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A search for double anti-kaon production in antiproton- 3 He annihilation at J-PARC

A search for double anti-kaon production in antiproton- 3 He annihilation at J-PARC. F.Sakuma, RIKEN. Tum-Riken Kick-Off Meeting @ TUM, May 10-11, 2010. This talk is based on the LoI submitted in June, 2009. Contents. (brief) Introduction of “Kaonic Nuclear Cluster” Possibility of

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A search for double anti-kaon production in antiproton- 3 He annihilation at J-PARC

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  1. A search for double anti-kaon production in antiproton-3Heannihilation at J-PARC F.Sakuma, RIKEN Tum-Riken Kick-Off Meeting@ TUM, May 10-11, 2010.

  2. This talk is based on the LoI submitted in June, 2009.

  3. Contents • (brief) Introduction of • “Kaonic Nuclear Cluster” • Possibility of • “Double-Kaonic Nuclear Cluster” • by Stopped-pbar Annihilation • Experimental Approach • Summary

  4. Kaonic Nuclear Cluster (KNC) the existence of deeply-bound kaonic nuclear cluster is predicted from strongly attractive KbarN interaction the density of kaonic nuclei is predicted to be extreme high density 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

  5. Theoretical Situation of KNC theoretical predictions for kaonic nuclei, e.g., K-pp • whether the binding energy • is deep or shallow • how broad is the width ? Koike, Harada PLB652, 262 (2007). DWIA 3He(K-,n)

  6. Experimental Situation of KNC E549@KEK-PS E548@KEK-PS 4He（stopped K-,p) 12C(K-,n) K-pnn? E549@KEK-PS 12C(K-,p) 4He（stopped K-,LN) unknown strength between Q.F. & 2N abs. Prog.Theor.Phys.118:181-186,2007. missing mass - deep K-nucleus potential of ~200MeV PLB 659:107,2008 no “narrow” structure K-pp/ K-pnn? K-pn/ K-ppn? arXiv:0711.4943

  7. Experimental Situation of KNC (Cont’d) peak structure  signature of kaonic nuclei ? K-pp? K-pp? K-pp? FINUDA@DAFNE OBELIX@CERN-LEAR DISTO@SATUREN NP, A789, 222 (2007) PRL, 94, 212303 (2005) PRL,104,132502 (2010) We need conclusive evidence with observation of formationanddecay ! L-p invariant mass

  8. Formation Decay Experimental Principle of J-PARC E15 search for K-pp bound state using 3He(K-,n) reaction neutron 3He K-pp cluster K- Missing mass Spectroscopyvia neutron Mode to decay charged particles p L exclusive measurement byMissing mass spectroscopy and Invariant mass reconstruction p- Invariant mass reconstruction p

  9. J-PARC E15 Setup Sweeping Magnet Beam Line Spectrometer Beam trajectory K1.8BR Beam Line CDS & target E15 will provide the conclusive evidence of K-pp neutron Neutron ToF Wall Beam Sweeping Magnet Neutron Counter flight length = 15m p n Cylindrical Detector System p- p 1GeV/c K- beam

  10. What will happen to put one more kaon in the kaonic nuclear cluster? Possibility of “Double-Kaonic Nuclear Cluster” by Stopped-pbar Annihilation

  11. Double-Kaonic Nuclear Cluster • The double-kaonic nuclear clusters have been predicted theoretically. • The double-kaonic clusters have much stronger binding energy and a much higher density than single ones. PL,B587,167 (2004). & NP, A754, 391c (2005). • How to produce the double-kaonic nuclear cluster? • heavy ion collision • (K-,K+) reaction • pbarA annihilation We use pbarA annihilation

  12. Double-Strangeness Production with pbar 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 However, if multi kaonic nuclear exists with deep bound energy, following pbar annihilation reactions will be possible! theoretical prediction B.E.=117MeV G=35MeV B.E.=221MeV G=37MeV

  13. Production Mechanism of K-K-pp with pbar+3He? • For example, the possible K-K-pp production mechanisms are as follows: • with stopped pbar • direct K-K-pp production with 3N annihilation • L*L* production with 3N annihilation followed by K-K-pp formation • with in-flight pbar • in addition above 2ways, • elementally pbar+pKKKK production followed by K-K-pp formation • Some theorist’s comment: If the K-K-pp bound system can be exist, such system could be L*L* molecular system by analogy between L* K-p. Then the binding energy could be small of about from 30 to 60 MeV. • it has been observed that cross section of pbar+p->KKKK with around 1GeV/c pbar-beam is very small of less than 1mb, so it would be very difficult experimentally. It’s worthwhile to explore these exotic system with pbar, although the mechanism is NOT completely investigated! A theoretical problem: The K-K- interactions have been calculated in lattice QCD as strongly repulsive interaction. However, these K-K- interactions are neglected simply in the PLB587,167 calculation which only shows the K-K-pp bound system.

