Double antikaonic nuclear clusters in antiproton- 3 He annihilation at J-PARC
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Transcript of Double antikaonic nuclear clusters in antiproton- 3 He annihilation at J-PARC
Double antikaonic nuclear clusters in antiproton-3He annihilation
at J-PARC
F.Sakuma, RIKEN
1LEAP2011 @ TRIUMF, April 27 - May 1, 2011.
C. CURCEANU (INFN Frascati, Italy), M. IWASAKI (RIKEN, Japan), P. KIENLE (TUM, Germany), H. OHNISHI (RIKEN, Japan),
M. TOKUDA (TITECH, Japan), K. TSUKADA (Tohoku-U, Japan), E. WIDMANN (SMI, Austria), T. YAMAZAKI (RIKEN/U-Tokyo, Japan),
J. ZMESKAL (SMI, Austria)
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(brief) Introduction of “Kaonic Nuclear Cluster”
Possibility of “Double-Kaonic Nuclear Cluster”
in pbar+A annihilation at restExperimental ApproachSummary
Outline
we will open new door to the high density matter physics, like the inside of neutron stars
Kaonic Nuclear Cluster (KNC)
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T.Yamazaki, A.Dote, Y.Akiaishi, PLB587, 167 (2004).
Density [1/fm3]
the density of the KNC is predicted to be high density more than normal nuclear-density (r0)
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.
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Experimental Situation of KNC
FINUDA@DAFNE
We need more evidences in various channels!
DISTO@SATURENPRL, 94, 212303 (2005) PRL,104,132502 (2010)
stopped-K- + A (L + p) + X 2.85GeV-p + p (L + p) + K+
B.E. = 115MeVG = 67MeV
B.E. = 103MeVG = 118MeV
Because there is a discrepancy between THEORETICAL PREDICTIONS and EXPERIMENTAL OBSERVATIONS…
K-ppLp?K-ppLp?
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J-PARC E15 Experiment
1GeV/cK- beam
p
p-p
n
NeutronToF Wall
K1.8BR Beam Line
neutron
Beam trajectory
CDS &target
SweepingMagnet
NeutronCounter
Beam LineSpectrometer
search for the K-pp using 3He(in-flight K-,n) reaction
flight length = 15m
Beam SweepingMagnet
CylindricalDetectorSystem
K-pp
Missing mass
Spectroscopy
via neutron Invariant mass
reconstruction
L
will start next year
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Possibility of “Double-KaonicNuclear Cluster”
in pbar+A annihilation at rest
What will happen to put one more kaon in the kaonic nuclear cluster?
Why at rest?probability of multi-nucleon annihilation
(exotic B>0 annihilation) should be larger than in-flight reactions
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Double-Kaonic Nuclear Cluster (DKNC)The double-kaonic nuclear clusters have been predicted theoretically.
How to produce the double-kaonic nuclear cluster?heavy ion collision(K-,K+) reactionpbarA annihilation
We use pbarA annihilation
PL,B587,167 (2004).
The double-kaonic clusters have much stronger binding energy and a much higher density than single ones.(AMD calc.)
ppn
ppnK-
ppnK-K-
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
the DKNC in pbarA annihilation?
if multi kaonic nuclear exists with deep bound energy, following pbar annihilation reactions will be possible!
-98MeV
3 0 109MeVppKKp He K K K K pp B - - -
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e.g.
0K K L L
We can investigate the DKNC with exclusive or semi-inclusive measurement
final state:the most energetic favored decay mode
p-pp p- p-p
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Related Topics
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
PRC75 022201(R) (2007).
12 ,C K K X- LL
The exclusive H search with stopped-pbar beam has never
been done.
3 0
+pp He K K pp-
L
Of course we can measure K-pp production with the dedicated
detector, simultaneously.
OBELIX@CERN-LEAR
NP, A789, 222 (2007).EPJ, A40, 11 (2009).
K-pp?4
p He K pp X
p
- L
H?
