physics objectives, performance requirements and …eppley/tof_review_2007/xdong_bnl_aug2_200… ·...

X. Dong / LBNL1

Aug. 2nd, 2007, DOE TOF Review, BNL

Physics objectives, Performance Requirements and Installation Plan

Xin DongLawrence Berkeley National Lab

Outline

➢ Physics Goals

➢ Performance Requirements for TOF

➢ Achievable Physics Objectives with TOF

➢ Near term BUR and TOF installation Plan

2X. Dong / LBNLAug. 2nd, 2007, DOE TOF Review, BNL

Long Term: medium thermal/chiral properties

U+U collisions jet fragments tagged by a hard direct

photon, a heavy flavor heavy quarkonium species Thermometers: dilepton, photon fundamental QCD symmetries

STAR Physics Goals

STAR white paper Nucl. Phys. A 757 (2005) 102

Near Term: thermalization evidence, phase boundary

v2 scaling for coalescence

jet quenching as parton energy loss energy scan to search for critical point heavy flavor yields and flow: color

screening and partonic collectivity

RHIC heavy ion programTo search QGP and measure its properties- a (locally) thermally equilibrated, deconfiedstate of matter

A hot, dense matter with partonic collectivity has been created.


Hadron PID

Lepton PID

v2 scaling for coalescence

jet quenching: parton energy loss

energy scan to search for critical

point

heavy flavor yields and flow: color

screening and partonic collectivity

U+U collisions

jet fragments tagged by a hard

direct photon, a heavy flavor

heavy quarkonium species

Thermometers: dilepton, photon

fundamental QCD symmetries

➢ PID spectra & v2

➢ PID correlations &

fluctuations

➢ Lepton spectra & v2

➢ Di-lepton pair

How to achieve


Performance requirements and Achievements

Requirements:

● Good timing resolution: < 100 ps in Au+Au collisions

● Small occupancy per channel: < 10-15%

● Rate capability: 200 Hz/cm2

● High efficiency: > 90%

Achievements from the prototypes:

• 85 ps timing resolution achieved in Au+Au.

• 3 cm x 6 cm, 120x32x6 read out, large granularity

• Rate capability: 500 Hz/cm2 (test beam, CERN)

• High efficiency: > 95%

Electron PID to low momentum~0.2 – intermediate p

T

Muon PID at low momentum~0.2 GeV/c


~80 (70)~82 (72)~20HF

~92 (73)~105 (92)~ 50200GeV Cu+Cu (ToT)Run V2005 ~94 (94)~125 (125)~ 8262GeV Cu+Cu (ToT)

~82 (71)~86 (74)~27FF/RFF

~86~96~40FF/RFF,

w/o E pVPD200GeV Au+Au

~89~105~5562GeV Au+Au

Run IV2004

~80~160~140200GeV p+p

~85~120~85200GeV d+AuRun III2003

TOFr (stop)

TOFr (overall)

pVPD

Time Resolution (ps)

Operation conditions

Performance of TOF prototypes


PID from TOFHadron PID

|1/β-1|<0.03

Electron PID

(Low mom) Muon PID

1) Hadrons: up to ~3-5 GeV/c with rdE/dx, reach ~12 GeV/c2) Electrons: ~0.2 - ~5GeV/c (or more)3) Muons: ~0.2 GeV/c

muon



➢ Freeze-out characteristics

➢ Hadronization scheme

➢ Energy loss

➢ PID correlations & fluctuations


➢ Di-lepton pair

Achievable Physics Topics with TOF


pT (GeV/c)0

~2 ~6

Jet quenchingpQCD at work, high density matter

Hydro at workstrong interactionscollectivity

NCQ scalingpartonic d.o.f

PID Spectra & v2

Freeze-out Hadronization scheme Jet energy loss

1) /K/p with limited pT reach

2) multi-stange particles and resonances have big statistics uncertainties

Freeze-out characteristics of multi-strange particles and resonances?Thermal/hard components in coalescence? Or scaling variables?

Before TOF

What will TOF do

1) more precision ,K,p measurements with full TOF2) much more efficient measurements for multi-strange baryons3) Add in resonance data points with help of TOF4) Calibrate (r)dE/dx to reach momentum beyond 10 GeV/c


(r)dE/dx calibration by TOF

Log10

(p)

Log 10

(dE

/dx )

TOF covers 0.2<pT<~5 GeV/c

dE/dx at relativistic (rdEdx) rise PID

covers ~3< pT< ~ 10 GeV/c

dE/dx calibration matters!!!


How TOF helps PID spectra & v2

STAR, PRL 97 (2006) 152301 STAR, PRC 75 (2007) 054906

Identified stable hadrons spectra and v2 measurements throughout whole p

T

Better yield, <pT> constrain

Baryon/meson difference in intermediate pT

B/M enhancement in Au+Au collisions Cronin Effect in d+Au collisionsSignificant improvement on multi-strange baryon and resonance measurements

pT (GeV/c)

v2

200 GeV

62 GeV


How TOF helps resonance reconstruction

Au+Au 200 GeV DataWith TPC only, the background shape of resonance invariant mass distributions is complicated mainly due to particle mis-identification.

K*

phi

From Data From simulation (proposal)

Yichun XuHaibin Zhang




➢ medium chemical/kinetic properties

➢ Un-statistical fluctuations


➢ Di-lepton pair



Jet associated particle correlationsLeadinghadrons

Medium

STAR PRL 95 (2005) 152301

away

near

Medium

mach cone

Au+Au central

Jason Ulery

• Away-side spectra approaching the bulk

• Chemically and/or thermally?

