV/uQ = +79

BOOSTER

Pol. Proton SourceAGS

1 MeV/uQ = +32

HEP/NP

TANDEMS

The PHENIX Collaboration

12 Countries
51 Institutions
400+ Collaborators

Welcome to PHENIX
Tale of the Tape:ÿBegun Operation June 2000
ÿ12 Detector subsystems
ÿ4 Spectrometer armsÿTotal weigh = 3000T
ÿ315,000 readout channels
ÿ >125 Varieties of custom
printed circuit boards
ÿ13 ASICs designed
specifically for PHENIXÿPipe-lined DAQ Front-end
ÿ500, GHz Optical Data Links
The PHENIX Experiment is designed to probe fundamental features ofthe strong nuclear force including:•The detection and characterization of the Quark-Gluon Plasma•The spin structure of the nucleons
The Configuration:•2 Forward Muon Arms
•2 Central Spectrometer Arms to measure photons, electrons, and hadrons•Event Characterizing Detectors• ૣ子・෩ૣ子対、• 光子（g線）、• ハドロン(バリオン、メソン)

パイ中間子（p+, p-, p0）
K中間子（K+, K-）• g線 ：火の玉の内ಊの情報• ૣ子・෩ૣ子対：
Ě火の玉の内ಊの情報
Ěベクター・メソン： r、f、Ｊ/y

g線

ૣ子
෩ૣ子

෩子、反෩子The Physics of PHENIX
QGP:• Temperature and Energy Density– dN/dy, ET , Single particle
spectra• Jet Quenching– High pT jets using leading po, p±• Space –Time Evolution– HBT(pp, KK,pp), Flow
– Event by Event Fluctuations• Deconfinement– J/Y, Y’Æ e+e-,m+m-, UÆmm• Chiral Symmetry Restoration– fÆe+e-,K+K-, f,w,r width/shift– DCC’s po/p±• Heavy Quark Production– K/ p , f, J/Y, Y’, U, D, B mesons• Thermal Radiation– g, g*Æ e+e-, m+m-

Nucleon Spin:• Gluon spin: DG– Direct g, high pT p’s• Sea quark spin: Du, Dd– W+/W- production– Drell-Yan
Polarization

Challenges for the Detector Design••••

High Particle Multiplicity/Event(dNc/dy @ 1000)
Maintain performance over large dynamic
range in E and pt ( 300 MeV – 50 GeV)
Significant particle ID rejections
e/p = 10 –4 , m/p = 10 –4, p/K/p = 10 –3
DAQ/Trigger operates in varying
environments

Energy Resolution ofPb Scin EMCal– Event rate O(10 kHz), Particle mult.
O(1000/evt)– Event rate O(1 MHz), Particle mult.
O(10/evt)
Pt res of Central Arm Tracking

The Detector’s Design Strategy
ÿ Detector Redundancyÿ Fine Granularity, Mass Resolution
ÿ High Data Rate
ÿ Good Particle ID
ÿ Limited Acceptance
Charged Particle Tracking:Drift Chamber
Pad Chamber
Time Expansion Chamber/TRD
Cathode Strip Chambers

Particle ID:
Time of Flight
Ring Imaging Cerenkov Counter
TEC/TRD
Muon ID (PDT’s)

Calorimetry:
Pb Scintillator
Pb Glass

Event Characterization:
Multiplicity Vertex Detector (Si Strip,Pad)
Beam-Beam Counter
Zero Degree Calorimeter

Some Unique PHENIX Technologies••

Large Area Cathode Strip Chamber with 100 mm position resolution
Fine-segmented EMCal (0.01 F, 0.01 h) with st < 0.5 ns•••••

Time Expansion Chamber that combines tracking, dE/dx and TRD
Drift Chamber configured as focusing –jet chamber
Ring Imaging Cerenkov Counter readout with 5000+ PMTs
Low mass, non-projective pixel-pad wire chambers covering ~100 m2
Time of Flight system with st < 100 ps••

Fully data-pipelined front-end electronics
All data, timing, control and serial communication between detector
and counting house is via optical link.