  14. Double-Strangeness Production Yieldby Stopped-pbar Annihilation From several stopped-pbar experiments, the inclusive production yields are: Naively, the double-strangeness production yield would be considered as: g : reduction factor ~ 10-2

  15. Past Experiments of Double-Strangeness Production in Stopped-pbar Annihilation Observations of the double-strangeness production in stopped pbar annihilation have been reported by only 2 groups, DIANA@ITEP and OBELIX@CERN/LEAR. Although observed statistics are very small, their results have indicated a high yield of ~10-4

  16. Past Experiments (Cont’d) • DIANA[Phys.Lett., B464, 323 (1999).] • pbarXe annihilation • p=<1GeV/c pbar-beam @ ITEP 10GeV-PS • 700-liter Xenon bubble chamber, w/o B-field • 106 pictures7.8x105 pbarXe inelastic  2.8x105 pbarXe @ 0-0.4GeV/c

  17. Past Experiments (Cont’d) • OBELIX(’86~’96) [Nucl. Phys., A797, 109 (2007).] • pbar4He annihilation • stopped pbar @ CERN/LEAR • gas target (4He@NTP, H2@3atm) • cylindrical spectrometer w/ B-field • spiral projection chamber, • scintillator barrels, jet-drift chambers • 2.4x105/4.7x104 events of 4/5-prong in 4He • pmin = 100/150/300MeV/c for p/K/p they discuss the possibility of formation and decay of K-K-nn and K-K-pnn bound system

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

  19. How to Measure? we focus the reaction: (although K-K-pp decay modes are not known at all,) we assume the most energetic favored decay mode: final state = K+K0LL We can measure the K-K-pp signal exclusively by detection of all particles, K+K0LL, using K0p+p- mode We need wide-acceptance detectors.

  20. Expected Kinematics K+K0X momentum spectra • assumptions: • widths of K-K-pp = 0 • isotropic decay (th.+11MeV) B.E=120MeV B.E=150MeV B.E=200MeV ~70MeV/c Kaon ~150MeV/c Kaon ~200MeV/c Kaon 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. ~200MeV/c p from K0S, ~800MeV/c L, ~700MeV/c p from L, ~150MeV/c p- from L

  21. Procedure of the K-K-pp Measurement • Key points of the experiment • high intensity pbar beam • wide-acceptance and low-material detector • How to measure the K-K-pp signal • (semi-inclusive) K0SK+ missing-mass w/ L-tag • (inclusive) LL invariant mass • (exclusive) K0SK+LL detection • *1 because of the low-momentum kaon, it could be hard to detect all particles • *2 semi-inclusive and inclusive spectra could contain background from 2N annihilation and K-K-pp decays, respectively

  22. Beam-Line We would like to perform the proposed experiment at J-PARC K1.8BR beam line (or K1.1) pbar stopping-rate evaluation by GEANT4 • Incident Beam • momentum bite : +/-2.5% (flat) • incident beam distribution : ideal • Detectors • Carbon Degrader : 1.99*g/cm3 • Plastic Scintillator : l=1cm, 1.032*g/cm3 • Liquid He3 target : f7cm, l=12cm, 0.080*g/cm3 1.3x103 stopped pbar/spill @ 0.65GeV/c, ldegrader~14cm • 30GeV-9mA, • 6.0degrees • Ni-target pbar production yield with a Sanford-Wang pbar stopping-rate

  23. Detector Design • Key points • low material detector system • wide acceptance with pID E15 CDS @ K1.8BR • B = 0.5T • CDC resolution : srf = 0.2mm • sz’s depend on the tilt angles (~3mm) • ZTPC resolution : sz = 1mm • srf is not used for present setup

  24. Trigger Scheme expected stopped-pbar yield = 1.3x103/spill All events with a scintillator hit can be accumulated pbar3He charged particle multiplicity at rest CERN LEAR, streamer chamber exp. NPA518,683 91990). K-K-pp event