Our experiment can check the OBELIX results of the K-pp with a
dedicated spectrometer
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Past Experiments of Double-Strangeness Production in Stopped-pbar Annihilation
They did NOT observe any double-strangeness event in pbar - C, Ti, Ta, Pb annihilation (~80,000 events, p < 400 MeV/c)
Reaction Frequency (90% C.L.)
pbarAL0L0X <4x10-4
pbarAL0K-X <5x10-4
pbarAK+K+X <5x10-4
pbarAHX <9x10-5
[Phys.Lett., B144, 27 (1984).]
There are NO results of the DKNC search, but several groups reported double-strangeness production in pbar+A annihilation
hydrogen bubble-chamber experiment @ BNL in association with the H-dibaryon search
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Past Experiments of Double-Strangeness Production in Stopped-pbar Annihilation
experiment Channel # of events yield (x10-4)DIANA@ITEP
[pbar+Xe]PLB464, 323 (1999).
K+K+X 4 0.31+/-0.16K+K0X 3 2.1+/-1.2
OBELIX@CERN/LEAR
[pbar+4He]NPA797, 109
(2007).
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-L n 16+/-4 1.21+/-0.29K+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
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Experimental Approach
The double-strangeness production yield of ~10-4 makes it possible to explore the exotic systems.
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Experimental Strategy
I. investigation of “double-strangeness production” in pbar+3He annihilation at rest, with high statistics data
II. search for “double-kaonic nuclear cluster” in pbar+3He annihilation at rest
Current situation of the double-strangeness production in pbar+A (A>2) annihilation at rest:
NO results using a dedicated spectrometer except for bubble chamber experiments.
NO results with high-statistics measurement.
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3 0
p He K K
p He K K
-
L
L L
3 0
+p He K K K K pp - -
L L
K1.8BR Beam LineCDS &
targetBeam Line
Spectrometer
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SetupWe will perform the proposed experiment
at J-PARC K1.8BR beam line
~2800 L smass =3.5+/-0.1MeV/c2
preliminary
key pointshigh intensity pbar beamlow mass material detectorwide acceptance detector
reconstructed pp- inv. mass in commissioning run (2010, Oct.)
0.9GeV-K- + A L + X
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pbar Beam @ J-PARC K1.8BR
pbar stopping-rate
50kW, 30GeV6.0degreesNi-target
pbar production yield witha 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
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Trigger Scheme
pbar+3He charged particle multiplicity at restCERN LEAR, streamer chamber exp. NPA518,683 (1990).
Nc Branch (%)1 5.14 +/- 0.043 39.38 +/- 0.885 48.22 +/- 0.917 7.06 +/- 0.469 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
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Experimental Strategy
I. investigation of “double-strangeness production” in pbar+3He annihilation at rest
II. search for “double-kaonic nuclear cluster” in pbar+3He annihilation at rest
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!
3 0
+p He K K K K pp - -
L L
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3 0
p He K K
p He K K
-
L
L L
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Double-Strangeness Measurement3
3 0
p He K K
p He K K
-
L
L L
K+K+L- channel K+K0LL channelK+K+
detection 2.4 x 10-1 LLdetection 4.1 x 10-2
K+K+Ldetection 4.4 x 10-2 LLK+
detection 2.1 x 10-2
K+K+Lp-
detection 2.8 x 10-2 LLK+K0
detection 2.9 x 10-3
CDS @ K1.8BR
evaluated using GEANT4 toolkitMany-body decay are considered to be isotropic decay.branching ratios of K0K0
S/K0Spp-/Lpp- are included.
acceptance is defined by CDC
acceptances of K+K+ and LL
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Double-Strangeness Measurement (Cont’d)
30kW, for 2weeksK+K+ event 750LL event 130
if we assumethe double-strangeness production-yield to be 10-4 / stopped-pbar
as reported by the OBELIX and DIANA groups:
expected yield
* The following are includedduty factor of the accelerator and apparatus : 21h/24hDAQ and analysis eff. : 0.7
sensitivity
1.0E+18 1.0E+19 1.0E+20
1E-06
1E-05
1E-04
1E-03
double K+double Λ
30kW, 2weeks30kW, 6weeks
30kW, 1week
50kW, 6weeks
100kW, 6weeks
OBELIX/
DIANA
number of proton on targetpr
oduc
tion-
yiel
d (/
stop
ped-
pbar )sensitivity to 100 double-
strangeness events (~10s) detection is evaluated by
the MC.
