1. J-PARC Heavy Ion Project Takao Sakaguchi Brookhaven National Laboratory for the J-PARC HI Collaboration

2. J-PARC HI Collaboration Nuclear Experimentalists and Accelerator Physicists S. Nagamiya (JAEA/KEK/RIKEN) H. Sako, K. Imai, K. Nishio, S. Sato, S. Hasegawa, K. Tanida, S. H. Hwang, H. Sugimura, Y. Ichikawa (ASRC/JAEA) H. Harada, P. K. Saha, M. Kinsho, J. Tamura (J-PARC/JAEA) K. Ozawa, K. Itakura, Y. Liu (J-PARC/KEK) T. Sakaguchi, M. Okamura (BNL) K. Shigaki (Hiroshima Univ.) M. Kitazawa, A. Sakaguchi (Osaka Univ.) T. Chujo, S. Esumi, B. C. Kim (Univ. of Tsukuba) T. Gunji (CNS, Univ. of Tokyo) H. Tamura, M. Kaneta (Tohoku Univ.) K. Oyama (Nagasaki Institute of Applied Science) H. Masui (Wuhan Univ.) 2 2015-09-21T. Sakaguchi, xQCD2015@Wuhan, China

3. Heavy-ion programs in the world Very high intensity beam is a feature of J-PARC HI accelerator Ion species: p, Si, Ar, Cu, Xe, Au(Pb), U, and also light ions for hypernuclei 2015-09-21 3 AcceleratorTypeBeam energy (AGeV) C.M. energy √s(AGeV) Beam rate / Luminosity Interaction rate (sec -1 ) Year of experiment RHIC Beam Energy Scan (BNL) Collider7.7-6210 26 -10 27 cm -2 s -1 (√s=20AGeV) 600~6000 (√s=20AeV) (  total =6b) 2004-2010 2019-2020 (e-cooling) NICA (JINR) Collider Fixed target 0.6-4.54-11 1.9-2.4 10 27 cm -2 s -1 (√s=9AGeV Au+Au) ~6000 (  total =6b) 2019- 2017- FAIR SIS100 (CBM) Fixed target 2-11(Au)2-4.71.5x10 10 cycle -1 (10s cycle,U 92+ ) 10 5 -10 7 (detector) 2022- J-PARCFixed target 1-19(U)1.9-6.210 10 -10 11 cycle -1 (~6s cycle) 10 7 -10 8 ? (0.1% target) ? References RHIC: A. Fedotov, LEReC Review, 2013 FAIR: FAIR Baseline Technical Review, C. Strum, INPC2013; S. Seddiki, FAIRNESS-2013, C. Hoehne, CPOD2014 NICA : A. Kovalenko, Joint US-CERN-Japan-Russia Accelerator School; A. Sorin, CPOD2014 T. Sakaguchi, xQCD2015@Wuhan, China

4. J-PARC KEK & JAEA) P.K. Saha HIAT2015 4

5. Neutrino experiment (NU) Materials & Life Science Facility (MLF) 3 GeV Rapid Cycling Synchrotron (RCS) Hadron Experimental Hall (HD) 400 MeV H - Linac 50 GeV Main Ring Synchrotron (MR) [30 GeV at present] J-PARC KEK & JAEA) P.K. Saha HIAT2015 5 Transmutation Experimental Facility (TEF)

6. HI Accelerator scheme in J-PARC (H. Harada and P. Saha, yet unofficial!) 2015-09-21T. Sakaguchi, xQCD2015@Wuhan, China 6 RCS (H -  p) 0.4  3 GeV MR 3  30 GeV (p) H - Linac: 0.4 GeV MLF p to NU proton (existing) p to HD HI (under planning) Figures: Not to scale

7. HI Accelerator scheme in J-PARC (H. Harada and P. Saha, yet unofficial!) 2015-09-21T. Sakaguchi, xQCD2015@Wuhan, China 7 RCS (H -  p) 0.4  3 GeV MR 3  30 GeV (p) H - Linac: 0.4 GeV MLF p to NU proton (existing) HI booster U 55+ →U 66+ 19.9  67 AMeV U 66+ →U 86+ 61.8 AMeV stripping U 35+ →U 55+ 19.9 AMeV HI Linac U 35+ 20 AMeV p to HD HI (under planning) Figures: Not to scale

