Highlights of STAR Mid-Term Upgrades

STAR Upgrade Concepts

The RHIC facility – Evolution and futureEquation of state and the QCD phase diagram 1. Dynamical considerations A. Evidence for Thermalization

B. Thermalization TimescaleC. Thermalization MechanismsD. Viscosity

2. Equation of StateA. Measurements of Energy DensityB. Initial Temperature: How to measure it?

3. Exploring the QCD Phase DiagramA. Search for the QCD critical pointB. Medium effects on properties of hadrons

4. Deconfinement 5. Hadronization Gluon Saturation Exploring the spin structure of the nucleon at RHIC-II

Summary of the RHIC II Science Working Groups

STAR upgrade concepts

1. Preserve large acceptance2. Extend forward coverage 3. Particle Identification4. Precise Secondary Vertex5. Leptons/photons6. Faster DAQ7. Cost-effective, do it best

Upgrades to keep the discoveries rolling …• Forward Meson Spectrometer

– Gluon density distributions, saturation effects, and transverse spin

• DAQ1000 Upgrade– order of magnitude increase in rate (1KHz)– extra livetime opens the door to rare physics

• Full Barrel MRPC TOF– extended hadron identification at intermediate pT

– Lepton identification at low momentum

• Heavy Flavor Tracker

– high precision Heavy Flavor Tracker near the vertex

– opens the door to direct topological ID of Charm & Beauty

• Forward GEM Tracker

– end cap tracker for W sign determination

• Muon Telescope (BNL LDRD)• Forward Reaction Plane Detector• A Crystal Calorimeter for low E photons - HBT

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DAQ1000 Concept

• Zero suppression done at RB in the DAQ room

Full ~460,000 10 bit words transferred over each fiber.

10ms readout time every event. 100hz max rate.

• No event buffering on FEE

TPC dead during digitization & readout time.

1% dead / hz readout.

• Zero suppression done at FEE in the Altro

Event transfer 16-20 times smaller

Combined with slightly faster link, will allow rates ~1000-5000 hz

• Event Buffering on FEE

TPC stays alive as long as throughput is < max

Deadtime only caused by TPC Drift..

0.004% dead / hz readout

Existing TPC DAQ 1000

TPC FEE and DAQ Upgrade – DAQ 1000

blue pen

PASAsALTROs

brown rulerFPGAs

Fiber Out via SIU

FEE In

• Faster, smaller, better … ( 10x )

• Current TPC FEE and DAQ limited to 100 Hz

• 1 kHz central3 kHz minBias5 kHz future

• Replace TPC FEE with next generation CERN ALTRO, PASA

• Make the FEE smaller and creates less heat

• No dead time (well, almost …)

• More efficient for rare physics probes

MRPC Time-of-Flight

collaboration between the United States (DOE) and China (NNSFC, MoST, MoE)in high-energy particle physics detector research

State-of-art Multi-gap Resistive Plate Chamber:6 gap, 3x6cm2 pad; 23,000 channels, -0.9<<0.9, 0<<2, r=220cm

Physics with TOF

• Generic detector for PID (hadron and lepton) at mid-rapidity

• Identified proton/pion at high pT• Jet-related spectra and correlation• Fluctuation K/, p/ (Critical point)• Resonances (,,J/) hadronic and dilepton

decay channels• Open Charm (daughter PID)

Leadinghadrons

Medium

Jet dissipates energyPRL95(2005)152301

130 GeV Au+Au: STAR, PRC72(2006)064907

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STAR Forward Meson Spectrometer (FMS)

Detectors are stacked on the west platform in two movable halves. This view is of the south FMS half, as seen through the retracted west poletip.

Schematic of the FMS as seen from the interaction point. The small-cell inner calorimeter has 476 detectors and the large cell outer calorimeter has 788 detectors.

FMS Highlighted Objectives [hep-ex/0502040]

1. A d(p)+Aud(p)+Au+X+X measurement of the parton model gluon density distributions xg(x) in gold gold nucleinuclei for 0.001< 0.001< xx <0.1 <0.1. For 0.01<x<0.1, this measurement tests the universality of the gluon distribution.

