Fast front-end L0 trigger electronics for ALICE FMD-MCP tests and performance

We present design details and new measurements of the performance of fast electronics for the Forward Multiplicity Detector for ALICE. These detectors based on sector type Microchannel Plates (MCP) forming several disks gave the very first trigger decision in the experiment (L0). Fast passive summators integrated with the detectors are used for linear summation of up to eight isochronous signal channels from MCP pads belonging to one sector. Two types of microelectronics design thin film summators were produced. We present test results for these summators, working in the frequency range up to 1 Ghz. New low noise preamplifiers have been built to work with these summators. The new design shows a good performance with the usable frequency range extended up to 1 Ghz. An upgrade of the functional scheme for the L0 ALICE pre-trigger design is also presented.Abstract:<P>List of figures <BR><UL><LI> Figure 1: <A HREF="L__FE_layout.eps">ALICE L0 Trigger Front-End Electronics Functional Scheme. </A><LI> Figure 2: <A HREF="farhat1.eps">UHF design for a fast passive summator based on directional couplers. </A><LI> Figure 3: <A HREF="sum-r-2.eps">Photo of an industrially produced passive summator based on circular bridges. </A><LI> Figure 4: <A HREF="2.eps">Oscillogram of the fast 4 signals separated by different delays shown at the fast output of the passive summator. </A><LI> Figure 5: <A HREF="n4.eps">The same as in Figure 4, but with the delays removed. </A><LI> Figure 6: <A HREF="circuit.eps">Fast preamplifier layout. </A><LI> Figure 7: <A HREF="n5.eps">Gain versus Frequency Response for fast preamplifier. </A><LI> Figure 8: <A HREF="3.eps">Transition response of the preamplifier for a 100 psec rise time step function. </A><LI> Figure 9: <A HREF="fedor10.eps">The shape of the MCP signal measured after the summator and fast preamplifier. </A>