A multi correlated sampler of the high resolution acquisition system for high rate fixed target KTeV experiments at Fermilab

Abstract

A new facility is being planned at Fermilab for fixed target experiments dealing with CP violation in rate neutral kaon decays; and precision measurements on the “direct” CP-violation parameters e′/ e in the 2 pi decay mode of the neutral kaon system. This new Kaons at the TeVatron(KTeV) beam line is expected to be in operation in 1994. The most important new detector component in the KTeV spectrometer is the precision electromagnetic calorimeter, consisting of bars of Cesium Iodide crystals. The choice has been motivated by its radiation hardness, speed and light output. The size of this detector is 2 meters square and includes over 3200 blocks which are coupled to photomultipliers. We expect a peak anode current pulse of 100 ma from an80 Gev deposit. The pulse shape approximates a signal with a FWHM of 25 nanoseconds, but contains some energy in a long tail that exists for more than 500 nanoseconds. The design for the data acquisition electronics will measure deposited charge in every channel in two 12 bit linear ranges: a low range of 2 MEV per count up to a maximum signal of 82 GEV and a range that will handle signals ten times larger with the same proportion in energy resolution. Since the total required dynamic range of this design is between 15 and 16 bit resolution, the problem of pedestal and pile up is seriously engaged with the configuration of this design.