1. A Search for Deeply Bound Kaonic Nuclear States at J-PARC
Toshihiko Hiraiwa
Kyoto University
for the J-PARC E15 Collaboration

2. Contents Introduction J-PARC E15 Experiment Summary and Outlook
Kaonic nuclei
Experiment & Theory
J-PARC E15 Experiment
Method
Current Status
Summary and Outlook
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3. Introduction
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4. Kaonic nuclear states K-nucleon interaction
Low energy K-p scattering data
Kaonic hydrogen level shift (KEK-PS E228)
Experimental searches for kaonic nuclei
KEK-PS E471/E549 : K- stopped in 4He
KEK-PS E548 : in-flight K- reaction on 12C, 16O
OBELIX : pbar annihilation on 4He
M.Iwasaki et al. , PRL 78, 3067(1997)
Strongly attractive (I=0)
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5. Experimental results on K-pp
FINUDA
First evidence for K-pp
Invariant mass of back-to-back Lp pairs in K- absorptions
B = 115±6±4 MeV G = 67±14±3 MeV
DISTO
pp -> X+K X+->Lp
B = 105±2 MeV G = 118±8 MeV
M.Agnello et al. ,
PRL 94, (2005)
T.Yamazaki et al. ,
arXiv: v1[nucl-ex]
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6. Theoretical study on K-pp
B.E [MeV]
G [MeV]
Method
Yamazaki and Akaishi 48
61 (mesonic)
Variational Method (ATMS)
Ivanov, Kienle, Marton, and Widdman
118
58 (non-mesonic)
Phenomenological Model
Shevchenko, Gal, and Mares
55-70
(mesonic)
Coupled Channel Faddeev Calculation
Ikeda and Sato
60-95
45-80
(mesonic)
Nishikawa and Kondo
~126
Skyrme Model
Dote, Hyodo, and Weise
20±3 (s-wave)
(mesonic)
Chiral SU(3) Variational Method
Arai, Oka, and Yasui
depend on gΛ*Λ*σ
Variational Method (as Λ*p state)
All calculations say, “K-pp bound state exists”
But …
A Deep or Shallow state?
Width is sufficiently narrow or not?
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7. J-PARC E15 Experiment
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8. J-PARC E15 Collaboration
S.Ajimura1, G.Beer2, H.Bhang3, P.Bühler4, L.Busso5,6, M.Cargnelli4, S.Choi3, C.Curceanu7, S.Enomoto8, D.Faso5,6, H.Fujioka9, Y.Fujiwara10, T.Fukuda11, Y.Fukuda12, C.Guaraldo7, R.S.Hayano10, T.Hiraiwa9, M.Iio13, T.Ishikawa10, S.Ishimoto14, T.Ishiwatari4, K.Itahashi13, M.Iwai14, M.Iwasaki12,13 , P.Kienle4,15, J.Marton4, Y.Matsuda16, Y.Mizoi11, O.Morra5, T.Nagae9, H.Noumi1, H.Ohnishi13, S.Okada7, H.Outa13, A. Romero Vidal7, Y.Sada9, A.Sakaguchi8, F.Sakuma13, M.Sato10, M.Sekimoto14, D.Sirghi7,17, F.Sirghi7,17, K.Suzuki4, S.Suzuki14, T.Suzuki10, H.Tatsuno10, M.Tokuda12, D.Tomono13, A.Toyoda14, K.Tsukada13, O. Vazquez Doce7,
E.Widmann4, T.Yamazaki10,13, H.Yim3, and J.Zmeskal4
1Osaka University, Japan, 2University of Victoria, Canada, 3Seoul National University, South Korea, 4Stefan Meyer Institut fur subatomare Physik, Austria, 5INFN Sezione di Torino, Italy, 6Universita’ di Torino, Italy, 7Tokyo University of Science, Japan, 8Laboratori Nazionali di Frascati dell’INFN, Italy, 9University of Tokyo, Japan, 10Osaka Electro-Communication University, Japan, 11Tokyo Institute of Technology, Japan, 12RIKEN, Japan, 13High Energy Accelerator Research Organization (KEK), Japan, 14Technische Universitat Munchen, Germany, 15INAF-IFSI, Sezione di Torino, Italy, 16Kyoto Univ., Japan
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9. J-PARC E15 experiment L neutron 3He K- p p-
Experimental search for K-pp bound states using in-flight (K-, n) reactions
K-pp
cluster
neutron K-
3He
Formation
Missing mass
Spectroscopy via neutron
Decay L p p-
Mode to decay charged particles
We can observe both the
“Formation” and “Decay” of K-pp bound state
Invariant mass reconstruction
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10. Experimental Setup J-PARC K1.8BR Neutron 1.0 GeV/c K- TOF length 15m
Neutron counter
Beam sweep magnet
Cylindrical Detector System
Neutron
1.0 GeV/c K-
TOF length 15m
Beamline Spectrometer
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11. Cylindrical Detector System
acceptance ~ 2.2p [sr]
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12. Solenoid magnet Performance
field strength : 0.5 T (max : 0.7 T)
aperture : 1.2 m
length : 1.2 m
Solenoid magnet has been already installed.
At the end of March 2010, the excitation test will be done!
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13. Cylindrical Detector Hodoscope (CDH)
used for trigger and PID
Plastic scintillator
Size : 99x30x700mm3 (WxTxL)
Configuration : 36 modules
PMT : fine mesh type (H8409)
cosmic ray test
sint ~ 70 psec
All the units are ready and installed !
sint = /- 2.9 ps
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14. Cylindrical Drift Chamber (CDC)
Size
Inner diameter : 300 mm
Outer diameter : 1060 mm
Length : 950 mm
Cell
hexagonal (Drift length~9mm)
Layer
15 layers (7 super layers) AA’A UU’ VV’ AA’ UU’ VV’ AA’
Read out : 1816 ch
Gas : Ar-C2H6 (50:50)
Efficiency : >99% for all layers (using 90Sr)
Efficiency curve
Using 90Sr