8. HI Accelerator scheme in J-PARC (H. Harada and P. Saha, yet unofficial!) 2015-09-21T. Sakaguchi, xQCD2015@Wuhan, China 8 RCS (H -  p) 0.4  3 GeV MR 3  30 GeV (p) H - Linac: 0.4 GeV MLF p to NU proton (existing) HI booster U 55+ →U 66+ 19.9  67 AMeV U 66+ →U 86+ 61.8 AMeV stripping U 35+ →U 55+ 19.9 AMeV HI Linac U 35+ 20 AMeV p to HD HI (under planning) Figures: Not to scale U 86+ 61.8  735.4 AMeV U 86+ →U 92+ 0.727 AGeV stripping

9. HI Accelerator scheme in J-PARC (H. Harada and P. Saha, yet unofficial!) 2015-09-21T. Sakaguchi, xQCD2015@Wuhan, China 9 RCS (H -  p) 0.4  3 GeV MR 3  30 GeV (p) H - Linac: 0.4 GeV MLF p to NU proton (existing) HI booster U 55+ →U 66+ 19.9  67 AMeV U 66+ →U 86+ 61.8 AMeV stripping U 35+ →U 55+ 19.9 AMeV HI Linac U 35+ 20 AMeV p to HD U 92+ 0.727  11.15 AGeV p/HI to HD HI (under planning) Figures: Not to scale U 86+ 61.8  735.4 AMeV U 86+ →U 92+ 0.727 AGeV stripping

10. HI Accelerator scheme in J-PARC (H. Harada and P. Saha, yet unofficial!) 2015-09-21T. Sakaguchi, xQCD2015@Wuhan, China 10 RCS (H -  p) 0.4  3 GeV MR 3  30 GeV (p) H - Linac: 0.4 GeV MLF p to NU proton (existing) HI booster U 55+ →U 66+ 19.9  67 AMeV U 66+ →U 86+ 61.8 AMeV stripping U 35+ →U 55+ 19.9 AMeV HI Linac U 35+ 20 AMeV p to HD U 92+ 0.727  11.15 AGeV p/HI to HD HI (under planning) Figures: Not to scale U 86+ 61.8  735.4 AMeV U 86+ →U 92+ 0.727 AGeV stripping A more than 10 11 U 86+ ions can be achieved with no significant beam losses. No serious beam dynamics issues even up to such an intensity. – Gives 4×10 11 U 92+ ions/cycle (6s) in the MR The RCS including proposed new HI accelerator scheme has no interference/conflict with existing programs that make use of proton beams.

11. Physics of high energy program Study of QCD phase structure – RHIC and LHC explored partonic matters (QGP) at high T and low  – J-PARC explores low T and high  region Core of neutron star, critical point Highest density expected at √s NN =8GeV (Randrup, PRC74(2006)047901) Observables: rare probes by taking advantage of high intensity beam – Hypernuclei – Exotic hadrons:  (1405), Dibaryon (H-dibaryon,  N, ,…), Kaonic nucleus (K - pp,…), Strangelet and more.. – e-by-e fluctuation (critical point search) – Di-electrons, di-muons (T, chiral sym.) – Thermal Photons (T) – YN, YY correlations (in high density) – flow (EOS) 2015-09-21 11 /0/0 JAM model, Y. Nara, Phys. Rev. C61,024901(1999) U+U (reaches 8.6  0 ) Au+Au T. Sakaguchi, xQCD2015@Wuhan, China

12. Particle production rates 12 Beam : 10 10 Hz 0.1% target  Interaction rate 10 7 Hz Centrality trigger 1%  DAQ rate = 100kHz In 1 month experiment:   ee 10 7 -10 9 D,J/  10 5- 10 6 (20AGeV) (10 3 -10 4 (10AGeV)) Hypernuclei 10 5 -10 10 Ref: HSD calculations in FAIR Baseline Technical Report (Mar 2006) A. Andronic, PLB697 (2011) 203 Charm Dilepton Hypernuclei 2015-09-21 AGS T. Sakaguchi, xQCD2015@Wuhan, China

