Transcript Slide 1

Heavy Flavor Upgrades for STAR and PHENIX
at RHIC
Jim Thomas
Lawrence Berkeley National Laboratory
With correspondence from Axel Drees, SUNYSB
Characterization of the QGP with Heavy Quarks
Physikzentrum, Bad Honnef
June 25-28, 2008
Jim Thomas
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Motivation: Heavy Flavor Energy Loss, v2, s
1) Non-photonic
electrons decayed
from - charm and
beauty hadrons
2) At pT ≥ 6 GeV/c,
RAA(n.e.) ~ RAA(h±)
STAR PRL, 98, 192301 (2007)
contradicts naïve
pQCD predictions
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.
Jim Thomas
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Essential Ingredients
• Direct measurement of C and B hadrons requires
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Jim Thomas
High Luminosity
Excellent PID
Excellent spacial resolution at the event vertex
Large Acceptance, High Rate and High Efficiency Tracking
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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
Jim Thomas
Goal: Align the arrival times of
the packets in the two beams
– 50 x 1026
(not 80 x 1026 )
• Electron cooling is out …
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Heavy Flavor Upgrades for STAR and PHENIX
STAR
PHENIX
Solenoidal field
Large Solid Angle Tracking
TPC’s, Si-Vertex Tracking
RICH, EM Cal, TOF
Axial Field
High Resolution & Rates
2 Central Arms, 2 Forward Arms
TEC, RICH, EM Cal, Si, TOF, -ID
Measurements of Hadronic observables
using a large acceptance spectrometer
Jim Thomas
Leptons, Photons, and Hadrons in
selected solid angles (especially muons)
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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
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The TOF Upgrade
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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
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Multi-Gap Resistive Plate Chamber TOF
State-of-art MRPC:
-0.9 < h < 0.9,
0 < f < 2p, r = 220cm 6 gaps,
23K channels, 120 modules
3x6cm2 pad;
Most significant collab. to date between USA & China in HEP detector research
1 tray in runs 2-7
5 trays in run 8
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~75% in run 9
100% in run 10
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Improving the “Time” in Time-of-Flight
• 2001:
No timing devices
(except Time Projection Chamber)
• 2002:
BBC (~1ns), ZDC (200ps)
• 2002-2008:
TOF tray+VPD (<100ps)
Run8: 76M pp
events
TOF+TPX
• 2008
TOF st: 81ps
Jim Thomas
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TPC FEE and DAQ Upgrade – DAQ 1000
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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 !
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ALICE FEE & DAQ
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Four steps to an order of
magnitude increase in data
acquisition rates
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TPC FEE (BNL&LBL)
TPC RDO (BNL)
DAQ Transmitter (CERN)
DAQ Receiver (CERN)
Dual CERN D-RORC with
fibers on the board
Single D-RORC with 1
fiber mezzanine
Mezzanine DDL
Jim Thomas
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The Heavy Flavor Tracker
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A new detector
– 18 m silicon pixels
to yield 6 m space
point resolution
– 436 M pixels
– Strasbourg MAPS chips
Direct Topological
reconstruction of Charm
– Detect charm decays
with small ct, including
D0  K p
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
4 layers of Si at mid rapidity, 2 PXL + 1 IST + 1 SSD (existing)
Jim Thomas
CBM/MAPS: See related posters by C. Dritsa and Selim Seddiki
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Concept of HFT Layers
SSD
IST
PIXEL
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.
Graded Resolution from the Outside – In
Resolution(s)
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
Numbers quoted above are for a Kaon at 750 MeV/c
A pion at 1 GeV/c would achieve ~ 25 m at the vertex
Jim Thomas
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The Pixel Detector surrounds the vertex with Si
End view
8 cm radius
2.5 cm radius
Inner layer
‘D-Tube Duct and Support
Outer layer
ALICE style carbon support
beams (green)
Since modified to increase
Jim Thomas
Sensor
Clearances
See Poster by J. Kapitan
and J. Thomas
A thin detector using 50 m Si
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to finesse the limitations imposed by MCS
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!
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Even the Lc
Simulations of the
most challenging
3-body decays
are encouraging
so far
This capability, which will be provided uniquely at RHIC by the HFT, is
crucial for determining whether the baryon/meson anomaly extends to
heavy quark hadrons
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A more complete view of the STAR Upgrade plan
TOF complete:
PID information for > 95% of kaons
and protons in the STAR acceptance
Clean e± ID down to 0.2 GeV/c
FMS complete:
d+Au and p+p
data from Run 8
DOE investment ~ $4900k
Chinese investment ~ $2700k
HFT partial
implementation
HFT complete
full topological PID for
c, b mesons
DOE investment : upper
limit of range ~ $14.7M
DOE investment ~ $400k
Run08
Run09
Run10
Run11
Planned LHC
1st heavy ion run
DAQ1000 complete
Immediate improvement
of 300% in sampled
luminosity for rare probes
(e.g. jets in p+p)
DOE investment ~ $1900k
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Run12
Run13
Run14
Run15
Increase in Au+Au luminosity to
50 x 1027 cm-2 sec-1
U+U available from EBIS
DOE investment ~ $7M
FGT complete:
Accurate charge sign determination
for W’s, DOE investment ~ $1900k
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Future PHENIX Subsystems
Silicon VTX and FVTX
MuTrig Station 1
MuTrig Station 2
Nose Cone Calorimeter
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MuTrig Station 3
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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.
