SEMINAR   Thursday, July 29th - h. 14:30 Aula edif. 22 Fisica del Nucleo       Mario Bragadireanu IFIN-HH Bucharest     SIDDHARTA Kaon Trigger     Abstract The most precise measurement on kaonic hydrogen was performed at DAFNE by the DEAR experiment in 2002. DEAR used as X-ray detector the Charge Coupled Device (CCD) which  represents an ideal detector, for 1 – 10 keV X-rays, in terms of energy resolution and stability but is a slow detector, consequently no trigger can be applied  at the rate of the charged kaons produced in DAFNE. SIDDHARTA experiment, continuing the scientific line started by DEAR, will use as X-ray detector the Silicon Drift Detector (SDD), whose main advantage, compared with the CCD, is the fast response. Accordingly, a trigger system, based on a fast charged kaon detector, should be used, in order to reduce the background coming from DAFNE.