Transcript Document

STAR MTD: Physics Motivation, R&D Results and
Requirements
Lijuan Ruan for STAR-MTD group
(Brookhaven National Laboratory)
Outline:
• Physics motivation with the STAR-MTD
• Simulation and R&D results
• Trigger details for the full system
• Conclusions
http://www.star.bnl.gov/~ruanlj/MTDreview2010/mtd.htm
http://drupal.star.bnl.gov/STAR/system/files/MTD_proposal_v14.pdf
03/30/2011
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What Have We Learnt So Far at RHIC
A hot, dense medium with partonic degrees of freedom
created at RHIC:
Jet quenching
Baryon enhancement, number of constituent quark
scaling in elliptic flow
…
Next:
Is the system thermalized and how does the system thermalize?
What are the properties of the strongly-coupled system?
What is the phase structure of QCD matter?
What exotic particles are produced at RHIC?
What is the mechanism for partonic energy loss?
Does QCD matter demonstrate novel symmetry properties?
What is the nature of the initial state in nuclear collisions
…
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Muons: Penetrating Probes
The initial temperature of sQGP; the mass origin of hadrons;
color screening features of heavy quarkonia …
Measurements
low mass di-muons
Physics
thermal radiation of QGP;
in-medium modifications of vector
meson (  ), chiral symmetry
restoration
intermediate mass di-muons
thermal radiation of QGP;
heavy flavor modification;
resonances in sQGP
large mass: heavy quarkonia
T of QGP, color screening,
quarkonium production mechanism
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Charm Contribution to Di-lepton Spectrum
PHENIX, PRC81,034911(2010)
NA60, PRL96,162302(2006)
1. Charm contribution to di-lepton spectra is significant at low mass at RHIC.
2. Charm contribution to di-lepton spectra might be dominant in the intermediate
mass region. Its correlation makes a big difference to access the thermal
radiation
03/30/2011contribution from
MTD QGP.
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Cocktail Simulation in 200 GeV p+p at STAR
STAR: π, KS, K*, , ρ
PHENIX: η, ω, J/
Z. Tang et al., PRC 79,051901(R)(2009); M. Shao et al.,
J. Phys. G: Nucl. Part. Phys. 37 (2010) 085104
ccbar: star measured cross section as input;
STAR Collaboration, PRL94(2005)062301
bbar/ccbar ratio from PYTHIA
Particle spectra from data were fit with Tsallis function, and
were used as an input to full GSTAR simulation
to generate e+e- invariant mass cocktail.
Same cuts were applied in simulation as in data.
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STAR-MTD Physics Motivation
A large area of muon telescope detector
(MTD) at mid-rapidity, allows for the
detection of
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di-muon pairs from QGP thermal radiation, quarkonia, light vector mesons,
possible correlations of quarks and gluons
as resonances in QGP, and Drell-Yan production
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single muons from the semi- leptonic decays of heavy flavor
hadrons
•
advantages over electrons: no  conversion, much less Dalitz decay
contribution, less affected by radiative losses in the detector
materials, trigger capability in Au+Au
•
trigger capability for low to high pT J/ in central Au+Au collsions
excellent mass resolution, separate different upsilon states
e-muon correlation to distinguish heavy flavor production from initial
lepton pair production
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Concept of Design of the STAR-MTD
A detector with long-MRPCs covers the
whole iron bars and leave the gaps inbetween uncovered. Acceptance: 45% at
||<0.5
118 modules, 1416 readout strips, 2832 readout
channels
Long-MRPC detector technology, HPTDC
electronics (same as STAR-TOF)
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Single Muon and J/ Efficiency
