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

A search for double anti-kaon production in antiproton-3He　

annihilation at J-PARC

Fuminori Sakuma, RIKEN

1Strangeness in Nuclei @ ECT*, 4-8, Oct, 2010.

2

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

3

Possibility of “Double-Kaonic Nuclear Cluster”

by Stopped-pbar AnnihilationExperimental ApproachSummary

Contents

4

Possibility of“Double-Kaonic Nuclear Cluster”

by Stopped-pbar Annihilation

What will happen to put one more kaon in the kaonic nuclear cluster?

5

Double-Kaonic Nuclear ClusterThe 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 -

How to produce the double-kaonic nuclear cluster?heavy ion collision(K-,K+) reactionpbarA annihilation

We use pbarA annihilation

PL,B587,167 (2004). & NP, A754, 391c (2005).

p p K K K K

The elementary pbar-p annihilation reaction with double-strangeness production:

This reaction is forbidden for stopped pbar, because of a negative Q-value of 98MeV

Double-Strangeness Production with pbar

If multi kaonic nuclear exists with deep bound energy, following pbar annihilation reactions would be possible!

-98MeV

3

3 0

4

4 0

106MeV

109MeV

126MeV

129MeV

pnKK

ppKK

pnnKK

ppnKK

p He K K K K pn B

p He K K K K pp B

p He K K K K pnn B

p He K K K K ppn B

- -

- -

- -

- -

-

-

-

-6

theoreticalprediction

B.E.=117MeVG=35MeV

B.E.=221MeVG=37MeV

K-K-pp in pbar+3He annihilation at rest?

7

The possible mechanisms of the K-K-pp production are as follows:1: direct K-K-pp production with 3N annihilation1’: L*L* production with 3N annihilation followed by the K-K-

pp formation2: elementally pbar+pKKKK production in nuclear matter

followed by the K-K-pp formationHowever, there are many unknown issues, like:

1: non-resonant LL is likely to be produced compared with the K-K-pp formation!

1’: how large is the L*L* binding energy, interaction?2: is it possible?

Anyway, if the K-K-pp exists, we can extrapolate simply the experimental results of the K-pp:

FINUDA@DAFNE B.E. ~ 120 MeV, G ~ 70 MeVDISTO@SATURNE B.E. ~ 100 MeV, G ~ 120 MeV

then, we can assume the double binding strength:B.E ~ 200 MeV, G ~ 100 MeV.

8

Past Experiments of Double-Strangeness Production in Stopped-pbar Annihilation

A result of a search for double-strangeness productions in antiproton-nuclei annihilations was reported by using the BNL bubble chamber, in association with the H-dibaryon search.

They did NOT observe any double-strangeness event in antiproton - C, Ti, Ta, Pb annihilation

(~80,000 events, p(pbar) < 400 MeV/c)

Reaction Frequency (90% C.L.)

pbarAL 0L 0X <4x10-4

pbarAL 0K-X <5x10-4

pbarAK+K+X <5x10-4

pbarAHX <9x10-5

[Phys.Lett., B144, 27 (1984).]

9

Past Experiments (Cont’d)

Observations of the double-strangeness production in stopped pbar annihilation have been reported by 2 groups, DIANA@ITEP and OBELIX@CERN/LEAR.

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-L n 16+/-4 1.21+/-0.29

K+K+K-L nn 4+/-2 0.28+/-0.14

Although observed statistics are very small,their results have indicated a high yield of ~10-4

10

Past Experiments (Cont’d)DIANA [Phys.Lett., B464, 323 (1999).]pbarXe annihilationp=<1GeV/c pbar-beam @ ITEP 10GeV-PS700-liter Xenon bubble chamber, w/o B-field106 pictures 7.8x105 pbarXe inelastic 2.8x105 pbarXe @ 0-0.4GeV/c

Channel events yield (10-4)

K+K+X 4 0.31+/-0.16

K+K0X 3 2.1+/-1.2

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

11

Past Experiments (Cont’d)OBELIX (’86~’96) [Nucl. Phys., A797, 109 (2007).]pbar4He annihilationstopped pbar @ CERN/LEARgas target (4He@NTP, H2@3atm)cylindrical spectrometer w/ B-fieldspiral projection chamber,

scintillator barrels, jet-drift chambers2.4x105/4.7x104 events of 4/5-prong in 4Hepmin = 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

12

K-pp Production with pbar at rest

3 0p He K K pp-

We can also measure K-pp productionwith the dedicated detector, simultaneously!