  25. Detector Acceptance Pbar+3He K++K0S+K-K-pp, K-K-pp LL, G(K-K-pp)=100MeV --- LL detection --- K0SK+ w/ L-tag detection --- K0SK+LL detection E15 CDS @ K1.8BR binding energy

  26. Expected K-K-pp Production Yield • pbar beam momentum : 0.65GeV/c • beam intensity : 3.4x104/spill/3.5s @ 270kW • pbar stopping rate : 3.9% • stopped-pbar yield : 1.3x103/spill/3.5s we assume K-K-pp production rate = 10-4 K-K-pp production yield = 2.3x104 /week @ 270kW DAQ & ana efficiency = 0.7 & duty factor = 0.7 expected K-K-pp yield = 1.1x104 /week @ 270kW w/o detector acceptance

  27. Expected K-K-pp Detction Yield Pbar+3He K++K0S+K-K-pp, K-K-pp LL, G(K-K-pp)=100MeV --- LL detection --- K0SK+ w/ L-tag detection --- K0SK+LL detection E15 CDS @ K1.8BR • K-K-pp production rate = 10-4 • Br(K-K-ppLL) = 100% binding energy

  28. Backgrounds • (semi-inclusive) K0SK+ missing-mass w/ L-tag • stopped-pbar + 3He  K0S + K+ + K-K-pp • stopped-pbar + 3He  K0S + K+ + L + L • stopped-pbar + 3He  K0S + K+ + S0 + S0 + p0 • … • stopped-pbar + 3He  K0S + K+ + K0 + S0 + (n) • stopped-pbar + 3He  K0S + K+ + K- + S0 + (p) • … 3N annihilation 2N annihilation • (inclusive) LL invariant mass • stopped-pbar + 3He  K0S + K+ + K-K-pp • L + L • stopped-pbar + 3He  K0S + K+ + K-K-pp • L + S0 • stopped-pbar + 3He  K0S + K+ + K-K-pp •  S0 + S0 • stopped-pbar + 3He  K0S + K+ + K-K-pp • L + L + p0 • … missing g missing 2g missing p0

  29. Expected Spectra • Monte-Carlo simulation using GEANT4 toolkit • reaction and decay are considered to be isotropic and proportional to the phase space • energy losses are NOT corrected in the spectra • w/o Fermi-motion expected spectrum with the assumptions: • production rate: • K-K-pp bound-state = 10-4 • (3N) K-K-LL phase-space = 10-4 • (3N) K+K0S0S0p0 phase-space = 10-4 • (2N) K+K0K0S0(n) phase-space = 10-4 • (2N) K+K0K-S0(p) phase-space = 10-4 • branching ratio of K-K-pp: • BR(K-K-ppLL) = 0.1 • BR(K-K-ppLS0) = 0.1 • BR(K-K-ppS0S0 = 0.1 • BR(K-K-ppLLp0) = 0.7 2L = LL detection 2K = K+K0 w/ L-tag detection 2L2K = K+K0LL detection

  30. Expected Spectra @ 270kW, 4weeks LL invariant mass (2K2L) LL invariant mass (2L) # of K-K-ppLL = 406 # of K-K-ppLL = 35 stopped pbar B.E=200MeV, G=100MeV 270kW, 4weeks • In the LL spectra, we cannot discriminate the K-K-pp going to LL signals from the backgrounds, if K-K-pp has theses decay modes. • In contrast, the K0 K+ missing mass spectroscopy is attractive for us because we can ignore the K-K-pp decay mode. K+K0 missing mass (2K2L) K+K0 missing mass (2K) # of K-K-pp = 203 # of K-K-pp = 1293

  31. Summary

  32. Summary • We propose to search for double strangeness production by pbar annihilation on 3He nuclei at rest. • The proposed experiment will provide significant information on double strangeness production and double strangeness cluster states, K-K-pp. • The experimental key points are high-intensity pbar beam and wide-acceptance/low-material detector system. We propose to perform the experiment at K1.8BR beam-line with the E15 spectrometer. • We are now preparing the proposal for J-PARC based on the LoI.

