1Jim Thomas

Heavy Flavor Upgrades for STAR and PHENIXat RHIC

Jim ThomasLawrence Berkeley National Laboratory

With correspondence from Axel Drees, SUNYSB

Characterization of the QGP with Heavy QuarksPhysikzentrum, Bad Honnef

June 25-28, 2008

2Jim Thomas

Motivation: Heavy Flavor Energy Loss, v2,

Surprising results - - challenge our understanding of the energy loss mechanism - force us to re-think about the collisional energy loss - Requires direct measurements of C- and B-hadrons.

1) Non-photonicelectrons decayedfrom - charm andbeauty hadrons

2) At pT ≥ 6 GeV/c,

RAA(n.e.) ~ RAA(h±)

contradicts naïve

pQCD predictions STAR PRL, 98, 192301 (2007)

3Jim Thomas

Essential Ingredients

• Direct measurement of C and B hadrons requires– High Luminosity

– Excellent PID

– Excellent spacial resolution at the event vertex

– Large Acceptance, High Rate and High Efficiency Tracking

4Jim Thomas

News from RHIC: Stochastic Cooling Works

• Stochastic cooling works at RHIC– van der Meer method

• Measure at one point and send the control signal across cord of the ring

– First time accomplished with a bunched beam

• Longitudinal cooling of one ring gave a 20% increase in Luminosity

• Goals– Longitudinal cooling achieved in one

ring in 2007

– Longitudinal cooling in the other ring in 2008

– Transverse cooling in one ring in ‘09

– Transverse cool the other in ’10 or ’11

• Goals– 50 x 1026 (not 80 x 1026 )

• Electron cooling is out …Goal: Align the arrival times of the packets in the two beams

5Jim Thomas

STAR Solenoidal field

Large Solid Angle TrackingTPC’s, Si-Vertex Tracking

RICH, EM Cal, TOF

Measurements of Hadronic observables using a large acceptance spectrometer

PHENIXAxial Field

High Resolution & Rates2 Central Arms, 2 Forward Arms TEC, RICH, EM Cal, Si, TOF, -ID

Leptons, Photons, and Hadrons in selected solid angles (especially muons)

Heavy Flavor Upgrades for STAR and PHENIX

6Jim Thomas

STAR Upgrades

• Full Barrel MRPC TOF to improve PID

• DAQ Upgrade (order of magnitude increase in rate)

• High precision Heavy Flavor Tracker near the vertex

• Mid Rapidity Muon Trigger & Tracker

7Jim Thomas

The TOF Upgrade

• Multiplate RPC technology

• Beautiful electron ID

• 85 ps timing resolution after slewing corrections

• Each tray has 72 channels

• 90 full trays this year, with new electronics

• Funded by the DOE & CNSF

• Construction and install in 2008, and 2009

8Jim Thomas

Multi-Gap Resistive Plate Chamber TOF

State-of-art MRPC: -0.9 < < 0.9, 0 < < 2, r = 220cm 6 gaps, 3x6cm2 pad;

23K channels, 120 modules

Most significant collab. to date between USA & China in HEP detector research

1 tray in runs 2-75 trays in run 8

~75% in run 9100% in run 10

9Jim Thomas

Improving the “Time” in Time-of-Flight

Run8: 76M pp events TOF+TPX

• 2001: No timing devices (except Time Projection Chamber)

• 2002:

BBC (~1ns), ZDC (200ps)

• 2002-2008:

TOF tray+VPD (<100ps)

• 2008 TOF t: 81ps

10Jim Thomas

TPC FEE and DAQ Upgrade – DAQ 1000

• Faster, smaller, better … ( 10x )

• Current TPC FEE and DAQ limited to 100 Hz

• Replace TPC FEE with next generation CERN based chips … 1 kHz readout

• Make the FEE smaller to provide space for a forward tracking upgrade

• Further improvements by only archiving “associated” clusters – build on L3 algorithms … 5 kHz !

