Final Results of the DEAR Experiment and Future Plans at the SIDDHARTA Experiment

T. Ishiwatari CHIRAL05, Feb. 15-17, 2005 RIKEN (JAPAN) 1/3 １

Final Results of the DEAR Experiment and

Future Plans at the SIDDHARTA Experiment

T. Ishiwatari,

Stefan Meyer Institut für subatomare Physik,

Austrian Academy of Sciences, Vienna, Austria

On behalf of the DEAR and SIDDHARTA Collaborations

LNF SMI INFN Trieste Univ. Fribourg Univ. Neuchâtel RIKEN Univ. Tokyo Univ. Victoria


7-6: 33.7 ± 8.1 (sta) ± 3.4 (sys)%

6-5: 55.5 ± 4.2 (sta) ± 5.5 (sys)%

5-4: 64.4 ± 15.6 (sta) ± 6.4 (sys)%

Shift: 1s = - 194 ± 37 (sta) ± 6 (sys) eV (replusive)

Width: 1s = 249 ± 111 (sta) ± 30 (sys) eV

Kaonic nitrogen X-ray yields at =3.4 NTP

Kaonic hydrogen K line

The results of the DEAR experiment

PLB593(2004)48

Acta Physica Slovaca 55(2005)69, Submitted to PRL


• The shift ε1s and width Γ1s in the 1s state

both of kaonic hydrogen and deuterium• Determination of isospin independent

KN scattering lengths requires data both kaonic

hydrogen and deuterium

• a0 and a1 are important for

deeply-bound kaon states, S0(3115),

KN -term, SU(3) chiral symmetry…

Motivation

S. Bianco et al.,Rev. Nuovo. Cimento

22 (1999) 1.

)(

4122)0(2

21232

1

ThirringBaumannGoldbergerDeser

aeVfmaaipKpKpKs

)(

4122)0(2

21232

1

ThirringBaumannGoldbergerDeser

aeVfmaaipKpKpKs


E1s1s

1s

}

E2p

wid

th

1s

[eV

]

-500 50000

200

400

600

800

1000

shift 1s [eV]

Dav

ies

et a

l, 19

79

Izyc

ki e

t al,

1980

Bir

d et

al,

1983

repulsive attractive

KpX (KEK)M. Iwasaki et al, 1997

=

- 3

23 ±

63

± 11

eV

=

407

± 2

08 ±

100

eV

DEAR

Kaonic hydrogen puzzle

s p d f

Stark effect


K-p and K-d atoms

Target K line (eV) Shift (eV) Width (eV) X-ray yield

Hydrogen 6480 ~200 ~250 ~1-3%

Deuterium 7810 ~325 (?)* ~630 (?)* ~0.2% (?)

Target 7-6 transition Shift (eV) Width (eV) X-ray yield

Nitrogen 7596 ~0 ~0 ~50%

1. Kaonic hydrogen K 2. Kaonic deuterium K high background

0. Kaonic nitrogen X-ray lines at high n transition

*A.N. Ivanov et al., EPJA23(2005)79


Impact on kaonic nitrogen X-ray measurement

The charged kaon mass The most precise values have a 60 keV difference

mK=493.696 ±0.007 MeV (K-C: Denisov 91)mK=493.636 ±0.011 MeV (K-Pb: Gall 88)

Electron screening effect must be studied

N

K

Low density

N e-

High-density

mK=493.677 ±0.016 MeV (PDG)

PDG, PLB (2004)1

A new kaon mass measurement is proposed using a nitrogen gas.

PLB 535 (2004) 52


DEAR

DAΦNE (LN Frascati)

electron – positron collider optimuzed to produce Φmeson at rest (1.020 GeV)

electron – positron collider optimuzed to produce Φmeson at rest (1.020 GeV)

TMP

CCD Electronics

Vacuum Chamber

APD Cryo-Cooler

Target Cell

CryoTigerCCD Cooling

CCD Pre-Amplifier

CCD55-Chips

kaons from Φ decay

http://www.oeaw.ac.at/imep/imep/lnfdear.htm


DEAR experimental setup

Shielding reduces background a factor~ 100


Experimental Setup

TMP

CCD Electronics

Vacuum Chamber

APD Cryo-Cooler

CryoTigerCCD Cooling

CCD Pre-Amplifier

CCD55-Chips

e+ e-

kaons from Φ decay


DAΦNE Luminosity

Φ production cross section ~ 3000nb (corrected for radiative losses)Integrated luminosity ~ 2pb-1 per day

~ 3 × 106 K- per day

Φ production cross section ~ 3000nb (corrected for radiative losses)Integrated luminosity ~ 2pb-1 per day

~ 3 × 106 K- per day

Kaon MonitorKaon Monitor

kaons are directly measured by the scintillators.