  33. Back-Up

  34. K-pp Production with pbar at rest Of course, we can measure K-pp production! From several stopped-pbar experiments, the inclusive production yields are: Very simply, expected K-pp yield is 100 times larger than the K-K-pp production! K-pp? OBELIX@CERN-LEAR NP, A789, 222 (2007) L-p invariant mass

  35. Expected Spectra @ 270kW, 4weeks K+K0LL missing-mass2 (2K2L) stopped pbar B.E=200MeV, G=100MeV 270kW, 4weeks

  36. Expected Spectra @ 50kW, 4weeks LL invariant mass (2K2L) LL invariant mass (2L) # of K-K-ppLL = 75 # of K-K-ppLL = 6 stopped pbar B.E=200MeV, G=100MeV 50kW, 4weeks K+K0 missing mass (2K2L) K+K0 missing mass (2K) # of K-K-pp = 38 # of K-K-pp = 239 37

  37. Expected Spectra @ 50kW, 4weeks K+K0LL missing-mass2 (2K2L) stopped pbar B.E=200MeV, G=100MeV 50kW, 4weeks

  38. in-flight experiment

  39. Detector Acceptance Pbar+3He K++K0S+K-K-pp, K-K-pp LL, G(K-K-pp)=100MeV --- LL detection --- K0SK+ w/ L-tag detection --- K0SK+LL detection stopped E15 CDS @ K1.8BR 1GeV/c binding energy

  40. Expected K-K-pp Production Yield • pbar beam momentum : 1GeV/c • beam intensity : 6.4x105/spill/3.5s @ 270kW we assume K-K-pp production rate = 10-4 for 1GeV/c pbar+p (analogy from the DIANA result of double-strangeness production although the result are from pbar+131Xe reaction) inelastic cross-section of 1GeV/c pbar+p is (117-45) = 72mb K-K-pp production CS = 7.2mb for 1GeV/c pbar+p

  41. Expected K-K-pp Production Yield (Cont’d) L3He parameters: * r = 0.08g/cm3 * l = 12cm • N = s * NB * NT • N : yield • s : cross section • NB : the number of beam • NT : the number of density per unit area of the target K-K-pp production yield = 1.5x105 /week @ 270kW BG rate: total CS = 117mb pbar = 6.4x105/spill BG = 1.4x104/spill DAQ & ana efficiency = 0.7 & duty factor = 0.7 expected K-K-pp yield = 7.5x104 /week @ 270kW w/o detector acceptance

  42. Expected K-K-pp Detection Yield Pbar+3He K++K0S+K-K-pp, K-K-pp LL, G(K-K-pp)=100MeV --- LL detection --- K0SK+ w/ L-tag detection --- K0SK+LL detection stopped E15 CDS @ K1.8BR 1GeV/c binding energy

  43. Expected Spectra @ 270kW, 4weeks LL invariant mass (2K2L) LL invariant mass (2L) # of K-K-ppLL = 94 # of K-K-ppLL = 1397 1GeV/c pbar B.E=200MeV, G=100MeV 270kW, 4weeks K+K0 missing mass (2K2L) K+K0 missing mass (2K) # of K-K-pp = 392 # of K-K-pp = 8095 44

  44. Expected Spectra @ 270kW, 4weeks K+K0LL missing-mass2 (2K2L) 1GeV/c pbar B.E=200MeV, G=100MeV 270kW, 4weeks

  45. with Dipole-setup @ K1.1

  46. Detector Design (Cont’d) new dipole setup @ K1.1 • The design goal is to become the common setup for the f-nuclei experiment with in-flight pbar-beam • B = 0.5T • Double Cylindrical-Drift-Chamber setup • pID is performed with dE/dx measurement by the INC • INC resolution : srf = 0.2mm , sz = 2mm (UV) • CDC resolution : srf = 0.2mm, sz = 2mm (UV) • CDC is NOT used for the stopped-pbar experiment

  47. Detector Acceptance Pbar+3He K++K0S+K-K-pp, K-K-pp LL, G(K-K-pp)=100MeV --- LL detection --- K0SK+ w/ L-tag detection --- K0SK+LL detection stopped dipole @ K1.1 1GeV/c binding energy

  48. Expected K-K-pp Detection Yield Pbar+3He K++K0S+K-K-pp, K-K-pp LL, G(K-K-pp)=100MeV --- LL detection --- K0SK+ w/ L-tag detection --- K0SK+LL detection stopped dipole @ K1.1 1GeV/c binding energy

  49. Expected Spectra @ 270kW, 4weeks LL invariant mass (2K2L) LL invariant mass (2L) # of K-K-ppLL = 282 # of K-K-ppLL = 27 stopped pbar B.E=200MeV, G=100MeV 270kW, 4weeks K+K0 missing mass (2K2L) K+K0 missing mass (2K) # of K-K-pp = 238 # of K-K-pp = 1719 50

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