11Jim Thomas

• Four steps to an order of magnitude increase in data acquisition rates

• TPC FEE (BNL&LBL)

• TPC RDO (BNL)

• DAQ Transmitter (CERN)

• DAQ Receiver (CERN)

Dual CERN D-RORC with fibers on the board

Mezzanine DDL

Single D-RORC with 1 fiber mezzanine

ALICE FEE & DAQ

12Jim Thomas

The Heavy Flavor Tracker

4 layers of Si at mid rapidity, 2 PXL + 1 IST + 1 SSD (existing)

• A new detector

– 18 m silicon pixelsto yield 6 m space point resolution

– 436 M pixels– Strasbourg MAPS chips

• Direct Topological reconstruction of Charm

– Detect charm decays with small c, including D0 K

• New physics

– Charm collectivity and flow to test thermalization at RHIC

– Charm Energy Loss to test pQCD in a hot and dense medium at RHIC

CBM/MAPS: See related posters by C. Dritsa and Selim Seddiki

13Jim Thomas

Concept of HFT Layers

Graded Resolution from the Outside – In Resolution()

TPC pointing at the SSD ( 23 cm radius) ~ 1 mm

SSD pointing at IST ( 14 cm radius) ~ 400 m

IST pointing at Pixel-2 ( 8 cm radius) ~ 400 m

Pixel-2 pointing at Pixel-1 (2.5 cm radius) ~ 70 m

pixel-1 pointing at the vertex ~ 40 m

Purpose of intermediate layers to get increasing resolution power with increasing hit-densities, so the high resolution hits in the inner pixel’s can be found, assigned and displaced vertices determined.

SSDSSD

ISTIST

PIXELPIXEL

Numbers quoted above are for a Kaon at 750 MeV/cA pion at 1 GeV/c would achieve ~ 25 m at the vertex

14Jim Thomas

Inner layer

Outer layer

End view

ALICE style carbon support beams (green)

2.5 cm radius

8 cm radius

Since modified to increase Sensor Clearances

‘D-Tube Duct and Support

The Pixel Detector surrounds the vertex with Si

A thin detector using 50 m Si to finesse the limitations imposed by MCS

See Poster by J. Kapitan and J. Thomas

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D0 Reconstruction Efficiency

- Central Au+Au collisions: top 10% events. - The thin detector allows measurements down to pT ~ 0.5 GeV/c.

- Essential and unique!

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Charm Hadron v2

- 200 GeV Au+Au minimum biased collisions (500M events). - Charm collectivity drag/diffusion constants medium properties!

17Jim Thomas

Even the c

Simulations of the most challenging 3-body decays are encouragingso far

This capability, which will be provided uniquely at RHIC by the HFT, is crucial for determining whether the baryon/meson anomaly extends toheavy quark hadrons

18Jim Thomas

A more complete view of the STAR Upgrade plan

Run08 Run10Run09 Run12Run11 Run13 Run15Run14

FMS complete:d+Au and p+pdata from Run 8

DAQ1000 completeImmediate improvementof 300% in sampled luminosity for rare probes(e.g. jets in p+p)

Increase in Au+Au luminosity to50 x 1027 cm-2 sec-1

U+U available from EBISDOE investment ~ $7M

HFT partial implementation

HFT completefull topological PID forc, b mesonsDOE investment : upperlimit of range ~ $14.7M

Planned LHC1st heavy ion run

DOE investment ~ $400k

DOE investment ~ $1900k

TOF complete:

PID information for > 95% of kaons

and protons in the STAR acceptance

Clean e± ID down to 0.2 GeV/c

DOE investment ~ $4900k

Chinese investment ~ $2700k

FGT complete:

Accurate charge sign determination

for W’s, DOE investment ~ $1900k

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Nose Cone Calorimeter

Silicon VTX and FVTX

MuTrig Station 1

MuTrig Station 2

MuTrig Station 3

Future PHENIX Subsystems

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PHENIX Upgrade Plan for Heavy Flavor

– A vertex detector to detect displaced vertices from the decay of mesons containing charm or bottom quarks.

• A powerful addition to PHENIX because currently there is no tracking inside the magnetic field

– A forward calorimeter to provide photon+jet studies over a wide kinematic range.

– A muon trigger upgrade to preserve sensitivity at the highest projected RHIC luminosities.