Our experiment can check the OBELIX results of the K-pp with a dedicated spectrometer

OBELIX@CERN-LEARNP, A789, 222 (2007).EPJ, A40, 11 (2009).

K-pp?

4

p He K pp X

p

- L

B.E. = -151.0+-3.2+-1.2 MeVG< 33.9+-6.2 MeVprod. rate > 1.2 x 10-4

13

H-dibaryon search with pbar at rest

3 0

p He K K H

L L

We can also search for H-dibaryon (H-resonance) by using LL invariant mass / missing mass:

E522@KEK-PS

Phys. Rev., C75 022201(R) (2007).

H?

12 ,C K K X- LL

The upper limit for the production cross section of the H with a mass range between the LL and XN threshold is found to be 2.1 +- 0.6 (stat.) +- 0.1 (syst.) mb/sr at a 90% confidence level.

the exclusive measurement has never been done using stopped pbar beam.

14

Experimental Approach

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

15

How to Measure?

3 0 ( )p He K K X X K K pp - - we focus the reaction:

(although K-K-pp decay modes are not known at all,)we assume the most energetic favored decay mode:

K K pp- - L L

We can measure the K-K-pp signal exclusively by detection of all particles, K+K0LL, using K0p+p- mode

final state = K+K0LL

We needwide-acceptance detectors.

16

Expected Kinematicsassumptions:widths of K-K-pp = 0isotropic decay

3 0Sp He K K K K pp - -

B.E=120MeV B.E=150MeV B.E=200MeV(th.+11MeV)

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+K0X momentum spectra

~70MeV/c Kaon ~150MeV/c Kaon ~200MeV/c Kaon

~200MeV/c p from K0S, ~800MeV/c L, ~700MeV/c p from L, ~150MeV/c p- from L

17

Procedure of the K-K-pp Searchkey points of the experimental setuphigh intensity pbar beamlow mass material detectorwide acceptance detector

methods of the measuremt(semi-inclusive) K0

SK+ missing-mass w/ L-tag(inclusive) LL invariant mass(exclusive) K0

SK+LL measurement

K1.8BR Beam Line

neutron

Beam trajectory

CDS &target

SweepingMagnet

NeutronCounter

Beam LineSpectrometer

The E15 spectrometer at K1.8BRsatisfies the above requirements

18

Detector Acceptance

E15 CDS @ K1.8BR

stopped-pbar+3He K++K0S+K-K-pp,

K-K-pp LL,G(K-K-pp)=100MeV

B.E.=120MeV B.E.=150MeV B.E.=200MeV0.00

0.05

0.10

0.15

acce

ptan

ce

--- LL detection--- K0

SK+ w/ L-tag detection--- K0

SK+LL detection

binding energy

9.0%

3.5%

0.8%

19

pbar Beam @ J-PARC K1.8BRWe would like to perform the proposed experiment

at J-PARC K1.8BR beam line

pbar stopping-rate

50kW, 30GeV6.0degreesNi-target

pbar production yield with a Sanford-Wang +

a pbar CS parameterization

250 stopped pbar/spill@ 0.7GeV/c, ldegrader~3cm

Incident Beammomentum bite : +/-2.5% (flat)incident beam distribution : idealDetectorsTungsten Degrader : r=19.25g/cm3

