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Alessandro Scordo LNF – INFN, Frascati SIDDHARTA Collaboration

Precision measurements on kaonic Atoms at DAFNE. Alessandro Scordo LNF – INFN, Frascati SIDDHARTA Collaboration Frascati – Spring School , 12/05/08 – 16/05/08. SIDDHARTA Experiment. LNF- INFN, Frascati, Italy IMEP- ÖAW, Vienna, Austria IFIN – HH, Bucharest, Romania

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Alessandro Scordo LNF – INFN, Frascati SIDDHARTA Collaboration

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  1. Precision measurements on kaonic Atoms at DAFNE Alessandro Scordo LNF – INFN, Frascati SIDDHARTA Collaboration Frascati – Spring School, 12/05/08– 16/05/08

  2. SIDDHARTA Experiment LNF- INFN, Frascati, Italy IMEP- ÖAW, Vienna, Austria IFIN – HH, Bucharest, Romania Politecnico, Milano, Italy MPE, Garching, Germany PNSensors, Munich, Germany RIKEN, Japan Univ. Tokyo, Japan Victoria Univ., Canada SIlicon Drift Detector for Hadronic Atom Research by Timing Applications

  3. SIDDHARTA Experiment (SIlicon Drift Detector for Hadronic Atom Research by Timing Application) Experimental Goals: • High precision (~eV) measurement of width • and shift of Kaonic Hydrogen Ka transition • 2. First measurement of Kaonic Deuterium

  4. Kaonic atoms

  5. n 4 3 2 1 s p d f E2p Kb Ka ~ 6.3 keV = DE2p1s G e E1s }

  6. Kaonic atoms Scattering lenghts can be written in terms of the ISOSPIN-DEPENDENT scattering lenghts: • Shift e and width G of 1s state are related to real and imaginary part of s-wave scattering lenght: • Neglecting isospin simmetry breaking corrections, we can write the Deser-Trueman relations [1] for kaonic hydrogen and deuterium: This term includes contributes due to 3 body problem and it can be numerically calculated [1] S.Deser et al., Phys.Rev. 96 (1954) 774; T.L.Truemann, Nucl. Phys. 26 (1961) 57; A.Deloff, Phys. Rev. C13 (1976) 730.

  7. Why SIDDHARTA? Scientific aims: Scattering lenghts calculations Useful in understanding: • Chiral simmetry breaking mechanism • Strange content of nucleons

  8. DEAR Results Results lead to a repulsive character of the interaction. (Phys. Rev. Lett. 94, 212302 (2005) ) Most precise measurement up to now! No deuterium measurement was achived, due to the too high DAFNE background!!! SIDDHARTA Background reduction is needed!

  9. Background in DAFNE SYNCHRONOUS: It’s associated to K production, wich means F decays. It can be considered an hadronic background ASYNCHRONOUS: It’s dued to final products of electromagnatic cascade wich is produced in DAFNE and to other materials wich are in the setup and that are activates from particle lost from the beam. It is also dued to Touschek effect (interaction between particles of the same bunch) The main contribute is the asynchronous one wich can be reducted using a trigger. DEAR detectors were CCD (Sylicon Pixel Type), Non triggerable (too slow)

  10. SIDDHARTA and SDDs In order to measure shift and width of kaonic hydrogen and deuterium K line with a few eV precision, we need a S/B ratio near unity. DEAR case was~ 1/70 Silicon Drift Detectors : -High efficiency in a wide energy range (from few hundreds eV to 15 KeV) - Good energy resoultion, (~150 eV at 110 K at 6 keV ) - Big surface (~cm2), wich provide big detected areas with few front end channels - High rates capability - Very fast reading, wich means triggerability

  11. SDD An electric field leads electrons, generated by particle flow (x-Rays or ionizing) to a small collector anode. At the same time holes are immediately removed from electron’s path by cathode strips. First time used as spectroscopy (energy) detectors! Designed for this experiment

  12. Detectors

  13. Target cell Cell is made of Kapton, a plastic material with no elements witch could have transition lines near 6 KeV

  14. Trigger system The trigger system has to provide the DAQ start and monitorize Kaon flux wich enter the setup Kaon produced in back to back configuration

  15. Day-One Setup on DAFNE, 22 Jan. 2008

  16. SIDDHARTA Kaon monitor lead shield SIDDHARTA Setup

  17. DAY1 Setup

  18. DAY1 Setup

  19. DAY1 Setup

  20. Before installing the detector and target system

  21. Installation of SIDDHARTA into final frame

  22. Installing cables and SDD detector HV + LV distribution board SDDs with pre-amplifier board signal and bus cables

  23. Working group

  24. Beam time request • Day-One setup • Tuning of setup / optimisation100 pb-1 • Precision measurement of kaonic hydrogen400 pb-1 (at the percent level) • Measurement of kaonic deuterium600 pb-1 (first measurement) • Further options: Additional kaonic deuterium measurement Kaonic helium studies (3He and 4He) other light kaonic atoms e.g. Li, Be…

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