The H1 Neural Network Trigger

Abstract

At the HERA ep collider the H1 experiment is successfully operating a set of hardwired digital neural networks at the second trigger level. The latency of the network triggers, which are of the feed-forward type, is about 20 microseconds. The inputs to the networks are suitably preprocessed 8 bit quantities, based on the trigger information available from the various subdetectors of H1 at level 1. In this article we describe the principles of the neural hardware trigger and its use within the overall H1 trigger strategy. We concentrate here on the preprocessing of the neural input and discuss further developments for the future high luminosity running at HERA beyond the year 2000. 1 Introduction Since its start in 1992 the HERA ep collider has constantly improved its machine currents and its luminosity. Before the switch to electrons in 1998 the largest integrated luminosity of about 35 pb \Gamma1 was collected in 1997. During these years it became clear that many high cross sectio..