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Experimental Studies on Kaonic Atoms at DAΦNE: Recent Results and Perspectives

Experimental Studies on Kaonic Atoms at DAΦNE: Recent Results and Perspectives. 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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Experimental Studies on Kaonic Atoms at DAΦNE: Recent Results and Perspectives

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  1. Experimental Studies on Kaonic Atoms at DAΦNE: Recent Results and Perspectives J. Marton Stefan Meyer Institut der ÖAW on behalf of the DEAR / SIDDHARTA Collaborations PANIC, October 24-28, 2005

  2. 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 PANIC, October 24-28, 2005

  3. 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 PANIC, October 24-28, 2005

  4. 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, FINUDA@DAΦNE (c.f. T. Suzuki et al., Phys. Lett. B597 (2004) 263,M. Agnello et al. PRL 94 (2005) 21303) PANIC, October 24-28, 2005

  5. 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 PANIC, October 24-28, 2005

  6. Goals 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 PANIC, October 24-28, 2005

  7. 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 % ! PANIC, October 24-28, 2005

  8. 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: corrections due to isospin-breaking PANIC, October 24-28, 2005

  9. 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 PANIC, October 24-28, 2005

  10. DEAR DAΦNE (LN Frascati) electron – positron collider collision energy tuned to the Φresonance at 1.02 GeV c.m. PANIC, October 24-28, 2005

  11. 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 PANIC, October 24-28, 2005

  12. 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 PANIC, October 24-28, 2005

  13. Shielding Overall shielding factor of the DEAR interaction region ~ 100 PANIC, October 24-28, 2005

  14. DEAR Setup at DAΦNE PANIC, October 24-28, 2005

  15. 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 PANIC, October 24-28, 2005

  16. Kaonic Nitrogen X-ray Spectrum PANIC, October 24-28, 2005

  17. 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 PANIC, October 24-28, 2005

  18. 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 PANIC, October 24-28, 2005

  19. attractive repulsive 1000 KpX (KEK) M. Iwasaki et al, 1997 KpX 800 widthG1s[eV] • = - 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 PANIC, October 24-28, 2005

  20. PANIC, October 24-28, 2005

  21. TH1 TH2 KpX TH3 DEAR Experiments vs.Theory TH1: U.G. Meißner et al., Eur. Phys. J. C 35 (2004)349 TH2: B. Borosoy et al., Phys. Rev. Lett. 94 (2005) 213401 TH3: SMI-Vienna A.N. Ivanov et al., Eur. Phys. J. A21 (2004) 11 J. Phys. G 31 (2005) 769 Eur. Phys. J. A25 (2005) 329  Precision experimental data are needed PANIC, October 24-28, 2005

  22. 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 PANIC, October 24-28, 2005

  23. SDD Structure Detector produced at the MPI Halbleiterlabor, Munich, Germany PANIC, October 24-28, 2005

  24. SDDs e- e+ Trigger scintillators not shown Kaon – X-ray Coincidence X-ray detector array : ~ 200 SDDs 1 cm2 each PANIC, October 24-28, 2005

  25. 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) PANIC, October 24-28, 2005

  26. 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…. PANIC, October 24-28, 2005

  27. 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 PANIC, October 24-28, 2005

  28. On the way to new precision experiments SIDDHARTA Silicon Drift Detectors for Hadronic Atom Research by Timing Applications Thank you PANIC, October 24-28, 2005

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