• Need PID 1<pT<4 GeV/c

3-Particle Correlations:

Conical emission • mach cone• Cerenkov radiation

PID correlations will allow us to study the medium properties: velocity of sound etc.


Large ( ) acceptance TOF extends PID correlation studies to include:

- flavor and baryon dependent hadronization dynamics

- semi-hard processes in medium

- distinguish energy/thermal vs pressure/flow structures

PID correlations

Jana Bielcikova


Energy scan: search for the critical end point

Full coverage of TOF detector is essential for the key measurements of particle ratios and <p

T> fluctuations etc.

K/ fluctuation 100K central events

Statistical error 10% 5%, with TOF

Systematics are more crucial: 1% mis-id will lead to 10% error

<p T> fluctuation 1) TOF can extend PID range to reduce uncertainty on e-by-e <p

T>

2) v2 could enhance apparent <pT> fluctuations w/o 2 coverage

Paul Sorensen





➢ Heavy flavor spectra: pQCD test & energy loss

mechanisms

➢ Heavy flavor v2: light flavor thermalization

➢ Di-lepton pair



Lepton spectra --- heavy quark spectra

Well constrain on the charm total yield and spectrum

Muon at low pT

electron at intermediate pT

Haibin Zhang, Yifei Zhang, Chen Zhong

Non-photonic electron suppression ~ hadron suppression

New energy loss mechanism, e.g.collisional energy loss should be included to account for the R

AA(e).


Lepton v2 --- heavy quark collectivity, light flavor thermalization

V. Greco et al., PLB 595 (2004) 202Heavy quark collectivityindicates light flavor thermalization

Electron approach:

Low pT (~1GeV/c) up to intermediate p

T

(5 GeV/c) measurement matters

Full TOF is dedicated in this direction!

Hadronic approach:

TOF+HFT will be a powerful combination





➢ Di-lepton pair

➢ Low mass: vector mesons in medium

➢ High mass: quarkonia



Di-lepton – vector mesons in medium

NA60 PRL 96 (2006) 162302

spectrum is consistent with broadening peak and no mass shift

TOF+HFT upgrades will make such a measurement feasible

Low mass di-lepton spectrum Vector meson in medium

Chiral symmetry restoration --- QGP signature


Di-lepton – J/ , (2S) ...

J/ production --- QGP signature

Color screening --- suppressionCoalescence --- enhancement

L.Grandchamp et al NPA 790 (2002) 415

Difference quarkonia states

PHENIX Acceptance: | |<0.35, =2* /2 STAR full TOF Acceptance: | |<0.9, =2*

pT (e)>1.5 GeV/c


TOF provides 2 and | |<0.9 coverage

Future upgrades will benefit from or enhance the capability of this detector

.e.g. Heavy Flavor Tracker (HFT) and TOF can be a powerful device for di-lepton and heavy flavor programs

Baseline detector for future upgrades

vector mesons; quarkonia

requiring hits to reject gamma conversion bg; by measuring e+e- from the

charm background

electron ID

charm total cross section, Nbin

dca distributionbackground free

muon ID

D0, D±, DS, ΛCprecise displaced vertexhadron ID

Physics measurementsHFTTOF


STAR BUR for Run 8, 9, 10

SVT, SSD outone sector of DAQ1000

DAQ1000 ?HFT protypes

DAQ1000

TOF: 5 trays

TOF: 65 trays

TOF: Full


TOF Installation Plan

Run 8Low material, one prototype of DAQ1000

TOF: 5 trays better match the DAQ1000 prototype sector

➢Electron spectra --- charm cross section and spectrum➢PID spectra --- “Cronin” effect

Run 9DAQ1000 in preparation, HFT prototypes

TOF: 65 trays by FY2008 Q4

Comprehensive measurements on PID spectra, v2, HBT, correlations

fluctuations in Au+Au 200 GeV collisions➢Di-lepton spectrum --- vector mesons in medium➢Direct D reconstruction with TOF+HFT --- one big step!

Run 10DAQ1000 ready

TOF: full coverage

Comprehensive measurements on PID spectra, v2, HBT, correlations,fluctuations at low energy colllisions➢Freeze-out characteristics➢Fluctuations --- search for critical end point


TOF Publications

✔ Identified particle elliptic flow in Au+Au 62 GeV, PRC 75 (2007) 054906✔ Identified baryon and meson distributions at large transverse momenta from

Au+Au collisions at 200 GeV, PRL 97 (2006) 152301✔ PID Cronin Effect in d+Au, PLB 616 (2005) 8.✔ Charm Cross section and spectra in p+p, d+Au, PRL 94 (2005) 062301.✔ Lots of conference proceedings, QM04, SQM04, QM05, SQM06, QM06 talks. ✔ 4 Ph. D theses.✔ 9 NIMA publications:

Nucl.Instrum.Meth.A538:243-248,2005 Nucl.Instrum.Meth.A533:60-64,2004 Nucl.Instrum.Meth.A492:344-350,2002 Nucl.Instrum.Meth.A508:181-184,2003 Nucl.Instrum.Meth.A478:176-179,2002Nucl.Instrum.Meth.A538:425-430,2005 Nucl.Instrum.Meth.A537:698-702,2005 Nucl.Instrum.Meth.A547:334-341,2006

Nucl.Instrum.Meth.A558:419,2006

➢ 2 Ph. D. theses

✔ More to come from prototype TOFrs 2 STAR papers in preparation

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