Tum-Riken Kick-Off TUM, May 10-11, 2010.

Tum-Riken Kick-Off Meeting @ TUM, May 10-11, 2010.
A search for double anti-kaon production in antiproton-3He　annihilation at J-PARC F.Sakuma, RIKEN Tum-Riken Kick-Off 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 “Double-Kaonic Nuclear Cluster” by Stopped-pbar Annihilation Experimental Approach Summary

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 Kaonic Nuclei Binding Energy [MeV] Width Central Density K-p 27 40 3.5r0 K-pp 48 61 3.1r0 K-ppp 97 13 9.2r0 K-ppn 118 21 8.8r0 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

Theoretical Situation of KNC
theoretical predictions for kaonic nuclei, e.g., K-pp Method Binding Energy (MeV) Width (MeV) Akaishi, Yamazaki PLB533, 70 (2002). ATMS 48 61 Shevchenko, Gal, Mares PRL98, (2007). Faddeev 55-70 90-110 Ikeda, Sato PRC76, (2007). 79 74 Dote, Hyodo, Weise NPA804,197(2008). chiral SU(3) 19+/-3 40-70 (pSN-decay) whether the binding energy is deep or shallow how broad is the width ? Koike, Harada PLB652, 262 (2007). DWIA 3He(K-,n)

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

Experimental Situation of KNC (Cont’d)
peak structure  signature of kaonic nuclei ? L-p invariant mass K-pp? K-pp? K-pp? PRL, 94, (2005) NP, A789, 222 (2007) PRL,104, (2010) We need conclusive evidence with observation of formation and decay !

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

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

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

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. B.E. [MeV] Width [MeV] Central-Density K-K-pp -117 35 K-K-ppn -221 37 17r0 K-K-ppp -103 - K-K-pppn -230 61 14r0 K-K-pppp -109 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

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

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.

Double-Strangeness Production Yield by 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

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, and experiment channel events yield (10-4) DIANA K+K+X 4 0.31+/-0.16 [pbar+Xe] K+K0X 3 2.1+/-1.2 K+K+S-S-ps 34+/-8 0.17+/-0.04 OBELIX K+K+S-S+np- 36+/-6 2.71+/-0.47 [pbar+4He] K+K+S-Ln 16+/-4 1.21+/-0.29 K+K+K-Lnn 4+/-2 0.28+/-0.14 Although observed statistics are very small, their results have indicated a high yield of ~10-4

Past Experiments (Cont’d)
DIANA [Phys.Lett., B464, 323 (1999).] pbarXe annihilation p=<1GeV/c ITEP 10GeV-PS 700-liter Xenon bubble chamber, w/o B-field 106 pictures 7.8x105 pbarXe inelastic  2.8x GeV/c Channel events yield (10-4) K+K+X 4 0.31+/-0.16 K+K0X 3 2.1+/-1.2

Past Experiments (Cont’d)
OBELIX (’86~’96) [Nucl. Phys., A797, 109 (2007).] pbar4He annihilation stopped CERN/LEAR gas target 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 channel events yield (10-4) K+K+S-S-ps 34+/-8 0.17+/-0.04 K+K+S-S+np- 36+/-6 2.71+/-0.47 K+K+S-Ln 16+/-4 1.21+/-0.29 K+K+K-Lnn 4+/-2 0.28+/-0.14 they discuss the possibility of formation and decay of K-K-nn and K-K-pnn bound system

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

wide-acceptance detectors.
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.

We have to construct low mass material detectors.
Expected Kinematics K+K0X momentum spectra assumptions: widths of K-K-pp = 0 isotropic decay B.E=120MeV (th.+11MeV) 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

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

Beam-Line We would like to perform the proposed experiment
at J-PARC K1.8BR beam line (or K1.1) 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 pbar stopping-rate evaluation by GEANT4 1.3x103 stopped pbar/spill @ 0.65GeV/c, ldegrader~14cm pbar stopping-rate 30GeV-9mA, 6.0degrees Ni-target pbar production yield with a Sanford-Wang

Detector Design E15 CDS @ K1.8BR Key points
low material detector system wide acceptance with pID E15 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 ZTPC Layer 1 2 3 4 radius 92.5 97.5 102.5 107.5 CDC Type A A’ U U’ V V’ Layer 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 radius 190.5 204.0 217.5 248.5 262.0 293.0 306.5 337.5 351.0 382.0 395.5 426.5 440.0 471.0 484.5

Trigger Scheme All events with a scintillator hit can be accumulated
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, ). Nc Branch (%) 1 5.14 +/- 0.04 3 /- 0.88 5 /- 0.91 7 7.06 +/- 0.46 9 0.19 +/- 0.08 <Nc> 4.16 +/- 0.06 K-K-pp event

Pbar+3He K++K0S+K-K-pp,
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 K1.8BR binding energy

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

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 K1.8BR K-K-pp production rate = 10-4 Br(K-K-ppLL) = 100% binding energy

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 L + S0  S0 + S0 L + L + p0 … missing g missing 2g missing p0

Expected Spectra expected spectrum with the assumptions:
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

Expected Spectra @ 270kW, 4weeks
LL invariant mass (2L) LL invariant mass (2K2L) # 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 (2K) K+K0 missing mass (2K2L) # of K-K-pp = 1293 # of K-K-pp = 203

Summary

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.