13. Hypernuclei Maximum yield expected at J-PARC Coalescence of high-density baryons – S=-3 Hypernuclei Precise secondary vertex reconstruction (mid rapidity) Closed geometry setup – Full intensity beam – Magnetic moment 13 A. Andronic, PLB697 (2011) 203 KEK Report 2000-11 Expression of Interest for Nuclear/Hadron Physics Experiments at the 50-GeV Proton Synchrotron J-PARC 2015-09-21 T. Sakaguchi, xQCD2015@Wuhan, China

14. “Strange Matter” production System should be “strange-rich” – Strangelets is one object to look at – Historical and on-going research AGS: e.g. PRC54, R15 (1996) RHIC: PRC76, 011901(R), (2007) Study strangeness-rich system existing in core of neutron star – Light quarks are converted to strange quarks under high baryon density environment – In order to avoid Pauli blocking and thus to reduce internal energy Trigger events by strange particles – Classify events by the fraction of strange particles to all the particles, “strangity” In addition to “centrality” – statistics-starved measurement suitable for J-PARC HI machine 2015-09-21 14 strangity E or T [MeV] Cartoon only PRD17, 1109(1978) Strangeness/baryon ratio as a function of baryon density (two models) T. Sakaguchi, xQCD2015@Wuhan, China

15. Energy density at J-PARC? 2015-09-21 15 (arXiv:1106.6324) Result from PHENIX experiment is a good guidance. (At Mid-rapidity and most central collisions) Energy per charged particle. Very little change in the transverse energy per charged particle from 7.7 GeV to 200 GeV and also to 2.76TeV Bjorken Energy density *   Power-law relation is seen: A  calculated by PHENIX T. Sakaguchi, xQCD2015@Wuhan, China

16. Energy density at J-PARC? 2015-09-21 16 (arXiv:1106.6324) Result from PHENIX experiment is a good guidance. (At Mid-rapidity and most central collisions) Energy per charged particle. Very little change in the transverse energy per charged particle from 7.7 GeV to 200 GeV and also to 2.76TeV Bjorken Energy density *  Power-law relation is seen: A  calculated by PHENIX If the global variables at J-PARC energy follows these trends, the system may be in a thermalized state  Possibility of “Strange Matter” search T. Sakaguchi, xQCD2015@Wuhan, China

17. Once “strange” matter is produced.. 2015-09-21 T. Sakaguchi, xQCD2015@Wuhan, China 17

18. Event-by-event fluctuations 3rd and 4th-order fluctuations are sensitive to critical point and phase boundary Direct comparison to lattice- QCD may be possible – Net-proton – Net-charge – Strangeness, etc.. High statistics in J-PARC – Wide y-pT acceptance required 2015-09-21T. Sakaguchi, xQCD2015@Wuhan, China 18 STAR, PRL 112, 032302 (2014) Variance :  2 = ~  2 [  (2) /  (1) ] Skewness: S  = /  2 ~  5.5 [  (3) /  (2) ] Kurtosis: K  2 = /  2 -3  2 ~  9 [  (4) /  (2) ] J-PARC region

19. Low-mass dileptons From STAR’s BES result – Low mass enhancement is well-described by cocktail + in-medium  modification (Rapp model) + thermal radiation How does it look like in even lower energy, i.e., in dense matter? – At J-PARC, measurement of both di-electrons and di-muons is planned 2015-09-21 19 F. Geurts, Thermal photon dilepton workshop, Aug, 2014 and NPA 904–905 (2013) 217c T. Sakaguchi, xQCD2015@Wuhan, China

20. Dileptons at J-PARC energy Landscape for J-PARC (√s~5GeV) Intermediate Mass Range – DDbar is very hard – Sensitive to QGP thermal radiation? Low Mass Range – in-medium modification of vector mesons (link to chiral symmetry restoration) – Thermal radiation 2015-09-21 20 Axel Drees S/B (combinatoric) for 0<M ee <2GeV/c 2 is ~10 -2 T. Sakaguchi, xQCD2015@Wuhan, China

21. Dileptons at J-PARC energy Landscape for J-PARC (√s~5GeV) Intermediate Mass Range – DDbar is very hard – Sensitive to QGP thermal radiation? Low Mass Range – in-medium modification of vector mesons (link to chiral symmetry restoration) – Thermal radiation 2015-09-21 21 Axel Drees S/B (combinatoric) for 0<M ee <2GeV/c 2 is ~10 -2 T. Sakaguchi, xQCD2015@Wuhan, China f B : Bose dist.  em : photon self energy photons dileptons