Plastic Scintillator : l=1cm, r=1.032g/cm3

Liquid He3 target : f=7cm, l=12cm, r=0.080g/cm3

pbar stopping-rate evaluation by GEANT4

6.5x103/spill/3.5s @ 0.7GeV/c

20

Expected double-strangeness Production Yieldpbar beam momentum : 0.7GeV/cbeam intensity : 6.5x103/spill/3.5s @ 50kWpbar stopping rate : 3.8%

stopped-pbar yield : 250/spill/3.5s

we assume: double-strangeness production rate = 10-4

duty factors of the accelerator and apparatus = 21h/24h

double-strangeness production yield = 540 / day @ 50kW [1day= 3shifts]

21

Trigger Scheme

pbar3He charged particle multiplicity at restCERN LEAR, streamer chamber exp. NPA518,683 (1990).

Nc Branch (%)

1 5.14 +/- 0.04

3 39.38 +/- 0.88

5 48.22 +/- 0.91

7 7.06 +/- 0.46

9 0.19 +/- 0.08

<Nc> 4.16 +/- 0.06

expected stopped-pbar yield = 250/spill @ 50kW

All events with a scintillator hit can be accumulated

expectedK-K-pp event

22

Backgrounds(semi-inclusive) K0

SK+ missing-mass w/ L-tagstopped-pbar + 3He K0

S + K+ + K-K-pp

stopped-pbar + 3He K0S + K+ + L + L

stopped-pbar + 3He K0S + K+ + L + L + p0 …

stopped-pbar + 3He K0S + K+ + K0 + S0 + (n)

stopped-pbar + 3He K0S + K+ + X0 + (n) …

3N annihilation

2N annihilation

23

Backgrounds (Cont’d)(inclusive) LL invariant mass

stopped-pbar + 3He K0S + K+ + K-K-pp

L + Lstopped-pbar + 3He K0

S + K+ + K-K-pp S0 + S0

stopped-pbar + 3He K0S + K+ + K-K-pp

S0 + S0 + p0 …

missing 2g

missing 2g+p0

B.E = 200 MeVG = 100 MeV

24

Expected Spectra

expected spectra are obtained withthe following assumptions:

Monte-Carlo simulation using GEANT4 toolkitreaction and decay are considered to be isotropic and proportional to the phase spaceenergy losses are NOT corrected in the spectraw/o Fermi-motionDAQ and analysis efficiency of 0.7

total yield : upper limit of pbarAKKX, 5x10-4

3N : 20% of total yield, and 3N:2N = 1:3

K-K-pp yield : 20% of total yield

production rate:• K-K-pp bound-state = 1x10-4

• (3N) K-K-LL phase-space = 5x10-5

• (3N) K+K0S0S0p0 phase-space = 5x10-5

• (2N) K+K0K0S0(n) phase-space = 3x10-4

These are optimistic assumptions

25

Expected Spectra (Cont’d)

non-mesonic : mesonic = 1 : 1

because the SSpp decay channel expected as the main mesonic branch of the K-K-pp state could decrease due to the deep binding energy of the K-K-pp

branching ratio of K-K-pp:• BR(K-K-ppLL) = 0.25• BR(K-K-ppS0S0 = 0.25• BR(K-K-pp S0S0 p0) = 0.5

mass [MeV]

26

Expected Spectra @ 50kW, 6weeks (126shifts)

In the LL spectra, we hardly discriminate the K-K-pp LL signals from the backgrounds clearly, but a cocktail approach could help us to explore the K-K-pp signals?

3 0 p He K K X L L 3 0 ( )p He K K X L L

# of K-K-ppLL = 357

LL invariant mass (2L) LL invariant mass (2K2L)

# of K-K-ppLL = 15

27

Spectra @ 50kW, 6weeks (126shifts) (Cont’d)

With a single L-tag, the 2N annihilation signals could overlap with the K-K-pp one, therefore we hardly distinguish the signal from the backgrounds.

3 0 p He K K X L 3 0 ( )p He K K X L L

The exclusive K0K+ missing mass spectrum is attractive because we can ignore the 2N-annihilation, even though the expected statistics are small.

