Development of Electromagnetic Calorimeter Trigger System at Super KEKB Factory

Abstract

The Super KEKB factory project is currently being prepared at KEK in Japan to probe of the Beyond Standard Model physics from B meson and Tau/Charm weak decays with the ultimate goal of the integrated luminosity of 50/fb. In order to reduce the amount of beam backgrounds and enhance the physics oriented events at the online level, a trigger system is indispensable. For this purpose, two kinds of main trigger components, track and energy triggers, are taken into account at 1st level trigger in Super Belle experiment. The energy trigger using CsI(Tl) crystal outputs with 200ns fast shaping time is composed of total energy and cluster counting components which are complementary each other. While the current electromagnetic calorimeter trigger system of Belle experiment at KEKB factory has used analog sum and discriminated signals with several types of hardwired trigger modules, Super Belle calorimeter trigger system operated at much higher beam background environment should have more flexible trigger algorithm. To achieve this goal, we plan to implement the digital process trigger architecture by the digitization of front-end fast analog signals using 12bit dynamic range, 100MHz sampling Flash ADC, and FPGA processes in which various trigger signals are formed through cascading and partitioning design.