21Jim Thomas

Pixel barrel (50 m x 425 m)Strip barrels (80 m x 3 cm)Endcap (extension) (75 m x 2.8 mm)

1 - 2% X0 per layer

barrel resolution < 50 m endcap resolution < 150 m

Silicon Vertex Tracker (VTX)

VTX barrel ||<1.2

Pixel Detectors at R ~ 2.5 & 5 cm Strip Detectors at R ~ 10 & 14 cm

Endcap 1.2<||<2.7

22Jim Thomas

• VTX characteristics– 2 inner pixel layers (50x425 m2) to measure DCA

radial position at 2.5 and 5 cm with ~ 1.2% X/X0

– 2 out strip-pixel (80x1000 m2) for p measurement and tracking

at 10 and 14 cm with ~ 3.% X/X0

• DCA resolution: given mostly by inner layer– Sufficient single hit resolution (~15 m)

– Close to beam axis to reduce effect of multiple scattering

||<1.2 ~ 2|z|cm

PHENIX Barrel VerTeX Detector

%10~15.0~p

TmBdl p

2

212

212

21

22

22

212

sin)(

r

rr

rrmsDCA

detector ~ 30 m ms ~ 30 m

D

e

beam

X

DCA, distance of closest approach

23Jim Thomas

Expected RAA(ce) and RAA(be) with VTX

Decisive measurement of RAA for both c and b

PHENIX VXT ~ 2 nb-1

RHIC II increases statistics by factor >10

24Jim Thomas

Expected v2(be) and v2(ce) with VTX

Decisive measurement of v2 for both c and b

PHENIX VXT ~2 nb-1

RHIC II increases statistics by factor >10

25Jim Thomas

Forward Upgrade Components

• Endcap Vertex Tracker – silicon pixel detectors

• Nosecone EM Calorimeter– W-silicon (42 X/X0)

– shower max

– tail catcherCerenkov

NoseconeCalorimeter

U-Tracker

Muon fromhadron decays

Muon from W

TailCatcher

D-Tracker

Silicon endcap

• Muon trigger– U-tracker (MuTr or new)

– D-tracker (timing with RPC’s)

– Cerenkov

charm/beauty & jets: displaced vertex

-jet,W,c: calorimeter

W and quarkonium: improved -trigger rejection

26Jim Thomas

• FVTX characteristics– Cover both muon arms with 4 pixelpad layers/endcap– 2 coverage in azimuth and 1.2 < | | < 2.4– ≥ 3 space points / track – DCA resolution < 200 µm at 5 GeV – Maximum Radiation Length < 2.4%– Fully integrated mechanical design with VTX

PHENIX Forward VerTeX Detector

27Jim Thomas

Tracking and DCA Resolution with the FVTX

prompt

Muon acceptanceD

CA

r-z

res

olut

ion

(cm

)

Momentum (GeV)

General performance– 3 or more planes hit per track

– Central Au+Au occupancy < 2.8%

– Good matching between FVTX and muon tracker

– Sufficient DCA resolution (<200 m) to separate prompt, heavy quark, and -K decays.

28Jim Thomas

Charmonium Spectroscopy with the FVTX

Measurement of ‘ in central Au-Au collisions

• Remove -K decaysBackground rejection factor 4

• Improve mass resolution:170 MeV 100 MeV

Au-Au

p-p

29Jim Thomas

Nose-Cone Calorimeter

• Replace existing PHENIX “nose-cones” (hadronic absorbers for muon arms) with Si-W calorimeter (Tungsten with Si readout)

• Major increase in acceptance forphoton+jet studies

• Prototype silicon wafer – 3 different versions of

“stri-pixel” detectors for the pre-shower and shower max layers

• Extended physics reach – q/q polarizations

via spin dependent W-production

– Small x-physics in d-A

– Extended A-A program

– high pT phenomena: 0 and -jet

30Jim Thomas

W-silicon sampling calorimeter

EM1 EM2 HAD

NCC characteristics (DOE funding FY08)40 cm from interaction point, 20 cm depth2 coverage in azimuth and 0.9 < < 3.0W-silicon sampling calorimeter

