The STAR Muon Telescope Detector: the past, present, and future

Transcription

1 Outline: Introduction The STAR Muon Telescope Detector: the past, present, and future The past: how we get there The present The future Conclusion Lijuan Ruan (Brookhaven National Laboratory) Sep/19/16 USTC, Lijuan Ruan 1

2 The MTD at STAR Multi-gap Resistive Plate Chamber (MRPC): gas detector, avalanche mode MTD A detector with long-mrpcs covers the whole iron bars and leave the gaps inbetween uncovered. Acceptance: 45% at η < (122) modules, 1416 (1464) readout strips, 2832 (2928) readout channels Long-MRPC detector technology, electronics same as used in STAR-TOF Sep/19/16 USTC, Lijuan Ruan 2

3 A heavy-ion collision event h Sep/19/16 USTC, Lijuan Ruan 3

4 Quarkonium as a QGP indicator color screening Courtesy from A. Mocsy Different quarkonium states: Heavy but small, 0.28, 0.56, 0.78 fm for ϒ(1S), ϒ(2S), ϒ(3S). provide distance scales to probe QGP: different dissociation temperatures. Sep/19/16 USTC, Lijuan Ruan 4

5 STAR-MTD Physics Motivation A large area of muon telescope detector (MTD) at mid-rapidity, allows for the detection of 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 single muons from the semi- leptonic decays of heavy flavor hadrons advantages over electrons: no γ 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/ψ 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 Sep/19/16 USTC, Lijuan Ruan 5

6 Quarkonium measurements for Run14 and beyond J/ψ J/ψ Sep/19/16 USTC, Lijuan Ruan 6

7 Electron-muon correlation measurements for Run 14 and beyond To obtain the charm correlation contribution to di-lepton continuum, we plan to Measure electron-muon correlation. This is to access the QGP thermal radiation contribution in the intermediate mass region. Sep/19/16 USTC, Lijuan Ruan 7

8 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(φ) cm 2, 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(φ) cm 2, Readout: trigger electronics, Time resolution: 300 ps Run 9: p+p Run : Au+Au, cosmic ray double stacks, 3 modules in a tray, module size: 87(z) 17(φ) cm 2, Readout: TOF electronics; trigger electronics for trigger purpose. Run 11 single stack, 1 module in a tray, module size: 87(z) 52(φ) cm 2, Readout: TOF electronics; trigger electronics for trigger purpose, Cosmic ray test performance: <0 ps Sep/19/16 USTC, Lijuan Ruan 8

9 The R&D Results for the MTD Long MRPC Technology with double-end readout HV: ±6.3 KV gas mixture: 95% Freon + 5% isobutane time resolution: ~60 ps spatial resolution: ~1cm efficiency: >95% 256 mm 25 mm 950 mm Y. Sun et al., nucl-ex/ ; NIMA 593, 430 (2008) Sep/19/16 USTC, Lijuan Ruan 9

10 Fermi Lab Beam Test Results (T963 May ) 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 Sep/19/16 USTC, Lijuan Ruan

11 Run Performance: Time and Spatial Resolution L. Li, UT Austin σ: 9 ps pure muons average p T : ~6 GeV/c Cosmic ray trigger (Z. Xu) Total resolution: 9 ps Start resolution (2 TOF hits): 46 ps Multiple scattering: 25 ps MTD intrinsic resolution: 96 ps System spatial resolution: 2.5 cm, dominated by multiple scattering σ: 2.5 cm Sep/19/16 USTC, Lijuan Ruan 11

12 Trigger Capability with MTD Acceptance RHIC II lumonisity in terms of collision rate: 40 k Hz; Au+Au projection: based on Run prototype performance. 1 ns trigger window: 80 Hz for dimuon trigger L0 trigger timing resolution (assumed) di-muon trigger efficiency of the timing cut 140 ps ±3.6σ (0%) Run Au+Au 200 ps ±2.5σ (98%) B. Huang, USTC 300 ps ±1.7σ (80%) Sep/19/16 USTC, Lijuan Ruan 12

13 MTD Trigger System 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. Sep/19/16 USTC, Lijuan Ruan 13

14 MTD System Requirement MTD requirements: Time resolution less than 0 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. The system must operate at low noise rate. The total noise rate should be less than 0.5 M Hz, 1 Hz/cm 2. The system must be safe, meet all BNL safely requirements. The system must not impair the performance of other STAR detectors. Sep/19/16 USTC, Lijuan Ruan 14

