1. Search for Double Antikaon Production in Nuclei by Stopped Antiproton Annihilation P. Kienle, Excellence Cluster Universe, TU München Introduction into the search for double kaonic nuclear cluster production by stopped antiproton annihilation Experimental approach @ J-PARC Experimental approach @ AD and FAIR

2. A Proposal for the CERN AD

4. 4 Possibility of “Double-Kaonic Nuclear Cluster” Production by Stopped-pbar Annihilation Possibility of “Double-Kaonic Nuclear Cluster” Production by Stopped-pbar Annihilation Prelude to „Double-Strange Nuclei“ @ LEAP W. Weise, arXiv: 0507.058 (nucl-th) 2005 P. Kienle, J. Mod. Phys., A22 (2007) 365 P. Kienle, J. Mod. Phys., E16 (2007) 905 J. Zmeskal et al. EXA/LEAP 08, Hyper, Int J. Zmeskal et al. „Double-Strangeness Pro- duction by Antiprotons, May 2009, CERN

6. Deeply Bound Di-Baryon Resonance with Strangness S =-1 Deeply Bound Di-Baryon Resonance with Strangness S =-1 Properties p+p -> K + +X @ high momentum transfer M X = 2.265 (2) GeV/c² -> B X = 105(2) MeV Γ X = 118(8) MeV/c² Assigned to deeply bound, dense K - pp cluster with B x about twice the value predicted by AY High observed production probability is predicted by the AY reaction model for the case of a high density cluster X Consequences for Double Strange Cluster Higher binding energy and higher density expected compared with single strange cluster T. Yamazaki et al.Hyp. Inter.DO: 10.1007/ s 10751- 0099997-5

7. Double-Kaonic Nuclear Cluster 7 Double-kaonic nuclear clusters have been predicted theoretically. Double-kaonic clusters are expected to have a stronger binding energy and a higher density than single ones. B.E. [MeV] Width [MeV] Central- Density K-K-pp-11735 K-K-ppn-22137 17  0 K-K-ppp-103- K-K-pppn-23061 14  0 K-K-pppp-109- 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). & NP, A754, 391c (2005).

8. The elementary p bar -p annihilation reaction: is forbidden for stopped p bar, because of a negative Q-value of 98MeV Double-Strangeness Production with p bar 8 However, if deeply bound multi kaonic nuclear clusters exist, production by p bar annihilation reactions will be possible !  98MeV theoreticalprediction B.E.=117MeV  =35MeV B.E.=221MeV  =37MeV

9. Double-Strangeness Production 9 2 groups only Observations of the double-strangeness production in stopped p bar annihilation have been reported by 2 groups only, DIANA@ ITEP and OBELIX@ CERN/LEAR. experimentchanneleventsyield (10 -4 ) DIANAK+K+XK+K+X40.31+/-0.16 [p bar +Xe]K+K0XK+K0X32.1+/-1.2 K+K+--psK+K+--ps 34+/-80.17+/-0.04 OBELIX K+K+-+n-K+K+-+n- 36+/-62.71+/-0.47 [p bar + 4 He] K+K+-nK+K+-n 16+/-41.21+/-0.29 K + K + K -  nn 4+/-20.28+/-0.14 Although the observed statistics is very low, their results have indicated a high yield of ~10 -4

10. 10 Experimental Approach for J-PARC Experimental Approach for J-PARC A double-strangeness production yield of ~10 -4 would make it possible to explore the exotic systems with a dedicated experiment

11. Search for the Most Elementary K - K - pp System 11 In the following discussion, we focus on the reaction: (although K - K - pp decay modes are not known,) we assume the most energetic favored decay mode: We can detect the K - K - pp signal with: exclusive measurement  all charged particles, K + K 0 , using K 0   +  - mode  K 0 , and K + ID using K 0  missing mass (semi-)exclusive measurement  K + K 0 missing mass with  -tag   invariant mass final state = K + K 0  We need wide-acceptance detectors.

12. Expected Kinematics 12 assumptions: widths of K - K - pp/H = 0 many-body decay = isotropic decay B.E=109MeV B.E=150MeV B.E=200MeV (threshold) In the K - K - pp production channel, the kaons have very small momentum of up to 300MeV/c, even if B.E.=200MeV. We have to construct low mass material detectors. K + K 0 X momentum spectra

13. Beam-Line 13 We would like to perform the proposed experiment at K1.1 or K1.8BR beam line at K1.1 or K1.8BR beam line Incident Beam momentum bite : +/-2.5% (flat) incident beam distribution : ideal Detectors Carbon Degrader : 1.99*g/cm 3 Plastic Scintillator : l=1cm, 1.032*g/cm 3 Liquid He3 target :  7cm, l=12cm, 0.080*g/cm 3 p bar stopping-rate evaluation by GEANT4 p bar stopping-rate  30GeV-9  A,  6.0degrees  Ni-target p bar production yield with a Sanford-Wang 1.3x10 3 stopped p bar /spill @ 0.65GeV/c, l degrader  14cm

14. Expected Double-Strangeness Yield 14 pbar beam momentum : 0.65GeV/c beam intensity : 3.4x10 4 /spill/3.5s pbar stopping rate : 3.9%  9.6x10 4 double-strangeness/month  9.6x10 3 K + K 0  /month branching ratio to K + K 0  final state : 0.1 stopped-p bar yield : 1.3x10 3 /spill/3.5s Double-strangeness production : 1x10 -4 /stopped-p bar a mere assumption!