1.4 cm Moliere radius

42 X0 and 1.6 abs

Lateral segmentation 1.5x1.5 cm2

3 longitudinal segments

2x2 tracking layers with 500 m strips separation for overlapping showers

%1/

%23

GeVEEE

PS tracking layers

Main objective: direct photon and measurements

PHENIX Forward EM Calorimeter (NCC)

31Jim Thomas

η=1-1.5

η=1.5-2

subtracted spectrum

subtracted spectrum

mμμγ-mμμ (GeV/c2)

Central Cu+Cu collisions

S/B ~10%

S/B~2%

γ

μμ

J/ in muon arm, in NCCConditional acceptance 58% if J/ detected

Determine invariant mass and subtract combinatorial background

Proof of principle MC simulationpp should work, CuCu probable

Full MC simulation in progress

/JC

Charmonium spectroscopy with the NCC

32Jim Thomas

RHIC 2 nb-1

With NCC/FVTX

RHIC 2 nb-1

W/O NCC/FVTX

RHIC 20 nb-1

With NCC/FVTX

Quarkonium Spectroscopy w/ Forward Upgrades

’

cJ

S)

S)

Reference model based on consecutive melting without regeneration(Note: This results in small ’, C yields, other models like regeneration model will give similar yields for J/, ’, C !)

33Jim Thomas

Timeline of PHENIX upgrades2008 2012

RHIC

2010

Inner pixel layers

cooling era for “RHIC II”

2014

Outer strip layers

Construction

VTX

Large acceptance tracking ||<1.2

Displaced vertex at mid rapidity

FVTX Displaced vertex at forward y

Physics

NCC Forward photon detection

34Jim Thomas

Summary

• The study of heavy flavor production provides key information to understand the properties of quark matter

• The scientific program at RHIC is rich and diverse– Rare probes and high pt phenomena are a rich source of new discoveries

– Strangeness, Charm, and Beauty are likely to yield even more new discoveries

– We have promising spin program that is making critical and unique measurements

• The scientific program at RHIC will keep getting better– The performance of the accelerator is improving each due to a carefully

planned set of upgrades.

– STAR will explore charm, beauty, and higher pt spectra at ever increasing data acquisition rates.

– PHENIX will add sophisticated PID and tracking near the vertex.

• These upgrades will yield exciting new physics results

Guaranteed

35Jim Thomas

Backup Slides and even more information …

36Jim Thomas

Key Experimental Probes of Quark Matter

• Rutherford experiment atom discovery of nucleus

SLAC electron scattering e proton discovery of quarks

penetrating beam(jets or heavy particles)

absorption or scattering pattern

QGP

Nature provides penetrating beams or “hard probes”and the QGP in A-A collisions

Penetrating beams created by parton scattering before QGP is formed High transverse momentum particles jetsHeavy particles open and hidden charm or bottom Calibrated probes calculable in pQCD

Probe QGP created in A-A collisions as transient state after ~ 1 fm

37Jim Thomas

Hard Probes: Open Heavy FlavorStatus

– Calibrated probe?

• pQCD under predicts cross section by factor 2-5

• Charm follows binary scaling

– Strong medium effects

• Significant charm suppression & v2

• Upper bound on viscosity ?

• Bottom potentially suppressed

– Open issues:

• Limited agreement with energy loss calculations!

• What is the energy loss mechanism?

• Are there medium effects on b-quarks?

Electrons from c/b hadron decays

Answers require direct observation of charm and beauty

Progress limited by: no b-c separation decay vertex with silicon vertex detectors

statistics (BJ/) increase luminosity

38Jim Thomas

Hard Probes: Quarkonium

Status– J/ production is suppressed

• Large suppression

• Similar at RHIC and SPS

• Larger at forward rapidity

• Ruled out co-mover and melting scenarios

• Consistent with melting J/ followed by regeneration

– Open issues:

• Are quarkonia states screened and regenerated?

• What is the regeneration (hadronization) mechanism?

• Can we extract a screening length from data?

