First Results from the

experiment at RHIC, part 1

Achim Franz

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RelativisticHeavyIonCollider located at Brookhaven National Laboratory

Long Island,

New York

Where is RHIC

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Search for and study of quark gluon plasmaquark gluon plasma in relativistic

heavy ion collisions @ s = 200 A GeV/c.

Study of spin physicsspin physics in polarized p - p interactions

@ 50 s 500 GeV/c.

Goals of the Relativistic Heavy Ion Collider

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The Quark Gluon Plasma, a phase transition

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Where is PHENIX

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Brazil: Sao PaoloCanada: McGillChina: Academia Sinica, CIAEFrance: SUBATECHGermany: MünsterIndia: BARC, Banaras Hindu University Israel: Weizmann InstituteJapan: CNS, Hiroshima, KEK, Kyoto,

Nagasaki, RIKEN, TITech., Tokyo, Tsukuba, Waseda

Korea: Korea, Myongji, YonseiRussia: IHEP Protvino, JINR Dubna,

Kurchatov, PNPI, St. Petersburg STUSweden: Lund

U.S. National Labs: BNL, LANL, LLNL, ORNLU.S. Universities: Abilene Christian,

Alabama-Huntsville, California-Riverside, Columbia, Florida State, Georgia State, Iowa State, New Mexico, New Mexico State, SUNY-Stony Book, Tennessee, Vanderbilt

Collaboration

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Collaboration Dec. 99

me

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P P ioneeringioneering

H H igh igh

E E nergy nergy

N N uclear uclear

I I on on

e e X X perimentperiment

Search for and study of quark gluon quark gluon plasmaplasma in relativistic heavy ion collisions @ s = 200 A GeV/c.– Focus on lepton and photon signatureslepton and photon signatures

to probe early time in collision (but some hadrons signatures too)

– High rate, sophisticated triggers rare and high pT processes

What is PHENIX

Study of spin physicsspin physics in polarized p - p interactions

@ 50 s 500 GeV/c.–Spin of the proton; structure functions (e.g., G)

–Parity violating asymmetries (e.g., in W production) as a probe of new physics

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What does PHENIX doMC

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• A polarized hadron collider is uniquely suited to some spin measurements: G (gluon fraction of proton spin) via

• Direct photons• High pT pions• J/ production

(sea-quark fraction of proton spin) via

• W+/W- production• Polarized Drell-Yan

• RHIC has been equipped To provide polarized beams of protons To make spin measurements of same in

PHENIX, STAR and specialized experiments like pp2pp.

du ,

What does PHENIX do

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Single Snake Operation

• Injection with Spin Flipped : Asymmetry Flipped

• Adiabatically Snake on: horizontal polarization

• Accelerate equivalent to 180o rotation: 180o rotated

Successful Spin commissioning

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• 3 “global” detectors • 2 “forward”

spectrometers

• 3 magnet

What is PHENIX• 2 “central”

spectrometers

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BB Beam Beam CounterMVD Multiplicity Vertex DetectorDC Drift ChamberPCx Pad ChambersRICH Ring Image Cherenkov counterTEC Time Expansion ChamberTOF Time Of Flight detectorPbSc Lead-Scintillator Cal.PbGl Lead-Glas Calorimeter

Central magnet: ~9m high, 500t∫ B dl = 0.78Tm @ 90°

Detectors installed/active this year

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Detectors installed this year

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08.08.96 History

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02.20.98

History

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01.29.99

History

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06.30.99

History

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11.30.99

History

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03.21.00

History

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09.05.00

History

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History

10.25.00

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How to Characterize a Collision

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IR

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• Common to all experiments (Luminosity)

• measure neutral energy within a 2 mrad cone about the beam direction, centrality trigger

Zero Degree Calorimeter

Single neutron peak

Coincidencewith BBC

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BBC Vertex resolution

2x64 Quartz Cherenkov counter wrapped around the beam pipe start timing (40ps), vertex location multiplicity

Beam Beam Counter

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Trigger Both the ZDC and BBC are used to make a decision if a collision

has occurred, plus event type selection, all in a few hundred ns.

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DataAQuisition

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First Event

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• RHIC machine studies and experiment commissioning: March thru June

• First collisions: June 15, 2000 at about half beam energy

• Initial operation (June) with 6+6 bunches yielded 500,000 PHENIX collisions.

• Final operation (July-September) with 55+55 bunches yielded nearly 45,000,000 PHENIX collisions!

• About five million events were put on tape, ~ 3TB of data !

Data

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02 04 06 08 0 100 120 140 160 180 200 2200

20

40

60

80

100

120

140

160

180

200 PC3 (east) vs PC1 (east)

05 0 100 150 200 2500

20

40

60

80

100

nTOF vs PC1 (east)PC1 (east) vs DC

Correlations

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Central arm, side viewDetail of South-West Side

PID with tracking and RICH

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Note: * No slewing correction * Applied track association cut : r = 5 cm * No acceptance/efficiency/decay corrections

TOF Particle Identification

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So far for the first part;continue with John. G. Lajoie

Iowa State University