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Double antikaonic nuclear clusters in antiproton- 3 He annihilation at J-PARC

Double antikaonic nuclear clusters in antiproton- 3 He annihilation at J-PARC. F.Sakuma , RIKEN. C. CURCEANU (INFN Frascati , Italy), M. IWASAKI (RIKEN, Japan), P. KIENLE (TUM, Germany), H. OHNISHI (RIKEN, Japan), M. TOKUDA (TITECH, Japan), K. TSUKADA (Tohoku-U, Japan),

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Double antikaonic nuclear clusters in antiproton- 3 He annihilation at J-PARC

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  1. Double antikaonic nuclear clusters in antiproton-3He annihilation at J-PARC F.Sakuma, RIKEN C. CURCEANU (INFN Frascati, Italy), M. IWASAKI (RIKEN, Japan), P. KIENLE (TUM, Germany), H. OHNISHI (RIKEN, Japan), M. TOKUDA (TITECH, Japan), K. TSUKADA (Tohoku-U, Japan), E. WIDMANN (SMI, Austria), T. YAMAZAKI (RIKEN/U-Tokyo, Japan), J. ZMESKAL (SMI, Austria) LEAP2011 @ TRIUMF, April 27 - May 1, 2011.

  2. Outline • (brief) Introduction of • “Kaonic Nuclear Cluster” • Possibility of • “Double-Kaonic Nuclear Cluster” • in pbar+A annihilation at rest • Experimental Approach • Summary

  3. Kaonic Nuclear Cluster (KNC) • KbarN interaction is clarified to be strongly attractive by Kaonic-atom experiments in 20th. • This leads the prediction of deeply-bound kaonic nuclear cluster (KNC), as many theorists pointed out. the density of the KNC is predicted to be high density more than normal nuclear-density (r0) Density [1/fm3] T.Yamazaki, A.Dote, Y.Akiaishi, PLB587, 167 (2004). we will open new door to the high density matter physics, like the inside of neutron stars

  4. Experimental Situation of KNC B.E. = 103MeV G = 118MeV B.E. = 115MeV G = 67MeV K-ppLp? K-ppLp? FINUDA@DAFNE DISTO@SATUREN PRL, 94, 212303 (2005) PRL,104,132502 (2010) stopped-K- + A  (L + p) + X 2.85GeV-p + p  (L + p) + K+ We need more evidences in various channels! Because there is a discrepancy between THEORETICAL PREDICTIONS and EXPERIMENTAL OBSERVATIONS…

  5. J-PARC E15 Experiment • search for the K-pp using 3He(in-flight K-,n) reaction Neutron ToF Wall K1.8BR Beam Line Sweeping Magnet Beam Line Spectrometer Beam trajectory CDS & target Neutron Counter neutron flight length = 15m Cylindrical Detector System Missing mass Spectroscopyvia neutron p Beam Sweeping Magnet n K-pp L Invariant mass reconstruction p- will start next year p 1GeV/c K- beam

  6. What will happen to put one more kaon in the kaonic nuclear cluster? Possibility of “Double-Kaonic Nuclear Cluster” in pbar+A annihilation at rest • Why at rest? • probability of multi-nucleon annihilation • (exotic B>0 annihilation) should be • larger than in-flight reactions

  7. Double-Kaonic Nuclear Cluster (DKNC) The double-kaonic nuclear clusters have been predicted theoretically. ppn The double-kaonic clusters have much stronger binding energy and a much higher density than single ones. (AMD calc.) ppnK- PL,B587,167 (2004). • How to produce the double-kaonic nuclear cluster? • heavy ion collision • (K-,K+) reaction • pbarA annihilation ppnK-K- We use pbarA annihilation

  8. the DKNC in pbarA annihilation? The elementary pbar-p annihilation reaction with double-strangeness production: -98MeV This reaction is forbidden for stopped pbar, because of a negative Q-value of 98MeV if multi kaonic nuclear exists with deep bound energy, following pbar annihilation reactions will be possible! e.g. the most energetic favored decay mode final state: p- p- p+ p p- p We can investigate the DKNC with exclusive or semi-inclusive measurement

  9. Related Topics Of course we can measure K-pp production with the dedicated detector, simultaneously. We can also search for H-dibaryon (H-resonance) by using LL invariant mass / missing mass. OBELIX@CERN-LEAR E522@KEK-PS H? K-pp? PRC75 022201(R) (2007). NP, A789, 222 (2007). EPJ, A40, 11 (2009). Our experiment can check the OBELIX results of the K-pp with a dedicated spectrometer The exclusive H search with stopped-pbar beam has never been done.

