# Presentation: 126589

## STAR’s Upgrades – A Path to the Future

Helen Caines
Yale University

RHIC/AGS Users Meeting
May 2008
Workshop on RHIC Upgrades

- Helen Caines
- Yale University
- RHIC/AGS Users Meeting
- May 2008
- Workshop on RHIC Upgrades

- Outline:
- 	Just Used
- 	Installed for Run 9
- 	Under Construction
- 	Contemplating

## STAR’s detector upgrades

**MRPC ToF barrel**
**Ready for run 10**

**RPSD**

- PMD

- FPD

- FMS

- EMC barrel

- EMC End Cap

**DAQ1000**
**Ready for run 9**

- HFT;           FGT: GEM-layers

- finished

- ongoing

- MTD

- R&D

## STAR’s coverage

- Photon capability from none to 4

## Aim to keep the discoveries rolling ...

- 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 Silicon tracker near the primary vertex
- Opens door to direct topological charm and beauty reconstruction
- Forward GEM Tracker
- End cap tracker for particle sign determination for W
- Muon Telescope (BNL LDRD)
- Forward Reaction Plane Detector
- A Crystal Calorimeter for low E photons
- Pb converter for -  HBT
- GEM alignment detector

**Underway**

**R&D/Proposals**

**More ideas**

## Ready for Run 9/10

## DAQ 1000 - TPC FEE and DAQ upgrades

- 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
- Zero suppression done at FEE. 16-20x smaller
- Make the FEE smaller. less heat
-       Almost no deadtime –rare physics program
- By only archiving “associated” clusters – build on L3 algorithms ... 5 kHz !

- Prototype in run 7, 1 sector in run8,
- Full system in run9

- TPC is now a fast detector!!!

## Commissioning in run 8

- 1/17/2008       Laser event (plus pileup)

- Data from DAQ1000 sector look good

- TPX dE/dx from TOF+TPX events
- DAQ1K at 1000Hz, 5—7% deadtime

##  PID plays crucial roles at RHIC

## Multi-gap Resistive Plate Chamber Time-of-Flight

- 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 2-7
- 5 trays in run 8

- ~75% in run 9
- 100% in run 10

## 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-:
- finally TOF t: 81ps

## Physics with the full TOF

- Hadron and lepton PID at mid-rapidity – (Energy scan)
- Identified p/ at high pT
- Jet-related PID spectra & correlations
- Fluctuation K/, p/ –
- 			(Critical point)
- Resonances (,,J/) hadronic and dilepton decay channels
- Open Charm (daughter PID)

- Proposal In, Construction Starting

## Poor man’s open heavy flavor measurements

- Electrons:
- EMC: pT>2 GeV/c
- TOF+TPC: 0.2<pT<4
- Muon:
- TOF+TPC: pT~=0.2
- K:
- Combinatoric K reconstruction

## The Heavy Flavor Tracker

- Thin 50 m Si pixels reduce limitations imposed by MCS and give 10 m space point resolution

- See Flemming’s talk later

- Direct Topological reconstruction of Charm
- Detect charm decays with small c, i.e.  D0  K 
- New physics
- Charm collectivity and flow to test thermalization at RHIC
- Charm Energy Loss to test pQCD in a hot and dense
-    Aiming for CD1 in Fall

## Flavor structure of the polarized proton sea

- Probe at RHIC via parity violating  W±  production and decay.

- Experimental signature: high pT lepton from W decay:

- For √s=500 GeV p+p collisions. The quark is usually a valence quark      large x

- Polarized PDFs only weakly constrained by fixed target data

- 

- Flavor separation possible via identification of  W’s charge

- 

- Need forward tracking

## Forward GEM Tracker (FGT)

- 6 triple-GEM disks covering 1 <  < 2
- outer radius ~ 40 cm
- inner radius varies with z position
- W charge sign reconstruction prob. >80% for 30 GeV pT over full EEMC acceptance and vertex spread ( >90% out to η= 1.8)

- See Bernd’s talk later

## Current upgrade timeline

- Run08

- Run10

- Run09

- Run12

- Run11

- Run13

- Run15

- Run14

- FMS complete:
- d+Au and p+p
- data from Run 8

- DAQ1000 complete
- Immediate improvement
- of 300% in sampled luminosity for rare probes
- (e.g. jets in p+p)

- Increase in Au+Au luminosity to
- 50 x 1027 cm-2 sec-1
- U+U available from EBIS
- DOE investment ~ $7M

- HFT partial
- implementation

- HFT complete
- full topological PID for
- c, b mesons
- DOE investment : upper
- limit of range ~ $14.7M

- Planned LHC
- 1st 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

## Ideas in germination

## Ideas in Germination

- Photon converter
-   HBT for direct photons
- Muon Telescope Detector
- J/ trigger
- GEM Calibration
- High pT resolution
- Reaction Plane Detector
- Improved resolution for v2 measurements
- Online trigger tracking
- Triggering and data reduction

## Direct  HBT

- 	Direct s:
- Produced in all stages of collision.
- Emitted without re-scattering
- Directly sensitive to T evolution
- Swamped by 0 decay bkgrd.