Jim Thomas
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Silicon Vertex Tracker (VTX)
VTX barrel |h|<1.2
Pixel Detectors at R ~ 2.5 & 5 cm
Strip Detectors at R ~ 10 & 14 cm
Pixel barrel
Strip barrels
Endcap (extension)
Endcap 1.2<|h|<2.7
(50 m x 425 m)
(80 m x 3 cm)
(75 m x 2.8 mm)
1 - 2% X0 per layer
barrel resolution < 50 m
endcap resolution < 150 m
Jim Thomas
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PHENIX Barrel VerTeX Detector
• VTX characteristics
e
X
– 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
|h|<1.2
f ~ 2p
|z|  10 cm
D
 beam
DCA, distance of closest approach
s
2
DCA
s


r  s 22 r12
r12
2
  ms
2
(r2  r1 )
sin 2 
2 2
1 2
s detector ~ 30 m
s ms ~ 30m
 Bdl ~ 0.15 Tm

• DCA resolution: given mostly by inner layer
sp
p
~ 10%
– Sufficient single hit resolution (~15 m)
– Close to beam axis to reduce effect of multiple scattering
Jim Thomas
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Expected RAA(ce) and RAA(be) with VTX
PHENIX VXT ~ 2 nb-1
RHIC II increases statistics by factor >10
Jim Thomas
Decisive measurement of RAA for both c and b
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Expected v2(be) and v2(ce) with VTX
PHENIX VXT ~2 nb-1
RHIC II increases statistics by factor >10
Jim Thomas
Decisive measurement of v2 for both c and b
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Forward Upgrade Components
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Endcap Vertex Tracker
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silicon pixel detectors
Nosecone EM Calorimeter
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Muon trigger
W-silicon (42 X/X0)
shower max
tail catcher
U-tracker (MuTr or new)
D-tracker (timing with RPC’s)
Cerenkov
Cerenkov
Muon from
hadron decays
Silicon endcap
Muon from W
U-Tracker
Nosecone
Calorimeter
charm/beauty & jets:
displaced vertex
Tail
Catcher
D-Tracker
g,g-jet,W,p0,h,c:
calorimeter
Jim Thomas
W and quarkonium:
improved -trigger rejection
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PHENIX Forward VerTeX Detector
• FVTX characteristics
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Cover both muon arms with 4 pixelpad layers/endcap
2p coverage in azimuth and 1.2 < | h | < 2.4
≥ 3 space points / track
DCA resolution < 200 µm at 5 GeV
Maximum Radiation Length < 2.4%
Fully integrated mechanical design with VTX
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Tracking and DCA Resolution with the FVTX
prompt
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 p-K decays.
DCA r-z resolution (cm)
p
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Muon acceptance
Momentum (GeV)
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Charmonium Spectroscopy with the FVTX
• Remove p-K decays
Background rejection
factor 4
• Improve mass resolution:
p-p
Au-Au
Jim Thomas
170 MeV  100 MeV
Measurement of ‘ in
central Au-Au collisions
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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 for
photon+jet studies
•
Prototype silicon wafer
– 3 different versions of
“stri-pixel” detectors for
the pre-shower and
shower max layers
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Extended physics reach
– Dq/q polarizations
via spin dependent
W-production
– Small x-physics in d-A
– Extended A-A program
– high pT phenomena:
p0 and g-jet
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PHENIX Forward EM Calorimeter (NCC)
W-silicon sampling calorimeter
NCC characteristics (DOE funding FY08)
40 cm from interaction point, 20 cm depth
2p coverage in azimuth and 0.9 < h < 3.0
W-silicon sampling calorimeter
1.4 cm Moliere radius
42 X0 and 1.6 labs
Lateral segmentation 1.5x1.5 cm2
3 longitudinal segments
sE
E

23%
 1%
E / GeV
2x2 tracking layers with 500 m strips
pg separation for overlapping showers
PS tracking layers
Main objective:
direct photon and p0 measurements
Jim Thomas
EM1
EM2
HAD
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Charmonium spectroscopy with the NCC
C  J /  g
μ
μ
Central Cu+Cu collisions
η=1-1.5
γ
subtracted
spectrum
S/B ~10%
J/ in muon arm, g in NCC
Conditional acceptance 58% if J/
detected
Determine invariant mass and
subtract combinatorial
background
Proof of principle MC simulation
pp should work, CuCu probable
Full MC simulation in progress
Jim Thomas
η=1.5-2
subtracted
spectrum
S/B~2%
mμμγ-mμμ (GeV/c2)
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Quarkonium Spectroscopy w/ Forward Upgrades
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 !)
