DAFNEにおけるK中間子原子実験
T. Ishiwatari
on behalf of SIDDHARTA collaboration
Stefan Meyer Institute for Subatomic Physics,
Austrian Academy of Sciences
参考文献: Phys. Lett. B 681 (2009) 310
arXiv: 1010.4631v1 [nucl-ex]

ストレンジネス核物理 2010

KEK (JAPAN), Dec. 2-4, 2010近年のKaonic atom 実験
標的：水素～ヘリウム
2つのパズル: 水素 1s とヘリウム4 2p
異常なシフトの観測値-> 近年の実験により問題解決-> さらなる高精度実験の必要性
いまだに未測定：
重水素 1sとヘリウム3 2p

実験的な困難
水素・重水素 2p-1s 遷移：
X線収量:小, 強い相互作用による幅:大(X線ピークが見えにくい）
高S/Nでかつ長期間のデータ収集が必要
ヘリウム3,4 3d-2p 遷移：X線収量:大だが、強い相互作用によるシフト、幅:小（X線ピークは見えやすいが、精度が大事）
高精度のエネルギー決定:要The kaonic hydrogen puzzle

Kaonic hydrogen experiments
Scattering data の解析によれば、shiftはrepulsiveになるはず。しかし、８０年代の実験ではいずれもattractive. KpXとDEARにより長年の問題を解決。

Kaonic hydrogen experiments
P.M.Bird, NPA404(1983)482

K-p 2p-1s

M.Iwasaki, PRL78(1997)3067
Kaonic hydrogen experiments
P.M.Bird, NPA404(1983)482

K-p 2p-1s

G.Beer, PRL94(2005)212302

Kaonic hydrogen experiments
近年の実験により、shiftはrepulsiveである
ことがわかったが、KpXとDEARの差が問題

The kaonic helium puzzle

Kaonic helium4 atom data (Z=2)

1971

Δ E 2 p = E exp − E e . m .
Shift

1979

Width

Average

1983

Optical model

The “Kaonic helium puzzle”

Possible non-zero shift of Kaonic helium (Z=2)

2005 Y.Akaishi, EXA05 proceedings (2005) Calculation results to produce
Y.Akaishi:EXA05

attractive

shifts as large as possible!

K--3HeBut, large shift(-40eV) cannot be
explained by any models.
K--4Herepulsive

Q: K-4He experimental results(~40 eV shift) correct?
Q: non-zero shift (~5 eV) on K-4He ?
Q: How about K-3He? (No data yet)
Large, small, tiny???

Need: New experiments
both on He-3 and He4

Optical model

K-nucl model

Tiny (~ 0eV)

Large(<±10(40 eV)
SmalleV)disagreeK-He4 exp
Large (-40(40 eV)eV)

K-4He 2p level shift
S.Okada et al.,
PLB653(07)387

Akaishi Prediction-10~ +10 eV

E570 results (’07)

Optical model~0eV

Δ E2 p = −43 ± 8 eV

1983

E570
3d-2p

2007
S.Okada et al.,
PLB653(07)387

4d-2p
5d-2p

Requirements for K-p X-ray measurements•Target: low density•Kaons:low-energy, small momentum spread•X-ray Detector : large-area, high detection efficiency
good resolution in energy & timing

SIDDHARTA experiment•Target: Gas target (large volume, and thin window)•Kaons: K‐’s from decay of φ(1020) at rest in Lab frameÆ DAΦNE collider•X‐ray Detector : large‐area, high detection efficiency
good resolution in energy & timingÆarray of SDD (silicon drift detector)

Comparison of X-ray detectors
Good time resolution

SDD

Good energy resolution

CCD

Si(Li)

T.Ishiwatari,Hyp. Int. 194(09)165

experiment

KpX

DEAR

E570

Detector

Si(Li)

CCD

SDD

Area

[mm2]

200

724

100

Thickness

[mm]

5

0.03

0.26

Δ E (FWHM)

[eV]

410

170

185

Δ t (FWHM)

[ns]

