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1
A Search for deeply-bound Kaonic nuclear state at the J-PARC E15 experiment
Yuta Sada
Kyoto University
On behalf of the J-PARC E15 collaboration
2
Contents
Introduction KN interaction and Kaonic nuclei
J-PARC E15 experiment K-pp bound state by measuring 3He(K-,n) reaction measuring 3He(K-,n/p) reaction Current Status
Summary
3
KN interaction and Kaonic nuclei K-nucleon interaction
Low energy Kp scattering Kaonic hydrogen level shift (KEK-PS E228)
Kaonic nuclei Kaon bound states with a few nucleons There are some experimental result
of the simplest Kaonic nuclei (KNN)
(FINUDA ,DISTO)
3
M.Iwasaki et al. , PRL 78, 3067(1997)
Strongly attractive (I=0)How strong?
To extract the information about KN interaction below KN threshold
FINUDA
DISTO
B = 105±2±5 MeV = 118±8±10MeV
B = 115±6±4 MeV = 67±14±3 MeV
4
J-PARC E15 experiment Experimental search for KNN bound states Experimental search for KNN bound states
using in-flight (Kusing in-flight (K--, N) reaction on , N) reaction on 33HeHe
4
K-3He Formation KNN
cluster
Neutron(proton)
p
p
-
Mode to decay charged particlesDecay
Missing
mass
Spectroscop
y
via neutron
or proton
Invariant
mass
reconstructio
n
We can observe both the“Formation” and “Decay” of KNN bound state(especially K-pp state is important)
5
Formation spectra : in-flight Formation spectra : in-flight 33He(KHe(K--,n),n)
T.Koike and T.Harada. , PLB652 (2007) 262
quasi-freebound
K- escape
K- conversion
KK-- + + 33He He “K “K--pp” + n @ Ppp” + n @ PKK=1GeV/c, =1GeV/c, =0º=0º
YA potential Signal can be
clearly seen!
Integrated production cross section amounts to ~3.0 mb/sr.
6
T
TpTn
Signal(DISTO) vs Signal(DISTO) vs Background(2NA+rescattering)Background(2NA+rescattering)
2NA and s-wave scattering
2NA and s-wave scattering
T.Hiraiwa 2010/12/2-4 Strangeness workshop 2010
By E15 exp.we will able to see clear signal!!
7
Isospin components of 3He(K-, n/p) reaction
At 3He(K, n) reaction, there are 2 reaction components (A, B)
->Can not separate A and B experimentally. At 3He(K, p) reaction, there is only reaction C. And reaction B and C are
isobaric analogical.
->To compare with both 3He(K-, n/p) reactions, We can get the information of isospin dependence of reactions
Reaction A Reaction B Reaction C
3He(K, n) Reaction 3He(K, p) Reaction
8
Reaction A(K-, n) reaction
Reaction B(K-, n) reaction
Reaction C(K-, p) reaction
bound
Theoretical Calculation of ( K-, n/p ) reaction
J. Yamagata-Sekihara, D. Jido, H. Nagahiro, and S. Hirenzaki., Phys. Rev. C80, 045204 (2009)
Calculation of (K- ,n/p)KNN missing-mass spectrum
Reaction A Reaction B Reaction C
3He(K, n) Reaction 3He(K, p) Reaction
9
J-PARC E15 experiment A search for a KNN bound state using in-flight (K-, N) reaction To measure the missing mass and invariant
mass of KNN states at the same time and isospin dependence of reactions
->More comprehensive understanding of KN interaction and Kaonic nuclei!
10
Current Status
11
Experimental Setup11
J-PARC K1.8BRNeutron
counter
Beam sweep magnet Cylindrical
Detector System
Beamline Spectrometer
1.0 GeV/c K-
NeutronTOF
length 14~15m
Proton
12
Liquid 3He target and Beamline spectrometers
Ni target0.75 GeV/cDC separator ON
Development and test of Liquid 3He target system was already completed!!Now Final test @J-PARC
• K- was successfully identified using TOF method.
• Hardware trigger for Kaon works very well.
• Beam tune is under way.
3He target Beamline
13
TOF counter13
• 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 = 9.2 MeV/c2 (Pn=1.3 GeV/c, TOF=150 ps)
• 10 x 3 x 150 cm3 Plastic Scintillator• Configuration : 27+34 layer• missing mass resolution for KNN = 6.8 MeV/c2 (Pp=1.3 GeV/c, TOF=100 ps)
Neutron Counter
Proton Counter
14
Cylindrical Detector System A newly developed system for
invariant mass study
14
Expected mass resolution : -~ 3.5 MeV/c2 for - ~ 13 MeV/c2 for K-pp( cdc = 200 m / Field : 0.5 T)
CDC
Hodoscope And Solenoid
15
CDS Current Status Commissioning using secondly beam
(/K beam 0.9GeV/c) (2010/10/22~10/24)
CH2
(5mm)
Cu(1mm)C
(5mm)
~40cm 10cm~4300
Vertex Point Z(very preliminary)
Invariant mass(P)(very preliminary)
CDS works well!!
Real Data!
16
Summary J-PARC E15 experiment
search for a KNN bound state using in-flight (K-, N) reaction To measure the missing mass and invariant mass of
KNN states at the same time and isospin dependence of reactions
The preparation is well under way. 3He Target and Beam line spectrometers are almost
ready CDS works well!!
Physics data is coming soon!
