1. Jamie Nagle (University of Colorado, Boulder) Department of Energy sPHENIX Science Review Jamie Nagle University of Colorado

2. Responding to the Recommendations 2 1.More clearly articulate improvements in physics understanding with sPHENIX in the context of ongoing studies at RHIC and LHC 2.Explore heavy-flavor tagged jet capabilities 3.Explore improved Upsilon resolution and statistics 4.Investigate more complete simulations to better understand instrumental effects 5.Explore extended pseudorapidity coverage for calorimetry 6.Consider prospects for increasing data rate and triggering 7.Investigate alternate jet observables to enhance useful range of jet finding

3. 3 Question #6 Consider prospects for increasing data rate and triggering Question #6 Consider prospects for increasing data rate and triggering

4. Data Rates Au+Au @ 200 GeV 4 In the original proposal, we conservatively assumed RHIC performance for Au+Au as in Run-14 (with full stochastic cooling in place). This corresponds to an ~8 kHz min.bias interaction rate within |z|<10 cm. In the original proposal, we used a Level-1 accept rate of 10 kHz as the baseline (a good match to the interaction rate). We noted that a limitation at this rate was the re-use of the PHENIX strip-pixel layers in the sPHENIX tracker. New tracking design (see Tony Frawley’s talk) no longer includes the strip-pixels for multiple reasons including rate capability and thickness

5. Updates from RHIC C-AD 5 As recommended, we asked the Collider-Accelerator Division for updated projections. No major funds for new investments in accelerator performance assumed. Factor of 2.5 improvement within z-vertex selection relative to Run-14. Thus, we revisited new Level-1 and DAQ archive goal.

6. New Level-1 DAQ Specs 6 15 kHz good match to sPHENIX DAQ Architecture and luminosities Tested PHENIX pixels  DCM2 readout at ~ 15 kHz In nominal one-year Au+Au run, one can thus record 100 billion Au+Au minimum bias events within |z|< 10cm With Au+Au rare triggers for physics that can be measure just with the calorimeters (i.e. wider z-vertex range), and can sample 0.6 trillion events. Cost/benefit analysis for widening the silicon vertex z-coverage does not warrant that change.

7. Rarest Triggers in Au+Au @ 200 GeV 7 For some of the calorimeter-only measurements, triggering in Au+Au would be needed to sample the full 0.6 trillion events. Photons Photon-jet correlations Straightforward to trigger on high energy EMCal Photons above E > 10 GeV Inclusive jets Dijets Jet patch trigger with event-by-event baseline subtract works for jet E > 35 GeV. Capability designed into calorimeter FEE and trigger information available sPHENIX GEANT-4 Simulation

8. Data Rates p+p @200 GeV 8 In the original proposal, we conservatively assumed RHIC performance for p+p @ 200 GeV as in Run-12. Updated C-AD projections including the Electron Lens provide a significant luminosity increase. Much of that being realized in Run-15. Run15 Peak and avg near double Run12 Avg lumi increases with peak Run15 Peak and avg near double Run12 Avg lumi increases with peak Run 12 Avg lumi levels off relative to peak Run 12 Avg lumi levels off relative to peak As you will see in the physics projections plots, this removes the p+p baseline as the statistics limiter. Need to demonstrate the Level-1 triggers can sample this luminosity without biasing physics. Unbiased measurements in Au+Au require clean p+p/p+A comparison.

9. Triggering in p+p and p+A @ 200 GeV 9 Jet trigger (EMCal + HCal) fully simulated in GEANT-4. Quark Jets Quark Jets and Gluon Jets sampled with very high efficiency for E T > 10 GeV without strong bias. Comparison with bias from EMCal only trigger.

10. Rate, Rate, Rate 10 Translates not just into extended reach, but more critically more differential measurements (see later slides). Statistics also lead to reducing systematic uncertainties.  