  10. Past Experiments of Double-Strangeness Production in Stopped-pbar Annihilation There are NO results of the DKNC search, but several groups reported double-strangeness production in pbar+A annihilation hydrogen bubble-chamber experiment @ BNL in association with the H-dibaryon search They did NOT observe any double-strangeness event in pbar - C, Ti, Ta, Pb annihilation (~80,000 events, p < 400 MeV/c) [Phys.Lett., B144, 27 (1984).]

  11. Past Experiments of Double-Strangeness Production in Stopped-pbar Annihilation Although observed statistics are very small, their results have indicated a high yield of ~10-4

  12. The double-strangeness production yield of ~10-4 makes it possible to explore the exotic systems. Experimental Approach

  13. Experimental Strategy • Current situation of the double-strangeness production in pbar+A (A>2) annihilation at rest: • NO results using a dedicated spectrometer except for bubble chamber experiments. • NO results with high-statistics measurement. investigation of “double-strangeness production” in pbar+3He annihilation at rest, with high statistics data search for “double-kaonic nuclear cluster” in pbar+3He annihilation at rest

  14. Setup We will perform the proposed experiment at J-PARC K1.8BR beam line K1.8BR Beam Line • key points • high intensity pbar beam • low mass material detector • wide acceptance detector CDS & target Beam Line Spectrometer 0.9GeV-K- + A  L + X ~2800 L smass=3.5+/-0.1MeV/c2 preliminary reconstructed pp- inv. mass in commissioning run (2010, Oct.)

  15. pbar Beam @ J-PARC K1.8BR • 50kW, 30GeV • 6.0degrees • Ni-target pbar stopping-rate evaluation by GEANT4 • Incident Beam • momentum bite : +/-2.5% (flat) • incident beam distribution : ideal 6.5x103/spill/3.5s @ 0.7GeV/c pbarproduction yield with a pbar CS parameterization • Detectors • Tungsten Degrader : r=19.25g/cm3 • Plastic Scintillator : l=1cm, r=1.032g/cm3 • Liquid He3 target : f=7cm, l=12cm, r=0.080g/cm3 250 stopped pbar/spill @ 0.7GeV/c, ldegrader~3cm pbar stopping-rate

  16. Trigger Scheme expected stopped-pbar yield = 250/spill @ 50kW All events with a scintillator hit can be accumulated pbar+3He charged particle multiplicity at rest CERN LEAR, streamer chamber exp. NPA518,683 (1990). expected K-K-pp event

  17. Experimental Strategy • present situation of the double-strangeness production in pbar+A (A>2) annihilation at rest: • NO results with a dedicated spectrometer and high intensity beam except for bubble chamber experiments. • high-statistics measurement is NOT performed! investigation of “double-strangeness production” in pbar+3He annihilation at rest search for “double-kaonic nuclear cluster” in pbar+3He annihilation at rest

  18. Double-Strangeness Measurement acceptances of K+K+ and LL • evaluated using GEANT4 toolkit • Many-body decay are considered to be isotropic decay. • branching ratios of K0K0S/K0Sp+p-/Lpp-are included. • acceptance is defined by CDC CDS @ K1.8BR

  19. Double-Strangeness Measurement (Cont’d) 30kW, 1week sensitivity 30kW, 2weeks 30kW, 6weeks sensitivity to 100 double-strangeness events (~10s) detection is evaluated by the MC. OBELIX/ DIANA 50kW, 6weeks 1.E-04 production-yield (/stopped-pbar) • * The following are included • duty factor of the accelerator and apparatus : 21h/24h • DAQ and analysis eff. : 0.7 100kW, 6weeks number of proton on target if we assume the double-strangeness production-yield to be 10-4 / stopped-pbar as reported by the OBELIX and DIANA groups: expected yield