15 Organization MTD group: 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 Sep/19/16 USTC, Lijuan Ruan 15

16 MTD Schedule Q4 (FY09) Q1-2 (FY) Q3-4 (FY) Q1-2 (FY11) Q3-4 (FY11) Q1-2 (FY12) Q3-4 (FY12) Q1-2 (FY13) Q3-4 (FY13) Q1 (FY14) MRPC Module Design Production Proposal Design US MTD Constru. Electronics Design Production Tray Design Production Install/ Commissio n 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. 20;STAR-MTD review held in Sep. 20. Sep/19/16 USTC, Lijuan Ruan 16

17 MTD Schedule MRPC Module Q4 (FY09) Q1-2 (FY) Design Q3-4 (FY) Q1-2 (FY11) Q3-4 (FY11) Production Q1-2 (FY12) Q3-4 (FY12) Q1-2 (FY13) Q3-4 (FY13) Q1 (FY14) Proposal Design US MTD Constru. Electronics Tray Design Design Production Production Install/ Commissio n Physics Data The project approved and funded in May 2011: % installation for Run12, 43% (63%) for Run13, 80% (96%-0%) for Run 14. Finished the project by Mar, 2014 MTD institutions: Brookhaven National Laboratory, University of California, Berkeley, University of California, Davis, Rice University, University of Science & Technology of China, Texas A&M University, University of Texas, Austin, Tsinghua University, Variable Energy Cyclotron Centre US institutions: the electronics, the assembly of the trays and the operation of the detector Chinese and Indian institutions: the fabrication of the MRPC modules Sep/19/16 USTC, Lijuan Ruan 17

18 MTD in Run12 Two-pack system for the installation, designed by B. Llope and J. Scheblein, proven to be successful. MRPC built at USTC and Tsinghua, trays assembled at UT-Austin. For Run 12, 13 trays on three backlegs installed by STSG. Sep/19/16 USTC, Lijuan Ruan 18

19 MTD Performance from Run 12 e-muon di-muon Efficiency Commissioned e-muon (coincidence of single MTD hit and BEMC energy deposition above a certain threshold) and di-muon triggers, event display for Cu+Au collisions shown above. Determined the electronics threshold for the future runs, achieve 90% efficiency at threshold 24 mv Y Resolution (cm) p T (GeV/c) Intrinsic timing and spatial resolution: < 0 ps and 1~2 cm, respectively. p T (GeV/c) Sep/19/16 USTC, Lijuan Ruan 19

20 MTD for Run 13 L-R: John, Bob, Bill, Matt, Tim, Chris, Chi, Hui, Wangmei, Alex, Anthony Not shown: Bingchu and Shuai 63% of the MTD system was installed at STAR for Run Detector worked fine: among 75 trays installed, 74 worked properly. However, a single beam loss event on Apr. 9 damaged the protection devices of 46 MINO boards. All the boards are repaired by doubling the protection devices. Trigger algorithm in place on May 9 th. Single-muon, di-muon, electron-muon triggers were commissioned on May th. Sep/19/16 USTC, Lijuan Ruan 20

21 MTD Performance from Run 13 At the L0 trigger, MTD timing lined up J/ψ signals observed in p+p 5 GeV collisions Event display for J/ψ event in p+p 5 GeV collisions Sep/19/16 USTC, Lijuan Ruan 21

22 MTD Performance from Run 13 With slewing correction implemented, a factor of two more rejection on background will be obtained. MTD-VPD timing resolution: 500 ps after slewing and position correction. Sep/19/16 USTC, Lijuan Ruan 22

23 MTD for Run tays (96%) installed in total in Nov Electronics was tested. 2. The MTD group was proposing to add SF6 into gas mixture to further suppress the noise rate and steamers and enhance the trigger capability. Four trays having large gas leaks were either jumped out or removed from STAR trays took data smoothly in 14.6 GeV Au+Au collisions and part of 200 GeV run. 4. Commissioned single-muon, e-muon and di-muon mtd triggers with trigger experts more trays in BL 8 and 19 were installed in Apr. 2014, which completed the construction. Sep/19/16 USTC, Lijuan Ruan 23

24 MTD performance from cosmic ray run in run 14 MTD hits can be matched with the tpc tracks. Sep/19/16 USTC, Lijuan Ruan 24

25 Correlation between trigger electronics hits and tof electronics hits Good correlation observed between trigger electronics readout and tof electronics readout Trigger coaxed cable mismatch for BL30-5 and BL30-4. QT board MT003, card C broken, replaced. Sep/19/16 USTC, Lijuan Ruan 25