22. And, also low p T direct photons.. Slope of the spectra is not process- dependent – Relates to the temperature of the system PHENX’s finding of inverse slope is 220MeV ALICE at LHC obtained 304MeV It is important to know the temperature of the system at J-PARC, too. 222015-09-21 T. Sakaguchi, xQCD2015@Wuhan, China PHENIX, PRL. 104, 132301 (2010) f B : Bose dist.  em : photon self energy photons dileptons

23. Experimental setup and challenge High rate capability – Fast detectors: Silicon trackers, GEM trackers, … – Extremely fast DAQ  triggerless DAQ (>= 100kHz) High granularity – Pixel size < 3x3mm 2 at 1m from the target,  <2deg, 10% occupancy Large acceptance (~4  ) – Coverage for low beam energies (CBM =8AGeV/c) – Maximum multiplicity for e-b-e fluctuations – Backward physics (target fragment region) Electron measurement – Field free region for RICH close to the target – Complemented by muons Toroidal magnet setup 23 2015-09-21 T. Sakaguchi, xQCD2015@Wuhan, China

24. Toroidal Beam View RICH Muon Tracker 24 HCAL EMCAL Toroid coils Better B  uniformity With larger number Of coils With 12 coils Variations ~+-20% Coils = insensitive area T. Sakaguchi, xQCD2015@Wuhan, China

25. 3.2m HCAL EMCAL ZCAL Beam RICH 4m4m Muon Tracker R=1m Top View Toroid 0.25m 0.5m 1.4m 5m5m 0.65 m 0.66m 0.4m 1.90m 0.9m 0.2m TOF SVD ZCAL Centrality MC + ZCAL Multiplicity counter C 5 F 12 radiator p<3.4GeV/c e-  separation EMCAL (e,  ID) PbWO 4, 15X 0  –  separation p>1.5 GeV/c Fe absorbers + Trackers p<0.8 GeV/c 4m TOF with 30ps p=0.8-1.5GeV/c RICH (Aerogel) Neutron counter 25

26. HCAL ZCAL Beam RICH 4m4m Muon Tracker R=1m Side View Toroidal coil 1.3m 0.5m 5m5m 0.66m 0.4m 1.90m 6.36m 0.2m 4.15m B=2T gap=0.65 BL=1.3Tm Forward trackers Troidal trackers Barrel trackers 0.65m EMCAL 26

27. GEANT4 (Toroidal) setup U+U at 10AGeV/c with JAM For simplicity – Half-spherical toroidal shape – Uniform B  field – No dead area due to coils 27 H. Sako, B.C. Kim 2015-09-21T. Sakaguchi, xQCD2015@Wuhan, China

28. Acceptance, PID and momentum resolution With TOF hits required – TOF resolution 50ps  /K separation upto 2.5GeV/c (2.5  )  p/p = 0.7% - 5% (0.5-5GeV/c) Not corrected for In-flight decay 28 Acc = 95.0% Acc. = 77.5% Acc. = 64.2% Acc. = 70.9% 2015-09-21T. Sakaguchi, xQCD2015@Wuhan, China Forward    protons yy pTpT pTpT y y m 2 (GeV 2 /c 4 ) Charge * p (GeV/c)

29. Simulated di-electron spectrum (preliminary) 29 Calculations by T. Gunji     2015-09-21 Solenoid+Dipole setup Based on  0 spectra of JAM Other hadrons m T -scaled b<1fm (0.25% centrality) Momentum resolution 2% Electron efficiency 50% (No detector response) 10 11 events ⇔ 100k events/s x 1 month running  isolation = rejection efficiency of close opening angle Dalitz pair T. Sakaguchi, xQCD2015@Wuhan, China

30. Summary A heavy-ion program at J-PARC is under design to study dense matter – Acceleration schemes with RCS and MR – Near-4  HI spectrometer with Toroidal to measure dileptons, hadrons, and photons Prospects – Design of accelerators and experiments Detailed design for accelerators Full simulation with RICH for dilepton spectrum Design for the closed setup for hypernuclei – R&D MRPC-TOF (Tsukuba, JAEA, KEK) in E16 for hadron measurements DAQ (JAEA,NIAS) – A conceptual design report (white paper) in this year 2015-09-21 30 T. Sakaguchi, xQCD2015@Wuhan, China

