A search for deeplybound kaonic nuclear states by inflight 3HeK,n reaction at JPARC

1
A search for deeply-bound kaonic nuclear states
by in-flight 3He(K-,n) reaction at J-PARC
J-PARC E15 experiment
S. Ajimura, G. Beer, H. Bhang, P. Buehler, L.
Busso, M. Cargnelli, J. Chiba,S. Choi, C.
Curceanu, D. Faso, H. Fujioka, T. Fukuda, Y.
Fukuda, C. Guaraldo, T. Hanaki, R. S. Hayano, A.
Hirtl, M. Iio, M. Iliescu, T. Ishikawa, S.
Ishimoto, T. Ishiwatari, K. Itahashi, M.
Iwasaki, P. Kienle, J. Marton, Y. Matsuda, Y.
Mizoi, O. Morra, T. Nagae, H. Ohnishi, S. Okada,
H. Outa, A. Sakaguchi, M. Sato, M. Sekimoto, D.
Sirghi, F. Sirghi, S. Suzuki, T. Suzuki, H.
Tatsuno, D. Tomono, A. Toyoda, E. Widmann, T.
Yamazaki, H. Yim, and J. Zmeskal

• Hiroaki Ohnishi
• RIKEN Nishina Center

2
Search for Kaonic nuclear bound state
Results of invariant mass analysis from E549
will be presented in INPC2007 conference by Dr.
T. Suzuki
Taken from OHP at Trento WS 2006
Phys. Rev. Lett. 94 212303 (2005)
Taken from OHP at Trento WS 2006
KEK E549
FINUDA
KEK E548
The situation is still controversial!
What we need to answer the basic question,
whether the deeply bound state really exists?
GSI FOPI
OBELIX
3
What we want to do ?

• Back to the original question
• Structure inside L(1405)
• multiquarks state?
• Double pole resonance ?
• bound state of K-p ?

• If we assume L(1405) to be a K-p bound state
• Second simplest bound state, K-pp, will also
  exist ( natural extension)

Existence of K-pp bund state Will open new door
to the physics of K-cluster
4
A search for deeply bound kaonic nuclear states

• Goal for the experiment J-PARC E15
• To answering the basic question whether the
  deeply bound state really exists?

• Direct production of K-pp clusters via
  3He(in-flight K-,n) reaction

K-pp cluster
neutron
3He
K-
Reaction
Missing mass Spectroscopyvia neutron
Decay
???
5
Possible K-pp decay modes
FINUDA
K-pp cluster
fit region
Dominant Decay mode YN
Phys. Rev. Lett. 94 , 212303 (2005)
K-pp??
B.E. 115 MeV
L p decay mode
p
L
S0 p decay mode
p-
g
p
L
p
p-
Invariant mass reconstruction
p
6
Experimental Principle

• 3He(K-,n) reaction

neutron
3He
K-pp cluster
K-
Missing mass Spectroscopyvia neutron
Mode to decay charged particles
p
L
p-
Invariant mass reconstruction
p
7
Signals from K-pp and Two nucleon
absorptionforward neutron
8
How was decay side?
Binding energy assumed as 100MeV gt emitted
proton momentum 500 MeV/c

• 3He(K-,n) K-pp formation

3He
K-

• Two nucleon absorption

Major background, i.e. event from two nucleon
absorption processcan be identified!
9
Design for the experiment
10
Beam Line at J-PARC
ES
Primary Proton beam

• K1.8BR Beam Line
• Design for low momentum Kaon (lt1.2 GeV/c )
• Single ES stage
• Beam line length 27.6m

• QDQ to focus at Final Focus (FF)
• Momentum resolution 2x10-4 (position
  resolution of the beam tracker assumed to be 200
  mm (s) )

11
E15 Detectorconcept
Experiment will be performed atK1.8BR beam line.
Neutron counter
Cylindrical detector system
12
Expected detector performance

• Expected decay mode for K-pp
• K-pp ? ?p ? pp-p
• K-pp ? S0p ? g?p ? g pp-p
• Assume GK-pp 60 MeV

13
Status of the preparation
14
Neutron counter

• We will use same neutron counter used for KEK
  E549 experiment ( exist! )

E549 neutron counter
3.2 m
1.5 m
20x5x150 cm3 (WXTXL) Plastic scintillator
Configuration 16 (wide) x 7 (depth) Surface
area 3.2m X 1.5m
15
Solenoid magnet
Solenoid magnet for E15 experiment has been
constructed. Field strength upto 0.7T Space
inside F1.2m, L1.2m weight 23 t
16
Cylindrical Drift Chamber

• Design work for CDC is in progress

Garfield simulation done by Dr. F. Sakuma
Basic concept

• Cell structure has been chosen as Hexagonal

• 15 readout layers AAA UU VV AA UU
  VV AA

• 1800 readout channels in total

• He based chamber gas will be used (to reduce
  material budget)

17
Target system
LN2 tank
4 K pot(4 K)
1 K tank(1.25 K)
3He heat exchanger
3He target cell
RD work for Liquid 3He target is in progress (
Dr. S. Ishimoto (KEK) and Dr. M. Iio (RIKEN) )
Prototype 3He target cell
18
Event rate estimation

• Parameters
• Assume production cross section as s
  3He(K-,n)K-pp 10 mb/sr
• Acceptance of Neutron counter 30 msr
• Target thickness 20cm, density 0.080 g/cm3
• Neutron detection efficiency 30
• Assume 1/3 of K-pp decay in to (Lp or S0p)
• Lp reconstruction efficiency in CDC 47
• Expected event rate
• 1.86x10-9 per an incident K-

• Event rate per day
• 0.8x106 K- per 3.53s (0.7s flat top)
• 24475 spill per day 1.96x1010 K- per day
• 50 events per day

We will expect about 1500 events in a month !!!
19
Summary

• J-PARC E15 experiment
• Search for simplest deeply bound kaonic nuclear
  state, the K-pp bound state, via the 3He(K-,n)
  reaction

• Detector construction is in progress
• Solenoid magnet constructed
• CDC under real design
• 3He target RD
• Other detectors conceptual design completed

• Experiment will be ready before Dec. 2008

20
Thank you very much
?
21
(No Transcript)