CCD Detector

16 CCD55-30 chips are used -1242 x 1152 pixels - pixel size 22.5 x 22.5 µm- total area per chip 7.24 cm2

- depletion depth ~30 µm- read-out time 2 min.- energy resolution ~150 eV @ 6keV- temperature stabilized at 165 K

16 CCD55-30 chips are used -1242 x 1152 pixels - pixel size 22.5 x 22.5 µm- total area per chip 7.24 cm2

- depletion depth ~30 µm- read-out time 2 min.- energy resolution ~150 eV @ 6keV- temperature stabilized at 165 K


CCD Pixel analysis

X-ray events single and double pixel eventsCharged particles large-sized eventsbackground suppression by pixel analysis


Selecting single- and double-pixel events as X-raysgives excellent background rejection

X-ray events


Experimental Data

Kaonic Nitrogen April: 3.-29.4.2002: ~9000 × 16 files (160GB) 14.2 pb-1 => 20.5 × 106 K-

Kaonic Nitrogen October: 6.-28.10.2002: ~7000 × 16 files (112GB) 17.4 pb-1 => 25.1 × 106 K-

Kaonic Hydrogen: 30.10.-16.12.2002: ~18000 × 16 files (288GB) 58.4 pb-1 => 84.1 × 106 K-

Hydrogen, no collisions: 16.-23.12.2002: ~2600 × 16 files (42GB)No kaons. Removed scrapers to produce high background


Kaonic Nitrogen X-ray Spectrum

Al

Si

Ca

Zr

Kaonic nitrogen lines ofthe 7-6, 6-5, and 5-4transitions are observed.The 7-6 and 5-4 transitions are overlapped with theTi and Sr lines, respectively.

The number of each X-ray peaks are obtained by the fit.

Efficiencies for kaons to stop the target, and for X-rays to be detected by the CCDs are estimated by the Monte Carlo.

10.8 pb-1


Three squential X-ray lines from kaonic nitrogen atoms in a gaseous targetThe transition yields for 7-6, 6-5, 5-4 are obtained as:

Kaonic nitrogen is a highly ionized system. Kaonic nitrogen has electrons with a few %.high precision measurement of the charged kaon mass possible

Kaon mass (test) mK- = 493.884 ± 0.314 MeV

Results of kaonic nitrogen

ΔmK- = 60 keVFuture measurement will allow to solve this problem


Kaonic Hydrogen

1s

1s

s p d f

E1s}

E2p

n

43

2

1

KkeV

K

Negligible shift and width in the n>1 states

Fe K= 6.4 keV

Y(KH) ~ 1-3%S/N~1:100

The yield of kaonic hydrogen is small, and the energy is close to Fe K.


Kaonic Hydrogen X-ray spectrum

Raw spectrum (background fitted with cubic function)


Experimental Data

Kaonic Nitrogen April: 3.-29.4.2002: ~ 9000 × 16 files (160GB) 14.2 pb-1 => 20.5 × 106 K-

Kaonic Nitrogen October: 6.-28.10.2002: ~ 7000 × 16 files (112GB) 17.4 pb-1 => 25.1 × 106 K-

Kaonic Hydrogen: 30.10.-16.12.2002: ~ 18000 × 16 files (288GB) 58.4 pb-1 => 84.1 × 106 K-

Hydrogen, no collisions: 16.-23.12.2002: ~2600 × 16 files (42GB)Background measurement without crossing beams at the IP


Countinuous background shapes

are subtracted.

•Two spectra are normailized.•Intensity of Fe K line from background data•Energy difference of K-linesare fixed.•Same Lorenzian width for the K-lines•Relative yields for K,Khigh ...are examined •Stability tests for the fitswith several fit ranges

Background subtracted spectra


Kaonic hydrogen X-ray spectrum

X-ray energy spectrum with subtraction of all the background components

Shift: 1s = - 193 ± 37 (stat.) ± 6 (syst.) eV Width: 1s = 249 ± 111 (stat.) ± 30 (syst.) eV

Shift: 1s = - 193 ± 37 (stat.) ± 6 (syst.) eV Width: 1s = 249 ± 111 (stat.) ± 30 (syst.) eV

•Repulsive shift

•K, K and K are clearly disentangled, for the first time

•With small errors


Results of kaonic hydrogen

wid

th

1s

[eV

]

KpX

-500 50000

200

400

600

800

1000

shift 1s [eV] D

avie

s et

al,

1979

Izyc

ki e

t al,

1980

Bir

d et

al,

1983

repulsive attractive

KpX (KEK)M. Iwasaki et al, 1997

=

- 3

23 ±

63

± 11

eV

=

407

± 2

08 ±

100

eV

DEAR

1s = - 193 ± 37 (stat.) ± 6 (syst.) eV

1s = 249 ± 111 (stat.) ± 30 (syst.) eV

aK-p = - 0.466 ± 0.104 + i 0.299 ± 0.174 fm


The SIDDHARTA project - experimental study of kaonic deuterium and helium

SiSilicon licon DDrift rift DDetector foretector for H Hadronic adronic AAtom tom RResearch and esearch and TTiming iming

