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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

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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

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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)

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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

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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

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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)

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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.

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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!!

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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

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Reaction A(K-, n) reaction

Reaction B(K-, n) reaction

Reaction C(K-, p) reaction

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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

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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!

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Current Status

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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

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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

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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

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Cylindrical Detector System A newly developed system for

invariant mass study

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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

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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!

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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!

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J-PARC E15 Collaboration17

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Back up

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Typical Event

Pt=145MeV/c

Pt=470MeV/c

CDH

Target

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: isospin of KNN z component of isospin KNNT: isospin of KN subsystem

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Background?? : two nucleon Background?? : two nucleon absorptionabsorption

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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!

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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!

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Background study (two nuclear absorption)2NA + N rescattering / conversion

looks like a “signal” ??(2NA itself is not a problem.)

2NA+N rescattering 2NA+ conversion

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Background study 2(Dalitz’s plot)

Signal can be distinguished between background !!

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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!!

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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

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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!

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Liquid 3He target 10-15 June 2010

meson2010

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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 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!!

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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

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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

int = 71.1 +/- 2.9 ps

Intrinsic 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 curveEfficiency curve

Using 90Sr

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Efficiency of >99% was achieved for all layers using 90Sr.

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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

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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)

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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

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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)

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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 ）

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XTCurve

Axial Layer

(Layer 1)

Stereo Layer

(Layer 4)

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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

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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