K+K0 missing mass (2KL) K+K0 missing mass (2K2L)

# of K-K-pp = 208 # of K-K-pp = 32

0.0E+00 5.0E-05 1.0E-04 1.5E-04 2.0E-040

1

2

3

4

5

6

7

8

ppKK production rate (/stopped-pbar)

stati

stica

l sig

nific

ance

(s)

28

Sensitivity to the K-K-pp signal

significance [s=S/sqrt(S+B)] is obtained in exclusive missing-mass spectra

5.0SS B

Integratedrange

ppK-K- rate = 1x10-4

--- BKK = 200 MeV--- BKK = 150 MeV--- BKK = 120 MeV

beam power : 50kW, 6weeksproduction rate:• K-K-pp bound-state = parameter• (3N) K-K-LL phase-space = 5x10-5 (fix)• (3N) K+K0S0S0p0 phase-space = 5x10-5 (fix)• (2N) K+K0K0S0(n) phase-space = 3x10-4 (fix)

4x10-57x10-5

1.1x10-4

2600 – 2760 MeV

0.0E+00 5.0E+19 1.0E+20 1.5E+20 2.0E+201E-05

1E-04

1E-03

number of proton on target

3s si

gnifi

canc

epp

KK p

rodu

ction

rate

(/

stop

ped-

pbar

)

29

Sensitivity to the K-K-pp signal (Cont’d)

significance [s=S/sqrt(S+B)] is obtained in exclusive missing-mass spectra

--- BKK = 200 MeV--- BKK = 150 MeV--- BKK = 120 MeV

beam power : parameterproduction rate:• K-K-pp bound-state = parameter• (3N) K-K-LL phase-space = 5x10-5 (fix)• (3N) K+K0S0S0p0 phase-space = 5x10-5 (fix)• (2N) K+K0K0S0(n) phase-space = 3x10-4 (fix)

30kW, 6weeks

100kW, 6weeks 270kW,

6weeks

50kW, 6weeks

K-K-pp

30

Sensitivity to the double-strangeness productionDon't forget that the double-strangeness production itself, in pbar+A annihilation at rest, is very interesting.(there are NO conclusive evidences)

production mechanism (multi annihilation/cascade/…)?hidden strangeness?H/XN?cold QGP? little bit old!

significance [s=sqrt(S)] of the LL is obtained in the inclusive K++K0+L+L event

0.0E+00 5.0E+19 1.0E+20 1.5E+20 2.0E+201E-08

1E-07

1E-06

1E-05

1E-04

number of proton on target

3s si

gnifi

canc

eLL

pro

ducti

on ra

te

(/st

oppe

d-pb

ar)

30kW, 6weeks 100kW,

6weeks270kW, 6weeks

50kW, 6weeks

LLOBELIX/DIANA

31

Summary

32

Summary

We will search for double anti-kaon nuclear bound states by pbar annihilation on 3He nuclei at rest, using the pbar + 3He K+ + K0 + X (X = K-K-pp) channel.

The produced K-K-pp cluster will be identified with missing mass spectroscopy using the K+K0 channel with a L-tag, and invariant mass analysis of the expected decay particles from the K-K-pp cluster, such as LL by using the E15 spectrometer at the K1.8BR beam line.

We are now improving this experiment toward the proposal submission to J-PARC.

33

34

Back-Up

35

Schedule

Year (JFY) K1.8BR K1.1 (fN)2009 beam-tune proposal2010 E17 R&D, design2011 E17 R&D, design2012 E15/E31 construction2013 E15/E31 commissioning2014 … 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/E31K1.1 : joint project with the fN experiment (E29)?

here?

