Plan of η mesic nucleus spectroscopy with (p,d) reaction at GSI and FAIR

Transcription

1 Hadron in Nucleus Kyoto Plan of η mesic nucleus spectroscopy with (p,d) reaction at GSI and FAIR Yoshiki K. Tanaka (Univ. of Tokyo) for the η-prime collaboration

2 η-prime collaboration K.-T. Brinkmann, S. Friedrich, H. Fujioka, H. Geissel, R.S. Hayano, Y. Higashi, S. Hirenzaki, Y. Igarashi, N. Ikeno, K. Itahashi, S. Itoh, M. Iwasaki, D. Jido, V. Metag, T. Nagae, H. Nagahiro, M. Nanova, T. Nishi, K. Okochi, H. Outa, K. Suzuki, T. Suzuki, Y.K. Tanaka, Y.N. Watanabe, H. Weick, H. Yamakami University Giessen, Kyoto University, GSI, The University of Tokyo, Nara Women's University, KEK RIKEN Nishina Center, Tokyo Metropolitan University, SMI 2

3 η meson Mass M=958 MeV/c 2 Γ=0.199 MeV Pseudoscalar meson ( J π =0 - ) Decay mode π + π - η(43%), ρ 0 γ(29%), π 0 π 0 η(22%) 3

4 η meson Mass Mass M=958 MeV/c 2 Γ=0.199 MeV UA(1) problem : Mη < 3Mπ Pseudoscalar meson ( J π =0 - ) Weinberg, 1975 Decay mode π + π - η(43%), ρπ(29%), π 0 π 0 γ(22%) 3 Mπ 4

5 η meson η η 0 UA(1) anomaly η π,k,η 8, η 0 K π π,k,η 8 massless m q = m s =0 m q = m s =0 m q = m s =0 qq =0 qq =0 qq =0 ChS manifest ChS broken dynamically ChS broken dynamically and explicitly 5

6 η meson UA(1) anomaly effect on η mass - KMT interaction in NJL model - related to the strength of chiral condensate <qq> - Kobayashi-Maskawa- t Hooft 6-point vertex by Hirenzaki Kobayashi, Maskawa, PTP44(70)1422 t Hooft, PRD14(76)3432. T. Kunihiro, Phys. Lett. B219(89)363. Klimt, Lutz, Vogl, Weise, NPA516(90)429. 6

7 in-medium mass - Chiral condensate <qq> - decreases by ~30% at ρ0. - Mass reduction expected e.g., NJL model calculation 150 MeV/c 2 mass reduction partial restoration of chiral symmetry -30 % K. Suzuki et al., PRL92(04) ρ0 7

8 in-medium mass η nucleus optical potential : Vη =(V0+iW0) ρ(r) ρ0 V0=Δm(ρ0), W0=-Γ(ρ0) / 2 - NJL model prediction ~ 150 MeV/c 2 reduction at ρ0 strong attraction? 8

9 in-medium mass η nucleus optical potential : Vη =(V0+iW0) ρ(r) ρ0 V0=Δm(ρ0), W0=-Γ(ρ0) / 2 - NJL model prediction ~ 150 MeV/c 2 reduction at ρ0 strong attraction? - CBELSA/TAPS (talk by M. Nanova) ~ 40 MeV/c 2 reduction at ρ0 - relatively small scattering length of the s-wave η -proton interaction a η p ~ 0.1 fm P. Moskal et al., PLB482(00)356. ~ 8 MeV/c 2 mass reduction at ρ0 H. Nagahiro et al., Phys. Lett. B 709 (2012) 87 9

10 in-medium width η nucleus optical potential : Vη =(V0+iW0) ρ(r) ρ0 V 0 =Δm(ρ0), W 0 =-Γ(ρ0) / 2 - Γ (ρ0) ~ MeV deduced by CBELSA/TAPS transparency ratio measurement 10

11 in-medium width η nucleus optical potential : Vη =(V0+iW0) ρ(r) ρ0 V 0 =Δm(ρ0), W 0 =-Γ(ρ0) / 2 - Γ (ρ0) ~ MeV deduced by CBELSA/TAPS transparency ratio measurement W0 smaller than possible mass reduction V0 η mesic nuclei may exist! 11

12 Theoretical spectra of 12 C(p,d) 11 C η η nucleus optical potential : proton energy 2.5 GeV Green s function method Vη =(V0+iW0) ρ(r) ρ0 V 0 =Δm(ρ0), W 0 =-Γ(ρ0) / 2 12

13 Theoretical spectra of 12 C(p,d) 11 C η η nucleus optical potential : proton energy 2.5 GeV Green s function method Vη =(V0+iW0) ρ(r) ρ0 V 0 =Δm(ρ0), W 0 =-Γ(ρ0) / 2 13

14 Experimental Plan at GSI 14

15 Missing mass spectroscopy of (p,d) reaction 2.5 GeV proton beam momentum measurement missing mass Target η mesic nuclei 1st Step : Inclusive measurement of (p,d) reaction at GSI - no assumption on decay process - small S/N ratio background processes (e.g., multi-pion production) 15