290

-

430

Comparison of X-ray detectors
Good time resolution

Si(Li)

SDD

SDD

Good energy resolution

CCD

Si(Li)

T.Ishiwatari,Hyp. Int. 194(09)165

experiment

KpX

DEAR

E570

Detector

Si(Li)

CCD

SDD

Area

[mm2]

200

724

100

Thickness

[mm]

5

0.03

0.26

Δ E (FWHM)

[eV]

410

170

185

Δ t (FWHM)

[ns]

290

-

430

SIDDHARTA Experimental Setup
Kaon beam at DAFNE

X-ray

SDDs

K−

e+ + e− →φ → K+ + K−
degraderKK- -beam
beamatatDAFNE
DAFNE
1.
1. Monochromatic
Monochromatic
2.
2. Low-energy
Low-energy
3.
3. Low
Lowhadronic
hadronicbackgroundbackground

e

−

φ
K

+

e+

Scintillators

SIDDHARTA Experimental Setup

SDDs

X-ray

K−
degraderTriple timing coincidence:
SDD (X-ray)*Scin (K+)*Scin (K-)

e

−

e+

φ

K+K- coincidence
200

K

175
150

Scintillators

Time difference between
SDDs and K+K- coincidence

125
100
75
50
25
0

+

2

3

4

5

SDD timing [μs]67New SDD chip &readout electronic
developed by SIDDHARTA
144 SDDs (1cm^2 each)
installedSIDDHARTA Experimental SetupKHe-4 energy spectrum at SIDDHARTAK-He data taking
PLB681(2009)310
x105
5

Ti foil

Mn KαNo-coincidence

4

Target

3
2

Ti Kα

Mn Kβ

Ti Kβ

Fe55
Degrader

1
0
100
80

coincidence

KHe Lα

Mn Kα

Ti Kα

60
Mn Kβ

Ti Kβ

40
20
0

ΔE = Eexp − Ee.m.
= 0 ± 6 (stat ) ± 2(syst) eV

4.5

5.0

4.5

6.0

Energy [keV]

6.5

7.0

Data taking periods of SIDDHARTA in 2009

K-He4 data with Fe source

55Fe source:
Good for reduce sys. error on K-4He
Bad for “background” events on K-H,K-D
Removed 55Fe source in other data

PLB681(2009)310

Use ofMn Ka (5.9 keV) from 55Fe

Systematic error = +/-2 eV

Data taking periods of SIDDHARTA in 2009

DAFNE shutdown in Summer

New alignment of setupÆImprove S/N ratio

K-He3 data (~4days)

K-d data
K-H data

55Fe source:
Good for reduce sys. error on K-4He
Bad for “background” events on K-H,K-D
Removed 55Fe source in other data

Data taking scheme at DAFNE
Instead of Fe source,“X-ray tube” data taken

Estimatedsystematic error ~ 5 eVcalibration data

Production data

K−

Ti/Cu foil

degrader

e

−

SDDs

SDDs

φ

e
Scintillators

K+

+

e−

e+
X-ray tube

Calibration datawith X-ray tube

SDD X-ray energy spectra
Calibration Ti&Cu

calibration data
SDDs
Ti/Cu foile−e+X-ray tube

Calibration datawith X-ray tube
Not correlated toKaon signals

Production data

SDD X-ray energy spectra
Calibration Ti&Cu

Energy scale determinedby X-ray tube data
Energy spectrum withuncorrected to kaon timing[Fig. (b)]
X-ray

SDDs

K−
degrader

e−

φ
K+

e+

Scintillators

Selected with K+K& SDD timing

Not correlated toKaon signals

Production data
Calibration datawith X-ray tube

SDD X-ray energy spectra
Kaon detector

Time difference between
SDD & Kaon detector

Calibration datawith X-ray tube
Not correlated toKaon signals

Production data

SDD X-ray energy spectra

High rate

Low rate

異なるrateによるpeak shift: 6.5 eV
エネルギー決定精度: +-3.5 eV
エネルギーが既知のX線によりずれの評価(Ti, Mn, Cu, Au X線とkaonic C, O 線）

Kaonic Helium-3 energy spectrum

X-ray energy of K-3He 3d-2p

Eexp = 6223.0 ± 2.4( sta ) ± 3.5( sys) eV

K-3He (3d-2p)

QED value: Ee.m. = 6224.6 eV

ΔE2 p = Eexp − Ee.m.

