55. Jahrestagung der ÖPG, September 2005 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 Exotic (kaonic, pionic) hydrogen atoms are used as sensitive probes for strong interaction Strong interaction shift ε 1s and width Γ 1s are directly observable by precision X-ray spectroscopy NuPECC Long Range Plan 2004 Fundamental Interactions: Recommendations … Exotic atom spectroscopy provides important input for the further development of low energy QCD. …

55. Jahrestagung der ÖPG, September 2005 DEAR LNF Work supported by TARI-INFN, Contract HPRI-CT and Contract No. RII3-CT G. Beer 1, A.M. Bragadireanu 2, M. Cargnelli 3, C. Curceanu(Petrascu) 4,2, J.P. Egger 5, H. Fuhrmann 3, C. Guaraldo 4 (spokesperson), M. Iliescu 4,2, T. Ishiwatari 3, K. Itahashi 6, M. Iwasaki 6, P. Kienle 3, B. Lauss 7, V. Lucherini 4, L. Ludhova 8, J. Marton 3, F. Mulhauser 8, T. Ponta 2,4, L.A. Schaller 8, R. Seki 9,10, D. Sirghi 4, F. Sirghi 4, P. Strasser 6, E. Widmann 3 and J. Zmeskal 3 1 Univ. of Victoria; 2 Inst. of Physics and Nuclear Engineering “Horia Hulubei”; 3 Stefan Meyer Institut of the Austrian Academy of Sciences; 4 INFN Laboratori Nazionali di Frascati; 5 Université de Neuchâtel; 6 RIKEN; 7 University of California; 8 Université de Fribourg; 9 California Institute of Technology; 10 California State University

55. Jahrestagung der ÖPG, September 2005 Kaonic hydrogen atoms used as probes for strong interaction  strong interaction shift ε 1s and width Γ 1s 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, (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) hydrogen6480  200  250 deuterium7810  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 a K - p Scattering Lengths For the determination of the isospin dependent scattering lengths a 0 and a 1 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 H 2  initial atomic capture   electromagnetic cascade  X-ray transitions  1s  1s s p d f E 1s } E 2p n K   keV ε 1s = E 2p-1s (meas.) – E 2p-1s (e.m.) K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 CryoTiger CCD 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 kaons from Φ decay Light-weight cylindrical target structure

55. Jahrestagung der ÖPG, September 2005 CCD-Detector Array Array of 16 CCD x 1152 pixels / chip - pixel size 22.5 x 22.5 µm - total area per chip 7.24 cm 2 - depletion depth ~30 µm - read-out time per CCD 2 min. - energy resolution ~150 6keV - temperature stabilized at 165 K Array of 16 CCD x 1152 pixels / chip - pixel size 22.5 x 22.5 µm - total area per chip 7.24 cm 2 - depletion depth ~30 µm - read-out time per CCD 2 min. - energy resolution ~150 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 DEAR Setup at DAΦNE

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 cm 2, 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

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) m K - = ± MeV Results on kaonic nitrogen Δm K - = 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 = ± 37 (stat.) ± 6 (syst.) eV  1s = 249 ± 111 (stat.) ± 30 (syst.) eV  1s = ± 37 (stat.) ± 6 (syst.) eV  1s = 249 ± 111 (stat.) ± 30 (syst.) eV

55. Jahrestagung der ÖPG, September 2005 DEAR Results width  1s  [eV] KpX shift  1s [eV] Davies et al, 1979 Izycki et al, 1980 Bird et al, 1983 repulsive attractive KpX (KEK) M. Iwasaki et al, 1997  = ± 63 ± 11 eV  = 407 ± 208 ± 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

55. Jahrestagung der ÖPG, September 2005 Kaon – X-ray Coincidence SDDs e-e- e+e+ Trigger scintillators not shown X-ray detector array : ~ 200 SDDs 1 cm 2 each

55. Jahrestagung der ÖPG, September 2005 Monte Carlo: K - d with SDDs Energy (keV) No timing SDD ‚single‘ coinc. SDD * Scint * Scint Background suppression to < Kaonic deuterium KK K  Ag K fluorescence lines (calibration) Large SDD energy resolution tested: ~ 160 Mn (cooling to -120°C, voltage 200V)

55. Jahrestagung der ÖPG, September 2005 Kaonic KEK

55. Jahrestagung der ÖPG, September 2005 Kaonic helium "puzzle" Theory gives more than 10 times smaller values but

55. Jahrestagung der ÖPG, September 2005 Kaonic L line X-ray spectrum Monte Carlo Simulation 10 4 K - He events and S/B ~ 4  ± 1.5 eV  ± 4.4 eV energy [keV] number of events

55. Jahrestagung der ÖPG, September 2005 What we can learn ?  Nature of S 0 (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. K β, K γ 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. K β, K γ 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 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 charged kaon mass…. 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 charged kaon mass…. SIDDHARTA Silicon Drift Detectors for Hadronic Atom Research by Timing Applications SIDDHARTA Silicon Drift Detectors for Hadronic Atom Research by Timing Applications

55. Jahrestagung der ÖPG, September 2005 Thank you On the way to new precision experiments SIDDHARTA Silicon Drift Detectors for Hadronic Atom Research by Timing Applications SIDDHARTA Silicon Drift Detectors for Hadronic Atom Research by Timing Applications