36

L(1405)/K-pp production in pbarA annihilation at rest

37

L(1405) production in pbarA annihilationthe things we have learned from the past experiments are:

1. the reactions whose quark-lines vanish are minority (Pontecorvo reactions)

pbar + d K0 + L + X pbar + d K0 + L

It would be too hard to investigate the L(1405) production using the simple channel in pbarA reaction

~10-3 ~10-6

CERN/LEAR, Crystal Barrel,Phys. Lett., B469, 276 (1999)

2. L (1405) production yield in pbar+A annihilation can be considered as

~ 1/10 x L(S0) production yieldby analogy with the p-+p reaction

38

L(1405) production in pbarA annihilation (Cont’d)

p-+p X, pp- = 4.5 GeV/c sqrt(s) = 3.2 GeVpbar+d X, at rest sqrt(s) = 2.8 GeV

p-+p L +K : 123.5 mbp-+p S0+K : 61.5 mbp-+p L (1405)+K0 : 18 mb

39

L(1405) production in pbarA annihilation (Cont’d)pbar+d L (S0)+X : ~3.3x10-3 per stopped-pbar

pbar+d L (S0)+K0 : ~4.5x10-6 per stopped-pbar

pbar+3He L (S0)+X : ~5.5x10-3 per stopped-pbar

pbar+d L (1405)+X : ~3x10-4 per stopped-pbar

pbar+d L (1405)+K0 : ~5x10-7 per stopped-pbar

pbar+3He L (1405)+X : ~5x10-4 per stopped-pbar

pbar+3He L (1405)+K0+ps : ~5x10-7 per stopped-pbar

extrapolate

taking account of the K0 detection efficiency of ~10-1, naively, the L* detection yield with the simple channel is the order of 10-8/stopped-pbar at least.

huge combinatorial background from involved pions could not be eliminated from L*pSppn decays, even if we can detect the neutron.

40

K-pp production in pbarA annihilation

1 nucleon annihilation (from K-)

2 nucleon annihilation (from L(1405))

3p He p n p p

K K p p

K K p p

K K pp

p

p

p

- -

- -

- -

e.g.:

3

0

0

0

(1405)

(1405)

p He p pn p

K p

K p

K K pp

p p

p p

p p

-

-

- -

L

L

e.g.:

pL* ~ 500MeV/c

pK- ~ 900MeV/c

yield ~ 10-2

yield ~ 10-4

3 nucleon annihilation (direct production) 3p He p ppn

K K ppp - -

e.g.:

41

K-pp production in pbarA annihilation (Cont’d)Let’s consider sticking probability R of L(1405) with proton as the following equation:

R ~ exp(-q2/pF2),

where q is the momentum transfer and pF is the Fermi motion of 3He which is ~ 100 MeV/c. If we assume q is ~ 500 MeV/c, then the probability R can be obtained to be ~ 10-11.

10th J-PARC PAC-meeting (Nagae)

However, if we apply their assumption of R ~ 1%

K-pp yield ~ 3x10-4 (L* yield) x 10-2 (sticking prob.) = 3x10-6

in pbar+3He annihilationpbar+dL*X

42

K-pp production in pbarA annihilation (Cont’d)


0.1

0.2

0.3

0.4

pbar+3He->K++p-+(K-pp)K-pp -> Lp,

G=100MeV

inv-mass (at rest)miss-mass (at rest)exclusive (at rest)inv-mass (1GeV/c)miss-mass (1GeV/c)ac

cept

ance

acceptance with the E15 CDS

43

K-pp production in pbarA annihilation (Cont’d)mass spectra

mass resolutionL p inv-mass : ~24MeV/c2

K+p- miss-mass : ~79MeV/c2

for example• at rest• pbar3He K+p-(K-pp)• K-ppLp• B.E.=100MeV,• G=100MeV

*** production yields are assumed to be the same for each process ***

Lp invariant mass K+p- missing mass

E15 w/ n : ~13MeV/c2 for Lp inv-mass

44

K-pp production in pbarA annihilation (Cont’d)from the past experiment (CERN-LEAR), the L production yield in pbar+3He annihilation is known to be 5.5x10-3/stopped-pbar.If we assume the ratio of 3NA/2NA is 10%, then the simplest BG pbar+3HeK+p-

