a search for double anti-kaon production in antiproton- 3 he annihilation at j-parc f.sakuma, riken...
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A search for double anti-kaon production in antiproton-3He
annihilation at J-PARC
F.Sakuma, RIKEN
1Tum-Riken Kick-Off Meeting @ TUM, May 10-11, 2010.
2
This talk is based on the LoI submitted in June, 2009.
3
(brief) Introduction of “Kaonic Nuclear Cluster”
Possibility of “Double-Kaonic Nuclear Cluster”
by Stopped-pbar AnnihilationExperimental ApproachSummary
Contents
we will open new door to the high density matter physics, like the inside of neutron stars
Kaonic Nuclear Cluster (KNC)
4
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)
5
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
6
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
7
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?
8
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
p
p-
Mode to decay charged particles
Missing
mass
Spectroscop
y
via neutron
Invariant
mass
reconstructio
n
9
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
10
Possibility of “Double-KaonicNuclear Cluster”
by Stopped-pbar Annihilation
What will happen to put one more kaon in the kaonic nuclear cluster?
11
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
However, if multi kaonic nuclear exists with deep bound energy, following pbar annihilation reactions will 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
12
theoreticalprediction
B.E.=117MeVG=35MeV
B.E.=221MeVG=37MeV
Production Mechanism of K-K-pp with pbar+3He?
13
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.
For example, the possible K-K-pp production mechanisms are as follows:with stopped pbar
①direct K-K-pp production with 3N annihilation② L*L* production with 3N annihilation followed by K-K-pp formation
with in-flight pbar
in addition above 2ways,③elementally pbar+pKKKK production followed by K-K-pp formation
It’s worthwhile to explore these exotic system with pbar,although the mechanism is NOT completely investigated!
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.
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
2( ) ~ 5 10R pp KK 3 0 2
4 0 2
( ( )) ~ 0.6 10
( ( )) ~ 1.1 10
R p He
R p He
2 5
( )
( ) ~ 10
R pA KKKK
R pp KK
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.
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
16
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
17
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
18
Experimental Approach
The double-strangeness production yield of ~10-4 makes it possible to explore the exotic systems.
19
How to Measure?
3 0p He K K 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
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.
20
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
21
Procedure of the K-K-pp Measurement
Key points of the experimenthigh intensity pbar beamwide-acceptance and low-material detector
How to measure the K-K-pp signal(semi-inclusive) K0
SK+ missing-mass w/ -tag(inclusive) invariant mass(exclusive) K0
SK+ 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-LineWe would like to perform the proposed experiment
at J-PARC K1.8BR beam line (or K1.1)
pbar stopping-rate
30GeV-9mA,6.0degreesNi-target
pbar production yield with a Sanford-Wang
1.3x103 stopped pbar/spill@ 0.65GeV/c, ldegrader~14cm
Incident Beammomentum bite : +/-2.5% (flat)incident beam distribution : ideal
DetectorsCarbon 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
23
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
24
Trigger Scheme
pbar3He charged particle multiplicity at restCERN LEAR, streamer chamber exp. NPA518,683 91990).
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 = 1.3x103/spill
All events with a scintillator hit can be accumulated
K-K-pp event
25
Detector Acceptance
E15 CDS @ K1.8BR
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
Pbar+3He K++K0S+K-K-pp,
K-K-pp LL,G(K-K-pp)=100MeV
binding energy
26
Expected K-K-pp Production Yieldpbar beam momentum : 0.65GeV/cbeam intensity : 3.4x104/spill/3.5s @ 270kWpbar 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 @ 270kWw/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
E15 CDS @ K1.8BR--- LL detection--- K0
SK+ w/ L-tag detection--- K0
SK+LL detection
B.E.=120MeV B.E.=150MeV B.E.=200MeV0
200
400
600
800
1,000
1,200
exce
pted
yie
ld
(/w
eek@
270k
W)
binding energy
K-K-pp production rate = 10-4
Br(K-K-ppLL) = 100%
28
Backgrounds(semi-inclusive) K0
SK+ missing-mass w/ L-tag
(inclusive) LL invariant mass
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
stopped-pbar + 3He K0S + K+ + K-K-pp
L + Lstopped-pbar + 3He K0
S + K+ + K-K-ppL + 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
expected spectrum with the assumptions:branching ratio of K-K-pp:• BR(K-K-ppLL) = 0.1• BR(K-K-ppLS0) = 0.1• BR(K-K-ppS0S0 = 0.1• BR(K-K-ppLLp0) = 0.7
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
2L = LL detection2K = K+K0 w/ L-tag detection2L2K = K+K0LL detection
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-motion
30
Expected Spectra @ 270kW, 4weeks
# of K-K-ppLL = 406
LL invariant mass (2L) LL invariant mass (2K2L)
# of K-K-ppLL = 35
K+K0 missing mass (2K) K+K0 missing mass (2K2L)
# of K-K-pp = 1293 # of K-K-pp = 203
stopped pbarB.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.
31
Summary
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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
34
Back-Up
35
K-pp Production with pbar at rest
3 0p He K K pp Of course, we can measure K-pp production!
From several stopped-pbar experiments, the inclusive production yields are:
2( ) ~ 5 10R pp KK
Very simply, expected K-pp yield is 100 times larger than the K-K-pp production!
OBELIX@CERN-LEAR
L-p invariant mass
NP, A789, 222 (2007)
K-pp?
