1. Iowa LED system for CMS HCAL By M. Miller Y. Onel University of Iowa, Iowa City, IA CMS Meeting, CERN December 1-8, 2001

2. Pulser Characteristics Pulser located at LED Pulser operates from +5.5 Volts and ground Output pulse of 5.5 Volts Circuit utilizes all bipolar devices Rise and fall times less than 6 nanoseconds Electrical pulse duration from 10 nanoseconds to 1 microsecond Circuit may be easily modified to drive multiple LED’s to achieve greater optical signal Signal amplitude is adjusted by varying LED cathode potential

3. Dual Pulser Circuit Card 1.Mounting of Circuit Card a. Card is mounted against metal plate to increase strength b. Existing 8-32 machine screw mounting is insufficient to support card 2.Potentiometer voltage adjustment is being used in place of analog to digital converter for testing purposes 3.Digital pulse input is two Lemo connectors rather than edge connector 4.Filtered output for reverse biasing the pin diodes @ 5 VDC is provided 5.Complete list of edge connector pins has not been provided, but +5 VDC and ground are connected 6.Circuit is being mounted as specified in “newcalibramodule” drawing

4. Photodiode Pulse Area vs. LED Voltage

5. Dual Pulser Card with Filtered Output for PIN Diode

6. Pulser in Calibration Unit

8. Waveform of Pulser Output Waveform of Pulser Output (green trace) and Photodiode Signal (Blue trace) Pulse Amplitude is 5.2 Volts.

9. Pulser Cards