Searching for a new form of matter on Long Island Steve Manly, University of Rochester

June 5, 2002REU Seminar, University of Rochester 1

Searching for a new form of matter on Long IslandSteve Manly, University of Rochester

12 June, 2000: 1st Collisions @ s = 56 AGeV

24 June, 2000: 1st Collisions @ s = 130 AGeV

July 2001: 1st Collisions @ s = 200 AGeV


Places to learn more:Particle and nuclear physics links

http://pdg.lbl.gov

http://particleadventure.org

http://www.aps.org/dpf/education.html

http://www.slac.stanford.edu/gen/edu/aboutslac.html

http://www.bnl.gov/bnlweb/sciindex.html

http://www.rhic.bnl.gov/

http://welcome.cern.ch/welcome/gateway.html

http://www.fnal.gov/

http://www.er.doe.gov/production/henp/np/index.html


The starting point

What is matter?


Stuff

Lump

A little bit

A molecule

An atom



Before


How do they interact?

After


What forces exist in nature?

What is a force?

How do forces change with energy or temperature?

How has the universe evolved?


The fundamental nature of forces: virtual particles

Et h Heisenberg E = mc2 Einstein

e-


Force Source Range StrengthGravitation mass infinite 10-39

Electromagnetism Electriccharge

infinite 10-2

Strong nuclear Colorcharge

10-15 m 1

Weak nuclear Weakcharge

10-18 m 10-5


quarks leptonsGauge bosons

u c t

d s b

e

e

W, Z, , g, Gg

Hadrons

Baryons qqq qq mesons

p = uud

n = udd

K = us or us

= ud or ud

Strong interaction

nuclei

e

atomsElectromagnetic

interaction


Quantum Chromodynamics - QCD

Gauge field carries the charge

q q

distance

energy density, temperature

rela

tive

stre

ngth

asymptotic freedom

qq qq

confinement

q q


Why do we believe QCD is a good description of the strong interaction?

Deep inelastic scattering: There are quarks.



No direct observation of quarks: confinement


ee

qqhadronseeR

)(




Event shapes



Measure the coupling




Relativistic heavy ions

•Two concentric superconducting magnet rings, 3.8 km circum.

•A-A (up to Au), p-A, p-p collisions, eventual polarized protons

•Funded by U.S. Dept. of Energy $616 million

•Construction began Jan. 1991, first collisions June 2000

•Annual operating cost $100 million

•Reached 10% of design luminosity in 2000 (1st physics run)!!

•AGS: fixed target, 4.8 GeV/nucleon pair

•SPS: fixed target, 17 GeV/nucleon pair

•RHIC: collider, 200 GeV/nucleon pair

•LHC: collider, 5.4 TeV/nucleon pair



The goalsEstablish/characterize the expected QCD deconfinement phase transition

quarks+gluons hadrons

Establish/characterize changes in the QCD vacuum at high energies: chiral symmetry restoration and/or disoriented chiral condensates

Polarized proton physics


Coin of the realm

Centrality

Energy density, number of participants, multiplicity, zero degree energy (nuclear fragments)

Temperature <Pt>

Entropy, energy density

Chemical potential species yields

Thermal equilibration

d

dE

d

dn tor

peripheral

central

Vary conditions by varying species, energy and centrality


Signatures/observables

Energy density or number of participants

Measured value

•Strange particle enhancement and particle yields

•Temperature

•J/ and ’ production/suppression

•Vector meson masses and widths

•identical particle quantum correlations

•DCC - isospin fluctuations

•Flow of particles/energy (azimuthal asymmetries)

•jet quenching

Each variable has different experimental systematics and model dependences on extraction and interpretation

MUST CORRELATE VARIABLES



Event in STAR


Isometric of PHENIX Detector


Perspective View of SpectrometerFrom F.Videbœk


The PHOBOS Detector (2001)

Ring Counters

Time of Flight

Spectrometer

• 4 Multiplicity Array

- Octagon, Vertex & Ring Counters• Mid-rapidity Spectrometer• TOF wall for high-momentum PID• Triggering

- Scintillator Paddles Counters- Zero Degree Calorimeter (ZDC)

Vertex

Octagon

ZDC

z

yx

Paddle Trigger Counter

Cerenkov

137000 silicon pad readout channels

1m


Central Part of the Detector

(not to scale)

0.5m


Silicon detector scheme

+HV

p+ Implant

n+

Polysilicon Drain Resistor

Dielectric 1

bias bussignal lines

Dielectric 2 vias metal 1metal 1metal 2metal 2

Primary detector technology

Silicon strips and pads300 microns



ARGONNE NATIONAL LABORATORY

Birger Back, Alan Wuosmaa

BROOKHAVEN NATIONAL LABORATORY

Mark Baker, Donald Barton, Alan Carroll, Joel Corbo, Nigel George, Stephen Gushue, Dale Hicks, Burt Holzman, Robert Pak, Marc Rafelski, Louis Remsberg, Peter Steinberg, Andrei Sukhanov

INSTITUTE OF NUCLEAR PHYSICS, KRAKOW

Andrzej Budzanowski, Roman Holynski, Jerzy Michalowski, Andrzej Olszewski, Pawel Sawicki , Marek Stodulski, Adam Trzupek, Barbara Wosiek, Krzysztof Wozniak

MASSACHUSETTS INSTITUTE OF TECHNOLOGY

Wit Busza, Patrick Decowski, Kristjan Gulbrandsen, Conor Henderson, Jay Kane , Judith Katzy, Piotr Kulinich, Johannes Muelmenstaedt, Heinz Pernegger, Michel Rbeiz, Corey Reed, Christof Roland, Gunther Roland,