11. 11 Question #5 Explore extended pseudorapidity coverage for calorimetry Question #5 Explore extended pseudorapidity coverage for calorimetry

12. RHIC Kinematics Reminder 12

13. Forward Calorimetry 13 Additional underlying event characterization and jet containment in A+A. Not critical to sPHENIX physics program, pursuing separately. As a first step, GEANT-4 simulation of instrumenting hadronic calorimetry in place of the flux return end doors. Very interesting p+p and p+A low-x physics, which are part of the fsPHENIX concept. Strong RIKEN interest in forward HCal

14. 14 Question #1 More clearly articulate improvements in physics understanding with sPHENIX in the context of ongoing studies at RHIC and LHC Question #1 More clearly articulate improvements in physics understanding with sPHENIX in the context of ongoing studies at RHIC and LHC

15. Emergent Phenomena 15 Discovery of QGP as perfect fluid was huge! We know a lot about how QGP behaves, but not so much about how it really works. Discovery of High T c Superconductors was huge! However, we still do not know what really carries the charge. Now it is critical to probe QGP (High T c Superconductors) at different length scales to get full insight.

16. Sensitivity, Statistics, Key Knobs 16 RHIC greater sensitivity in key channels from kinematics RHIC ability to engineer surface bias and parton type RHIC sensitivity to emergence of perfect fluidity where coupling is strongest near transition temperature Key knobs to get at this physics, and with clear connection to sPHENIX observables

17. 17 Jet Geometry Engineering Thorsten Renk has explored the ability to engineer the surface and energy loss bias to gain more information. Works particularly well at RHIC due to steeply falling jet spectrum. sPHENIX can measure these jets with no minimum p T selection and no online trigger bias. Thus, one can explore the full range of engineered geometries. Systematic measurements enabled “tomography”

18. Photon-Tagged Jets 18 “The steeper falling cross sections at RHIC energies lead not only to a narrower zJ γ distribution in p+p collisions but also to larger broadening end shift in the. “ LHCRHIC Dai, Vitev, Zhang, PRL 110 (2013) 14, 142001  q  (E=20 GeV), S/B is 20x better at RHIC  Underlying event 2.5x smaller

19. 19 Path Dependence E quark E photon sPHENIX unique mapping of path (L) dependence of parton-QGP interactions. Key to resolving strongest coupling near transition temperature and why.

20. Different Medium, Different Jets 20 Can we observe the strongest coupling near T c definitively Inner workings? (quasiparticles, fields, Sound modes) How do the parton shower and medium evolve together?

21. Jet-Medium Interactions 21 Strongest coupling near T c as Perfect Fluid Emerges pQCD  s running, are probes weakly coupled at all scales? Coupling Strength

22. Stronger Coupling Near T c 22 “Jet Quenching is a few times stronger near T c relative to the QGP at T > T c.” Liao and Shuryak, PRL (2009) “The surprisingly transparent sQGP at the LHC [compared to RHIC]” Horowitz and Gyulassy, NPA (2011) “Large v 2 is striking in that it exceeds expectations of pQCD models even at 10 GeV/c.” PHENIX, PRL (2010)

23. Detailed Path Dependence 23

24. Upsilon Melting 24 sPHENIX combined with LHC measurements can really pin down screening effects and temperature dependence

25. 25 Parton virtuality evolves quickly and is influenced by the medium at the scale it probes Thick lines indicate where the QGP influences virtuality evolution RHIC Jet Probes LHC Jet Probes QGP Influence Bare Color Charges Thermal Mass Gluons Perfect Fluid Only Unique critical microscope resolution at RHIC. Measurement overlap between RHIC and LHC very important too. Jet Probes of QGP Structure

26. Virtuality Evolution 26 Rise in R AA at LHC is important – though different models have different underlying physics. YAJEM rise results for virtuality evolution, i.e. changing scale for resolving the medium. Key test at RHIC and with precision

27. Scale in the Medium 27 Limit of infinitely massive scattering centers yields all radiative e-loss. Medium parton qhat  scattering of leading parton  radiation e-loss ehat  energy transferred to the QGP medium q  scattering of leading parton which then radiates e  energy transfer from parton to QGP particle ^ ^ Importance of Beauty-tagged jets at RHIC and LHC Heavy b-mass suppresses radiation! Collisional energy loss much more important Collisional Radiative