Back-Up

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! L-p invariant mass K-pp? NP, A789, 222 (2007)

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

LL invariant mass (2L) LL invariant mass (2K2L) # 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 (2K) K+K0 missing mass (2K2L) # of K-K-pp = 239 # of K-K-pp = 38 37

in-flight experiment

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 K1.8BR 1GeV/c binding energy

Expected K-K-pp Production Yield
pbar beam momentum : 1GeV/c beam intensity : 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

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 = 1.5x kW 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 = 7.5x kW w/o detector acceptance

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 K1.8BR 1GeV/c binding energy

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

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

with K1.1

Detector Design (Cont’d)
new dipole 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 INC (wire chamber) Type A A’ U U’ V V’ Layer 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 radius 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 CDC Type A A’ U U’ V V’ Layer 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 radius 500 525 550 575 600 625 650 675 700 725 750 775 800 825 850

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 K1.1 1GeV/c binding energy

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 K1.1 1GeV/c binding energy

LL invariant mass (2L) LL invariant mass (2K2L) # 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 (2K) K+K0 missing mass (2K2L) # of K-K-pp = 1719 # of K-K-pp = 238 50

LL invariant mass (2L) LL invariant mass (2K2L) # of K-K-ppLL = 1112 # of K-K-ppLL = 76 1GeV/c pbar B.E=200MeV, G=100MeV 270kW, 4weeks K+K0 missing mass (2K) K+K0 missing mass (2K2L) # of K-K-pp = 7915 # of K-K-pp = 435 52

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

Interpretation of the Experimental Results
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 the mechanism is NOT known well because of low statistics of the experimental results! single-nucleon annihilation rescattering cascades multi-nucleon annihilation B=0 B>0 B>0

K+K0LL Final State & Background
This exclusive channel study is equivalent to the unbound (excited) H-dibaryon search! Q-value X momentum LL mass L-L angle K-K-pp very small ~ at rest MLL > 2ML back to back H-dibaryon large boosted MLL ~ 2ML ~ 0 Possible background channels direct K+K0LL production channels, like: be distinguished by inv.-mass only  major background source S0gL contaminations, like: be eliminated by the kinematical constraint, ideally

Expected Kinematics (Cont’d)
MH = 2ML LL spectra L momentum L-L opening-angle LL inv. mass strong correlation of LL opening-angle in K-K-pp/H productions

Schedule Year (JFY) K1.8BR K1.1 (fN) 2009 beam-tune proposal 2010 E17
R&D, design 2011 2012 E15/E31 construction 2013 commissioning 2014 … data taking The proposed experiment will be scheduled in around JFY2014, whether we conduct the experiment at K1.8BR or K1.1 beam-line. K1.8BR : after E17/E15/E31? K : joint project with the fN experiment?

Past Experiments of Stopped-pbar Annihilation

charged particle multiplicity at rest
form Rivista Del Nuovo Cimento 17, 1 (1994). CERN LEAR streamer chamber exp. NIM A234, 30 (1985). They obtained

KKbar production-rate for pbar+p at rest
form Rivista Del Nuovo Cimento 17, 1 (1994). the KKbar production-rate R for pbar+p annihilation at rest (obtained from hydrogen bubble chamber data) There is a great deal of data on the production of strange particles on 1H and 2H but only few ones on heavier nuclei.

L/K0s production-rate and multiplicity for pbar+A at rest
form Rivista Del Nuovo Cimento 17, 1 (1994). charge multiplicities decrease by ~1 when L/K0S is produced

DIANA [Phys.Lett., B464, 323 (1999).] pbarXe annihilation p=<1GeV/c ITEP 10GeV-PS 700-liter Xenon bubble chamber, w/o B-field 106 pictures 7.8x105 pbarXe inelastic  2.8x GeV/c pbarXeK+K+X : events  (0.31+/-0.16)x10-4 pbarXeK+K0LX : 3 events  (2.1+/-1.2)x10-4  4 events  3 events

interpretation of the DIANA result (pbarXe)
from J.Cugnon et al., NP, A587, 596 (1995). The observed double strangeness yield is explained by conventional processes described by the intranuclear cascade model, as listed in the following tables. They also show the B=2 annihilations, described with the help of the statistical model, are largely able to account for the observed yield: i.e., the branching ratio of the LLKK state in pbar-NNN annihilation is equal to ~10-4 at rest (B=1 annihilations are not so helpful). However they claim the frequency of even B=1 annihilation is of the order of 3-5% at the most [J.Cugnon et al., NP, A517, 533 (1990).] (is it common knowledge ?), so they conclude it would be doubtful to attempt a fit of the data with a mixture of B=0 and 2 annihilations. On the other hand, the Crystal Barrel CERN/LEAR concludes their pbardLK0/S0K0 measurements disagree strongly with conventional two-step model predictions and support the statistical (fireball) model.

experimental values are not final values of the DIANA data

support the statistical model
Crystal Barrel (’86~’96) [Phys. Lett., B469, 276 (1999).] pbar4He annihilation stopped CERN/LEAR liquid deuteron target cylindrical spectrometer w/ B-field SVX, CDC, CsI crystals ~106 events of 2/4-prong with topological triggers support the statistical model

OBELIX (’86~’96) [Nucl. Phys., A797, 109 (2007).]
pbar4He annihilation stopped CERN/LEAR gas target cylindrical spectrometer w/ B-field spiral projection chamber, scintillator barrels, jet-drift chambers 238,746/47,299 events of 4/5-prong in 4He pmin = 100/150/300MeV/c for p/K/p 34+/-8 events  (0.17+/-0.04)x10-4 4-prong 5-prong * (xx) is not observed 4+/-2 events  (0.28+/-0.14)x10-4 36+/-6 events  (2.71+/-0.47)x10-4 16+/-4 events  (1.21+/-0.29)x10-4 they discuss the possibility of formation and decay of K-K-nn and K-K-pnn bound system

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