2. Characterization of correlated pion cross sections as a function of Q2 (pT

2) to search for the onset of gluon saturation effects associated with macroscopic macroscopic gluon fields. gluon fields. (again d-Au)(again d-Au)

3. Measurements with transversely polarized transversely polarized protonsprotons that are expected to resolve the origin of resolve the origin of the large transverse spin asymmetriesthe large transverse spin asymmetries in reactions for forward forward production. production. (polarized (polarized pp)pp)

DOE milestone

FMS for d-Au saturation physicsFMS for d-Au saturation physicsp+p and d+Au ++X correlations with forward

hep-ex/0502040p+p in PYTHIA d+Au in HIJING

Conventional shadowing will change yield, but not angular correlation. Saturation will change yield and modify the angular correlation.

Sensitive down to xg ~ 10-3 in pQCD scenario; few x 10-4 in CGC scenario.

The Heavy Flavor Tracker

The PXL: 2 layers of Si at mid rapidity

Mid-rapidity Pointing Devices: IST + SSD

• The PXL is a new detector– 30 m silicon pixels

to yield 10 m space point resolution

• 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

– C & B Energy Loss to test pQCD in a hot and dense medium at RHIC

• The proposed Tracking Upgrades include

– PXL (2 layers)

– IST (2 layers)

– SSD (existing layer)

= PXL + IST + SSD

GEANT View of the Heavy Flavor Tracker

Charmed hadron Simulation Results Detector radii:

TOFTPC (60 cm)SSD (23 cm)IST2 (17 cm)IST1 (12 cm)PXL2 (7.0 cm)PXL1 (2.5 cm)

• The Monte Carlo reconstructed yield of D0 is very good– A complex pT dependence … however efficiency vs pT is the FOM

– D0 decay length is ~ 125 m– IST helps reduce search radius on HFT and thus reduces ghost track inefficiencies as well as

allows more relaxed kinematic cuts on the data– Kinematic cuts in the software are a significant contributor to the total efficiency

Accessing Quark Helicities with W Bosons

• Maximal Party-Violation in Weak Interaction: Inherent spin sensitivity of W production

• Charge of the Boson provides flavor tagging:

d u W

d u W

RHIC: 500 GeV CME in p+p collisions the quark is usually a valence quark (large x)

Forward GEM Tracker (FGT)

• 6 triple-GEM disks covering 1 < < 2

outer radius ~ 40 cm

inner radius varies with z position

• charge sign reconstruction probability of W above 80% for 30 GeV pT over the full

acceptance of the EEMC for the full vertex spread ( > 90% out to η= 1.8)

Probability to get the correct charge sign

GEM Prototypes meet Requirements

3 layers: 10x10cm2

120 GeV beam resolution x ~ 51 µm, y ~ 63 µm

32 GeV beam resolution x ~ 66 µm, y ~ 78 µm

Efficiency plateau of ~ 90% (includes dead, noisy areas)

Detector electronics based on APV25S1 front-end chip (developed for CMS)

TechEtch foils

FNAL T963 (May 2-15, 2007)

Schedule

Beam Use Request strongly coupled with detector upgrades to optimize the maximum physics output

References

• STAR Decadal Plan• STAR (Tim Hallman) 2007 Annual DOE Review • The STAR Detector Upgrade Plan (Jim Thomas) 2007 RHIC&A

GS Annual Users Meeting• Overview of STAR Upgrades (Zhangbu Xu) 2006 RHIC&AGS A

nnual Users Meeting• STAR Upgrade Plans and R&D (Richard Majka)• STAR Beam Use Request (BUR2006)• Forward Meson Spectrometer (FMS)• Time-of-Flight Proposal• DAQ1000• Heavy Flavor Tracker (HFT) • Forward GEM Tracker (FGT)• STAR Future Physics and Upgrade Planning (internal)