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Präzisionsmessungen mit kaonischen Atomen – von DEAR zu SIDDHARTA. J. Marton Stefan Meyer Institut der ÖAW on behalf of the DEAR / SIDDHARTA Collaborations. Motivation. Exotic (kaonic, pionic) hydrogen atoms are used as sensitive probes for strong interaction

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pr zisionsmessungen mit kaonischen atomen von dear zu siddharta
Präzisionsmessungen mit kaonischen Atomen – von DEAR zu SIDDHARTA

J. Marton

Stefan Meyer Institut der ÖAW

on behalf of the DEAR / SIDDHARTA Collaborations

55. Jahrestagung der ÖPG, September 2005

motivation
Motivation
  • Exotic (kaonic, pionic) hydrogen atoms are used
  • as sensitive probes for strong interaction
    • Strong interaction shift ε1s and width Γ1s are
    • directly observable by precision X-ray spectroscopy

… Exotic atom spectroscopy provides

important input for the further development of low energy QCD. …

NuPECC Long Range Plan 2004

Fundamental Interactions:

Recommendations

55. Jahrestagung der ÖPG, September 2005

dear collaboration @ lnf
DEAR Collaboration @ LNF
  • G. Beer1, A.M. Bragadireanu2, M. Cargnelli3, C. Curceanu(Petrascu)4,2, J.P. Egger5, H. Fuhrmann3, C. Guaraldo4 (spokesperson), M. Iliescu4,2, T. Ishiwatari3, K. Itahashi6, M. Iwasaki6, P. Kienle3, B. Lauss7, V. Lucherini4, L. Ludhova8, J. Marton3, F. Mulhauser8, T. Ponta2,4, L.A. Schaller8, R. Seki9,10, D. Sirghi4, F. Sirghi4, P. Strasser6, E. Widmann3 and J. Zmeskal3
  • 1Univ. of Victoria; 2Inst. of Physics and Nuclear Engineering “Horia Hulubei”; 3Stefan Meyer Institut of the Austrian Academy of Sciences; 4INFN Laboratori Nazionali di Frascati;5Université de Neuchâtel; 6RIKEN; 7University of California; 8Université de Fribourg; 9California Institute of Technology; 10California State University

Work supported by TARI-INFN,

Contract HPRI-CT-1999-00088

and

Contract No. RII3-CT-2004-506078

55. Jahrestagung der ÖPG, September 2005

kaonic hydrogen motivation
Kaonic Hydrogen: Motivation

Kaonic hydrogen atoms used

as probes for strong interaction

  • strong interaction shift ε1sand width Γ1s

directly observable by X-ray spectroscopy

  • K-p: Information on Λ(1405)

 deeply bound states (kaonic nuclear Clusters)

Breaking news from KEK, [email protected]ΦNE

(c.f. T. Suzuki et al., Phys. Lett. B597 (2004) 263,M. Agnello et al. PRL 94 (2005) 21303)

55. Jahrestagung der ÖPG, September 2005

motivation cont d
Motivation cont‘d
  • Kaonic hydrogen / deuterium
    • Kp simplest exotic atom with strangeness
    • kaonic hydrogen „puzzle“ solved –

but:precision data missing

    • kaonic deuterium never measured before
    • atomic physics: new cascade calculations to be tested

55. Jahrestagung der ÖPG, September 2005

goals
Goals

Precision measurement of strong interaction shift

and width of kaonic hydrogen and kaonic deuterium

at the highest precision

  • Determination of the isospin dependent

scattering lengths

      • no extrapolation to zero energy
  • Testing chiral symmetry breaking in systems

with strangeness

55. Jahrestagung der ÖPG, September 2005

k p and k d atoms
Kaonic

atom

e.m. position

of K line

(eV)

(eV)

(eV)

hydrogen

6480

 200

 250

deuterium

7810

 325

 630

K-p and K-d atoms
  • K-p (K-d) e.m. bound kaonic atoms
  • Bohr radius ~80 fm
  • binding energy ~9 keV
  • strong interaction range ~1 fm
  • strong interaction treated perturbatively

X-ray Yield

~1-3%

~0.2 %

!