Ti Ka
K-C K-OK-N

ΔE2 p = −2 ± 2( sta ) ± 4( sys) eV
世界初！
K-3He X線の観測と強い相互作用によるシフト値

arXiv:1010.4631v1 [nucl-ex], submitted to PLB

K-3He (3d-2p)

DAFNE shutdown in Summer

ΔE2 p = −2 ± 2( sta ) ± 4( sys) eV

K-4He (3d-2p)

ΔE2 p = +5 ± 3( sta ) ± 4( sys) eV (Preliminary)

K-3He (3d-2p)

DAFNE shutdown in Summer

ΔE2 p = −2 ± 2( sta ) ± 4( sys) eVComparison of results
Kaonic 4He 2p level shift
TargetShift [eV]KEK E570

Liquid+2±2±2 eV

SIDDHARTA (w/ 55Fe)

Gas+0±6±2 eV

SIDDHARTA (New)Gas+5±3±4 eV(preliminary)

Kaonic 3He 2p level shift
TargetShift [eV]

SIDDHARTA

Gas-2±2±4 eV

J-PARC E17

Liquid??±?±? eVshift ΔE2 p = Eexp − Ee.m.

ΔE2 p > 0 (" attractive" shift ),ΔE2 p < 0 (" repulsive" shift ),Comparison of results
PLB653(2007)387
KEK E570

Sato, ECT* Workshop 2009

Kaonic 4He 2p level shift
TargetShift [eV]

Liquid+2±2±2 eV

1. calibration/ and peak shapefrom Ti (4.5 keV) and Cu (8.0 keV).
Apply for K-4He (6.4 keV)
2. Simulation of Compton tail using
measured kaon stopping distribution.
Sys err = uncertainty of above
Voigt
Compton

Shelf
PileupTailComparison of results
PLB681(2009)310
SIDDHARTA (Test)

Ishiwatari, ECT* Workshop 2009

Kaonic 4He 2p level shift
TargetShift [eV]Gas

+0±6±2 eV

1. Calibration and peak shapefrom Mn (5.9 keV)
Sys err = energy non-linearity, uncertainty
of corrections of temporalfluctuation & rate dependency
NIM A in press

Comparison of results
This Talk
TargetShift [eV]

SIDDHARTA (He-4)

Gas+5±3±4 eV(preliminary)

SIDDHARTA (He-3)

Gas-2±2±4 eV

Positions of X-ray peaks with known energy

Compared to several X-ray peaks
with known energy
Sys err = uncertainty ofenergy determination
obtained from them+/-4.0 eV

New method

Comparison of results
Shift [eV]

Reference

KEK E570+2±2±2

PLB653(07)387

SIDDHARTA (He4 with 55Fe)+0±6±2

PLB681(2009)310

SIDDHARTA (He4)+5±3±4

Preliminary

SIDDHARTA (He3)-2±2±4arXiv:1010.4631,
Submitted to PLB*error bar = ± ( stat ) 2 + ( syst ) 2

Comparison of results
Shift [eV]

Reference

KEK E570+2±2±2

PLB653(07)387

SIDDHARTA (He4 with 55Fe)+0±6±2

PLB681(2009)310

SIDDHARTA (He4)+5±3±4

Preliminary

SIDDHARTA (He3)-2±2±4arXiv:1010.4631,
Submitted to PLB

Not as large as 40 eV
in both of He-3 & He-4

Question: both 0-eV shift?
Within error, consistent with 0 eV,andWithin error, cannot exclude 0-eV shift
E17: More precision measurement on KHe3