31. Backup 2015-09-21 31 T. Sakaguchi, xQCD2015@Wuhan, China

32. J-PARC HI Accelerator scheme (H. Harada) MR RCS HI booster HI LINAC U 35+ 20.0MeV/u U 55+ →U 66+ 19.86→67.0 MeV/u U 86+ 62.34→735.21 MeV/u U 66+ →U 86+ 67.0→62.34 MeV/u U 86+ →U 92+ 735.21→727.0M eV/u U 92+ 727.0Mev/u→11.15 GeV/u (30GeV@p) stripping U 35+ →U 55+ 20.0→19.86 MeV/u 32 2015-09-21T. Sakaguchi, xQCD2015@Wuhan, China

33. Advantages and issues of HI scheme in the RCS P.K. SahaHIAT201533 Advantages: ● Use existing building and devices. -- Reduction of space and budget to accelerate up to ~GeV/u (U) for MR injection. ● Large acceptance -- transverse (  tr ) > 486  mm mrad, longitudinal (  p/p) > ±1% ● Well understood and optimized accelerator performance up to designed 1 MW. -- Realistic discuss on beam dynamics issues and measures for high intensity HI................... Issues: ● Parallel operation between MLF and MR with p and HI, respectively must be done. ● Most of the machine parameters fixed for p must be used for HI (At present, no choice for changing most of the parameters between cycles). ● Vacuum pressure level: ~10 -8 Torr (no problem for p). Not satisfied for HI w/ lower charge states (U 86+ is thus considered).

34. HI Injection to RCS 2015-09-21 34 Beam transport lines to MLF to MR RCS H-H- H- stripping Injection 1 st foil H -  H + Extraction section RF section HI Injection? Only kicker magnets Inj. Beam dump Candidate place: End of extraction straight section Only injection kicker magnets are necessary in RCS in addition T. Sakaguchi, xQCD2015@Wuhan, China

35. Low and High energy programs at J-PARC Low energy program (LINAC) Primarily for unstable nuclei study Ion species – Ne, Ar, Fe, Ni, Kr, Xe,…,U Beam energy – 1 - 10 AMeV (U) Beam current – 10-30 pmA – 10ms, 25Hz High energy program (50GeV MR) Primarily for QCD matter study Ion species – p, Si, Ar, Cu, Xe, Au(Pb), U – Also light ions for hypernuclei Beam energy – 1 - 19 AGeV (U, √s NN = 2 - 6.2GeV) Rate – 10 10 -10 11 ions per cycle (~ 2-3 sec) 2015-09-21 35 T. Sakaguchi, xQCD2015@Wuhan, China Very high intensity beam is a feature of J-PARC HI accelerator

36. 36 Existing 3 GeV and 50 GeV synchrotrons HI injector and injection section in RCS are necessary Proven performance for high-intensity proton beam for RCS and MR Slowly extracted proton beams 2.5x10 13 /cycle  1.3x10 14 /cycle (2017) Well understood accelerator performance Optics, lattice imperfections, acceleration, beam loss Parallel RCS operations for MR(HI) and MLF(proton) are a must. (similarly to current operation) Limited freedom in RCS for operation parameters (magnets, RF cavity…) Advantages/limitation of RCS/MR for HI beam 2015-09-21  The injection booster is being designed to fit to RCS operations T. Sakaguchi, xQCD2015@Wuhan, China

37. Realistic simulation results: Beam survival (RCS) 2×10 10 ~1×10 11 ppb (P. K. Saha, J-PARC) Beam survival: > 99.97% even for 1×10 11 ppb Beam loss point: Collimator (100%) [ For 1 MW proton at present: ~99.8%, beam loss mainly due to foil scattering.] Same machine parameters as proton Beams (except for RF system) 2015-09-21 37 T. Sakaguchi, xQCD2015@Wuhan, China