16 Missing mass spectroscopy of (p,d) reaction 2.5 GeV proton beam momentum measurement missing mass Target η mesic nuclei 1st Step : Inclusive measurement of (p,d) reaction at GSI - no assumption on decay process - small S/N ratio background processes (e.g., multi-pion production) high-statistics measurement needed! w/ high-intensity beam + thick target 16

17 GSI facilities 12 C target momentum analysis proton beam 2.5 GeV, /spill 17

18 Experimental setup at FRS p (T=2.5GeV, /spill) 12 C target 2 (4 g/cm ) d (P= GeV/c, β= , ~0.5 khz) MWDC 2 momentum compaction slit dispersive Fragment Separator (FRS) Scintillator 72m Aerogel Cherenkov 18

19 Experimental setup at FRS p (T=2.5GeV, /spill) 12 C target 2 (4 g/cm ) d (P= GeV/c, β= , ~0.5 khz) momentum measurement MWDC 2 momentum compaction slit dispersive Fragment Separator (FRS) Scintillator 72m Aerogel Cherenkov 19

20 Experimental setup at FRS p (T=2.5GeV, /spill) p/d separation 12 C target 2 (4 g/cm ) - Aerogel Cherenkov (veto trigger) - TOF (offline) p (β= , ~50 khz) d (P= GeV/c, momentum measurement β= , ~0.5 khz) MWDC 2 momentum compaction slit dispersive Fragment Separator (FRS) Scintillator 72m Aerogel Cherenkov 20

21 Experimental setup at FRS p (T=2.5GeV, /spill) 12 2 C target (4 g/cm ) secondary background d (P= GeV/c, β= , ~0.5 khz) momentum measurement MWDC 2 momentum compaction slit dispersive Fragment Separator (FRS) Scintillator 72m Aerogel Cherenkov 21

22 Experimental setup at FRS p (T=2.5GeV, /spill) 12 C target 2 (4 g/cm ) d (P= GeV/c, β= , ~0.5 khz) overall missing-mass resolution : σ = 1.6 MeV/c 2 sufficient! momentum measurement MWDC 2 momentum compaction slit dispersive Fragment Separator (FRS) Scintillator 72m Aerogel Cherenkov 22

23 Simulated spectrum in 4.5 days DAQ Inclusive spectrum assuming 4.5 day DAQ V0, W0 : real, imaginary part of optical potential - background processes based on COSY-ANKE data/simulation [2] counts/2mev counts/2mev counts/2mev counts/2mev (V, W )= (200, 5) MeV 0 0 (V, W )= (200, 10) MeV 0 0 (V, W )= (200, 20) MeV 0 0 (V, W )= (150, 5) MeV 0 0 ʼ (V, W )= (150, 10) MeV 0 0 (V, W )= (150, 20) MeV 0 0 πʼ (V, W )= (100, 5) MeV 0 0 (V, W )= (100, 10) MeV 0 0 Simulation (V, W )= (100, 20) MeV S/N ratio ~ O(1/100) at most counts/2mev counts/2mev [2] S. Barsov et al., EPJ A21, 521 (2004); I. Lehmann, Ph.D thesis (2003) Excitation Energy [MeV] Excitation Energy [MeV] Excitation Energy [MeV] Excitation Energy [MeV] Excitation Energy [MeV] Excitation Energy [MeV]

24 Structure-finding sensitivity 24

25 Structure-finding sensitivity 25

26 Preparation status and Prospect Aerogel Cherenkov detector - high-index aerogel (n=1.18) - developed and tested in 2012 MWDC - use conventional type - setting up on-going FRS optics mode - new optics mode of FRS has been developed. - further improvement is in progress. 26

27 High index aerogel Cherenkov detector - n=1.18 high-refractive-index silica aerogel - PID (p/d) at trigger level 27 cm PMT 4 aerogel module mirror box + PMT 2 cm aerogel thick aerogel proton proton proton photon photon mirror mirror box side view PMT 4 PMT 4 PMT 4 27

28 High index aerogel Cherenkov detector - n=1.18 high-refractive-index silica aerogel - PID (p/d) at trigger level count [a.u.] Test results with deuteron beam@gsi signal-like β=0.84 background-like β= cm aerogel module mirror box + PMT number of photoelectrons We achieved > 99.5% BG rejection w/ a few % signal overkill at online level 28

29 Preparation status and Prospect Aerogel Cherenkov detector - high-index aerogel (n=1.18) - developed and tested in 2012 MWDC - use conventional type - setting up on-going FRS optics mode - new optics mode of FRS has been developed. - further improvement is in progress. 29