15. Detector Design I 15 design concept low material detector system wide acceptance with PID useful for other experiments E15 setup @ K1.8BR CDC TypeAA’AUU’VV’AA’UU’VV’AA’ Layer123456789101112131415 radius190.5204.0217.5248.5262.0293.0306.5337.5351.0382.0395.5426.5440.0471.0484.5 ZTPC Layer1234 radius92.597.5102.5107.5 B = 0.5T CDC resolution :  r  = 0.2mm  z ’s depend on the tilt angles (~3mm) ZTPC resolution :  z = 1mm  r  is not used for present setup We are considering 2-types of detector

16. Detector Design II 16 New dipole setup @ K1.1 CDC TypeAA’AUU’VV’AA’UU’VV’AA’ Layer123456789101112131415 radius500525550575600625650675700725750775800825850 INC (wire chamber) TypeAA’AUU’VV’AA’AUU’VV’AA’A Layer1234567891011121314151617 radius100120140160180200220240260280300320340360380400420 The design goal is to become the common setup for the  -nuclei experiment with in-flight p bar -beam B = 0.5T Double Cylindrical-Drift-Chamber setup pID is performed with dE/dx measurement by the INC INC resolution :  r  = 0.2mm,  z = 2mm (UV) CDC resolution :  r  = 0.2mm,  z = 2mm (UV) CDC is NOT used for the stopped-p bar experiment

17. Expected Signals 17 E15  inv-mass with E15 setup E15 K + K 0 miss-mass with E15 setup NEW  inv-mass with NEW setup NEW K + K 0 miss-mass with NEW setup  K-K-pp = 34MeV  H = 14MeV  K-K-pp = 27MeV  H = 0.7MeV  K-K-pp = 12MeV  H = 45MeV  K-K-pp = 8MeV  H = 25MeV 53 K - K - pp events/month 42 K - K - pp events/month 17 K - K - pp events/month 24 K - K - pp events/month Backgrounds from  0   have to be taken into account

18. Summary 18 Outlook We are investigating further realistic estimation of the K + K 0  yield and the backgrounds for (semi-)inclusive measurements. We are now preparing the proposal for J-PARC based on the LoI. We propose to search for double strangeness production by p bar annihilation on helium nuclei at rest. The proposed experiment will provide significant information on double strangeness production and double strangeness cluster states, like K - K - pp.

19. Experimental Approach for AD of CERN and FAIR

24. Thanks for Your Attention

25. Interpretation of the Experimental Results 25  Although observed statistics are very small, the results have indicated a high yield of ~10 -4, which is naively estimated to be ~10 -5.  Possible candidates of the double-strangeness production mechanism are:  rescattering cascades,  exotic B>0 annihilation (multi-nucleon annihilation) formation of a cold QGP, deeply-bound kaonic nuclei, H-particle, and so on single-nucleon annihilation rescattering cascades multi-nucleon annihilation B=0 B>0 B>0 the mechanism is NOT known well because of low statistics of the experimental results!

26. DIANA RESULTS 26 DIANA [Phys.Lett., B464, 323 (1999).] p bar Xe annihilation p=<1GeV/c p bar -beam @ ITEP 10GeV-PS 700-liter Xenon bubble chamber, w/o B-field 10 6 pictures  7.8x10 5 p bar Xe inelastic  2.8x10 5 p bar Xe @ 0-0.4GeV/c Channeleventsyield (10 -4 ) K+K+XK+K+X40.31+/-0.16 K+K0XK+K0X32.1+/-1.2

27. channeleventsyield (10 -4 ) 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 OBELIX RESULTS 27 OBELIX (’86~’96) [Nucl. Phys., A797, 109 (2007).] p bar4 He annihilation stopped p bar @ CERN/LEAR gas target ( 4 He@NTP, H 2 @3atm) cylindrical spectrometer w/ B-field spiral projection chamber, scintillator barrels, jet-drift chambers 2.4x10 5 /4.7x10 4 events of 4/5-prong in 4 He p min = 100/150/300MeV/c for  /K/p they discuss the possibility of formation and decay of K - K - nn and K - K - pnn bound system

28. Expected Kinematics II 28 M H = 2M   momentum  inv. mass  spectra  opening-angle strong correlation of  opening-angle in K - K - pp/H productions

29. Trigger Scheme 29 p bar3 He charged particle multiplicity at rest CERN LEAR, streamer chamber exp. NPA518,683 91990). 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 = 1.3x10 3 /spill & All events with a scintillator hit will be accumulated

30. Expected Signals I 30 assumptions: widths of K - K 0 pp/H = 0 B.E. of K - K - pp = 200MeV M H = 2xM  branching ratio to K + K 0  final state = 0.1 DAQ & analysis efficiency = 0.7  6.7x10 3 K + K 0  /month Generated ratio  K - K - pp:H:  = 0.1:0.1:0.8 KKpp   and H   decay branches are assumed to be 100%  0   contribution is NOT considered for the inclusive measurements  p bar + 3 He  K + K 0 S + X (X=KKpp/H/  ) events are generated isotropically at the center of the detector system  # of generated events is 200k for each case  obtained yields are scaled by the estimated K + K 0  yield  chamber resolution, multiple scattering and energy losses are fully took into account using GEANT4 toolkit  charged particles are traced with spiral fit  invariant mass : inclusive events K + K 0 missing mass : semi-inclusive events (w/ one more  )

32. K + K 0 ΛΛ Final State & Background 32 This exclusive channel study is equivalent to the unbound (excited) H-dibaryon search! Q-valueX momentum  mass  angle K - K - ppvery small~ at restM  > 2xM  back to back Possible background channels direct K + K 0  production channels, like:  0   contaminations, like: be eliminated by the kinematical constraint be distinguished by inv.-mass only  major background source