38. Target of high energy program RHIC and LHC HI collisions explore QGP at high T and low  – phase transition is smooth cross over At J-PARC, we aim at studies of QCD phase structures (critical point and phase boundary) in high density regime (~neutron star)  high statistics with world’s highest intensity HI beams 2015-09-21 38 [1] Y. Aoki et al, Nature 443 (2006) 675 [2] K. Adcox et al, PRL 89 (2002) 022301 [3] A. Adare et al, PRL 104 132301 T. Sakaguchi, xQCD2015@Wuhan, China

39. Physics shoplist and observables Dileptons (dielectron and dimuon) Systematic and high statistics hadron measurements – Strange meson and baryons – Event-by-event fluctuations – Two particle correlations (YN, YY correlations in high baryon density) – flow (related to EOS?) Rare probes – Hypernuclei – Exotic hadrons  (1405) Dibaryon (H-dibaryon,  N, ,…) Kaonic nucleus (K - pp,…) Strangelet and more.. – Charm J/ , D, charmed baryons Photons – Thermal photons from QGP J-PARC  /K beams 2015-09-21 39 J-PARC E16 p+A Onset of QGP Search for critical point Properties of Dense matter T. Sakaguchi, xQCD2015@Wuhan, China

40. Results to be highlighted in this talk Global Observables (Charged multiplicity and Bjorken energy density) Fluctuation (Net-charge, net-protons, particle ratio) System size (HBT) and dynamics (collective motion) 2015-09-21 40 STAR white paper for BES (June, 2014) And, K/p K/  p/  fluctuation (arXiv:1410.5375) T. Sakaguchi, xQCD2015@Wuhan, China

41. Temperature (T) and Baryo-chemical potential (   : ≈ nucleon density) – Deducing from particle production ratio, using Grand Canonical Stat Model 2015-09-21 41 Statistical quantity of the system See, e.g., A. Andonic, P. Braun-Munzinger, J. Stachel, NPA 772(2006)167 Spin d.o.f. Particle numbers: n i Chemical potential  i  b : Baryon,  I3 : Isospin  S : Strangeness,  C : Charm T. Sakaguchi, xQCD2015@Wuhan, China

42. Higher Moments of Net-protons Net-proton fluctuation. Skewness and Kurtosis are compared with Skellman distribution (double-Poisson) baseline Kurtosis are above Skellman baseline in peripheral collisions below 19.6 GeV. UrQMD shows monotonic behavior. A transition at 20GeV? Individual proton/anti-proton production scenario is reasonably agreeing with the observed fluctuation 2015-09-21 42 STAR, PRL 112, 032302 (2014) Variance :  2 = ~  2 [  (2) /  (1) ] Skewness: S  = /  2 ~  5.5 [  (3) /  (2) ] Kurtosis: K  2 = /  2 -3  2 ~  9 [  (4) /  (2) ] BRAHMS, PRL93, 102301(2004)STAR, PRC81, 024911(2010) T. Sakaguchi, xQCD2015@Wuhan, China

43. Low-mass dileptons Maximum low mass enhancement around J-PARC energies? Dielectron – low p T, lower m –  conversion at low m Dimuon – high p T, higher m – ,K   decay background – Utilize highest beam intensity High statistics at J-PARC – Moment analysis  direct comparison to spectrum functions 43 J-PARC 2015-09-21 T. Galatyuk, EM probes of Strongly Interacting Matter, ECT*, Trento 2007 Low-mass dilepton enhancement factor Measured / cocktail in m=0.2-0.8 GeV/c 2 Highest baryon density ~ 8GeV (Randrup, PRC74(2006)047901) PHENIX Au+Au 200 AGeV T. Sakaguchi, xQCD2015@Wuhan, China

44. BES-II plan Energy scan in 2018-2019 STAR will do energy scan using 7.7GeV and fixed target in the same period PHENIX will install a new sPHENIX detector in 2018. It may or may not be able to catch up 2019 run 2015-09-21 44 T. Sakaguchi, xQCD2015@Wuhan, China

45. 2015-09-21 45 (fm/c) log t pTpT 1 10 10 7 ( GeV/c ) hadron decays hadron gas sQGP hard scatt Cartoon only: sources of , mean p T vs time Sources of photons (before RHIC) Cartoon courtesy of Gabor David T. Sakaguchi, xQCD2015@Wuhan, China