Leslie Rosenberg, Pradeep Sarin, Stephen Steadman, George Stephans, Gerrit van Nieuwenhuizen, Carla Vale, Robin Verdier, Bernard Wadsworth, Bolek Wyslouch

NATIONAL CENTRAL UNIVERSITY, TAIWAN

Chia Ming Kuo, Willis Lin, JawLuen Tang

UNIVERSITY OF ROCHESTER

Joshua Hamblen, Erik Johnson, Nazim Khan, Steven Manly, Inkyu Park, Wojtek Skulski, Ray Teng, Frank Wolfs

UNIVERSITY OF ILLINOIS AT CHICAGO

Russell Betts, Edmundo Garcia, Clive Halliwell, David Hofman, Richard Hollis, Aneta Iordanova, Wojtek Kucewicz, Don McLeod, Rachid Nouicer, Michael Reuter, Joe, Sagerer

UNIVERSITY OF MARYLAND

Abigail Bickley, Richard Bindel, Alice Mignerey

The Phobos Collaboration


• 6% cut on paddle signal

gives ~6% events with highest Npart

Measuring Centrality in PHOBOS

DATA

Simulation

Npart

Paddle Signal

Npart

Au Au

x

z


Phobos and global event-by-event variables

RingsN Octagon RingsP

Small acceptance tracking capabilityLarge acceptancemultiplicity detector



1m2m

5m

0 1 2 3 4 512345

coverage for vtx at z=0

Large acceptance multiplicity detector



1m2m

5m

0 +3-3 +5.5-5.5

Study patterns/asymmetries of hits and energy deposition


-1.1m

1.1m2.3m

-2.3m

5.0m

-5.0m

• || < 5.5 (, 0 (

Interaction Point

Octagon, vertex and ring detectors

Ring counter


-1.1m

1.1m2.3m

-2.3m

5.0m

-5.0m

• || < 5.5 (, 0 (


octagon

vertex detector


-1.1m

1.1m2.3m

-2.3m

5.0m

-5.0m

• || < 5.5 (, 0 (


vertex detector


b (reaction plane)

Elliptic flow

dN/d(R ) = N0 (1 + 2V1cos (R) + 2V2cos (2(R) + ... )

Determine to what extent is the initial state spatial/momentum anisotropy preserved in the final state.

• Sensitive to the initial equation of state and the degree of thermalization.

• Affects other variables, such as HBT and spectra.


Reaction Plane


Elliptic Flow

-2.0 < < -0.1

RingPRingNSubE (a) SubE (b)

na n

b

0.1 < < 2.0

•Subevent technique: correlate reaction plane in one part of detector to asymmetry in hit pattern in other part of detector

•Correct for imperfect reaction plane resolution

(formalism given in A. M. Poskanzer,S. A. Voloshin Phys. Rev. C 58, 1671)


Determining the collision point

High Resolution

extrapolate spectrometer tracks

Low Resolution

octagon hit density peaks at vertex z position

Other techniques (vertex detector hits, timing) not used in flow analysis


Event Selection

Rings PRings N Octagon

z

Spec holes

Vtx holes


Event SelectionSpec vertex available


z

Acceptance/symmetry issues where spec vtx efficiency is highest


Event Selection


z

-30 cm-38 cm

Symoct analysis:•Lower statistics•symmetric detector


Event Selection


z

+10 cm-10 cm

Mid-z analysis:•higher statistics•must deal with symmetry and acceptance issues•coming soon


In all calculations, hits are weighted bywi = (wi

a)(OCC(,))

iii

iii

a

w

w

)2cos(

)2sin(

tan2

1 12

Reaction plane determined in subevent ‘a’

)(2cos 22baR Resolution determined from

two subevents in a given event

Average done over all events in a given centrality bin


Phase space weighting --- wia

For each annulus in eta, weight hits by thenormalized, inverse integrated hit density


Reaction plane angle (radians)

Events/bin

Flatness of reaction plane (130 GeV data, symoct analysis)


Nasty little details - signal suppression

hit saturation/occupancy

Sensitivity to flow reduced as occupancy grows

Can parametrize signal reduction as function of occupancy

measure occupancy from energy or number of occupied and unoccupied pads assuming Poisson statistics


,1

),(

eOCC

Where

unocc

occ

N

N1ln

Find tracks per hit pad [OCC(,)] in segments of the detectorCannot integrate over as done for dN/d analysis



Non-flow background

z

flow signal



Non-flow background

z

Non-flow background



Non-flow background

z

flow signal

+ non-flow background

Dilutes the flow signal

•Estimate from MC and correct

•Remove Background Or both


Background suppression

Works well in Octagon

dE

(keV)

cosh

Background!

Techniques do not work in rings because angle of incidence is ~90

Beampipe

Detector

Demand energy deposition be consistent with angle

For 1<||<2, demand no isolated hits


Nasty little details - effect of magnet asymmetry

Similar effect in

Field dependent shift in


R

wiobs 22

2cosv

Resolution and occupancy corrected, all data-driven

Average over hits in an eventAverage over all events in appropriate centrality oreta bin


Large V2 Signal compared to lower energy, closer to hydrodynamic limit implying substantial thermalization

Centrality Dependence


Averaged over centrality

V2 drops for || > 1.5

V2 vs

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Searching for a new form of matter on Long Island Steve Manly, University of Rochester