• Recent Lattice QCD developments: Quarkonium states do not melt at TC

J/

Deconfinement Color screening

Answers require “quarkconium” spectroscopy

Progress limited by:statistics (J/, Y) increase

luminosity statistical significance (’) mass resolutionphoton detection (C) forward calorimeter

39Jim Thomas

Detection of decay vertexwill allow a clean identification of charm and bottom decays

m cGeV m

D0 1865 125 D± 1869 317

B0 5279 464 B± 5279 496

Direct Observation of Open Charm and Beauty

D Au

e,

AuD

X

J/

B

X

K

ee

Heavy flavor detection with VTX and FVTX in PHENIX:

• Beauty and low pT charm via displaced e and/or -2.7<<-1.2 ,|<0.35 , 2.7<<1.2 • Beauty through displaced J/ ee () -2.7<<-1.2 ,|<0.35 , 2.7<<1.2 • High pT charm through D K |<0.35

40Jim Thomas

Heavy flavor detection with the VTX

• Results of simulation of Au+Au collision.

• After a 2 cut, D0 decays clearly separated from bulk of hadrons

D

e

beam

X

DCA, distance of closest approach

3<pT<4 GeV/c

~ 40m

41Jim Thomas

D/B Monte Carlo Simulations with FVTX

42Jim Thomas

Heavy Ion RAA with FVTX

• Mechanisms for heavy/light quark suppression poorly understood

• Clear distinction among models, e.g. I.Vitev’s radiative, collisional and dissociative energy loss predictions

43Jim Thomas

Heavy Ion RAA with FVTX (II)

Statistical separation of charm and bottom with DCA cuts

44Jim Thomas

Future Quarkonium Spectroscopy with PHENIX

• RHIC II luminosity upgrade– Electron cooling and stochastic cooling

– Increase integrated luminosity 2 nb-1 to 20 nb-1 per run

precision measurements of RAA and v2 for J/

• FVTX: Track muons to primary vertex, – reject decay background (K)

– Improved mass resolution clean and significant ‘

– Background Rejection Upsilon at mid rapidity

– Rapidity dependence J/, ’, and

• FVTX: Detected displaced vertex for charm and beauty decays– Precise charm and beauty reference

• NCC: add photon measurement at forward rapidity– Measurement of C →J/ γ possible

45Jim Thomas

Quarkonium Spectroscopy at RHIC II

J/ measurements will reach high precision

46Jim Thomas

PHENIX Central Arm Upgrades

• Enhanced Particle ID– TRD (east) – Aerogel/TOF (west)

• Vertex Spectrometer– flexible magnetic field– VTX: silicon barrel vertex tracker– HBD

High pT phenomena: , K, p separation to 10 GeV/c

charm/beauty: TRD e/ above 5 GeV/c

charm/beauty: displaced vertex

e+e- continuum: Dalitz rejection

HBD

VTXHBDVTX

TRD

Aerogel/TOF

47Jim Thomas

Improving STAR’s muon capabilities

Simulations

Install a large area mid-rapidity muon telescope. Allows detection of:

Di-muon pairs:Quarkonia, QGP thermal radiation,Drell-Yan

Single muons : Heavy flavor semi-leptonic decays

Advantage over e:No conversion, Less Dalitz decay, Less radiative losses to detector material

+-

e+e-

48Jim Thomas

The Muon Trigger Detector concept

48

Prototype Installed in RUN 7-8

Long MRPC Technology with double-end readout. 20x larger than ToF modules

HV: 6.3 KV

gas: 95% Freon + 5% Isobutane

10 gas gaps: 250 m

time resolution: ~60 ps

spatial resolution: ~1cm

Place scintillators outside magnet covering iron bars

Muon efficiency: 35-45%Pion efficiency: 0.5-1% Muon-to-Hadron Enhancement Factor: 100-1000 (including track matching, ToF, dE/dx)

49Jim Thomas

Hadron Rejection and Muon Trigger

Iron bars

•Muon penetrates iron barsOther particles are stopped

•Good Time Resolution (60ps)rejects background (>100)

•1 hit per 5 head-on Au+AuDimuon trigger (>25)

•Large coverage: diameter of 7 meters

J/ trigger, separate +- states

Full Hijing AuAu event