1. Physics motivation 2. J-PARC E45 3. Detector status 5. Summary 11/21/2014 1

Transcription

1 Baryon spectroscopy with (p,2p) reactions at J-PARC E45 Hiroyuki Sako ASRC/J-PARC, JAEA for J-PARC E45 Collaboration PWA8/ATHOS3, 13 Apr 2015, GWU 1. Physics motivation 2. J-PARC E45 3. Detector status 5. Summary 11/21/2014 1

2 J-PARC E45 Studies of baryon resonances in (p,2p) reactions for Precise measurements of baryon resonance properties Many resonances have not been established experimentally ppn has strong coupling to high mass resonances Not enough (p,2p) experimental data since 1970 s Deeper understanding of non-perturbative QCD Search for new baryon states e.g. hybrid baryons (qqqg) p N* p p N N 2

3 Baryon mass: Exp vs QM (PDG) Missing baryons Quark model does not describe well N* mass levels. Orders of mass levels are different PDG 2014 **** *** * ** Most of the N*s so far were Measured from established 3

4 Dynamical coupled-channels model (ANL-Osaka) Partial wave (LSJ) amplitude of a b reaction: Physical N*s will be a mixture of the two pictures: For details see Matsuyama, Sato, Lee, Phys. Rep. 439,193 (2007) Kamano s talk (Apr 14) Reaction channels: baryon coupled-channels effect meson cloud meson core Transition potentials: 2012 May 18 exchange potentials of ground state mesons and baryons JAEA Seminar bare N* states 4

5 Importance of Npp Decay H. Kamano, et al. PRC (2009) 5

6 World s pn ppn data Only 240K bubble chamber data in 1970 s No channel coupling With channel coupling ppn center of mass energy H. Kamano et al., PRC 79, (2009). 6

7 Note: Not real mass! Recent Lattice QCD calculations J. Dudek et al., PRD85 (2012) Hybrid baryons (qqqg) N(939) 7

8 400 MeV LINAC 3 GeV Synchrotron Neutrino Beams (T2K experiment) Materials and Life Experimental Facility Bird s eye photo in January of Hadron Exp. Facility J-PARC (MW proton synchrotron)

9 Strange ness Hadron Experimental Facility Hypernuclei d u d s u /cycle p beams 10 8 /cycle p beams 10 6 /cycle K beams (2017) cycle ~ 6s Z L,X LL, X Hypernuclei L, S Hypernuclei N SKS 6 LLHe K1.8 Pentaquark + K1.8BR KL K1.1 K meson Implantation of Kaon and the nuclear shrinkage Quark E16 Free quarks Bound quarks 2014/03/17 Kaonic nucleus J-PARC HI WS, K. Ozawa Why are bound quarks heavier? Vector meson in nucleus 9

10 E45 HypTPC Spectrometer Measure (p,2p) in large acceptance TPC in dipole magnetic field p - p p + p - n, p 0 p - p + p p 0 p + p, p + p + n pn KY (2-body reaction) p - p K 0 L, p + p K + S + (I=3/2, D*) 2 charged particles + 1 neutral particle missing mass technique Trigger with hodoscope p +- beam on liquid-h target (p= GeV/c W= GeV) p beam LH target Superconducting Helmholtz Dipole magnet Hyp-TPC 10

11 Gas vessel HypTPC Field cage (sensitive volume) Large acceptance H-target inside TPC 70φ Target holder 500φ P-10 gas p + E=180V/cm High-rate capable TPC Gating Grid GEM(Gas Electron Multiplier) Suppression of positive-ion backflow causing position distortions p - beam n e- Liquid H target ionization p - Electron drift ~550 B=1.5T Good position resolution with magnetic field and finesegmented pads p/k/p separation de/dx vs p Gating grid wires GEM (e amplification) Pad plane 11

12 544 GEM (Gas Electron Multiplier) Target position GEM (250mmx250mm) sheets 3-GEM layers 50mm + 50mm +100mm thick Gain ~ 10 4 Hit distribution (GEANT) Segmented electrodes to reduce spark rate / electrode to minimize acceptance loss when an electrode is broken due to discharge 12

13 Readout pad configuration Pad size 2.4 x 9 mm 2 (inner layer) 2.4 x 13 mm 2 (outer layer) 32 pad rows (rings) No. of pads = Position resolution <300mm (L>10cm) 520 Dp/p=1-3% (p,p)

14 Detector simulation (GEANT) p1 p- p p3 p2 p- coplanarity =cosine of angle Between p1 and (p2xp3) 3-body reaction Elastic scattering (Same trigger condition) p - p p - p 0 p reaction MM 2 (π ± p) Rejected events by coplanarity cut Cut on coplanarity cut. Only 3-body reaction can be survived.

