55. Jahrestagung der ÖPG, September 2005
Präzisionsmessungen mit kaonischen Atomen – von DEAR zu SIDDHARTA
J. MartonStefan Meyer Institut der ÖAW
on behalf of the DEAR / SIDDHARTA Collaborations
55. Jahrestagung der ÖPG, September 2005
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
NuPECC Long Range Plan 2004Fundamental Interactions: Recommendations
… Exotic atom spectroscopy providesimportant input for the further development of low energy QCD. …
55. Jahrestagung der ÖPG, September 2005
DEAR Collaboration @ LNF
Work supported by TARI-INFN,Contract HPRI-CT-1999-00088and
Contract No. RII3-CT-2004-506078
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
55. Jahrestagung der ÖPG, September 2005
Kaonic hydrogen atoms used
as probes for strong interaction
strong interaction shift ε1s and width Γ1s
directly observable by X-ray spectroscopy
K-p: Information on Λ(1405)
deeply bound states (kaonic nuclear Clusters)
Kaonic Hydrogen: Motivation
Breaking news from KEK, FINUDA@DAΦNE(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
• 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
Motivation cont‘d
55. Jahrestagung der ÖPG, September 2005
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
Goals
55. Jahrestagung der ÖPG, September 2005
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
Kaonic atom
e.m. position
of K line
(eV)
(eV)
(eV)
hydrogen 6480 200 250
deuterium 7810 325 630
X-ray Yield
~1-3%
~0.2 % !
55. Jahrestagung der ÖPG, September 2005
Relation of strong interaction shift and width to the complex Kp scattering length aK-p
Scattering Lengths
)(
4122)0(2
21232
1
ThirringBaumannGoldbergerDeser
aeVfmaaipKpKpKs
For the determination of the isospin dependent scattering lengths a0 and a1 the hadronic shift and width of kaonic hydrogen and kaonic deuterium are necessary
But: isospin-breaking and e.m. corrections
55. Jahrestagung der ÖPG, September 2005
Kaonic Hydrogen
Negative kaons stopped in H2 initial atomic capture electromagnetic cascade X-ray transitions
1s
1s
s p d f
E1s}
E2p
n
43
2
1
KkeV
ε1s = E2p-1s(meas.) – E2p-1s(e.m.)
K
As the kaon interacts strongly with the nucleus the 1s energy level is shifted and broadened
Shift and width of states n>1 negligible
55. Jahrestagung der ÖPG, September 2005
DEAR
DAΦNE (LN Frascati)
electron – positron collider collision energy tuned to the Φ resonance at 1.02 GeV c.m.
electron – positron collider collision energy tuned to the Φ resonance at 1.02 GeV c.m.
55. Jahrestagung der ÖPG, September 2005
Experimental Set-up
TMP
CCD Electronics
Vacuum Chamber
APD Cryo-Cooler
Target Cell
CryoTigerCCD Cooling
CCD Pre-Amp
CCD55-Chips
e+ e-
X-ray energy measurement of kaonic K lines with an array of 16 CCD X-ray detectors
X-ray energy measurement of kaonic K lines with an array of 16 CCD X-ray detectors
kaons from Φ decayLight-weight cylindrical target structure
55. Jahrestagung der ÖPG, September 2005
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
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
Overall shielding factor of the DEAR interaction region ~ 100
55. Jahrestagung der ÖPG, September 2005
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
3 X-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
Results on kaonic nitrogen
ΔmK- = 60 keV
55. Jahrestagung der ÖPG, September 2005
Resulting K-p X-ray Spectrum
X-ray energy spectrum with all background fit-components subtracted
1s = - 193 ± 37 (stat.) ± 6 (syst.) eV1s = 249 ± 111 (stat.) ± 30 (syst.) eV
1s = - 193 ± 37 (stat.) ± 6 (syst.) eV1s = 249 ± 111 (stat.) ± 30 (syst.) eV
55. Jahrestagung der ÖPG, September 2005
DEAR Results w
idth
1
s[e
V]
KpX
-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 attractiveKpX (KEK)M. Iwasaki et al, 1997
=
- 3
23 ±
63
± 11
eV
=
407
± 2
08 ±
100
eV
DEAR
55. Jahrestagung der ÖPG, September 2005
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
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
55. Jahrestagung der ÖPG, September 2005
Triple coincidence: SDDX * ScintK * ScintK
Scintillator
Scintillator
D2 gas
SD
D
e+
e-
K+
K-
X-ray
Triple coincidence: SDDX * ScintK * ScintK
Scintillator
Scintillator
D2 gas
SD
D
e+
e-
K+
K-
X-ray
Kaon – X-ray Coincidence
SDDs
e-
e+
Trigger scintillators not shown
X-ray detector array : ~ 200 SDDs 1 cm2 each
55. Jahrestagung der ÖPG, September 2005
Monte Carlo: K-d with SDDs
Energy (keV)Energy (keV)
No timingSDD‚single‘
coinc.SDD * Scint * Scint
Backgroundsuppressionto < 10-3
Kaonic deuterium
K K
Ag K fluorescencelines (calibration)
Large SDD energy resolution tested: ~ 160 eV @ Mn(cooling to -120°C, voltage 200V)
55. Jahrestagung der ÖPG, September 2005
Kaonic helium "puzzle"
Theory gives more than10 times smaller values
but
55. Jahrestagung der ÖPG, September 2005
Kaonic L line X-ray spectrum
Monte Carlo Simulation104 K-He eventsand S/B ~ 4 ± 1.5 eV ± 4.4 eV
energy [keV]
nu
mb
er o
f ev
ents
55. Jahrestagung der ÖPG, September 2005
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
"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
"Hadronic atoms are a wonderful tool to measure QCD amplitudes at threshold."J. Gasser, Proc. DAFNE04
55. Jahrestagung der ÖPG, September 2005
Summary and Outlook
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.
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.
DEAR one of the first experiments at DAΦNE
First production of exotic atoms at DAΦNE shown
Measurements on kaonic nitrogen and finally kaonic hydrogen
Large SDDs and new set-up in progressNew 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 charged kaon mass….
Large SDDs and new set-up in progressNew 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 charged kaon mass….
SIDDHARTASilicon Drift Detectors for Hadronic AtomResearch by Timing Applications
SIDDHARTASilicon Drift Detectors for Hadronic AtomResearch by Timing Applications