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Search for double anti-kaon nuclear bound states at J-PARC

Search for double anti-kaon nuclear bound states at J-PARC. F.Sakuma, RIKEN. Strangeness WS @ ECT*, 15-19, Oct, 2012. Outline. (brief) Introduction of “Kaonic Nuclear Cluster” “Double-Kaonic Nuclear Cluster” search using p bar + 3 He annihilation at rest using p+p reaction

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Search for double anti-kaon nuclear bound states at J-PARC

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  1. Search for double anti-kaon nuclear bound statesat J-PARC F.Sakuma, RIKEN Strangeness WS @ ECT*, 15-19, Oct, 2012.

  2. Outline • (brief) Introduction of “Kaonic Nuclear Cluster” • “Double-Kaonic Nuclear Cluster” search • usingpbar+3He annihilation at rest • usingp+p reaction • using anti-duetron beam? • 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. some predictions show the density of the KNC is high density more than normal nuclear-density 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 The latest results will be given in M. Iwasaki’s talk Invariant mass reconstruction p- p 1GeV/c K- beam

  6. What will happen to put one more kaon in the kaonic nuclear cluster? “Double-Kaonic Nuclear Cluster”

  7. Double-Kaonic Nuclear Cluster (DKNC) The double-kaonic nuclear clusters have been predicted theoretically. ppn ppnK- PL,B587,167 (2004). • The double-kaonic clusters have • much stronger binding energy • much higher density • than single ones. (AMD calc.) ppnK-K-

  8. Two New Calculations M.Hassanvand, Y.Akaishi, T.Yamazaki PRC84(2011)015204, Proc.Jpn.Acad.Ser.B87(2011)362 Deeply bound & Compact B=50~200MeV, G~75MeV N.Barnea, A.Gal, E.Z.Liverts arXiv:1203.5234 NOT Deeply bound & NOT Compact B~30MeV, G~80MeV

  9. Experimental Approaches to Search for DKNC • How to produce the double-kaonic nuclear cluster? • heavy ion collision • (K-,K+) reaction • pbarA annihilation • p+p reaction • … • dbarA annihilation • ① K1.8BR • ② primary • ③ K1.8BR We would like to perform exotic states search at J-PARC!

  10. ① “Double-Kaonic • Nuclear Cluster” search • Using • pbar+3He annihilation at rest

  11. 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 Then we can investigate the DKNC with exclusive or semi-inclusive measurement

  12. Past Experiments of Double-Strangeness Production in Stopped-pbar Annihilation 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).]

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

  14. Expected K-K-pp Cross-Section? --- the K-K-pp is assumed to be produced by L*L* collision --- double-strangeness production yield in pbarA: ~ 10-4 free L* production yield: ~ Lx0.1 free L*L* production yield: ~ LLx0.01 L*L* production yield in pbarA: ~ 10-6 even if all L*L* become the K-K-pp state, K-K-pp production yield in pbarA: ~ 10-6 small production yield is expected … moreover, Q-value of L*L* production in pbar3He reaction is negative (Q = -55MeV)

  15. 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 toward search for “double-kaonic nuclear cluster” in pbar+3He annihilation at rest

  16. Experimental Setup We will perform the experiment at J-PARC K1.8BR beam line K1.8BR Beam Line stopped-pbar beam initial beam mom. : 0.7GeV/c w/ tungsten degrader (t=31mm) 460/spill(6s) @ 30kW, Pt-target CDS & target Beam Line Spectrometer Lpp- Engineering run (2012, Jun.)

  17. 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

  18. Double-Strangeness Measurement (Cont’d) sensitivity 30kW, 3weeks • s=S/sqrt(S+B) • backgrounds are assumed to be, • K-: S:B=9:1  K+K+: S:B=8:2 • L: S:B=7:3  LL: S:B=5:5 • from engineering run, and the S/N ratio is NOT depend on the production ratio DIANA/OBELIX K+K+: 1100 LL: 200 • duty factor of the accelerator and apparatus : 21h/24h • DAQ and analysis eff. : 0.7 Lpp- Engineering run (2012, Jun.)

  19. 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 toward search for “double-kaonic nuclear cluster” in pbar+3He annihilation at rest

  20. 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

  21. Assumptions evaluate sensitivity to the K-K-pp observation using these assumptions • 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

  22. Sensitivity to the K-K-pp signal (Exclusive) s=S/sqrt(S+B) in exclusive measurement 50kW, 6weeks --- BKK = 120 MeV --- BKK = 150 MeV --- BKK = 200 MeV 100kW, 6weeks 3s significance of K-K-pp yield (/sopped-pbar) 270kW, 6weeks 30kW, 6weeks number of proton on target Expected K-K-pp production yield in pbarA: ~ 10-6  We have less sensitivity to the K-K-pp with the assumptions

  23. Expected Spectra @ 50kW, 6weeks • assumptions: • K-K-pp production yield • = 10-4/stopped-pbar • B.E. = 200 MeV • G = 100 MeV 3He(pbar, LL/K+K0)X measurements give us some hints?

  24. Related Topics in pbarA annihilation 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? yield ~ 10-4 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.