Lp is ~5x10-4.beam power : 50kW, 6weeksproduction rate:• K-pp bound-state = 1x10-4

• (3N) K-p-Lp phase-space = 5x10-4

K-ppLp/S0p/p0S0p=100/0/0

50/50/0

25/25/50

from OBELIX

B.E.=100MeVG=100MeV

in-flight experiment

46

Detector Acceptance

E15 CDS @ K1.8BR

Pbar+3He K++K0S+K-K-pp,


--- LL detection--- K0


SK+LL detection

stopped1GeV/c


0.05

0.10

0.15pbar+3He->K++K0+(K-K-pp)

K-K-pp -> LL, G=100MeV

acce

ptan

ce

binding energy

47

Expected double-strageness Production Yieldpbar beam momentum : 1GeV/cbeam intensity : 7.0x104/spill/3.5s @ 50kW

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

48

Expected double-strangeness Production Yield (Cont’d)

Expected double-strangeness yield = 2.1x103 /day @ 50kWw/o detector acceptance

L3He parameters: * r = 0.08g/cm3

* l = 12cmN = s * NB * NT• N : yield• s : cross section• NB : the number of beam• NT : the number of density per unit area of the target

BG rate: total CS = 117mbpbar = 7.0x104/spill BG = 1.6x103/spill

duty factors of the accelerator and apparatus = 21h/24h

49

Expected Spectra @ 50kW, 6weeks

# of K-K-ppLL = 716


# of K-K-ppLL = 24

K+K0 missing mass (2KL) K+K0 missing mass (2K2L)

# of K-K-pp = 776 # of K-K-pp = 41

1GeV/c pbar


50

Expected Spectra @ 50kW, 6weeks (Cont’d)

K+K0 missing mass (2KL)

# of K-K-pp = 776


beam power : 50kW, 6weeksproduction rate:• K-K-pp bound-state = parameter• (3N) K-K-LL phase-space = 5x10-5 (fix)• (3N) K+K0S0S0p0 phase-space = 5x10-5 (fix)• (2N) K+K0K0S0(n) phase-space = 3x10-4 (fix)

# of K-K-pp = 389

K+K0 missing mass (2KL)

ppK-K- rate = 0.5x10-4

The in-flight K+K0 missing mass spectrum looks nice, however, the backgrounds and the K-K-pp signal are unified in case the K-K-pp production yield is less than ~ 0.5x10-4!

51


K+K0LL missing-mass2 (2K2L)

1GeV/c pbar

52

Other backups

53

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

2( ) ~ 5 10R pp KK - 3 0 2

4 0 2

( ( )) ~ 0.6 10

( ( )) ~ 1.1 10

R p He

R p He

-

-

L S

L S

2 5

( )

( ) ~ 10

R pA KKKK

R pp KK g -

54

Interpretation of the Experimental ResultsAlthough 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-nucleonannihilation

rescatteringcascades

multi-nucleonannihilation

B=0 B>0B>0

the mechanism is NOT known well

because of low statistics

of the experimental results!

55

K+K0LL Final State & Background3 0

0

p He K K X

K K

L LThis exclusive channel study is equivalent tothe 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 channelsdirect K+K0LL production channels, like:

S0gL contaminations, like:

3 0

3 0 0 ...

p He K K

p He K K p

L L

L L

3 0 0

0

p He K K

K K g

L S

L L

be eliminated by the kinematical constraint,

ideally

be distinguished by inv.-mass only major background source

56

Expected Kinematics (Cont’d)3 0p He K K L L

MH = 2ML

3 0p He K K H

L momentum LL inv. massLL spectra

L-L opening-angle

strong correlation of LL opening-angle in K-K-pp/H productions

57

Detector DesignKey pointslow material detector systemwide acceptance with pID E15 CDS @ K1.8BR

CDCType A A’ A U U’ V V’ A A’ U U’ V V’ A A’