A Crowded Experimental HallMuID

EMCAL

TOF

MuTrk

TEC/TRD

PCs

DC

RICH
BBCMVD
ZDC

Event Characterization Detectors

Beam-Beam Counter and Zero Degree Calorimeter
BBC•

•

•

BBC is 2 arrays of 64 PMTs with quartz
radiators– Provides T0 for PHENIX. st = 41 ps
ZDC is Cu-W calorimeter with fiber readout.
– Common centrality measure for all 4 RHIC
experiments
Combined they provide the PHENIX LVL1
centrality trigger
ZDC

Event Characterization Detectors

Multiplicity Vertex Detector•

Two concentric barrels of 300mmSi strips•

Two endplates of Si pads•

Total coverage of -2.5 < h< +2.5•

28,672 Si strips, 6048 Si pads•

Determines event vertex andmeasures particle
multiplicity/event•

Electronics is bare die on ceramicMulti- Chip Module

Vertes resolution

5 mm RMSTracking Detectors:••••

Drift Chamber

Jet -chamber anode/cathodestructure modified for HI highmultiplicity
Joint Russia/US design &construction
All Titanium framesx = 120 mm , two-track sep = 2mm

Identified particle
spectra using tracking
system and TOF

Tracks in DC fromCentral Au-Au collision

DC wires with kapton
wire dividers

Tracking Detectors:• Cathode wire chambers using fine granularity pixel
pad readout– 2-D hit position, sx = sy ~ O( mm)– 173k channels total, ~ 100 m2 detector coverage• Low-mass , rigid honeycomb/circuit board
construction• All signal digitization takes place on-board in
detector active region. Solves interconnect
problem.
Min bias
multiplicity
distribution atmid-rapidity

Pixel Pad Cathode Pattern

Clusters in PC fromCentral Au-Au collision

Pad Chambers
PC1PC3

Tracking Detectors:

Time Expansion ChamberN tracks• 24 TEC Chambers arranged in 4, 6-Chamber sectors• Used for tracking and PID (dE/dx,TR). sx = 260 mm• dE/dx: e/π = 5% at 500 MeV/c (4 pls), e/π = 1.5%(6pls) Important for momentum resolution
pT >4.0 GeV/c• Designed for TRD Upgrade . High momentum e/π

Sum FADC counts/recon. tracksx = 260 mm

Tracks in TEC fromCentral Au-Au Collisions

TRD Radiator

PHENIX TEC/TRD Electronics
Up to 20,500 Instrumented TEC/TRD Channels

32 channel Preamp/Shaper PCB
w/ remote calibration control
and ~1 fC RMS system noise

3 ASICs designed for TEC/TRD:•Octal Preamp/Shaper w/ tail cancellation and dual gain
for both dE/dx and TR. Full serial control of gain,
shaping time and tail cancellation.
•Non-linear, 40 MHz, FADC with 9-bit dynamic range,
9-bit precision and 5-bit encoding.
•Digital Memory Unit for data formatting with
programmable delay and memory depth.

64 channel Front End Module(FEM)
w/ digitizing , data formatting andoptical data transmission

Tracking Detectors:••••

Cathode Strip Chambers

First cathode-strip chambers (CSC) used in anexperiment
Low mass honeycomb-printed circuit board
and etched metalized-mylar design
Each CSC station has a position resolution ofsx=100 mm
20k electronics channels/spectrometer arm
Raw di-muon
spectrum, no cuts

Residual ~ 300 mm

CSC Station 1

Reconstructed muon
In Au-Au CollisionParticle ID Detectors: Time of Flight• 1000 finely segmented slats readout w/ 2000
PMTs
• Combines with BBC timing for an overall
time resolution of sTOF < 96 ps• K/p separation <~ 2 GeV/c• p/K separation <~ 4 GeV/c385cm
200cm

Clusters in TOF fromCentral Au-Au collision
200cm

96 slats/panel

10 panels

Particle ID Detectors: Ring Imaging Cerenkov Counter•••PHENIX electron signal

Gas radiator CO2 , e/p separation for p < 5GeV/c
5120 PMTs sensitive to single
photoelectrons,st < 1 ns
Ring resolution ~1o in both F and h

All charged
With RICH hit

Random backgroundE/p ratio :RICH-EMCal
PHENIX

RUN 12280 SEQ 0014 EVENT 850
South SideRings in RICH fromCentral Au-Au collision

East ArmWest ArmDC
DCPC1
PC1
RICH
RICH
TECPC3
6 PMT RICH ring EMCal
TOFEMCal
2.55 GeV/c track
2.5 GeV EMCal hit
electron candidate
View from North Side

