DEAReXperiment DA NE EXOTIC ATOMS RESEARCH LNF SPRING SCHOOL Bruno Touschek In Nuclear, Subnuclear and Astroparticle Physics M.Iliescu, May 22, 2003 Frascati (Italy)

M. Augsburger j, G. Beer b, S.Bianco c, A.M. Bragadireanu c,i, M. Bregant d, W.H. Breunlich a, M. Cargnelli a, D. Chatellard j, J.-P. Egger k, F.L. Fabbri c, B. Gartner a, C. Guaraldo c, R.S. Hayano f, M. Iliescu c,i, T. Ishiwatari e, K.Itahashi e, T.M. Ito l, M. Iwasaki e, R. King a, P. Knowles j, T. Koike h, B. Lauss c,a, V. Lucherini c, L. Ludhova a, J. Marton a, E. Milotti d, F. Mulhauser j, S.N. Nakamura g, C. Petrascu c,i, T. Ponta i, A.C. Sanderson b, L.A. Schaller j, L. Schellenberg j, H. Schneuwly j, R. Seki l,m, D. Sirghi c,i, F. Sirghi c,i D. Tomono e, T. Yoneyama e, E. Zavattini d, J. Zmeskal a a Institute for Medium Energy Physics, Austrian Academy of Sciences, Austria b Univ. of Victoria, Dept. of Physics and Astronomy, Canada c Laboratori Nazionali di Frascati dell'INFN, Italy d Univ. degli Studi di Trieste, Dip. di Fisica and INFN Sezione di Trieste, Italy e Tokyo Institute of Technology, Japan f Univ. of Tokyo, Dept. of. Physics, Japan g Inst. of Physical and Chemical Research (RIKEN), Japan h KEK, High Energy Accelerator Research Organization, Japan i Inst. of Physics and Nuclear Engineering - " Horia Hulubei ", Romania j Univ. de Fribourg, Inst. de Physique, Switzerland k Univ. de Neuchâtel, Inst. de Physique, Switzerland l W.K.Kellogg Radiation Laboratory, California m Department of Physics and Astrophysics, California State UniversityInstitute for Medium Energy Physics, Austrian Academy of Sciences, AustriaUniv. of Victoria, Dept. of Physics and Astronomy, CanadaLaboratori Nazionali di Frascati dell'INFN, ItalyUniv. degli Studi di Trieste, Dip. di Fisica and INFN Sezione di Trieste, ItalyTokyo Institute of Technology, JapanUniv. of Tokyo, Dept. of. Physics, JapanInst. of Physical and Chemical Research (RIKEN), JapanKEK, High Energy Accelerator Research Organization, JapanInst. of Physics and Nuclear Engineering - " Horia Hulubei ", RomaniaUniv. de Fribourg, Inst. de Physique, SwitzerlandUniv. de Neuchâtel, Inst. de Physique, SwitzerlandW.K.Kellogg Radiation Laboratory, CaliforniaDepartment of Physics and Astrophysics, California State University The DEAR Collaboration

The determination of the isospin dependent KN scattering lengths through a few percent measurement of the shift and the width of the K line of kaonic hydrogen and the first measurement of kaonic deuterium (Deser - Trueman) The objective of DEAR

A measurement of KN scattering lengths at the percent level would enable the determination of the KN sigma terms with a precision of about 20% or less, to be compared with the 70% uncertainty of the present estimates. Sigma terms are directly connected with the chiral symmetry breaking part of the strong interaction Hamiltonian. Also, the fraction of strangeness content in proton can be derived with better accuracy from KN and N sigma terms (Jaffe 87) The implications of DEAR results

Kaonic Hydrogen cascade } n4321n4321 s p d f K keV K Strong Interaction causes: energy shift compared to pure Coulomb interaction level width due to the short lifetime caused by Kaon capture What DEAR measures

CCD-55 detectors positioning in the cryogenic setup e-e- e+e+ K+K+ IP D2 D1 D7 D8 A1 A2 A3 A4 A5 A6 A7 A8 D3 D4 D6 D5 K-K-

Charge-Coupled Devices are solid state detectors with a pixel structure. They are excellent detectors for soft X rays in the high background environment of a collider, for the powerful rejection capability (given by the topology of X-ray events -single pixels-), together with a very good energy resolution, high efficiency and large active area. Background suppression by single pixel selection How DEAR measures KH transitions: X-ray spectroscopic CCDs

Target and cryogenic setup layout Target and cryogenic setup layout

Operating conditions: 20 K, 3 bar (~40 bar NTP) Fiber-glass reinforced kapton target

Requirements: high compaction to allow optimal shielding and light materials to reduce Bremsstrahlung - fiberglass frames - cooling system mounted on the top - thin Al cold finger - reduced diameter of the socket group and, consequently, of the vacuum chamber CCD mounting, cryogenics and on-cell electronics CCD mounting, cryogenics and on-cell electronics

Pb walls Pb platform Vacuum jacket shielding Overall shielding factor of the DEAR interaction region ~ 100 Target e+e- Interaction point Pb collimators DEAR shielding

-Resolution and L.N. characteristics: thermal noise FWHM of about 15 eV energy resolution at 5.9 keV (Mn K line) 136 eV, charge transport correction not applied -Linearity: ~ Instability: below 4 eV/month -Charge transport inefficiency: ~ Synchronous readout of 16 large area detectors (CCD55-30) -Data flow MB/sec -Dual bus real-time system equipped with N.I. boards -Injection synchronization -Software dual slope integration DAQ performance

Shift (eV) [ Width (eV) [ Davies et al, 1979 Izycki et al, 1980 Bird et al, 1983 Constant Scattering Length K-Matrix Potential Model Cloudy Bag Model Consituent Quark Model Iwasaki et al, 1997 KpX DEAR preliminary result State of art of Kaonic Hydrogen measurement and theoretical predictions