*error bar = ± ( stat ) 2 + ( syst ) 2

Kaonic hydrogen X-ray energy spectra

KAl (6-4)

KC (6-4)

KN (5-4)

Pb Lβ

Pb Lα

KC (7-5)

KO (6-5)

Kaonic hydrogenregionKC (6-5)

Counts/ 40 eV

Ti KαKC (5-4)

Kapton window(C22H10N2O5)

Kaonic hydrogen X-ray energy spectra

KH
(2-1)

Kaonic hydrogenregion

KH
(3-1)

KH
(4-1),..
(9-1)

preliminary

ε 1s ≈ −300 eV, Γ1s ≈ 500 eV
Systematic error in study

KAl (6-4)

KC (6-4)

KN (5-4)

Pb Lβ

Pb Lα

KO (6-5)

KC (7-5)

KC (6-5)

Counts/ 40 eV

Ti KαKC (5-4)

Kapton window(C22H10N2O5)

expected KD pattern

KAl (6-4)

KC (6-4)

KN (5-4)

KC (7-5)

KN (6-5)
Cu KαKO (7-6)

Ti KβKO (6-5)

KC (6-5)Ti KαCounts/ 40 eV

Kaonic deuterium X-ray energy spectra

KC (5-4)

Kaonic deuterium
regionrepulsive
Nov.22 Scientific committee, LNF

Attractive残された課題• K-3Heと4Heの幅の決定-存在するデータの再解析• K-3Heと4Heのシフト差(??)• Kaonic deuterium のX線を観測したい-Isospinごとの散乱長を求めるのに不可欠-測定は難しいが長年の夢• Kaonic atom (Z>=3)のX線の再測定-データはdeep potential 有利？(by Friedman)-存在するデータの精度向上、アイソトープ差(新データ欲しい by Friedman, Gal, Wycech )• charged kaon massの測定

Kaonic atom data with Z>3
1. Errors on shift & width are large.
2. Isotope difference on shift & width were notmeasured in almost all the targets (Except Boron).
3. X-ray yield vs. target density
4. Metal or solid targets were used
(Except: hydrogen, deuterium, He-3&He-4, nitrogen)
Text book:Fundamentals in hadronic atom theory (A. Deloff)

Kaonic atom

Pionic atom

Kaonic atom data with Z>3

K-Li: Attractive shift??
K-10B,11B: Isotope difference?
K-O: Abnormal shift??

ECT*, 4-8Oct.2010, by Friedmanまず初めに測るべき原子 (by Friedman)

Meson2010, Friedman
Yield per stopped kaon

X-ray perstopped K

C(3-2)

Si(4-3)Ni(5-4)Sn(6-5)

Pb(8-7)

0.028

0.13

0.045

0.076

0.27

Shiftと幅のまとめ：Friedman, NPA579(1994)518
X-ray yieldのまとめ：Wiegand, PRA9 (1974) 2282

Summary• SIDDHARTA:４つの標的(水素,重水素,He3,He4)を用いK中間子原子X線観測• 新データ:K-p 1s shift
ΔE1s ≈ −300 eV, Γ1s ≈ 500 eV• 世界初：K-3He 2p shift
ΔE2 p = −2 ± 2( sta ) ± 4( sys) eV• K-3Heでも K-4He 2p shiftは~±10 eV以下
• より高精度の実験必要 E17に期待！
• 重い核も含め基礎データを増やしましょう！

Supported by

HadronPhysics I3 FP6 European Community

European Community Research Infrastructure

program: Contract No. RII3-CT-2004-506078

Integrating Activity “Study of Strongly
Interacting Matter” (HadronPhysics2,
Grant Agreement No. 227431) under theSeventh Framework Programme of EU

Austrian Federal Ministry of
Science and Research BMBWK[650962/0001 VI/2/2009]

Romanian National Authority for
Scientific Research[2-CeX 06-11-11/2006]

Grant-in-Aid for Specially Promoted
Research (20002003), MEXT, Japan

Austrian Science Fund (FWF):[P20651-N20]