  20. Experimental Strategy • present situation of the double-strangeness production in pbar+A (A>2) annihilation at rest: • NO results with a dedicated spectrometer and high intensity beam except for bubble chamber experiments. • high-statistics measurement is NOT performed! investigation of “double-strangeness production” in pbar+3He annihilation at rest search for “double-kaonic nuclear cluster” in pbar+3He annihilation at rest

  21. Procedure of the K-K-pp Search • methods of the measuremt • (semi-inclusive) K0K+ missing-mass w/ L-tag • (inclusive) LL invariant mass • (exclusive) K0K+LL measurement --- K0K+ w/ L-tag --- LL --- K0K+LL acceptance • evaluated using GEANT4 toolkit • G(K-K-pp) = 100 MeV • isotropic decay • branching ratios of K0K0S/K0Sp+p-/Lpp-are included. K-K-pp binding energy

  22. Backgrounds (semi-inclusive) K0K+ missing-mass w/ L-tag signal • stopped-pbar + 3He  K0 + K+ + K-K-pp • stopped-pbar + 3He  K0 + K+ + L + L • stopped-pbar + 3He  K0 + K+ + L + L + p0 … • stopped-pbar + 3He  K0 + K+ + K0 + S0 + (n) • stopped-pbar + 3He  K0 + K+ + X0 + (n) … 3N annihilation 2N annihilation K0K+ missing-mass *each spectrum is obtained with the same production yield

  23. Backgrounds (Cont’d) (inclusive) LL invariant mass signal • stopped-pbar + 3He  K0S + K+ + K-K-pp • L + L • stopped-pbar + 3He  K0S + K+ + K-K-pp •  S0 + S0 • stopped-pbar + 3He  K0S + K+ + K-K-pp •  S0 + S0 + p0 … missing 2g missing 2g+p0 LL invariant mass B.E = 200 MeV G = 100 MeV *each spectrum is obtained with the same production yield

  24. Expected Yield Sensitivity to the K-K-pp observation is estimated using the MC • branching ratio: • BR(K-K-ppLL) = 0.25 • BR(K-K-ppS0S0 = 0.25 • BR(K-K-pp S0S0 p0) = 0.5 assumptions • total yield : upper limit of pbarAKKX, 5x10-4 • 3N : 20% of yield, and 3N:2N = 1:3 • K-K-pp yield : parameter • production yield: • K-K-pp bound-state = ? • (3N) K-K-LL phase-space = 5x10-5 • (3N) K+K0S0S0p0 phase-space = 5x10-5 • (2N) K+K0K0S0(n) phase-space = 3x10-4 • non-mesonic : mesonic= 1 : 1

  25. Sensitivity to the K-K-pp signal (Exclusive) significance [s=S/sqrt(S+B)] is obtained in exclusive missing-mass spectra 50kW, 6weeks --- BKK = 120 MeV --- BKK = 150 MeV --- BKK = 200 MeV 100kW, 6weeks 3s significance of K-K-pp production yield (/stopped-pbar) 270kW, 6weeks 30kW, 6weeks number of proton on target

  26. Expected Spectra @ 50kW, 6weeks • assumption in the figures: • K-K-pp production yield • = 10-4/stopped-pbar • B.E. = 200 MeV • G = 100 MeV K+K0 missing mass (2K2L) LL invariant mass # of K-K-pp = 32 # of K-K-pp LL = 357 The signal can be discriminated from the other backgrounds in the exclusive K+K0 missing mass spectrum. LL invariant mass K+K0 missing mass # of K-K-pp LL = 15 # of K-K-pp = 208

  27. Summary • We will search for Double-Kaonic Nuclear Cluster (DKNC) by pbar + 3He annihilation at rest, using the pbar + 3He  K+ + K0 + X (X = K-K-pp) channel @ J-PARC K1.8BR beam line. • In preparation for the DKNC search, double-strangeness production measurement will be conducted as a first step. • We are now improving this experimental idea toward the proposal submission to J-PARC.

  28. Schedule The proposed experiment will start in around JFY2015???

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