4
p He K pp X
p
36
Expected Spectra @ 270kW, 4weeks
stopped pbarB.E=200MeV, G=100MeV
270kW, 4weeks
K+K0LL missing-mass2 (2K2L)
37
Expected Spectra @ 50kW, 4weeks
37
# of K-K-ppLL = 75
LL invariant mass (2L) LL invariant mass (2K2L)
# of K-K-ppLL = 6
K+K0 missing mass (2K) K+K0 missing mass (2K2L)
# of K-K-pp = 239 # of K-K-pp = 38
stopped pbarB.E=200MeV, G=100MeV
50kW, 4weeks
38
Expected Spectra @ 50kW, 4weeks
stopped pbarB.E=200MeV, G=100MeV
50kW, 4weeks
K+K0LL missing-mass2 (2K2L)
in-flight experiment
40
Detector Acceptance
E15 CDS @ K1.8BR
Pbar+3He K++K0S+K-K-pp,
K-K-pp LL,G(K-K-pp)=100MeV
binding energy
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
stopped1GeV/c
41
Expected K-K-pp Production Yield
pbar beam momentum : 1GeV/cbeam 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
42
Expected K-K-pp Production Yield (Cont’d)
DAQ & ana efficiency = 0.7 & duty factor = 0.7
expected K-K-pp yield = 7.5x104 /week @ 270kWw/o detector acceptance
K-K-pp production yield = 1.5x105 /week @ 270kW
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 = 6.4x105/spill BG = 1.4x104/spill
43
Expected K-K-pp Detection Yield
E15 CDS @ K1.8BR
Pbar+3He K++K0S+K-K-pp,
K-K-pp LL,G(K-K-pp)=100MeV
binding energy
--- LL detection--- K0
SK+ w/ L-tag detection--- K0
SK+LL detection
stopped1GeV/c
B.E.=120MeV B.E.=150MeV B.E.=200MeV0
5001,0001,5002,0002,5003,0003,5004,0004,500
exce
pted
yie
ld
(/w
eek@
270k
W)
44
Expected Spectra @ 270kW, 4weeks
44
# of K-K-ppLL = 1397
LL invariant mass (2L) LL invariant mass (2K2L)
# of K-K-ppLL = 94
K+K0 missing mass (2K) K+K0 missing mass (2K2L)
# of K-K-pp = 8095 # of K-K-pp = 392
1GeV/c pbarB.E=200MeV, G=100MeV
270kW, 4weeks
45
Expected Spectra @ 270kW, 4weeks
1GeV/c pbarB.E=200MeV, G=100MeV
270kW, 4weeks
K+K0LL missing-mass2 (2K2L)
with Dipole-setup @ K1.1
47
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
48
Detector Acceptance
dipole @ K1.1--- LL detection--- K0
SK+ w/ L-tag detection--- K0
SK+LL detection
Pbar+3He K++K0S+K-K-pp,
K-K-pp LL,G(K-K-pp)=100MeV
binding energy
B.E.=120MeV B.E.=150MeV B.E.=200MeV0.00
0.05
0.10
acce
ptan
ce
stopped1GeV/c
49
Expected K-K-pp Detection Yield
dipole @ K1.1--- LL detection--- K0
SK+ w/ L-tag detection--- K0
SK+LL detection
Pbar+3He K++K0S+K-K-pp,
K-K-pp LL,G(K-K-pp)=100MeV
binding energy
stopped1GeV/c
B.E.=120MeV B.E.=150MeV B.E.=200MeV0
500
1,000
1,500
2,000
2,500
3,000
3,500
exce
pted
yie
ld
(/w
eek@
270k
W)
50
Expected Spectra @ 270kW, 4weeks
50
# of K-K-ppLL = 282
LL invariant mass (2L) LL invariant mass (2K2L)
# of K-K-ppLL = 27
K+K0 missing mass (2K) K+K0 missing mass (2K2L)
# of K-K-pp = 1719 # of K-K-pp = 238
stopped pbarB.E=200MeV, G=100MeV
270kW, 4weeks
51
Expected Spectra @ 270kW, 4weeks
stopped pbarB.E=200MeV, G=100MeV
270kW, 4weeks
K+K0LL missing-mass2 (2K2L)
52
Expected Spectra @ 270kW, 4weeks
52
# of K-K-ppLL = 1112
LL invariant mass (2L) LL invariant mass (2K2L)
# of K-K-ppLL = 76
K+K0 missing mass (2K) K+K0 missing mass (2K2L)
# of K-K-pp = 7915 # of K-K-pp = 435
1GeV/c pbarB.E=200MeV, G=100MeV
270kW, 4weeks
53
Expected Spectra @ 270kW, 4weeks
1GeV/c pbarB.E=200MeV, G=100MeV
270kW, 4weeks
K+K0LL missing-mass2 (2K2L)
54
55
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!
56
K+K0LL Final State & Background3 0
0
p He K K X
K K
This 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+K0 production channels, like:
0 contaminations, like:
3 0
3 0 0 ...
p He K K
p He K K
3 0 0
0
p He K K
K K
be eliminated by the kinematical constraint,
ideally
be distinguished by inv.-mass only major background source
57
Expected Kinematics (Cont’d)3 0p He K K
MH = 2ML
3 0p He K K H
L momentum LL inv. mass
LL spectra-L L opening-angle
strong correlation of LL opening-angle in K-K-pp/H productions
58
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/E31?K1.1 : joint project with the fN experiment?
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
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 2
5.35 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 p
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
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