Calibration electronics for the central calorimeter at CDF

The Collider Detector at Fermilab (CDF) is a 5000 tons detector built to study 2 TeV proton-antiproton collisions at the Fermilab Tevatron. In the CDF detector the successful calibration of the central calorimeter is critical for understanding the events in the central region. The central calorimeter has about 1800 PMTs. Long term variations are monitored by ¹³⁷Cs sources which can be moved through the modules. Short term gain changes are also monitored by light flasher systems. The procedure has an accuracy of 1-2%. All the calibration systems for the electromagnetic calorimeter are controlled by, and read out with a calibration card, within the front end electronic system. The calibration card for the next collider run, starting in the spring of the year 2000, is a VME based upgrade of the RABBIT based calibration card which was used during the previous data taking period (1992-1995). The board was completely redesigned, while maintaining the original functionality. We describe the functionality and discuss the design of the board, present the results from tests on a prototype, and show the performance achieved using the board in commissioning the central calorimeter