17
J-PARC E15 Collaboration17
18
Back up
19
Typical Event
Pt=145MeV/c
Pt=470MeV/c
CDH
Target
20
: isospin of KNN z component of isospin KNNT: isospin of KN subsystem
21
Background?? : two nucleon Background?? : two nucleon absorptionabsorption
21
2NA + N rescattering / conversion looks like a “signal” ?? (2NA itself is not a
problem.)
2NA is very small
12C(K-,n) @ 1GeV/c
12C(K-,p)
T. Kishimoto et al., Prog.Theor.Phys. 118(2007)181.
De Broglie wave length @ 1 GeV/c ~ 1.2 fmNN distance in 3He ~ 2.25 fm
Proc. Jpn. Academy,Series B83 (2007) 144.
These probabilities are expected to be very small ...Anyway, let’s see how they look like!
22
Motivation of measuring 3He(K, n/p) reaction
Only 3He(K, n) reaction channel was proposed @ E15 exp.
→because K- is more attractive proton than neutron, so K-pp is most bounded simply.
But isospin components of KNN from 3He(K, n) reaction is mixed strongly attractive one and another one.
only measuring 3He(K, n) reaction, we can not separate strongly attractive one and another one.
He(K, n) reaction
3He(K, p) reaction
→Both measuring 3He(K-, n/p) is needed!
23
Background study (two nuclear absorption)2NA + N rescattering / conversion
looks like a “signal” ??(2NA itself is not a problem.)
2NA+N rescattering 2NA+ conversion
24
Background study 2(Dalitz’s plot)
Signal can be distinguished between background !!
25
Identification of Identification of pn final state pn final state by CDS & NCby CDS & NC
2010/12/2-4 ストレンジネス研究会 2010 25
Possible background- 0pn final state + missing- QF- + missing- QF-, conv. + missing
Other processes can be clearly separated!!
26
Solenoid magnet
Field strength : 0.5 T(maximum field : 0.7 T)
Aperture : 1.2 m Length : 1.2 m
10-15 June 2010
meson2010
26
Characteristic curve (B vs Characteristic curve (B vs A)A)
current [A]
Field
str
ength
[T
]
Performance
Excitation test have been performed in May 2010.
Design value (max field : 0.7T) was successfully achieved!
27
Liquid 3He target 10-15 June 2010
meson2010
27
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 Temperature in the Target CellCell
1.3 K1.3 K
Pressure in the Target CellPressure in the Target Cell 33 hPa33 hPa
Liq. Liq. 44He ConsumptionHe Consumption 45 L/day45 L/day
Heat Load to the 1K PartsHeat Load to the 1K Parts 0.19 W0.19 W
Cooling test with 200L Cooling test with 200L 33He He gasgas
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
CalculationCalculation
Development and test of Liquid 3He target system was already completed!!
28
What are needed to measure 3He(K-,p)
Drift chambers are for knowing the reaction point TOF start and TOF wall for proton are for measuring
to TOF( time of flight) of flight proton Glass TIR is talk the next slide in detail
29
Cylindrical Detector Hodoscope (CDH)
29
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
int = 71.1 +/- 2.9 ps
Intrinsic time resolution ~ 71 ps
30
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 curveEfficiency curve
Using 90Sr
30
Efficiency of >99% was achieved for all layers using 90Sr.
31
Theoretical study on K-pp
KK--pp bound states should exist!pp bound states should exist! A deep state or shallow state? Decay width is sufficiently narrow?
10-15 June 2010
meson2010
31
B.E [MeV] [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 Model
Dote, 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)
32
Plan of CDS commissioning Commissioning by using Cosmic Ray
Test of Solenoid Magnet Test of CDC in Magnetic Field
Momentum Reconstruction Efficiency, Resolution Pt/Pt
Commissioning by Secondly beam p elactic scattering (monochromatic beam)
Check of Pt Resolution by defined momentum Invariant mass of K0s and
Check of Mass resolution and peak position
33
Cosmic Ray Data
Test of Solenoid magnet and
taking data of Cosmic ray
Amount of data field -0.5T (+ beam direction) 2010/5/20~5/28 total 35hour
~500,000 event
filed +0.5T 2010/8/30~9/4 25hour
~400,000 event
Characteristic curve (B vs Characteristic curve (B vs A)A)
0 200 400 600 800 1000 Current [A]
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
Field
str
ength
[T
]
AchievedDesign value !(max field : 0.7T)
34
CDC Efficiency
Achieved
Average 99% over!
1.0
0.8
0.6
0.4
0.2
0
Effi
cien
cy
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Layer definition
Eff= Num of Hit of the layer / Num of Reconstructed Track
( hit is in cell size) ( without the layer of measurement )
35
XTCurve
Axial Layer
(Layer 1)
Stereo Layer
(Layer 4)
36
400
300
200
100
0
Resi
dual [
m]
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Layer
Axial Stereo Axial Stereo Axial
Residual of Hit Position
Achived 200~350m To get Intrinsic resolution,
Need to comparie with Simulation
=209m
Residual (Layer1)
Residual [m]
Result of liner track
37
Data with Secondly beam
beam (0.9GeV/c)
for p elastic scatteringTo check Pt resolution
beam (0.9GeV/c) for Invariant mass of and K0s To check mass resolution and peak point
Total time [h]
Integrated Trigger
Trigger
+
(0.9GeV/c)5.5 1.9 ×106 trigger×
CDH1hit
K
(0.9GeV/c)25 6.8 ×106 K trigger×
CDH2hit
Material Size[mm] Thickness[mm](g/cm2)
Position[mm]
Polyethylene 500×500 5.0(0.50) +420
C 500×500 5.0(0.90) +50
Cu 300×300 1.0(0.90) -50
Secondly beam
Set up
•Target
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