  25. ② “Double-Kaonic • Nuclear Cluster” search • usingp+p reaction

  26. Experimental Principle 8GeV production decay • the produced K-K-pp can be identified by both • missing-mass spectrum DM(K+K+) • invariant-mass spectrum M(LL)

  27. Expected Cross-Section T.Yamazaki, et al., Proc.Jpn.Acad.Ser.B87(2011)362 • The free L production CS in p+p collision is known to be sL ~ 10-3 x stotal ~ 50mb • The free L* production CS at 2.83GeV is known to be sL* ~4.5mb ~ 0.1 x sL • The double-L production CS is expected to be sL+L~ 10-3 x 10-3 x stotal~ 50nb • Thus, the double-L* production CS is expected to be sL*+L*~ 0.1 x 0.1 x sL+L~ 0.5nb • The DISTO result indicates the K-pp production CS is as much as L* production CS, so we simply assume K-K-pp production CS to be sK-K-pp ~sL*+L* ~ 0.5nb Of course, these are very rough estimations and depend on incident energy

  28. Proton Yield @ Primary Beam Line Primary beam line (1010-12 proton/spill) will be used as high-resolution un-separated secondary beam line • Good momentum resolution: Dp/p~0.1% • High Intensity Secondary Beam：1.0 x 106 Hz (6 x 106 per spill, 6 sec spill length) @ 15GeV p If yield of proton is assumed to be as same as that of pion, Prof. Noumi ~108 proton/spill(6s) is expected with pp~8-10GeV

  29. Expected Production Yield • CS : sK-K-pp ~ 0.5nb • Beam : 8 GeV proton 108 / 6s x 1 month (30d) = 4x1013 • Target : LH2target 0.85 g/cm2 (= SKS target, 0.0708 g/cm3 12 cm) ~104 / month K-K-pp

  30. Kinematics B.E = 200MeV K+ [momentum vs. cos(qlab)] production & decays are assumed to be isotropic p(K+2) vs. p(K+1) cos(qlab)(K+2) vs. cos(qlab)(K+1) L [momentum vs. cos(qlab)] p(L2) vs. p(L1) cos(qlab)(L2) vs. cos(qlab)(L1)

  31. Experimental Setup for example … E16 spectrometer + hadron-spectrometer upgrade +15 • E16 experiment: • investigation of vector meson modification in medium (p+A) • precise di-lepton measurement with high statistics • 1010 proton /spill with thin targets -15 -45 +45 +15 -15 ee acceptance KK acceptance

  32. Detector Acceptance generated events K+ flab (degree) B.E = 200MeV detector acceptance qlab (degree) L L p- p

  33. Detector Acceptance (Cont’d) double-K+ accepted event double-L accepted event acceptance = 16%  1600 / month acceptance = 0.7%  30 / month • LL decay :100% • ppp-p- decay: 40% K+ [mom vs. cos(qlab)] K+ [mom vs. cos(qlab)] p- from L [mom vs. cos(qlab)] p from L [mom vs. cos(qlab)] p- from L [mom vs. cos(qlab)] p from L [mom vs. cos(qlab)] acceptance for the exclusive measurement is 0.0% measurement of p(p, K+K+)X reaction could be feasible

  34. ③ “Double-Kaonic • Nuclear Cluster” search • usingdbar beam?

  35. dbar+A annihilation? Anti-deuteron (dbar) beam has never been realized. Using high-power proton accelerator (~270kW), we could use the world's first dbar beam at J-PARC! dbar+d annihilation (B=0) • Why dbar+A annihilation? • Nobody has done, and nobody knows. • In baryonic number B=0 annihilation, four nucleon masses are released in small region, followed by creation of the highly energetic/excited blob. • In B>0 annihilation, more exotic matter could be produced. • Increase of strangeness production could be observed as same as QGP/hadronic-gas formation in A+A reaction. • Such anomalous condition, exotic state such as H-dibaryon and K-K-pp could be generated. - - - - - - - - p n u p u u d d d n u d u d d u

  36. dbar beam @ J-PARC? dbar production in p+A reaction 30GeV p+Be, 4.5 degrees @ AGS • At AGS, dbar production was studied in 30GeV p+Be reaction in 1960’s • production angle: 4.5 degrees • dbar/p- = (5.5±1.5)x10-8 @ 5GeV/c after p- decay & dbar abs. correction •  dbar/pbar ~ 10-6 dbar beam @ J-PARC K1.8BR D.E.Dorfan, et al., PRL14(1965)1003 • pbar intensity in 30GeV p+Pt reaction at 6 degrees is 7*103 /1kW/spill(6s) from the commissioning result in 2012 Feb. •  2*105 pbar/spill(6s) @ 30kW, Pt-target • Assumptions: • dbar/pbar ~ 10-6 • decrease of dbar yield caused by absorption in 60mm Pt-target is twice of pbar yield dbar intensity @ K1.8BR = 0.1 dbar/spill(6s) @ 30kW, Pt-target dbar production @ K1.8BR will be checked toward realizing dbar beam

  37. Summary • Single-Kaonic Nuclear Cluster Search (K-pp): • The E15 experiment will finally start physics run in this FY. • Double-Kaonic Nuclear Cluster Search (K-K-pp): • pbar+3He annihilation at rest @ K1.8BR • double-strangeness measurement will be conducted as a first step • measurement of 3He(pbar, LL/K0K+)X reaction will be given us some hints of the K-K-pp • 8 GeV/c p+p reaction @ primary • p(p, K+K+)X measurement using the E16 spectrometer could be feasible • dbar beam @ K1.8BR • expected yield: 0.1 dbar/spill(6s) with 30kW, Pt-target

  38. Thank you!

  39. Schedule

  40. Backup

  41. 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 pbar production 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

  42. 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

  43. 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

  44. 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

  45. Kaon identification K+ [mom vs. cos(qlab)] n=1.02 however, proton contamination is … ???

  46. Past Experiment … KEK-PS E248 (AIDA) 12GeV p+p  K++K++X

  47. dbar beam line @ J-PARC Proceeding of “Low Energy Antiproton Physics Conference (LEAP 98)”

  48. 1GeV/c dbar beam line ~ 30 dbar/pulse @ 50GeV (full power?)

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