55. Jahrestagung der ÖPG, September 2005

scattering lengths
Scattering Lengths

Relation of strong interaction shift and width

to the complex Kp scattering length aK-p

For the determination of the isospin dependent

scattering lengths a0 and a1 the hadronic shift

and width of kaonic hydrogenandkaonic deuterium

are necessary

But: isospin-breaking and e.m. corrections

55. Jahrestagung der ÖPG, September 2005

kaonic hydrogen
n

4

3

2

1

Kaonic Hydrogen

s p d f

Negative kaons stopped in H2 initial atomic capture 

 electromagnetic cascade  X-ray transitions

Shift and width

of states n>1 negligible

E2p

Kg

G1s

Ka ~ 6.3 keV

ε1s = E2p-1s(meas.) – E2p-1s(e.m.)

E1s

e1s

}

As the kaon interacts strongly with the nucleus the 1s energy level is shifted and broadened

55. Jahrestagung der ÖPG, September 2005

da ne ln frascati
DEARDAΦNE (LN Frascati)

electron – positron collider

collision energy tuned

to the Φresonance

at 1.02 GeV c.m.

55. Jahrestagung der ÖPG, September 2005

experimental set up
Experimental Set-up

APD Cryo-Cooler

X-ray energy measurement of kaonic K lines with an array of 16 CCDX-ray detectors

TMP

CryoTiger

CCD Cooling

CCD Electronics

Vacuum Chamber

CCD Pre-Amp

Target Cell

CCD55-Chips

kaons from Φ decay

e+ e-

Light-weight cylindrical target structure

55. Jahrestagung der ÖPG, September 2005

ccd detector array
CCD-Detector Array
  • Array of 16 CCD55-30
  • 1242 x 1152 pixels / chip
  • pixel size 22.5 x 22.5 µm
  • total area per chip 7.24 cm2
  • depletion depth ~30 µm
  • read-out time per CCD 2 min.
  • energy resolution ~150 eV @ 6keV
  • temperature stabilized at 165 K

55. Jahrestagung der ÖPG, September 2005

shielding
Shielding

Overall shielding factor

of the DEAR interaction region ~ 100

55. Jahrestagung der ÖPG, September 2005

dear setup at da ne
DEAR Setup at DAΦNE

55. Jahrestagung der ÖPG, September 2005

features of the experiment
Features of the Experiment
  • Low energy (16 MeV) nearly mono-energetic (Δp/p ~ 0.1%) kaons

from  meson decay

(pion-induced background largely suppressed

compared to proton accelerator, ~ factor 100)

  • Light weight cryogenic target for low X-ray background
  • Carefully chosen structure materials

(checked by different analysis methods, e.g. XFA)

  • Optimized gas density for high X-ray yield (cryogenic gas target, 3% LHD)
  • CCD array for X-ray detection (16 CCD-55, large area 116 cm2,

pixel analysis for background reduction, excellent energy resolution)

  • Shielding for background reduction
  • Performance verified first with kaonic nitrogen measurement

55. Jahrestagung der ÖPG, September 2005

kaonic nitrogen x ray spectrum
Kaonic Nitrogen X-ray Spectrum

55. Jahrestagung der ÖPG, September 2005

results on kaonic nitrogen
Results on kaonic nitrogen
  • 3X-ray transitions first measured
  • Extraction of the transition yields for 7-6, 6-5, 5-4
  • Impact on cascade calculations
  • Kaonic nitrogen nearly fully stripped of electrons:

high precision measurement of the charged kaon mass possible

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

ΔmK- = 60 keV

55. Jahrestagung der ÖPG, September 2005

resulting k p x ray spectrum
Resulting K-p X-ray Spectrum

X-ray energy spectrum

with all background

fit-components subtracted

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

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

55. Jahrestagung der ÖPG, September 2005

dear results
attractive

repulsive

KpX (KEK)

M. Iwasaki et al, 1997

1000

KpX

widthG1s[eV]