26 MTD matching efficiency Matching efficiency ranges 65-85%. Sep/19/16 USTC, Lijuan Ruan 26

27 MTD in 200 GeV Au+Au collisions in Run 2014 Position resolution for muon at p T > 2 GeV/c is about 11 cm, dominated by multiple-scattering effect. Muons tend to arrive earlier compared to background hits from the MTD-VPD timing distribution. Sep/19/16 USTC, Lijuan Ruan 27

28 The sampled luminosity for 200 GeV Au+Au collisions in Run 14 dimuon_upsiloneff di-muon_upsiloneff ] -1 L [ub ] -1 L [ub Mon Jun 16 11:48: /Mar 31/Mar 14/Apr 28/Apr 12/May26/May 09/Jun 23/Jun 07/Jul day Tue Jun 28 11:02: /Feb 06/Mar 03/Apr 01/May 29/May 26/Jun 24/Jul day We sampled 11 nb -1 luminosities for 200 GeV Au+Au collisions for Upsilon program in Run 14. Plus 9 nb -1 in Run 16. In total, we have 20 nb -1. Sep/19/16 USTC, Lijuan Ruan 28

29 0.5% SF6 is flowing to the MTD The noise rate is reduced. Streamer signals are suppressed. At the same time, monitor the TPC performance and SF6 concentration in the TPC gas. Thank Alexei Lebedev, Jim Thomas, Bill Christie for the efforts. Sep/19/16 USTC, Lijuan Ruan 29

30 The recap for the project The R&D very successful from Run , led to an upgrade project. Great thanks to Yongjie Sun for the R&D work, who led the module production at USTC. Overcome a few setbacks, overall it is a smooth project. Owe a lot to students at USTC Chi Yang, Qian Yang, Shuai Yang, Wangmei Zha for the installation, the test and on-call. The performances met our requirement, in terms of noise rate and timing resolution. One thing related to beam upstream background, which increase the dimuon trigger rate by more than a factor of 2. will be discussed later. Sep/19/16 USTC, Lijuan Ruan 30

31 Quarkonium with the MTD Different quarkonium states: heavy but small, different dissociation temperature J/ψ through its dileptonic decay: indicator of deconfinement of quarks and gluons color screening Courtesy from A. Mocsy Sep/19/16 USTC, Lijuan Ruan 31

32 2 dy) [nb/gev/c] σ/(dp 2 ) d T T B 1/(2πp PRL 113 (2014) JHEP 05 (2015) 3 J/ψ cross section and x T scaling in p+p collisions J/ψ cross section 500 GeV - STAR J/ψ e + e, y <1 STAR J/ψ µ + µ CGC+NRQCD NLO NRQCD p T, y <0.5 STAR preliminary [GeV/c] ] 2 [nb/(gev/c) 3 σ/dp 3 B Ed n s/gev) ( 28 STAR p+p 500 GeV 27 STAR p+p 500 GeV x T scaling STAR p+p 200 GeV CDF UA2 UA1 PHENIX x T =2p / s T ISR FNAL ALICE ATLAS CMS 4 π (n=6.6) p(n=6.6) J/ψ(n=5.6) PRC 80, (2009) Inclusive J/ψ cross section measured in 0 < p T < 20 GeV/c CGC+NRQCD and NLO NRQCD agree with data x T scaling of high-p T J/ψ observed for 500 GeV p+p collisions Breaking of x T scaling : affected by soft process Sep/19/16 USTC, Lijuan Ruan 32

33 J/ψ yield extraction 3 Full statistics from 2014 Au+Au 200 GeV run 3 Counts 30 STAR preliminary p T > 0 GeV/c 200 GeV -1 L ~ 14.2 nb y <0.5, p > 0 GeV/c J/ψ T,J/ψ = 24935, S/B = 1:28.6 N J/ψ Counts 1 STAR preliminary p T > 5 GeV/c 200 GeV -1 L ~ 14.2 nb y <0.5, p > 5 GeV/c J/ψ T,J/ψ N J/ψ = 1129, S/B = 1: Significance = 21.9σ Significance = 15.2σ 0.5 Unlike-sign pairs ( 0.15) Like-sign pairs ( 0.15) Mixed-event ( 0.15) Unlike-sign pairs Like-sign pairs Mixed-event M µ - [GeV/c ] + µ Signal extraction Mixed-event à combinatorial background. Fit background-subtracted unlike-sign with Gaussian+pol3 Signal = (counting in[2.9,3.3] GeV/c 2 ) (residual background) M µ - [GeV/c ] + µ No bremsstrahlung tail N ~ S/B ratio & Significance S/B = 1:29, ~ pt > 0 GeV/c S/B = 1:1.8, ~ pt > 5 GeV/c Sep/19/16 USTC, Lijuan Ruan 33

