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ストレンジネスとエキゾティクス・理論の課題. March 1-3 2007 Toba. A search for deeply bound kaonic nuclear states by in-flight 3 He(K - ,n) reaction. Hiroaki Ohnishi RIKEN For the J-PARC E15 collaboration. K - pp cluster. neutron. reaction. A search for deeply bound kaonic nuclear states. - PowerPoint PPT Presentation
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Hiroaki OhnishiRIKEN
For the J-PARC E15 collaboration
A search for deeply bound kaonic nuclear states
by in-flight 3He(K-,n) reaction
ストレンジネスとエキゾティクス・理論の課題 March 1-3 2007 Toba
A search for deeply bound kaonic nuclear states
Direct production of K-pp cluster via Direct production of K-pp cluster via 33He(K-,n) reactionHe(K-,n) reaction
K-3He K-pp
clusterneutron
reaction
Missing mass
spectroscopy
???
Decay?
Goal for the experiment J-PARC E15Goal for the experiment J-PARC E15 To answering the basic questionTo answering the basic question
: whether the deeply bound state really exists?: whether the deeply bound state really exists?
Possible K-pp decay mode
K-ppcluster
FINUDA
fit region
K -pp??
Phy
s. R
ev. L
ett.
94, 2
1230
3 (2
005)
Invariant mass reconstruction
+-p-+p
K-pp2370 MeV
2275 MeV
2267 MeV
0p
p
2131 MeV
2054 MeV
p
p
-
p decay mode
Dominant Decay mode
= YN
p
p
-
p decay modeB.E. = 115 MeV
Formation of K-pp via 33He(K-,n) reactionHe(K-,n) reaction
K-3He K-pp
clusterneutron
Missing mass
reaction
decay
This mode allows us to investigate K-pp cluster with both missing mass and invariant mass spectroscopy
p
p
-
Only charged particles in final state
Invariant
mass
Detector concept• Missing mass spectroscopy with forward going neutron
• Bound state tagging with the measurement of decay product – Good charged particle detection efficiency– Good charged particle momentum resolution
K- beam momentum used for the experiment 1 GeV/c
In the case, if B.E. = 100 MeV ( FINUDA case)
Momentum of outgoing neutron will be 1.3 GeV
reconstruction will be crucial for this measurement
E15 DetectorExperiment will be performed atK1.8BR beam line.
Neutron counter
Cylindrical detector systemCDH
CDC
Solenoid Magnet
K-Proton
Proton
GEANT4 detector simulation
B.E. = 100 MeV
• Expected decay mode for K-pp – K-pp Λp pπ-p ➾ ➾– K-pp ➾ 0p ➾ Λp ➾ pπ-p
• Assume K-pp= 60 MeV
Invariant mass of Λp (MeV)
∑ channel Λ channel
Expected detector performance
p
p
-
p decay mode
p
p
-
p decay mode
Possible K-pp decay mode(2)
+-p-+p
K-pp2370 MeV
2275 MeV
2267 MeV
0p
p
2131 MeV
2054 MeV
Back to the beginning
Akaishi-Yamazaki predictionbased on (1405) as KN bound state
Y.Akaishi & T.Yamazaki, PLB 535(2002) 70.
Question
BR( K-pp → p)BR( K-pp → YN)
1) Can we identify K-pp bound state only from missing mass?
= ???
In this case,K-pp can be decay to
mode
p
np
p
p
YN mode
0p
p
+
2) How to tag formation of K-pp bound state via decay product?
Hyperon production
Concerning on the decay mode of K-pp →p
• Can we use +- from target region as a tag of decay ?
mode
p
np
p
p
K-pp decay mode pn p
n
n from decayp
+
--
+
n from decay
n
proton cannotescape from target
Still need to investigate
Summary
• J-PARC E15 experiment– Search for simplest deeply bound kaonic nucl
ear state, K-pp bound state via 33He(K-,n) reactionHe(K-,n) reaction
• Detector construction is in progress
• Experiment will be ready before Dec. 2008
Λ
Λ momentum (MeV/c) momentum (MeV/c)
K-pp state
σ(
MeV
)
σ(
MeV
)
• Expected decay mode for K-pp – K-pp Λp pπ-p ➾ ➾– K-pp ➾ 0p ➾ Λp ➾ pπ-p
• Assume K-pp= 60 MeV
Invariant mass of Λp (MeV)
∑ channel Λ channel
Expected detector performance
p
p
-
p decay mode
p
p
-
p decay mode