1. Double antikaonic nuclear clusters in antiproton- 3 He annihilation at J-PARC F.Sakuma, RIKEN 1 LEAP2011 @ TRIUMF, April 27 - May 1, 2011. 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)

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

3. we will open new door to the high density matter physics, like the inside of neutron stars Kaonic Nuclear Cluster (KNC) 3 T.Yamazaki, A.Dote, Y.Akiaishi, PLB587, 167 (2004). Density [1/fm 3 ] high density the density of the KNC is predicted to be high density more than normal nuclear-density (  0 ) K bar N interaction strongly attractive K bar N interaction is clarified to be strongly attractive by Kaonic-atom experiments in 20 th. deeply-bound kaonic nuclear cluster (KNC) This leads the prediction of deeply-bound kaonic nuclear cluster (KNC), as many theorists pointed out.

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

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

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

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

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

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

10. 10 Past Experiments of Double-Strangeness Production in Stopped-p bar Annihilation They did NOT observe any double-strangeness event in p bar - C, Ti, Ta, Pb annihilation (~80,000 events, p < 400 MeV/c) ReactionFrequency (90% C.L.) p bar A   0  0 X <4x10 -4 p bar A   0 K - X <5x10 -4 p bar A  K + K + X <5x10 -4 p bar A  HX<9x10 -5 [Phys.Lett., B144, 27 (1984).] There are NO results of the DKNC search, but several groups reported double-strangeness production in p bar +A annihilation hydrogen bubble-chamber experiment @ BNL in association with the H-dibaryon search

11. 11 Past Experiments of Double-Strangeness Production in Stopped-p bar Annihilation experimentChannel# of eventsyield (x10 -4 )DIANA@ITEP [p bar +Xe] PLB464, 323 (1999). K+K+XK+K+X40.31+/-0.16 K+K0XK+K0X32.1+/-1.2 OBELIX@CERN/LEAR [p bar + 4 He] NPA797, 109 (2007). K+K+--psK+K+--ps 34+/-80.17+/-0.04 K+K+-+n-K+K+-+n- 36+/-62.71+/-0.47 K+K+-nK+K+-n 16+/-41.21+/-0.29 K + K + K -  nn 4+/-20.28+/-0.14 Although observed statistics are very small, their results have indicated a high yield of ~10 -4

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

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

14. K1.8BR Beam Line CDS & target Beam Line Spectrometer 14 Setup We will perform the proposed experiment at J-PARC K1.8BR beam line at J-PARC K1.8BR beam line ~2800   mass =3.5+/-0.1MeV/c 2 key points high intensity p bar beam low mass material detector wide acceptance detector reconstructed p  - inv. mass in commissioning run (2010, Oct.) 0.9GeV-K  + A   + X

15. 15 p bar Beam @ J-PARC K1.8BR p bar stopping-rate  50kW, 30GeV  6.0degrees  Ni-target p bar production yield with a p bar CS parameterization 250 stopped p bar /spill @ 0.7GeV/c, l degrader  3cm Incident Beam momentum bite : +/-2.5% (flat) incident beam distribution : ideal Detectors Tungsten Degrader :  = 19.25g/cm 3 Plastic Scintillator : l=1cm,  =1.032g/cm 3 Liquid He3 target :  =7cm, l=12cm,  =0.080g/cm 3 p bar stopping-rate evaluation by GEANT4 6.5x10 3 /spill/3.5s @ 0.7GeV/c

16. 16 Trigger Scheme p bar + 3 He charged particle multiplicity at rest CERN LEAR, streamer chamber exp. NPA518,683 (1990). NcBranch (%) 15.14 +/- 0.04 339.38 +/- 0.88 548.22 +/- 0.91 77.06 +/- 0.46 90.19 +/- 0.08 4.16 +/- 0.06 expected stopped-p bar yield = 250/spill @ 50kW All events with a scintillator hit can be accumulated expected K-K-pp event

17. 17 Experimental Strategy I.investigation of “double-strangeness production” in p bar + 3 He annihilation at rest II.search for “double-kaonic nuclear cluster” in p bar + 3 He annihilation at rest present situation of the double-strangeness production in p bar +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!