28. Heavy Quark Jets 28 Beauty Quark Forward radiation suppressed, dead-cone. Separating collisions versus radiative energy loss. Key handle on what is being scattered from in medium

29. Jet Energy Distribution Coleman-Smith et al.Vitev et al. Additional sensitivity to contributions of radiative and collisional energy loss mechanisms

30. New Interest in p+A 30 sPHENIX provides discriminating power on p+A physics explanations Enabled by p+p/p+A HCal triggering (as done in CMS for example) sPHENIX covers up to very high Bjorken x 2. x 2 ~ 0.06

31. Current RHIC Capabilities, Why sPHENIX? 31 PHENIX – high rate, deadtimeless DAQ, but very limited acceptance STAR – large acceptance, modest rate, no HCal, limited Upsilon acceptance/separation Rate, Rate, Rate  unbiased physics samples, differential observables Critical triggering in p+p and p+A for full comparisons Upsilon Hadrons Kinematic Reach Photon Statistics p+A

32. Why sPHENIX with LHC? 32 Kinematics give RHIC observables key sensitivity Difference quark/gluon admixture Probing critical dependencies in temperature, virtuality, scale Enormous statistics without bias for fully differential analyses Extension in energy, temperature, scale, etc. have proven in this field to provide invaluable constraints on the underlying physics.

33. Summary Connection from the QCD Lagrangian to phenomena of confinement and asymptotic freedom was fundamental Connection from QCD to the emergent phenomena of near perfect fluidity of the Quark-Gluon Plasma near the phase transformation is just as fundamental Pinning down  /s tells us the nature of the QGP, more importantly we need to reconcile: Most important discovery in field: perfect fluid & Crucial part of QCD: weak coupling at short distances Without sPHENIX this critical scientific answer will be lost

34. 34 BACKUP MATERIAL

35. Observables Roadmap 35 QuestionsObservablesNeeds Are there relevant screening lengths in QGP Is QGP Coupling Strongest near T c ? At what length scale does the QGP go from strong to weak coupling? How do parton showers evolve in the QGP? Are there quasiparticles in medium? Are there significant medium response modes to high energy partons? Upsilon three state suppression Jet inclusive spectra Dijet correlations Jet fragmentation functions Heavy flavor tagged jets Jet – global event structure observables  -jet/h correlations Large Acceptance High Rate Electron ID Photon ID Full Calorimetric Coverage

36. A New Detector at RHIC High data acquisition rate capability, 15 kHz Sampling 0.6 trillion Au+Au interactions in one-year Maximizing efficiency of RHIC running BaBar Magnet 1.5 T Coverage |  | < 1.1 All silicon tracking Heavy flavor tagging Electromagnetic Calorimeter Hadronic Calorimeter

37. Forward Calorimetry 37 There is an LOI for an Electron Ion Collider Detector built around the BaBar Magnet and sPHENIX Calorimetry http://arxiv.org/abs/1402.1209 There is also strong interest in forward sPHENIX, Including the hadron-going spectrometer from the above LOI. http://www.phenix.bnl.gov/phenix/WWW/publish/dave/sPHENIX/pp_pA_whitepaper.pdf

38. 38 T 3 [GeV 3 ] Time [fm/c] Differential measure is most sensitive to coupling near T c

39. Beauty Jets and Radiation Suppression 39 Slide from Yen-Ji Lee (QM14)

40. PRL 2011 Guangyou Qin, Berndt Muller Larger modification at RHIC, more of parton shower equilibrated into medium. 40

41. Quark-Gluon Kinematics 41 Photon-Tagged Jets also identify the partner as a light quark jet. Gluons are elusive, and yet very important with a much stronger color coupling to the medium. Triggering on a 20 GeV R=0.2 jet, has a very strong surface bias and selects out quark jets. Partner probability to be a gluon jet to the quark is ~ 65%. Excellent opportunity to compare quark and gluon samples. Again, opportunity as a function of L.