RICH-EMCal Match

Particle ID Detectors: EM Calorimeter•

60 m2 of calorimeter•

Very Fine Segmentation .01 x .01 (DF x Dh)•

Timing st ~ 400 ps Pb Glass•sE = 8.2%/√E+1.9% Pb Scin, sE = 5.8%/√E+1.0% Pb Glass(6 Sectors Pb Scin, 2 Sectors PbGlass)

Mean Values and Widths of popeaks

st ~ 400 ps Pb Scin

24,768 channels total, all PMTs
Clusters inEMCalfrom
Central AuAuCollisions

st ~ 400 ps
Pb Scintillator
EMCal Module

Pb Glass EMCalModule

Particle ID Detectors: Muon ID• 5 layers of steel absorber plate interleavedwith 5 layers of Iarocci tubes (2x,2y 4planes/layer)• Active cross section of each wall 10m x 10m• Muon low energy cutoff off 1.9 GeV/c• Permanently sealed in place behind shieldwall
MuID posresolution

Reconstructed muon
In Au-Au Collision

Number of hits/eventcm
Gap 3, Panel0, Vertical
Red: Data

Hit Background

Blue: HIJING simulation

Tube x position(cm)Data Acquisition System/Trigger

Data Acquisition System/Trigger
Run Control Display

Participant-spectatormodelと衝突係数

Participant-spectator 描像• impact parameter（衝突係数）によって、衝突の様相が決まる
Spectator -- beam fragment

Participant

Spectator -- target fragment

Spectators

Participants

衝突係数の決定
Participant-spectator 描像を利用する• Beam fragment の運動エネルギー– ハドロンカロリメータ•∝

AFEN → fragment の核子数

• 横エネルギー（ET）– ハドロンカロリメータ、ૣ磁カロリメータ• Participant 領域からの放出エネルギー• 粒子多重度– 荷ૣ粒子検出器• Participant 領域からの放出粒子数

CERN-SPS WA98 実験

CERN-SPS NA49 実験

Centrality の決定（NA49）• 前方ハドロンカロリメータ（VCAL）EVCAL vs. Nch• Nch ：TPC でのトラックの数• 強い反相関Centrality (PHENIX)
• BBC
• ZDC
• EMCal– PbSc+PbGl• トラッキングチェンバー– PC1,PC2,PC3– DC– TEC

グローバル用検出器
Mid
rapidity,Et

Forward, spectator Energy
charged, neutral
Zero Degree Calorimeter(PHENIX,Central)

EMCal

Beam-BeamCounterビーム・ビーム検出器（BBC）
Hiroshima U, Columbia, LANL, and BNL• 一対：ビーム‫ބ‬に沿って੶前方(3.0< h < 3.9)にध置• ビーム衝突事象を検出→ 衝突位置、衝突時間、衝突係数を与える• 64個の検出素子• 各素子：
チェレンコフ輻射体（石英）＋１インチ径メッシュ型
PMT

BBC Performance in Year-1
Timing resolution of an element

Multiplicity distribution at BBC

stiming=48 psaverage
DTi [ps] = Ti - Tnorth/ southnumber of mips

Online Vertex selection in LL-1
sposition=6 mm

collision profile
events trigged
by BBC LL-1
collision events
at |Z|>150 cm

vertex position [cm]

ZDC Layout• ハドロンカロリメータ：RHIC の４実験に共通• 衝突型加速器では、spectator 全体を捕らえることは困難• 0度方向の中性子数 → 衝突の中心度の単ੴ関数ではな
いZDCからのデータ• 0度方向の運動エネルギー数• 金・金衝突→中性子の– 全体の1/3は Coulomb dissociation 反応

Centrality の決定（PHENIX）• BBC-ZDC プロット
– ZDCエネルギー（∝中性子数）は中心衝突と周辺衝突で減少– 総ハドロン断面積に対する割合→centralityの決定• Glauber model– Np、Ncoll を‫ב‬算Np と Ncoll• Np：関与ಊの核子数– 主に衝突係数によって決まる– Wounded nucleon 模型の wounded
nucleon 数• 一度しかカウントしない– p-p 衝突では Np = 2• Ncoll：核子の総衝突回数– 繰りೊしをԴす– 1個あたりの平均衝突回数：n ~Ncoll/(0.5Np)– ハードプロセスの場合、Ncoll が良い指標