1.E-04
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Experimental Strategy
I. investigation of “double-strangeness production” in pbar+3He annihilation at rest
II. search for “double-kaonic nuclear cluster” in pbar+3He annihilation at rest
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!
3 0
+p He K K K K pp - -
L L
3
3 0
p He K K
p He K K
-
L
L L
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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
3 0
+p He K K K K pp - -
L L
B.E.=120MeV B.E.=150MeV B.E.=200MeV0.00
0.05
0.10
0.15ac
cept
ance
--- K0K+ w/ L-tag --- LL--- K0K+LL
K-K-pp binding energy
evaluated using GEANT4 toolkit G(K-K-pp) = 100 MeVisotropic decaybranching ratios of K0K0
S/K0Spp-/Lpp- are
included.
acceptance
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Backgrounds(semi-inclusive) K0K+ missing-mass w/ L-tag
stopped-pbar + 3He K0 + K+ + K-K-ppstopped-pbar + 3He K0 + K+ + L + Lstopped-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
signal
*each spectrum is obtained with the same production yield
K0K+ missing-mass
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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
signal
*each spectrum is obtained with the same production yield
LL invariant mass
production yield:• K-K-pp bound-state = ?• (3N) K-K-LL phase-space = 5x10-5
• (3N) K+K000p0 phase-space = 5x10-5
• (2N) K+K0K00(n) phase-space = 3x10-4
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Expected Yield
total yield : upper limit of pbarAKKX, 5x10-4
3N : 20% of yield, and 3N:2N = 1:3
K-K-pp yield : parameter
Sensitivity to the K-K-pp observation is estimated using the MC
non-mesonic : mesonic = 1 : 1
branching ratio:• BR(K-K-ppLL) = 0.25• BR(K-K-pp00 = 0.25• BR(K-K-pp 00 p0) = 0.5
assumptions
1.0E+19 1.0E+201E-05
1E-04
1E-03
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Sensitivity to the K-K-pp signal (Exclusive)
significance [s=S/sqrt(S+B)] is obtained in exclusive missing-mass spectra
--- BKK = 120 MeV--- BKK = 150 MeV--- BKK = 200 MeV
30kW, 6weeks
100kW, 6weeks
270kW, 6weeks
50kW,6weeks
number of proton on target
3s si
gnifi
canc
e of
K- K- p
p pr
oduc
tion
yiel
d (/
stop
ped-
pbar )
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Expected Spectra @ 50kW, 6weeks3 0 ( )p He K K X L L
# of K-K-pp = 32
K+K0 missing mass (2K2L)
0 K K X L L
# of K-K-ppLL = 357
LL invariant mass
0 ( )K K X L L
LL invariant mass
# of K-K-ppLL = 15
0 K K X L
K+K0 missing mass
# of K-K-pp = 208
assumption in the figures:K-K-pp production yield
= 10-4/stopped-pbar
B.E. = 200 MeV G = 100 MeV
The signal can be discriminated from the other backgrounds in the exclusive K+K0 missing
mass spectrum.
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Summary
We will search for Double-Kaonic Nuclear Cluster (DKNC) by pbar + 3He annihilation at rest, using the pbar + 3He K+ + K0 + X (X = K-K-pp) channel @ J-PARC K1.8BR beam line.
In preparation for the DKNC search, double-strangeness production measurement will be conducted as a first step.
We are now improving this experimental idea toward the proposal submission to J-PARC.
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Schedule
Year (JFY) K1.8BR2009 beam-tune2010 beam-tune2011 recovery2012 E17/E152013 E15/E312014 E15/E312015 here?
The proposed experiment will start in around JFY2015???