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

ZTPCLayer 1 2 3 4

radius 92.5 97.5 102.5 107.5

B = 0.5TCDC resolution : srf = 0.2mm

sz’s depend on the tilt angles (~3mm)ZTPC resolution : sz = 1mm

srf is not used for present setup

58



with Dipole-setup @ K1.1

60

Detector Design (Cont’d)new dipole setup @ K1.1

CDCType A A’ A U U’ V V’ A A’ U U’ V V’ A A’

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

INC (wire chamber)Type A A’ A U U’ V V’ A A’ A U U’ V V’ A A’ A

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

The design goal is to become the common setup for the f-nuclei experiment with in-flight pbar-beamB = 0.5TDouble Cylindrical-Drift-Chamber setuppID 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

61

Detector Acceptance

dipole @ K1.1--- LL detection--- K0


SK+LL detection

Pbar+3He K++K0S+K-K-pp,


binding energy


0.05

0.10

acce

ptan

ce

stopped1GeV/c

62


62

# of K-K-ppLL = 138


# of K-K-ppLL = 14

K+K0 missing mass (2K) K+K0 missing mass (2K2L)

# of K-K-pp = 327 # of K-K-pp = 46

stopped pbar

63


stopped pbar


64


64

# of K-K-ppLL = 554

LL invariant mass (2L) LL invariant mass (2K2L)# of K-K-ppLL = 38

K+K0 missing mass (2K) K+K0 missing mass (2K2L)

# of K-K-pp = 1473 # of K-K-pp = 82

1GeV/c pbar

65


1GeV/c pbar


Past Experiments of Stopped-pbar Annihilation

pbar+3He charged particle multiplicity at restCERN LEAR, streamer chamber exp.NP A518, 683 (1990).

nc1 5.14 +- 0.403 39.38 +- 0.885 48.22 +- 0.917 7.06 +- 0.469 0.19 +- 0.08

<nc> 4.155 +- 0.06

branch(%)

charged particle multiplicity at restform Rivista Del Nuovo Cimento 17, 1 (1994).

pbar+4He charged particle multiplicity at restCERN LEAR, streamer chamber exp.NP A465, 714 (1987).[data in nuovo- ciment is listed below, which is a higher statistics than NPA465]

nc1 3.36 +- 0.352 5.03 +- 0.423 33.48 +- 0.924 12.26 +- 0.635 35.68 +- 0.936 3.51 +- 0.367 6.24 +- 0.478 0.19 +- 0.089 0.24 +- 0.10

<nc> 4.097 +- 0.07

branch(%)

CERN LEAR streamer chamber exp.NIM A234, 30 (1985).

70.4 2.5%

29.6 2.5%

0.42 0.05

a

a

a a

pp

pn

pn pp

s

s

s s

They obtained

KKbar production-rate for pbar+p at restform Rivista Del Nuovo Cimento 17, 1 (1994).

the KKbar production-rate R for pbar+p annihilation at rest(obtained from hydrogen bubble chamber data)

0 0

0 0

0 0 0 0 0

0 0 0 0

1.733 0.067%

1.912 0.141%

1.701 0.082%

3 1 2.149 0.065%4 25.35 0.18%

S

R K K

R K K

R K K R K K

R K R K K R K K R K K

R KK R K K R K K R K K R K K

-

-

-

- -

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 annihilationp=<1GeV/c pbar-beam @ ITEP 10GeV-PS700-liter Xenon bubble chamber, w/o B-field106 pictures 7.8x105 pbarXe inelastic 2.8x105 pbarXe @ 0-0.4GeV/cpbarXeK+K+X : 4 events (0.31+/-0.16)x10-4

pbarXeK+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 collaboration @ CERN/LEAR concludes their pbardLK0/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

Crystal Barrel (’86~’96) [Phys. Lett., B469, 276 (1999).]pbar4He annihilationstopped pbar @ CERN/LEARliquid deuteron targetcylindrical spectrometer w/ B-fieldSVX, CDC, CsI crystals~106 events of 2/4-prong with topological triggers

