Silicon frontend electronics and high particle rates at LHC

In this work, we have exploited the possibility of swapping the functionalities of the two stages of fast frontend electronics based on the usual preamplifier and shaper structure. Measurements on a prototype of the CMS frontend chip (APV6) confirm what expected from general considerations: invariance of the output shape and amplitude, and tolerance to very high particle rates. The noise may increase marginally because of the different impedance of the first stage, which depends on the peaking time. (1 refs).