1S)
-1-1
RHIC 2
20nb
nb
W/O NCC/FVTX
With
NCC/FVTX
2S)
c
J
’
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Timeline of PHENIX upgrades
2010
2008
2012
2014
RHIC
cooling era for “RHIC II”
Inner pixel layers
VTX
Outer strip layers
FVTX
Large acceptance tracking |Dh|<1.2
Displaced vertex at forward y
Forward photon detection
NCC
Jim Thomas
Displaced vertex at mid rapidity
Construction
Physics
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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
Jim Thomas
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Backup Slides and even more information …
Jim Thomas
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Key Experimental Probes of Quark Matter
• Rutherford experiment
SLAC electron scattering
a  atom
e  proton
discovery of nucleus
discovery of quarks
QGP
penetrating beam
(jets or heavy particles)
absorption or scattering pattern
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  jets
Heavy 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
Jim Thomas
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Hard Probes: Open Heavy Flavor
Electrons from c/b hadron decays
Status
– 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 bquarks?
Answers require direct observation of charm and beauty
Progress limited by:
no b-c separation  decay vertex with silicon vertex detectors
Jim Thomas
statistics (BJ/)  increase luminosity
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Hard Probes: Quarkonium
Deconfinement  Color screening
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
Answers require “quarkconium” spectroscopy length from data?
• Recent Lattice QCD
Progress limited by:
developments: Quarkonium
statistics (J/, Y)
 increase
luminosity
states do
not melt at TC
statistical significance (’)
 mass resolution
photon detection (C)
 forward calorimeter
Jim Thomas
J/
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Direct Observation of Open Charm and Beauty
Detection of decay vertex
will allow a clean identification
of charm and bottom decays
X
D
Au
m
GeV
D
ct
m
D0
D±
1865 125
1869 317
B0
B±
5279 464
5279 496
e,
K
Au
B
J/
p
X
e
e
Heavy flavor detection with VTX and FVTX in PHENIX:
• Beauty and low pT charm via displaced e and/or 
• Beauty through displaced J/  ee ()
•JimHigh
Thomas pT charm through D  p K
-2.7<h<-1.2 , |h|<0.35 , 2.7<h<1.2
-2.7<h<-1.2 , |h|<0.35 , 2.7<h<1.2
|h|<0.35
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Heavy flavor detection with the VTX
X
e
D
 beam
DCA, distance of closest approach
3<pT<4 GeV/c
s ~ 40m
• Results of simulation of Au+Au
collision.
• After a 2 cut, D0 decays clearly
separated from bulk of hadrons
Jim Thomas
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D/B Monte Carlo Simulations with FVTX
Jim Thomas
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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
Jim Thomas
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Heavy Ion RAA with FVTX (II)
Statistical separation of charm and bottom with DCA cuts
Jim Thomas
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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,
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–
–
–
reject decay background (Kn)
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
Jim Thomas
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Quarkonium Spectroscopy at RHIC II
J/ measurements will
reach high precision
Jim Thomas
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PHENIX Central Arm Upgrades
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Enhanced Particle ID
– TRD (east)
–
–
–
–
Aerogel/TOF (west)
VTX
Vertex Spectrometer
flexible magnetic field
VTX: silicon barrel vertex tracker
HBD
VTX
HBD
HBD
Aerogel/TOF
TRD
charm/beauty:
TRD e/p above 5 GeV/c
High pT phenomena:
p, K, p separation to 10 GeV/c
Jim Thomas
charm/beauty:
displaced vertex
e+e- continuum:
Dalitz rejection
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Improving STAR’s muon capabilities
Install a large area mid-rapidity muon telescope.
Allows detection of:
Di-muon pairs:
Quarkonia,
QGP thermal radiation,
Drell-Yan
+-
Simulations
Single muons :
Heavy flavor semi-leptonic decays
Advantage over e:
No g conversion,
Less Dalitz decay,
Less radiative losses to detector material
Jim Thomas
e+e-
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The Muon Trigger Detector concept
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
Prototype Installed in RUN 7-8
Muon efficiency: 35-45%
Pion efficiency: 0.5-1%
Muon-to-Hadron Enhancement
Factor: 100-1000
(including track matching, ToF,
dE/dx)
Jim Thomas
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Hadron Rejection and Muon Trigger
J/ trigger, separate +- states
• 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
Iron bars
Jim Thomas
Full Hijing AuAu event
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