AApplicationspplications

Development of a triggered soft X-ray detection system,based on Silicon Drift Detectors (SDD),

with high energy resolution and high background reduction

for applications in exotic atom research


Kaon – X-ray coincidence

Triple coincidence: SDDX * ScintK * ScintK

Scintillator

Scintillator

D2 gas

SD

De+

e-

Φ

X-ray

K+

K-

Φ K+ + K-

An improvement of the S/ N of ~ 2 – 3 orders of magnitude

S/N =1:1005:1for kaonic Hydrogen


SDD design for SIDDHARTA

sensitive area

3 x 100 mm²

chip size: 34 x 14 mm²

integrated temperature sensors


Possible SDD and target setups

New design for triggered target-detector system Large area SDDs (1cm2 each, total area ~ 200 cm2)

e+

e-

Cryogenic gas target volume

SDDs

Scintillators

R

L

(1) toroidal topology

With 200 cm2 SDDs, only part of thecylindrical surface can be covered

SDDs

e-

e+

(2) Conventional topology

Trigger scintillators not shown


Kaonic deuterium (Monte Carlo)

Energy (keV)Energy (keV)

SDD w/o coinc.

coinc.SDD * Scint * Scint

Backgroundsuppressionto > 103

Kaonic deuterium

K KAg K fluorescencelines (calibration)

Width 1s ~ 630 eVShift 1s ~ 330 eVA.N. Ivanov et al., EPJA23(2005)79

Yield Y(K) ~ 0.2%

MIPs (e+/e-) in SDD

Kaon decays

= 15 eV=35 eVS/B=1:1

Signal rate ~ 2.2x10-3 /s130 /d (duty cycle=2/3 of d.)


Kaonic Helium-4 Puzzle (large shift and width in 2p state)

E (Fe K) = 6.4038 keVE(exp)-E(Fe)= ~10 eV

K-He L p (eV)

p (eV)

Experiments

Baird (’83) -50 ± 12 100±40

Batty (’79) -35 ± 12 30±30

Wiegand(’71) -41 ± 33 -----------

Theory

Baird (’83) -0.2 0.2

Akaishi (’02) -0.44 3.3

Kaonic helium puzzle

Akaishi (’02) -11 21

Assuming a deeply bound kaon state exists(YA02 model)

Abnormal shift and large uncertainty in width

In the kaonic 4He2p state


Summary

The results of kaonic hydrogen are Repulsive shift of the K line is verified. Most accurate determination of the shift and width. Kβ, K lines are disentangled for the first time.

The results of kaonic nitrogen are3 sequential X-rays was measuredYields of kaonic nitrogen at a gas target was obtainedKaonic nitrogen is highly ionizedKaon mass can be obtained


Outlook

• Large area SDDs -- trigger capability (SIDDHARTA)

• New target and detector system in progress

New experiments – exciting physics

• First measurement of kaonic deuterium

• Much precise measurement of kaonic hydrogen.

• Further perspectives: kaonic helium (He-3, He-4). Precision measurement of charged kaon mass.

SIDDHARTASilicon Drift Detectors for Hadronic AtomResearch by Timing Applications

SIDDHARTASilicon Drift Detectors for Hadronic AtomResearch by Timing Applications


News on exotic atoms

International Conferenceon Exotic Atoms, EXA05February 21 – 25, 2005Vienna

www.oeaw.ac.at/smi/exa05


Kaonic Hydrogen Data Analysis

•Determination of background shape•Finding all the fluorescence X-ray peaks

1. Kaonic hydrogen spectrum2. “no collision” spectrum3. Kaonic nitrogen spectrum

• subtraction of the continuous background and fluorescence X-ray lines

as Background data

as Signal data


SDD structure

SDD with integrated JFET

Detector produced at the MPI Halbleiterlabor, Munich, Germany

n

n+

p+ -V cc

p+

100

150

200

250

300

-60 -50 -40 -30 -20 -10 0 10 20

temperature [°C]

FW

HM

[e

V]

100 mm² SDD

typ. 10 mm²SDDnoise fit


Exp. = liq. 4He

No experiment of 3He

E (K He L) = 6.464 keVE (Fe K) = 6.4038 keV


K-He L p (eV) p (eV)

Experiments

Baird (’83) -50 ± 12 100 ± 40

Batty (’79) -35 ± 12 30±30

Wiegand (’71) -41 ± 33 --------------

Theory

Baird (’83) -0.2 0.2

Akaishi (’02) -0.44 3.3

Kaonic helium puzzle

Akaishi (’02) -11 21

Assuming a deeply bound kaon state exists(YA02 model)

E 2p (K He) = 6.464 keVE (Fe K) = 6.4038 keV


Transition E (calc.) E (exp.) Rel. Int. Yield(%)

3d-2p 6.464 6.414±0.012 100±6 8.9±4.5

4d-2p 8.723 8.674 26±4 2.3±1.2

5d-2p 9.768 9.719 18±3 1.6±0.8

6d-2p 10.331 10.282 4±3 0.4±0.3

Energies & yields of K-He L lines (Baird)

E (Fe K) = 6.4038 keVE(exp)-E(Fe)= ~10 eV


Kaonic He L X-ray yields (Koike)


Exp. = liq. 4He

No experiment of 3He

E (K He L) = 6.464 keVE (Fe K) = 6.4038 keV

Final Results of the DEAR Experiment and Future Plans at the SIDDHARTA Experiment

Documents

Transcript of Final Results of the DEAR Experiment and Future Plans at the SIDDHARTA Experiment