18. 18 Double-Strangeness Measurement K + K +  - channelK + K 0  channel K + detection 2.4 x 10 -1  detection 4.1 x 10 -2 K + K +  detection 4.4 x 10 -2  K + detection 2.1 x 10 -2 K + K +  - detection 2.8 x 10 -2  K + K 0 detection 2.9 x 10 -3 CDS @ K1.8BR evaluated using GEANT4 toolkit Many-body decay are considered to be isotropic decay. branching ratios of K 0  K 0 S /K 0 S      /   p   are included. acceptance is defined by CDC acceptances of K + K + and 

19. 19 Double-Strangeness Measurement (Cont’d) 30kW, for 2weeks K + K + event750  event 130 if we assume the double-strangeness production-yield to be 10 -4 / stopped-p bar as reported by the OBELIX and DIANA groups: expected yield * The following are included duty factor of the accelerator and apparatus : 21h/24h DAQ and analysis eff. : 0.7 sensitivity 30kW, 2weeks 30kW, 6weeks 30kW, 1week 50kW, 6weeks 100kW, 6weeks OBELIX/ DIANA number of proton on target production-yield (/stopped-p bar ) sensitivity to 100 double- strangeness events (~10  ) detection is evaluated by the MC. 1.E-04

20. 20 Experimental Strategy I.investigation of “double-strangeness production” in p bar + 3 He annihilation at rest II.search for “double-kaonic nuclear cluster” in p bar + 3 He annihilation at rest present situation of the double-strangeness production in p bar +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!

21. 21 Procedure of the K - K - pp Search methods of the measuremt (semi-inclusive) K 0 K + missing-mass w/  -tag (inclusive)  invariant mass (exclusive) K 0 K +  measurement --- K 0 K + w/  -tag ---  --- K 0 K +  K - K - pp binding energy  evaluated using GEANT4 toolkit   (K - K - pp) = 100 MeV  isotropic decay  branching ratios of K 0  K 0 S /K 0 S      /   p   are included. acceptance

22. 22 Backgrounds (semi-inclusive) K 0 K + missing-mass w/  -tag  stopped-p bar + 3 He  K 0 + K + + K-K-pp  stopped-p bar + 3 He  K 0 + K + +  +   stopped-p bar + 3 He  K 0 + K + +  +  +  0 …  stopped-p bar + 3 He  K 0 + K + + K 0 +  0 + (n)  stopped-p bar + 3 He  K 0 + K + +  0 + (n) … 3N annihilation 2N annihilation signal *each spectrum is obtained with the same production yield K 0 K + missing-mass

23. 23 Backgrounds (Cont’d) (inclusive)  invariant mass  stopped-p bar + 3 He  K 0 S + K + + K-K-pp   +   stopped-p bar + 3 He  K 0 S + K + + K-K-pp   0 +  0  stopped-p bar + 3 He  K 0 S + K + + K-K-pp   0 +  0 +  0 … missing 2  missing 2  +   B.E = 200 MeV  = 100 MeV signal *each spectrum is obtained with the same production yield  invariant mass

24. production yield: K - K - pp bound-state = ? (3N) K - K -  phase-space = 5x10 -5 (3N) K + K 0  0  0  0 phase-space = 5x10 -5 (2N) K + K 0 K 0  0 (n) phase-space = 3x10 -4 24 Expected Yield  total yield : upper limit of p bar A  KKX, 5x10 -4  3N : 20% of yield, and 3N:2N = 1:3  K - K - pp yield : parameter Sensitivity to the K-K-pp observation is estimated using the MC  non-mesonic : mesonic = 1 : 1 branching ratio: BR(K - K - pp   ) = 0.25 BR(K - K - pp   0  0 = 0.25 BR(K - K - pp   0  0  0 ) = 0.5 assumptions

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

26. 26 Expected Spectra @ 50kW, 6weeks # of K - K - pp = 32 K + K 0 missing mass (2K2  ) # of K - K - pp   = 357  invariant mass # of K - K - pp   = 15 K + K 0 missing mass # of K - K - pp = 208 assumption in the figures: K - K - pp production yield = 10 -4 /stopped-p bar B.E. = 200 MeV  = 100 MeV The signal can be discriminated from the other backgrounds in the exclusive K + K 0 missing mass spectrum.

27. 27 Summary Double-Kaonic Nuclear Cluster (DKNC) by p bar + 3 He annihilation at rest We will search for Double-Kaonic Nuclear Cluster (DKNC) by p bar + 3 He annihilation at rest, using the p bar + 3 He  K + + K 0 + X (X = K - K - pp) channel @ J-PARC K1.8BR beam line. double- strangeness production In preparation for the DKNC search, double- strangeness production measurement will be conducted as a first step. proposal submission to J-PARC We are now improving this experimental idea toward the proposal submission to J-PARC.

28. 28 Schedule Year (JFY)K1.8BR 2009beam-tune 2010beam-tune 2011recovery 2012E17/E15 2013E15/E31 2014E15/E31 2015here? The proposed experiment will start in around JFY2015???