G. Lin, Yale Univ.
J/ efficiency
1. muon efficiency at |η|<0.5: 36%, pion efficiency: 0.5-1% at pT>2 GeV/c
2. muon-to-pion enhancement factor: 50-100
3. muon-to-hadron enhancement factor: 100-1000 including track matching,
tof and dE/dx
4. dimuon trigger enhancement factor from online trigger: 40-200 in central
Au+Au collisions
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Comments on Simulations
Simulations
Conditions
Efficiency of single muon and J/
Include TPC tracking efficiency, MTD
acceptance, matching between TPC
and MTD
J/ and  signal versus background
J/,  RAA, v2 projection
µ-e correlations
Signal from STAR measurements;
Inclusive muons: reconstructed from
prototype performance from Runs 7-8,
track matching included, tof cut is not
applied
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High Mass Di-muon Capabilities
Z. Xu, BNL LDRD 07-007; L. Ruan et al., Journal of Physics G: Nucl. Part. Phys. 36 (2009) 095001
1. J/: S/B=6 in d+Au and S/B=2 in
central Au+Au
2. With HFT, study BJ/ X; J/
using displaced vertices
3. Excellent mass resolution: separate
different upsilon states
Heavy flavor collectivity and color
screening, quarkonia production
mechanisms:
J/ RAA and v2; upsilon RAA …
Quarkonium dissociation temperatures – Digal, Karsch, Satz
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Future Measurement Projection
J/
Υ
J/
J/ RAA and v2;
Υ RAA versus Npart…
Z. Tang, USTC
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Upsilon Statistics Using MTD at |y|<0.5
Delivered luminosity: 2013 projected;
Sampled luminosity: from STAR operation performance
Collision
system
Delivered
lumi.
12 weeks
Sampled
lumi.
12 weeks
(70%)
Υ counts
Min. lumi.
precision
on
Υ (3s)
(10%)
Min. lumi.
precision
on
Υ (2s+3s)
(10%)
200 GeV
p+p
200 pb-1
140 pb-1
390
420 pb-1
140 pb-1
500 GeV
p+p
1200 pb-1
840 pb-1
6970
140 pb-1
50 pb-1
200 GeV
Au+Au
22 nb-1
16 nb-1
1770
10 nb-1
3.8 nb-1
Upsilon in 500 GeV p+p collisions can also be measured with good precision.
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High luminosity for Υ & J/ from e+e-
STAR high pT J/
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Compared to Υ  e+e- with HFT
Material budget with HFT
similar to that at year 2004
With HFT, it’s hard to
separate different upsilon
states;
e+e- channel samples
collisions of |vz|<5 cm;
can not sample full
luminosity due to
more material at |vz|>5 cm
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Distinguish Heavy Flavor and Initial Lepton Pair
Production: e-muon Correlation
Z. Xu, BNL LDRD 07-007; L. Ruan et al., Journal of Physics G: Nucl.
Part. Phys. 36 (2009) 095001
NA60, PRL100,022302(2008)
e correlation simulation with Muon Telescope
Detector at STAR from ccbar:
S/B=2 (Meu>3 GeV/c2 and pT(e)<2 GeV/c)
S/B=8 with electron pairing and tof association
R. Rapp, hep-ph/0010101
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MTD: construction starts in FY2011;
project completion in FY2014
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The details for the R&D modules
Conditions
Modules and readout
Cosmic ray and Fermi-lab T963 beam tests
double stacks,
module size: 87(z)17() cm2,
Performance: 60 ps, ~0.6 cm at HV  6.3 kV
Run 7: Au+Au
Run 8: p+p, d+Au
double stacks, 2 modules in a tray, module
size: 87(z)17() cm2,
Readout: trigger electronics,
Time resolution: 300 ps
Run 9: p+p
Run 10: Au+Au, cosmic ray
double stacks, 3 modules in a tray, module
size: 87(z)17() cm2,
Readout: TOF electronics; trigger electronics
for trigger purpose.