30 FRS optics simulation with GICOSY newly-developed mode using GICOSY[1] S2 : achromatic focus S4 : dispersive focus (D=4cm/%) Small dispersion kept throughout FRS ± 3% Bρ acceptance ± 65 MeV in Eη beam plot for X, Y = ± 1.5 mm X = ± 8 mrad Y = ± 10 mrad δ = δp/p0 = ± 1.5 % n X-MAX 0.2 m X-MAX m Y-MAX m Y-MAX 0.2 m target o 30 dipole D1 X-direction quadrupole MAGNETIC SECTOR Y-direction MAGNETIC SECTOR S1 D2 MAGNETIC SECTOR MAGNETIC SECTOR S4 S3 S2 achromatic MAGNETIC SECTOR D3 SC1 in progress MAGNETIC SECTOR MAGNETIC SECTOR D4 MWDC dispersion D=4cm/% MAGNETIC SECTOR SC [1] m 10 m 30

31 FRS optics simulation with GICOSY newly-developed mode using GICOSY[1] S2 : achromatic focus S4 : dispersive focus (D=4cm/%) Small dispersion kept throughout FRS ± 3% Bρ acceptance ± 65 MeV in Eη beam plot for X, Y = ± 1.5 mm X = ± 8 mrad Y = ± 10 mrad δ = δp/p0 = ± 1.5 % [1] n X-MAX 0.2 m X-MAX m Y-MAX m [X,δ] target X-direction quadrupole cm/% TA cm/% MAGNETIC SECTOR o 30 dipole D1 MAGNETIC SECTOR S1 D2 MAGNETIC SECTOR MAGNETIC SECTOR S2 MAGNETIC SECTOR D3 MAGNETIC SECTOR S3 SC1 MAGNETIC SECTOR D4 MWDC ETA-S2-ACHR-5 BEAM PLOT XX.XX.XXX YY:YY:YY Dispersion m 10 m 31 achromatic in progress standard: -6.5cm/% MAGNETIC SECTOR S4 dispersion D=4cm/% SC new: 4 cm/% S4

32 Preparation status and Prospect Aerogel Cherenkov detector - high-index aerogel (n=1.18) - developed and tested in 2012 MWDC - use conventional type - setting up on-going FRS optics mode - new optics mode of FRS has been developed. - further improvement is in progress. 32

33 Preparation status and Prospect Aerogel Cherenkov detector - high-index aerogel (n=1.18) - developed and tested in 2012 MWDC - use conventional type - setting up on-going FRS optics mode - new optics mode of FRS has been developed. - further improvement is in progress. Experiment is now almost ready. Integrity test at COSY is scheduled in Jan First pilot experiment at GSI is expected in

34 Future Plan at FAIR 34

35 FAIR facilities Facility for Antiproton and Ion Research (FAIR) p-linac SIS-18 SIS-100 / SIS-300 UNILAC HESR PANDA CBM Rare Isotope Production Target Super-FRS Plasma Physics Antiproton Production Target 50 m Atomic Physics RESR/ CR FLAIR NESR 35

36 Future plan at FAIR 1st Step : Inclusive measurement of (p,d) reaction with FRS at GSI 2nd Step : Semi-exclusive measurement of (p,dp) with Super-FRS at FAIR missing-mass measurement w/ S-FRS Target η mesic nuclei 36

37 Future plan at FAIR 1st Step : Inclusive measurement of (p,d) reaction with FRS at GSI 2nd Step : Semi-exclusive measurement of (p,dp) with Super-FRS at FAIR missing-mass measurement w/ S-FRS decay of η mesic nuclei : η N ηn or πn η NN NN Target η mesic nuclei Tagging proton in coincidence with deuteron drastically improve S/N ratio sensitivity to smaller V0 37

38 Experimental setup at Super-FRS Target + decay proton counter deuteron pre-separator 2.5 GeV proton from SIS-100 Super-FRS momentum analysis SCI 38 MWDC 2 Aerogel Cherenkov

39 signal η mesic nuclei background multi-π production cosθ (Lab.) Tagging decay proton count [a.u.] 1 nucleon absorption 2 nucleon absorption Proton by FSI proton momentum [GeV/c] 39 cos (Lab.) π - FSI proton momentum [GeV/c] proton momentum [GeV/c] JAM simulation (preliminary)

40 Decay proton counter Requirements : - π/p separation - proton momentum of GeV/c Sampling calorimeter - PID(π/p) by ΔE i pattern and Range - ~10 layers of Scintillator and Brass On-going study : - optimization of detector configuration and algorithm of pattern recognition proton beam deuteron proton conceptual design 40

41 Belle-II CDC readout board - 64ch readout board (ASD+FADC+TDC) - Dead time ~ 0.5% at 10 khz trigger rate (2012 Mar. JPS meeting, Taniguchi et al. ) - for readout MWDCs On-going work : - modification to fit general purposes (event matching etc.) - testing data acquisition with MWDC 41

42 Summary We are planning missing-mass spectroscopy of η mesic nuclei with (p,d) reaction to study in-medium properties of η meson. With large mass reduction (~100MeV) and narrow decay width (~20MeV), η mesic nuclei may be observed in inclusive spectrum. Inclusive measurement using FRS at GSI is almost ready. First pilot experiment is expected in At FAIR, we plan a semi-exclusive measurement of (p,dp) reaction with decay proton counter and Super-FRS. Tagging decay protons could improve S/N ratio drastically. R&D is presently on-going. 42