0 6

0 0 6

5

( ) (2.35 0.45) 10

( ) (2.15 0.45) 10

( ) (1.3 1.0) 10

Br pd K

Br pd K

Br pd pp

-

-

- -

L

S

support the statistical model

OBELIX (’86~’96) [Nucl. Phys., A797, 109 (2007).]pbar4He annihilationstopped pbar @ CERN/LEARgas target (4He@NTP, H2@3atm)cylindrical spectrometer w/ B-fieldspiral projection chamber, scintillator barrels, jet-drift chambers238,746/47,299 events of 4/5-prong in 4Hepmin = 100/150/300MeV/c for p/K/p

4

( )

( )

( )

( )

s s

p He

K K p K K nnp

K K n K K nnn

K K n K K p nn

K K K nn K K K p nn

p p

p p p p

p p

p

- - - -

- - - -

- - -

- - -

S S

S S

S L

L

34+/-8 events (0.17+/-0.04)x10-4

4-prong

5-prong

5-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

Introduction

we will open new door to the high density matter physics, like the inside of neutron stars

Kaonic Nuclear Cluster (KNC)

77

the existence of deeply-bound kaonic nuclear cluster is predicted from strongly attractive KbarN interaction

Kaonic Nuclei

BindingEnergy[MeV]

Width[MeV]

CentralDensity

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).

the density of kaonic nuclei is predicted to be extreme high density

Method Binding Energy (MeV) Width (MeV)

Akaishi, YamazakiPLB533, 70 (2002). ATMS 48 61

Shevchenko, Gal, MaresPRL98, 082301 (2007). Faddeev 55-70 90-110

Ikeda, SatoPRC76, 035203 (2007). Faddeev 79 74

Dote, Hyodo, WeiseNPA804,197(2008). chiral SU(3) 19+/-3 40-70 (pSN-decay)

78

Theoretical Situation of KNCtheoretical predictions for kaonic nuclei, e.g., K-pp

Koike, HaradaPLB652, 262 (2007).DWIA

•whether the binding energy is deep or shallow•how broad is the width ?

3He(K-,n)

no “narrow” structurePLB 659:107,2008

79

Experimental Situation of KNC

4He（ stopped K-,p)E549@KEK-PS

12C(K-,n)

12C(K-,p)

missing mass

E548@KEK-PS

Prog.Theor.Phys.118:181-186,2007.

arXiv:0711.4943

unknown strength between Q.F. & 2N abs.

deep K-nucleus potential of ~200MeV

-

K-pnn?

K-pp/K-pnn?

K-pn/K-ppn?

4He（ stopped K-,LN)E549@KEK-PS

80

Experimental Situation of KNC (Cont’d)

FINUDA@DAFNE OBELIX@CERN-LEAR

We need conclusive evidencewith observation of formation and decay !

DISTO@SATUREN

L-p invariant mass

PRL, 94, 212303 (2005) NP, A789, 222 (2007)

peak structure signature of kaonic nuclei ?

K-pp?K-pp?

PRL,104,132502 (2010)

K-pp?

81

Experimental Principle of J-PARC E15

search for K-pp bound state using 3He(K-,n) reaction

K- 3He Formation

exclusive measurement byMissing mass spectroscopy

andInvariant mass reconstruction

Decay

K-ppcluster

neutron

L p

pp-

Mode to decay charged particles

Missing

mass

Spectroscop

y

via neutron

Invariant

mass

reconstructio

n

82

J-PARC E15 Setup

1GeV/cK- beam

p

p-p

n

NeutronToF Wall

CylindricalDetectorSystem

Beam SweepingMagnet

K1.8BR Beam Line

flight length = 15mneutron

Beam trajectory

CDS &target

SweepingMagnet

NeutronCounter

Beam LineSpectrometer

E15 will provide theconclusive evidence of K-pp

Documents

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