15. CDC test with cosmic ray
Cosmic-ray test of CDC was done at J-PARC
By comparing with a simulation, Intrinsic resolution ~ 200 mm.
Residual
Intrinsic resolution
cosmic ray
s=206 mm
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16. Expected mass spectra of K0s
Monte Carlo Simulation (Geant4)
K- p -> K0s n (PK=1GeV/c) K0s->p-p+
CDC resolution : 200 mm Field strength : 0.5 T p-
K0s vertex p+
K0s
Expected mass resolution
s ~ 6.7 MeV/c2
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17. Expected mass spectra of K-pp (L)
K-pp -> L p L -> pp-
Generate Lp isotropically assuming the two decay
B.E. : 100 MeV Width : 0 MeV
Expected mass resolution s~ 3.0 MeV/c2 for Lambda
s ~ 13 MeV/c2 for K-pp p
K-pp vertex p p-
L vertex
K-pp
Lambda
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18. Liquid 3He target
Cooling test with 200L 3He gas
Calculation
Development and test of Liquid 3He target system was already completed!!
Temperature in the Target Cell
1.3 K
Pressure in the Target Cell
33 hPa
Liq. 4He Consumption
45 L/day
Heat Load to the 1K Parts
0.19 W
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19. Beamline spectrometer
In Feb. 2009, K1.8BR beamline tuning started with 1.1 GeV/c beam
success in p/K/p separation using TOF method　( flight length = 7.7m )
In this autumn, 0.75 GeV/c beam tuning started. (for E17 exp.)
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20. Neutron counter rearrange E549 neutron counter support frame for E15
20 x 5 x 150 cm3 Plastic Scintillator
Configuration : 16 (wide) x 7 (depth)
Surface area : 3.2m x 1.5m
missing mass resolution for K-pp s = 9.2 MeV/c2 (Pn=1.3 GeV/c, sTOF=150 ps)
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21. Thank you for your attention!
Summary and outlook
J-PARC E15 experiment
search for a K-pp bound state using in-flight (K-, n) reactions
measure the missing mass and invariant mass of K-pp states simultaneously
K1.8BR beamline tuning already started.
Other detector components will be ready soon.
We will start to take data in 2011!
Thank you for your attention!
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22. Back up
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23. Momentum resolution
Transverse momentum resolution was estimated by Geant4 simulation
Theoretical calculation is found in R.Gluckstern, NIM 24 (1963) 381.
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24. Vertex resolution sx ~5.4mm sy ~4.9mm sz ~4.3mm K0s vtx sx ~3.2mm
Lambda vtx
K-pp vtx with beam and p from K-pp
sx ~ 0.92mm
sy ~0.89mm
sz ~5.6mm
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25. Simulation(1) p+ p-
K0s
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26. Simulation(2) p from Kpp p from L p from L L from Kpp
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27. To improve z-resolution, Z-TPC is newly constructing
Z-Vetex TPC (Z-TPC)
gas:P10 (150V/cm)
expected resolution (w/o B-field)
however, rf-resolution is limited by pad size, e.g., 20.0/sqrt(12) = 5.8mm
To improve z-resolution,
Z-TPC is newly constructing
sz(Lpp-): 7mm  2mm
w/o
Z-TPC w/
~500mm
~300mm
f280mm
f170mm
readout-pad
pad size:20x4mm
# of pad:4x4x9=144
field strip
double sided flexible print circuit board
8mm strip
10mm pitch

28. J-PARC P28 experiment (semi-)inclusive measurement
exclusive measurement X± K-
3He p
（undetected)
3He K- p
(n; undetected) Λ
(search for K-pn bound state)

29. proton detector system
[new]
TOF start/stop counters - momentum measurement
Drift chambers - scattering angle measurement - consistency check
Glass Cherenkov - particle identification (K- / p)
[new]
TOF stop counter
[extended]
[existing in E15 setup]

30. Hodoscope Counter (CDH)
CDH is used for the charged trigger and particle identification.
expected pID using ToF measurements
Feb. 2009
Plastic Scintillator :
99x30x700 mm3 （WＸTＸL）Configuration : 36 modules
PMT: Hamamatsu H8409 (fine mesh) x 72
sint = 76psec
CDH system has been mounted inside the Solenoid Magnet

31. Expected Spectrometer Performance
Calculated using Geant4
momentum resolution for p, K, p
we can distinguish the two non-mesonic decay modes for K-pp
K-pp  Lp  pp-p
K-pp  S0p  gLp  gpp-p
S0 channel
L channel
GK-pp= 60 MeV
invariant mass resolution for K-pp and L
Invariant mass of Lp (MeV)
mass resolution
K-ppLp
Lpp-
w/o chamber-resolution
5.8 MeV/c2
1.6MeV/c2
w/ chamber-resolution
18.7MeV/c2
2.5MeV/c2