Run 11
single stack, 1 module in a tray, module
size: 87(z)52() cm2,
Readout: TOF electronics; trigger electronics
for trigger purpose,
Cosmic ray test performance: <100 ps
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The R&D Results for the MTD
Long MRPC Technology with
double-end readout
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256 mm
950 mm
25 mm
HV: 6.3 KV
gas mixture: 95% Freon + 5% isobutane
time resolution: ~60 ps
spatial resolution: ~1cm
efficiency: >95%
Y. Sun et al., nucl-ex/0805.2459; NIMA 593, 430 (2008)
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Fermi Lab Beam Test Results (T963 May 2-15 2007)
Y. Sun et al., NIMA 593, 430 (2008)
T963 spokesperson: Z. Xu
HV: 6.3 KV
gas mixture: 95% Freon + 5%
isobutane
time resolution: ~60-70 ps
spatial resolution: ~0.6-1cm
efficiency: >95%
consistent with cosmic test results
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Run 10 Performance: Time and Spatial
Resolution
L. Li, UT Austin
σ: 109 ps
pure muons
average pT: ~6 GeV/c
Cosmic ray trigger (Z. Xu)
Total resolution: 109 ps
Start resolution (2 TOF hits): 46 ps
σ: 2.5 cm
Multiple scattering: 25 ps
MTD intrinsic resolution: 96 ps
System spatial resolution: 2.5 cm,
dominated by multiple scattering
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Trigger Capability with MTD Acceptance
RHIC II lumonisity in terms of collision rate: 40 k Hz;
Au+Au projection: based on Run 10 prototype performance.
1 ns trigger window: 80 Hz for dimuon trigger
Run10 Au+Au
L0 trigger timing
resolution
(assumed)
di-muon trigger efficiency
of the timing cut
140 ps
3.6σ (100%)
200 ps
2.5σ (98%)
300 ps
1.7σ (80%)
B. Huang, USTC
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MTD Trigger System
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•
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The primary physics goal requires triggering on di-muon events sampling full
luminosity.
To select muons and reject hadronic showers that punch through the magnet steel,
a timing cut will be applied to the MTD signals.
Since the MTD pickup strips are ~90 cm in length and readout from both ends, the
sum (E+W)/2 will be calculated in the trigger and compared to the collision time.
The average arrival time at MTD boxes in different eta region is different due to
difference in path length.
The occupancy in the MTD is very low, only one east and one west signal is sent to
trigger from the 60 strips of 5 MTD boxes in the same eta region at 5 nearby
backlegs. This allows for a correction on the arrival time in the high eta region at
trigger level. The correction could be larger than 1 ns in the highest eta region.
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MTD Trigger System
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Each 12 strip MRPC is readout by 4 NINO frontend ASICs on a MINO
card. Each NINO reads out 6 east ends or 6 west ends. The NINO
produces a logic output signal if any of the 6 inputs is above threshold.
•
The 10 NINO signals and the corresponding east/west signals are
logically combined by the MTRG card and a single east and west signal
is sent to trigger from 5 MTD boxes in the same eta range at the 5
nearby backlegs.
•
Each QT can produce 8 (E+W)/2 sums. 4 QT boards required in all.
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The QT is currently in use for the STAR trigger system.
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MTD System Requirement
MTD requirements:
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Time resolution less than 100 ps, spatial resolution ~ 1 cm.
•
The mechanics design must allow a convenient replacement of individual MTD
box and access to the BEMC box.
•
The system must be able to operate in the fringe field from 0.5 Tesla STAR
magnet field.
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The system must operate at low noise rate. The total noise rate should be less
than 0.5 M Hz, 1 Hz/cm2.
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The system must be safe, meet all BNL safely requirements.
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The system must not impair the performance of other STAR detectors.
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Organization
MTD group:
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Brookhaven National Laboratory: L. Ruan, Z. Xu, K. Asselta, W. Christie, C.
D’Agostino, J. Dunlop, J. Landgraf, T. Ljubicic, J. Scheblein, R. Soja, A.H. Tang, T.
Ullrich
University of California, Berkeley: H.J. Crawford, J. Engelage
University of California, Davis: M. Calder′on de la Barca S′anchez, R. Reed, H.D. Liu
Rice University: J. Butterworth, G. Eppley, F. Geurts, W.J. Llope, D. McDonald, T.