- Analysis challenging

- However HBT correlations only exist between direct photons.
- Correlation peak gives direct photon yield down to low pT
- Importantly, HBT gives information on temperature vs. size development through all stages of collision!

- Simulations show that a real measurement is possible in STAR with minimum addition (converter).

## The photon converter

- 10% radiation length Pb photon converter at R~43 cm (inside TPC)
- Converter retractable so that for most of the run it would not interfere with tracking in ||<1 region.
- Analysis effic. improved, especially at low relative momentum. Reconstruct one  via converter and other in BEMC

- Run with DAQ1000 to measure  HBT at low pT.

## 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-

## The Muon Trigger Detector concept

- 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)

## Hadron Rejection and Muon Trigger

- Iron bars

- Muon penetrates iron bars
- Other particles are stopped
- Good Time Resolution (60ps) rejects background (>100)
- 1 hit per 5 head-on Au+Au
-   Dimuon trigger (>25)
- Large coverage: diameter of 7 meters

- A BNL 2007 LDRD project

-  **J/****** trigger,  separate +- states

- Full Hijing AuAu event

## Performance in STAR 

-  z distribution of matched MTD hits has two components:
- narrow () and broad (hadron) ones
-          from data: pT>2 GeV/c,          (z) of muon: ~10 cm
-          from simu: pT=2.5 GeV/c,      (z) of muon: ~9 cm
-  hadron rejection: 200-300 (via track matching)
-  time resolution: 300 ps  Improve our electronics for full scale detector

- Simulations

- 

- 

- Data

- z (cm)

- pT (GeV/c)

## Novel “Problems” just around the corner

- Can we understand the distortion at high luminosity and maintain the momentum resolution?
- Can we analyze all the data from DAQ1000 effectively?
- Can we improve our reaction plane, especially at low energies?

## GEM alignment detector

-  As luminosity increases the TPC distortions due to residual charge in chamber increase.
-    Resolution 
-   Focus on high pT  
-  Vital that we can correct for these distortions on track-by-track basis
-  Capitalize on GEM technology and readout developed for FGT and place a few detectors outside of TPC radius
-  Measure precise points (~100 m) on tracks at outer radius of TPC in strategic locations to provide a strong constraint on the space charge distortion corrections.

## Online tracking for high pT charged hadron

- DAQ1000, 12 weeks, 50% data-time, 1000Hz:
- 		3.63 billion events, how to handle????
- Central 0-5%:
-       pT>4 GeV/c, (h++h-) raw yield: 6.52e-02 per event, 236M evts
-       pT>5 GeV/c, (h++h-) raw yield: 1.37e-02 per event,  50M evts
-       pT>6 GeV/c, (h++h-) raw yield: 4.15e-03 per event,  15M evts
- p+p:
-       pT>4 GeV/c, (h++h-) raw yield: 3.10e-04 per event, 1.13M evts
-       pT>5 GeV/c, (h++h-) raw yield: 6.52e-05 per event,  237K evts
-       pT>6 GeV/c, (h++h-) raw yield: 1.97e-05 per event,    72K evts

- Needs ~20% primary track momentum resolution at 5 GeV/c
- EMC and GEM Patches for calibration online?

## Seeds from EMC+TOF for Dilepton tracking

- Dielectron and background rates for TPC+TOF+EMC+Online
- Events needed could be reduced from  ~1billion to <100 million
- Using seeds from EMC+TOF reduces tracks from 1000s to a few

| Pt (GeV/c) | Electron per event  | Rejection factor |
| --- | --- | --- |
| >1.0 | 0.31 | 10 |
| >1.5 | 0.06 | 278 |
| >2.0 | 0.016 | 4000 |

- EMC

- EMC

- At least 10% dE/dx resolution ~150ps TOF calibration

- MTD could provide dimuon seeds

- Both ideas need further exploration!

## Forward ToF detector

- MRPC ToF rings  at forward rapidity  2.75<|η|<3.75
- 	128 MRPC modules located at z = ±6.5m.
- Granularity to provide good estimate of the reaction-plane
- even in U+U collisions.
- PID forward, tracking from FTPC’s
-  v1 and particle ratios
- Start-time signal for barrel ToF for low E scan
-  (current VPD may not fire due to small acceptance and low mult. VPD covers only 55% of area in range 4.4<η<4.9)
- Good background rejection during low E scan

## On the right path towards an upgraded future