34 Invariant yield of J/ψ ] -2 dy) [(GeV/c) dp N/(2πp 2 B lld T T GeV L ~ 14.2 nb - J/ψ µ + µ, y < % % %/ %/ STAR preliminary p T (GeV/c) First mid-rapidity measurement of J/ψ yield in Au+Au collisions via the di-muon channel for 0 < p T < 15 GeV/c Sep/19/16 USTC, Lijuan Ruan 34

35 J/ψ suppression: R AA = σ inel N coll d 2 N AA / dydp T d 2 σ pp / dydp T R AA 1.8 STAR 200 GeV 0-60% J/ψ µ + µ, y < STAR preliminary 0-20% R AA Suppression at Low-p T Dissociation Regeneration % (GeV/c) (GeV/c) Cold nuclear matter effect p T 40-60% At high pt, strong suppression in 0-20% and a rising trend in 20-60% central collisions Dissociation Formation time effect; B feed down Sep/19/16 USTC, Lijuan Ruan 35 p T

36 J/ψ suppression: R AA = σ inel N coll d 2 N AA / dydp T d 2 σ pp / dydp T R AA 1.8 STAR 200 GeV 0-60% J/ψ µ + µ, y < J/ψ e e, y < 1 (MB) J/ψ e e, y < 1 (HT) STAR preliminary 0-20% Di-electron: STAR PLB 722 (2013) 55 STAR PRC 90, (2014) R AA % (GeV/c) (GeV/c) p T 40-60% p T Consistent with di-electron channel results for the entire p T range within uncertainties in all centralities Sep/19/16 USTC, Lijuan Ruan 36

37 J/ψ at RHIC and LHC Different quarkonium states: heavy but small, different dissociation temperature J/ψ through its dileptonic decay: indicator of deconfinement STAR Collaboration, SQM2016 Sep/19/16 USTC, Lijuan Ruan 37

38 ϒ with the MTD STAR Collaboration, SQM , 0.56, 0.78 fm for ϒ(1S), ϒ(2S), ϒ(3S). Negligible contribution from b and bbar recombination at RHIC A better probe to study color-screening feature of QGP. A hint of ϒ(2S+3S) less suppressed at RHIC than at LHC! Sep/19/16 USTC, Lijuan Ruan 38

39 Towards the future Work on e-muon correlation to distinguish heavy flavor production from initial lepton pair production Plan to release the Run combined ϒ results in 200 GeV Au+Au to QM2017. Plan to release the Run 15 p+p and p+a J/ψ and ψ(2s) results to QM2017. Longer term beyond 2020: improve the trigger capabilities: Information from one module, 12 strips form one trigger-pair input. Probably most cost-effective à improve the timing resolution from 500 ps to 300 ps at trigger level. Larger scintillator plus SIPM readout outside MTD. Additional hit requirement should reduce the rate very significantly. We will test the idea in the coming Run 17 and 18 by installing scintillators and MTD trays outside two backlegs. Increase the acceptance? Sep/19/16 USTC, Lijuan Ruan 39

40 Summary R&D over many years led to a successful final-design. Overcome a few setbacks, generally still a very smooth operation. Young-generation scientists got trained and become important taskforces for future projects. Physics on quarkonia are coming out. Still work on e-muon correlation. There are ways to improve the trigger capability. Precise ϒ measurements could be very exciting. Stay tuned for the future physics exciting results! Sep/19/16 USTC, Lijuan Ruan 40

41 Backup Sep/19/16 USTC, Lijuan Ruan 41

42 The timing resolution at the trigger level Detailed information at MtdCalibration_run12_trg.pdf. 1. Tof electronics calibration: 150 ps ( ps) (include resolution from tof electronics, and from the multiple-scattering effect) 2. Trigger electronics with the same tof offline calibration procedures: 300 ps ( ps) 300ps= 150 ps ps (VPD from QT) ps (QT intrinsic for MTD) 3. Trigger electronics with online method: ( ps) 400 ps = 150 ps ps ps ps (t0 offset has a strip-by-strip variation and module-by-module difference for the trays in the same eta positions at different backlegs) Sep/19/16 USTC, Lijuan Ruan 42