42. Over-constraining the Problem 42

43. Direct Photon-Jet/h 43 In Au+Au central collisions for p T > 20 GeV, direct photons dominate S/B > 3 Simple isolation cuts with full calorimetry give additional handle and enable p+p and p+A comparison measurements sPHENIX has excellent direct photon capabilities LHC RHIC

44. RHIC dominated by “fake jets”? No. 44 arXiv:1203.1353 Phys. Rev. C86 (2012) 024908 Simple Answer = Over Key Kinematic Ranges Jet Physics is accessible with sPHENIX without requiring jet bias cuts Multiple techniques being developed in the field to extract jet results. This is a demonstration of one such technique following the ATLAS method.

45. Unique Measurement Example 45 Predictions that Fragmentation Function D(z) = p / E parton will have dramatic high-z suppression If E jet < E parton in A+A due to out of cone radiation or medium excitation or … then shifting z denominator sPHENIX enables precision measurement Cannot be done otherwise at RHIC Coupled with precision measure at LHC across different jet energies and different QGP couplings  Definitive Answers arXiv:0710.3073

46. RHIC and LHC Together 46 It is fundamental to making major (paradigm changing) advances in the field to probe the QGP (through different temperature evolutions) at a range of length scales. That program requires sPHENIX for precision overlapping and unique measurements from both RHIC and LHC Kinematic differences also play a major role with sPHENIX changing the data landscape and constraining the underlying physics and QGP properties

47. LHC Physics in the Next Ten Years 47 Run 2 Run 3 Pb+PbPb+Pb/p+Pb Pb+Pb/p+Pb/Ar+Ar sPHENIX measurements well timed with LHC Run-3 measurements Very good for enabling theory focus on simultaneous understanding RHIC

48. LHC Higher Energy Jet Observations 48 Large suppression of balanced dijets with p T,1 > 120 GeV/c Fully calorimetric measurement, no low p T cutoff on constituents Original expectation is huge suppression of high z Fragmentation Functions. Not observed. Correlated bias in which jets and how much of their energy is reconstructed. Key check with  -jet/h

49. STAR Jet Program 49 Very good jet capabilities Large acceptance, tracking + EMCal Exciting recent results from QM2014 Trigger on jet > 20 GeV requiring online trigger of > 5.4 GeV in one EMCal tower and all p T > 2 GeV Expect Surface Bias on Trigger And Long Path on Opposite Side However, only modest suppression of balanced jets

50. 50 Now re-run jet algorithm with all particles around originally found jets Dijet asymmetry identical in pp and AA! Very different result from theory expectations and LHC results. If full jet energy recovered, real unbiased FF measurements available to sPHENIX. Biased di-jet case may select particular geometry. Perhaps biased towards both jets tangential.

51. RHIC Jet Discriminating Power 51 http://arxiv.org/abs/arXiv:1207.6378 Major new detector project at RHIC Large coverage calorimetry coupled with high rates

52. Near Transition Temperature Enhancement 52

53. 53 Single hadron v 2 Single hadron R AA

54. RHIC with sPHENIX and STAR 54 sPHENIX DAQ bandwidth 15 kHz STAR DAQ bandwidth 2 kHz Deadtimeless DAQ Full digitized calorimeter information for EMCal high tower and patch trigger Level-1 triggered (full flexibility) sPHENIX A+A can record 100B and sample 600B Full out MB currently, STAR would record 10B HCal enables full jet patch trigger in p+p, p+A Utilizes EMCal trigger in p+p, p+A and A+A HCal enables fragmentation function measure with p and E independent HCal enables charged hadron triggering HCal enables good photon isolation cuts Utilizes EmCal and Tracks HCal rejects electron backgrounds Electron ID with TPC, TOF, EMCal HCal acts as magnetic flux return HCal in detector with tracking – both ATLAS/ Only STAR/ALICE jet types CMS jets and STAR/ALICE jets for comparison Upsilon large acceptance and mass resolution STAR MTD 1/7 of acceptance, lower resolution sPHENIX huge data sample with jets with very good statistics in the energy range 20-70 GeV, includes key overlap with LHC jet range and methods HCal resolution best in upper range, sPHENIX uniquely enables FF measurement, enables to dial the surface engineering bias to do full tomography