the s earch for deeply b ound kaonic n uclear s tates at j-parc
DESCRIPTION
The s earch for deeply b ound kaonic n uclear s tates at J-PARC. Toshihiko Hiraiwa Kyoto University On behalf of the J-PARC E15 collaboration. Contents. Introduction KN interaction Kaonic nuclei J-PARC E15 Experiment Experimental method Present Status Summary and Outlook. - PowerPoint PPT PresentationTRANSCRIPT
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The search for deeply bound kaonic nuclear states at J-PARCToshihiko HiraiwaKyoto UniversityOn behalf of the J-PARC E15 collaboration
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Contents•Introduction
▫KN interaction▫Kaonic nuclei
•J-PARC E15 Experiment▫Experimental method▫Present Status
•Summary and Outlook
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Introduction
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Low-energy KN interaction•K-nucleon interaction
▫Low energy Kp scattering ▫Kaonic hydrogen level shift (KEK-PS E228)
•Kaonic nuclei▫Kaon bound states with a few nucleons▫Extract the information about KN
interaction below KN threshold
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M.Iwasaki et al. , PRL 78, 3067(1997)Strongly attractive (I=0)
How strong?
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•DISTO
▫ pp K+X+, X+ pL▫ B = 105±2(stat)±5(syst) MeV
G = 118±8(stat)±10(syst )MeV
•FINUDA
▫ Invariant mass of back-to-back Lp pairs in K- absorptions
▫ B = 115±6(stat)±4(syst) MeVG = 67±14(stat)±3(syst) MeV
Experimental results on K-pp10-15 June 2010
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M.Agnello et al. , PRL 94, 212303 (2005)
T.Yamazaki et al. , PRL 104, 132502 (2010)
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Theoretical study on K-pp
• K-pp bound states should exist!▫A deep state or shallow state?▫Decay width is sufficiently narrow?
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B.E [MeV] G [MeV] Method
Yamazaki and Akaishi 48 61 (mesonic)
Variational Method (ATMS)
Shevchenko, Gal, and Mares 55-70 90-110
(mesonic)Coupled ChannelFaddeev Calculation
Ikeda and Sato 60-95 45-80 (mesonic)
Coupled ChannelFaddeev Calculation
Nishikawa and Kondo ~126 Skyrme ModelDote, Hyodo, and Weise
20±3 (s-wave)
40-70 (mesonic)
Chiral SU(3)Variational Method
Arai, Oka, and Yasui depend on gΛ*Λ*σVariational Method(as Λ*p state)
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J-PARC E15 Experiment
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J-PARC E15 Collaboration 10-15 June 2010
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J-PARC E15 experiment Experimental search for K-pp bound states
using in-flight (K-, n) reaction on 3He
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K- 3He Formation K-ppcluster
neutron
L p
pp-
Mode to decay charged particlesDecay
Missing
mass
Spectroscop
y
via neutron
Invariant
mass
reconstructio
n
We can observe both the“Formation” and “Decay” of K-pp bound state
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Experimental Setup 10-15 June 2010
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J-PARC K1.8BR Neutron
counter
Beam sweep magnet
Cylindrical Detector System
Beamline Spectrometer
1.0 GeV/c K-
NeutronTOF length 15m
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Cylindrical Detector System• A newly developed system for invariant mass
study
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Expected mass resolution : - s ~ 3.0 MeV/c2 for L - s ~ 13 MeV/c2 for K-pp( scdc = 200 mm / Field : 0.5 T)
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Present status
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Solenoid magnet
• Field strength : 0.5 T(maximum field : 0.7 T)
• Aperture : 1.2 m• Length : 1.2 m
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Characteristic curve (B vs A)
current [A]
Field
stre
ngth
[T
]
Performance
Excitation test have been performed in May 2010.
Design value (max field : 0.7T) was successfully achieved!
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Cylindrical Detector Hodoscope (CDH)
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Plastic scintillation counters for trigger and PID
• Size : 99 x 30 x 700 mm3
(W x T x L)• Configuration : 36 modules• PMT : fine-mesh type (H8409)
Cosmic-ray test
sint = 71.1 +/- 2.9 psIntrinsic time resolution ~ 71 ps
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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 curve
Using 90Sr
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Efficiency of >99% was achieved for all layers using 90Sr.
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CDC test with cosmic ray• Check the performance of CDC
with cosmic ray• By comparing with a simulation,
Intrinsic resolution ~ 200 mm.
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s=206 mm
cosmic ray
Residual Intrinsic resolution
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Current status of CDS 10-15 June 2010
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• All of the components(CDC, CDH) have been installed into the solenoid magnet.
Typical Event Display
Pt ~ 180 MeV/c
Pt ~ 220 MeV/c
CDS commissioning with 0.5 T magnetic field is now under way using cosmic ray.
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Liquid 3He target 10-15 June 2010
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1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.00
50
100
150
200
250
Temperature [K]V
apor
Pre
ssur
e [h
Pa]
He-3He-4
Temperature in the Target Cell 1.3 KPressure in the Target Cell 33 hPa
Liq. 4He Consumption 45 L/dayHeat Load to the 1K Parts 0.19 W
Cooling test with 200L 3He gas
1 2 3 4 5 6
1.1
1.2
1.3
1.4
1.5
Time [hour]
Tem
pera
ture
[K]
Evaporator Heat Exchanger Target Cell
1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.00
50
100
150
200
250 He-3 He-4
Calculation
Development and test of Liquid 3He target system was already completed!!
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Beamline spectrometer10-15 June 2010
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Ni target0.75 GeV/cDC separator ON
K-
BHD-T0 TOF [ns]
• K- was successfully identified using time-of-flight method.
• Hardware trigger for Kaon works very well.
• Beam tune for J-PARC E17 exp. is under way.
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Neutron counter 10-15 June 2010
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3.2 m
1.5 m
E549 neutron counter
support frame for E15
rearrange
• 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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Summary and outlook•J-PARC E15 experiment
▫search for a K-pp bound state using in-flight (K-, n) reaction
▫measure the missing mass and invariant mass of K-pp states simultaneously
•The preparation is well under way.•Physics data is coming soon!
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Thank you for your attention!
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Back up
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Expected mass spectra of K0s• Monte Carlo Simulation
(Geant4)• K- p -> K0s n (PK=1GeV/c)
K0s->p-p+
• CDC resolution : 200 mmField strength : 0.5 T
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Expected mass resolution s ~ 6.7 MeV/c2
p+
p-
K0s vertex
K0s
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Expected mass spectra of K-pp (L)• K-pp -> L p
L -> pp-
▫ Generate Lp isotropically assuming the two decay
• B.E. : 100 MeVWidth : 0 MeV
• Expected mass resolutions~ 3.0 MeV/c2 for Lambdas ~ 13 MeV/c2 for K-pp
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Lambda
p-
p
pL vertex
K-pp vertex
K-pp
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Momentum resolution 10-15 June 2010
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Transverse momentum resolution was estimated by Geant4 simulation
Theoretical calculation is found in R.Gluckstern, NIM 24 (1963) 381.
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Z-position dep. of magnetic field
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z-position [cm]
mag
netic
fiel
d [T
]