800

  • = - 323 ± 63 ± 11 eV

G = 407 ± 208 ± 100 eV

DEAR

600

Izycki et al, 1980

400

200

Bird et al, 1983

Davies et al, 1979

0

-500

0

500

shifte1s[eV]

DEAR Results

55. Jahrestagung der ÖPG, September 2005

next steps
Next Steps

Goal: High precision X-ray spectrocopy with X-ray timing

 New X-ray detectors SDDs: JRA in I3HP (EU FP6)

in cooperation with LNF, MPG, PNSensor, Politecnico Milan,

IFIN-HH

  • timing capability  background suppression

by using the kaon-X ray time correlation

  • excellent energy resolution
  • high efficiency, large solid angle
  • radiation hardness
  • compact versatile design

New dedicated target-detector set-up

In the next stage of the experiment we expect an improvement in the signal / background ratio of ~ 2 – 3 orders of magnitude

55. Jahrestagung der ÖPG, September 2005

sdd structure
SDD Structure

Detector produced at the MPI Halbleiterlabor, Munich, Germany

55. Jahrestagung der ÖPG, September 2005

kaon x ray coincidence
SDDs

e-

e+

Trigger scintillators not shown

Kaon – X-ray Coincidence

X-ray detector array : ~ 200 SDDs

1 cm2 each

55. Jahrestagung der ÖPG, September 2005

slide24
Monte Carlo: K-d with SDDs

Background

suppression

to < 10-3

Kaonic deuterium

Ag K fluorescence

lines (calibration)

Ka

Kb,g

No timing

SDD

‚single‘

Energy (keV)

Energy (keV)

coinc.

SDD * Scint * Scint

Large SDD energy resolution tested: ~ 160 eV @ Mn

(cooling to -120°C, voltage 200V)

55. Jahrestagung der ÖPG, September 2005

kaonic helium @ kek
Kaonic Helium @ KEK

55. Jahrestagung der ÖPG, September 2005

kaonic helium puzzle
Kaonic helium "puzzle"

Theory gives more than

10 times smaller values

but

55. Jahrestagung der ÖPG, September 2005

kaonic l line x ray spectrum
Kaonic L line X-ray spectrum

Monte Carlo Simulation

104 K-He events

and S/B ~ 4

e: ± 1.5 eV

G: ± 4.4 eV

number of events

energy [keV]

55. Jahrestagung der ÖPG, September 2005

what we can learn
What we can learn ?
  • Nature of S0(3115) state

observed recently at KEK

  • Experimental information on

anti-kaon – nucleon interaction

T. Suzuki, Phys. Lett. B597(2004) 263

55. Jahrestagung der ÖPG, September 2005

epilogue
Epilogue

"Hadronic atoms are a wonderful tool to measure

QCD amplitudes at threshold."

J. Gasser, Proc. DAFNE04

"The most important experiment to be carried out in low energy K-meson physics today is the definitive determination of the energy level shifts in K-p and K-d atoms, because of their direct connection with the physics of the KN interaction and their complete independence of all other kind of measurements which bear on this interaction“

R.H. Dalitz

55. Jahrestagung der ÖPG, September 2005

summary and outlook
Summary and Outlook

DEAR one of the first experiments at DAΦNE

First production of exotic atoms at DAΦNE shown

Measurements on kaonic nitrogen and finally kaonic hydrogen

Final DEAR results on strong interaction shift and width in K-p:

  • repulsive shift in K-p verified.
  • smaller values and higher precision for shift and width.
  • Kβ, Kγ line pattern observed for the first time.

SIDDHARTA

Silicon Drift Detectors for Hadronic Atom

Research by Timing Applications

Large SDDs and new set-up in progress

New experiments – physics program

  • Measurement of kaonic deuterium (first measurement ever)
  • Precision measurement of kaonic hydrogen (percent level).
  • Further perspectives:kaonic helium (He-3, He-4).

Precision measurement of chargedkaon mass….

55. Jahrestagung der ÖPG, September 2005

slide31
On the way to new precision experiments

SIDDHARTA

Silicon Drift Detectors for Hadronic Atom

Research by Timing Applications

Thank you

55. Jahrestagung der ÖPG, September 2005

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