15 Particle identification p - p K + p - p + K + p p + p/k : p<=0.5 GeV/c p/p : p<=1.1 GeV/c w/ Hodoscope TOF s T = 100ps 15

16 Trigger efficiency 2-charged particle trigger (inefficiency due to double hit) 80 cm Proposed hodoscope with 32 segments.

17 17 Acceptance p + p p + p 0 p reaction

18 Data statistics (p,2p) cross section : ~2 mb p Beam rate : ~10 6 / cycle (6s) Liquid H target : 5cm length TPC acceptance : 40% 160 events / cycle Dominant background: elastic scattering (s total = 40 mb trigger rate = 3200 events / cycle ~ 800 Hz in maximum (4s flat top)) Energy range : GeV No. of bins : p - beam : 24 (energy) x 20 (angle) p + beam : 23 (energy) x 20 (angle) No. of events / bin : 32 K 30M events in 15 days Increase world s ppn data (240K) by factor of

19 TPC prototype test NIMA763(2014)65-81 Beam test at RCNP Proton beam at 400 MeV Beam rate up to 10 6 Hz /cm 2 Hit position distortion <0.1mm Proton beam TPC 3m SSD Ion backflow ~ 5% (bench test) Efficiency vs rate Position resolution (B=0) s x =0.40mm (4mm pad) 19

20 10cm HypTPC test GET(General Electronics for TPC) readout system 70cm AsAd(amplifier/ADC) r-cobo (data collector) HypTPC Mar 2015

21 HypTPC test with 55 Fe (x-ray) source Gain : 120fC, Shap T: 70ns, GEM Curr.: 315 ma 2.7 kev peak 5.9 kev peak ΔE/E :14.3 ± 0.2 % (Peak)/(Esp. Peak): 0.52 ± 0.01 Diffusion size : 1.87 ± 0.02 mm cf. prototype TPC(5 cm to 10 cm) : 1.7 ~ 2.0 mm The TPC operation is consistent with the prototype TPC!!

22 Physics possibilities with HypTPC H-dibaryon (E42) : K - C K + H X, H LL,Lp - p L(1405) : p - p K 0 L(1405) L(1405) Lg (KN compositeness, T. Sekihara, PRC89 (2014) ) K - pp : p + d K + K - pp K - pp Lp,S 0 p,lp 0 p,s 0 p 0 p X excited states: K - p K + X - *, X -* LK -, S 0 K -, S - K 0, X - p 0, X 0 p -, X - g K - p K 0 X 0*, X 0* LK 0, S 0 K 0, S + K -, X - p + 22

23 Summary J-PARC-E45 is proposed to study baryon excited states in (p,2p) reactions, which will improve previous data statistics by two orders of magnitude. Large acceptance TPC in high rate operation will realize the experiment. E45 spectrometer will be ready for beams in 2016 with the TPC and the magnet. PWA with dynamical coupled channels model in collaboration with theorists (H. Kamano, T. Sato,..) 23

24 E45 collaboration list K. H. Hicks, S. Chandavar, J. Goetz, W. Tang (Ohio University, USA) H. Sako, K. Imai, S. Hasegawa, S. Sato, K. Shirotori, S.H. Hwang (Japan Atomic Energy Agency, Japan) S.H. Kim, S.J. Kim, S.Y. Kim, A. Hi, J.Y. Park, S.Y.Ryu (Pusan National University, Korea) J.K. Ahn (Korea University, Korea) H. Fujioka, S. Nakamura, M. Niiyama (Kyoto University, Japan) K. Ozawa (KEK, Japan) B. Bassalleck, Y. Han (University of New Mexico, USA) K. Joo, N. Markov, N. Harrison, T. O Connell, E. Seder (University of Connecticut, USA) B. Briscoe, F. Klein, I. Strakovsky, R. Workman (George Washington University, USA) R. Schumacher (Carnegie Melon University, USA) D. M. Manley (Kent State University, USA) L. Guo (Florida International University, USA) P. Cole, A. Forest, D. McNulty (Idaho State University, USA) T.S.-H. Lee (Argonne National Lab, USA) T. Sato, H. Kamano (Osaka University, Japan) Y. Azimov (Petersburg Nuclear Physics Institute,Russia) V. Shklyar (University of Giessen, Germany) A. Svarc (Ruder Boskovic Institute, Hungary) S. Ceci (RBI-Zagreb, Hungary) M. Hadzimehmedovic, H. Osmanovic (University of Tulza, Bosnia/Herzegovina) 46 people form USA, Japan, Korea, and Europe 24