46. 2015-09-21 46 (fm/c) log t pTpT 1 10 10 7 ( GeV/c ) hadron decays hadron gas sQGP Cartoon only: sources of , mean p T vs time Sources of photons (at J-Parc energy) Mass (GeV/c 2 ) 0.5 1  *  e+e- virtuality Dileptons Measurement via: – Real photons:  – Internal conversion:   ->ee,   ->  – external conversion:   ->ee Photon Production: Yield   s T. Sakaguchi, xQCD2015@Wuhan, China

47. A calculation for J-Parc energy Using UrQMD, low p T photons are calculated at FAIR energy –  is dominant (Bremsstralung) Elliptic flow is estimated of the order of 1-2% 2015-09-21 47 Grimm and Baeuchle, arXiv:1211.2401 T. Sakaguchi, xQCD2015@Wuhan, China

48. 2015-09-21 48 Focus on the mass region where  0 contribution dies out Look for M<<p T and M<300MeV/c 2 – qq ->  * contribution is small Convert to real photon yield ratio using Dalitz decay formula Connecting to dilepton analysis One parameter fit: (1-r)f c + r f d f c : cocktail calc., f d : direct photon calc. PRL104,132301(2010), arXiv:0804.4168 q  g q e+e+ e-e- e+e+ e-e- External conv. Internal conv. T. Sakaguchi, xQCD2015@Wuhan, China

49. Beam Energy Scan of dielectrons LMR excess observed for all energies systematic measurement of excess Model calculations appear to provide robust description from RHIC down to SPS energies Measurements consistent with in-medium ρ broadening – expected to depend on total baryon density 49 2015-09-21 F.Geurts (STAR), NPA 904–905 (2013) 217c T. Sakaguchi, xQCD2015@Wuhan, China

50. NA60 low mass: comparison with models Excess shape consistent with broadening of the  (Rapp-Wambach) Models predicting a mass shift (Brown-Rho) ruled out These conclusions are also valid as a function of p T (see parallel talk) Predictions for In-In by Rapp et al. (2003) for = 140 Theoretical yields folded with NA60 acceptance and normalized to data in the mass window m  < 0.9 GeV 2015-09-21 50 T. Sakaguchi, xQCD2015@Wuhan, China

51. 2015-09-21 51 Analysis Reconstruct Mass and pT of e+e- – Same as real photons – Identify conversion photons in beam pipe using and reject them Subtract combinatorial background Apply efficiency correction Subtract additional correlated background: – Back-to-back jet contribution – well understood from MC Compare with known hadronic sources π0π0 π0π0 e+e+ e-e- e+e+ e-e- γ γ π0π0 e-e- γ e+e+ T. Sakaguchi, xQCD2015@Wuhan, China

52. Hadron physics in one slide 2015-09-21 52 Daniel Cebra, APS April meeting, 2013 EPJC 72 (2012)1945 T. Sakaguchi, xQCD2015@Wuhan, China

53. An ambitious probe: Muons No photon conversion – Ideal for high rate experiment Main background for muons –  from  (BR= 99.9%,  =2.60e-8 s) –  from K (BR= 63.6%,  =1.24e-8 s) A challenging measurement – Need careful design on absorber thickness to stop hadrons and let muons punch through Čerenkov detector is helpful? – e.g., Aerogel: n=1.005-1.08 –  : p>1.05~0.25GeV/c, –  : p>1.39~0.34GeV/c – Also look at Čerenkov cone angle 2015-09-21 53 From b<1fm JAM simulation T. Sakaguchi, xQCD2015@Wuhan, China

54. PID and momentum resolution TOF resolution 50ps  /K separation 2.5GeV/c (2.5  )  p/p = 0.7% - 5% (0.5-5GeV/c) 54 Forward Barrel 2015-09-21T. Sakaguchi, xQCD2015@Wuhan, China

55. JFY 2009 JFY 2008 JFY 2006 / 2007 Neutrino Beam Line to Kamioka (NU) Materials & Life Science Facility (MLF) 3 GeV Rapid Cycling Synchrotron (RCS) Hadron Experimental Hall (HD) 400 MeV H - Linac 50 GeV Main Ring Synchrotron (MR) [30 GeV at present] J-PARC (JAEA & KEK) 1 MW 0.75 MW 55