Nussbaum, J. Roberts, K. Xin, L. Bridges
University of Science & Technology of China: H.F. Chen, B.C. Huang, C. Li,
M. Shao, Y.J. Sun, Z.B. Tang, X.L. Wang, Y.C. Xu, Z.P. Zhang, H. Zeng,
Y. Zhou
Texas A&M University: Y. Mohammed, S. Mioduszewski
University of Texas, Austin: A. Davila, G.W. Hoffmann, L. Li, C. Markert, L.
Ray, J. Schambach, D. Thein, M. Wada
Tsinghua University: J.P. Chen, K.J. Kang, Y.J. Li, Y. Wang, X.L. Zhu
Variable Energy Cyclotron Centre: Z. Ahammed, P.P. Bhaduri, S.
Chattopadhyay, A.K. Dubey, M.R. Dutt-Mazumdar, P. Ghosh, S.A. Khan,
S. Muhuri, B. Mohanty, T.K. Nayak, S. Pal, R. Singaraju, V. Singhal, P.
Tribedy, Y.P. Viyogi
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MTD Schedule
Q4
(FY09)
Q1-2
(FY10)
Design
MRPC
Module
Q3-4
(FY10)
Q1-2
(FY11)
Q3-4
(FY11)
Q1-2
(FY12)
Q3-4
(FY12)
Q1-2
(FY13)
Q3-4
(FY13)
Q1
(FY14)
Production
Proposal
Design
US MTD
Constru.
Electronics
Design
Production
Design
Tray
Production
Install/Com
mission
Physics
Data
Finish the project by Mar, 2014 and make 80% of the full system ready for year 2014 run
MTD proposal submitted to BNL in Feb. 2010;STAR-MTD review held in Sep. 2010.
The project approved in Mar. 2011. Now in the process of setting up charge numbers.
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Summary
•
MTD will advance our knowledge of Quark Gluon Plasma:
trigger capability for low to high pT J/ in central Au+Au collsions
excellent mass resolution, separate different upsilon states
e-muon correlation to distinguish heavy flavor production from initial
lepton pair production
different background contribution provides complementary
measurements for dileptons
•
The prototype of MTD works at STAR from Run 7 to Run 10. Results
published at L. Ruan et al., Journal of Physics G: Nucl. Part. Phys. 36 (2009) 095001;
0904.3774; Y. Sun et al., NIMA 593 (2008) 430.
muon purity>80%; the primary muon over secondary muon ratio: good
for quarkonium program
the trigger capability with L0 and L2: promising for dimuon program:
Upsilon, J/ elliptic flow v2 and RAA at high pT
•
The larger Run 11 modules with slightly wider readout strips show a
comparable performance as the modules in Runs 7-10, based on
cosmic ray tests at USTC and Tsinghua.
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Backup
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STAR-MTD in Year 2007 and 2008
beam species
interaction rate (Hz)
trigger rate
Sampled L
events
matched hits
Au+Au
20 k
0.5-2 Hz
270 b-1
0.31 M
7k
d+Au
100 k
0.5-2 Hz
29 nb-1
1.60 M
78 k
p+p
300 k
0.5-2 Hz
404 nb-1
0.56 M
8k
• iron bars as hadron absorber
• 403 cm away from TPC center, ||<0.25
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Performance of a Prototype at STAR
• MTD hits: matched with real
high pT tracks
• z distribution has two
components: narrow (muon)
and broad (hadron) ones
• spatial resolution (narrow
Gaussian) is ~10 cm at pT>2 GeV
• narrow to broad ratio is ~2;
can be improved with dE/dx and
tof cut
• are the particles in the narrow
Gaussian muons?
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Runs 9-10 Prototype
Issues from Runs 7-8:
Time resolution for the full system:
300 ps
Start resolution: 160 ps (start
detector with trigger readout)
Multiple scattering: 70 ps
Intrinsic MTD resolution: 200-300 ps
Is this real?  install a prototype
with TOF electronics in run9
Runs 9-10:
3 modules, one tray covered:
87(z)51() cm2
18 channels on each side
2 TINO,TDIG, TTRG boards,
1 TCPU board
Both ends go to trigger QT
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