Nuclear Instruments and Methods in Physics Research A281 (1989) 469-479 469 North-Holland, Amsterdam CALIBRATION OF ELECTROMAGNETIC CALORIMETERS IN HIGH ENERGY EXPERIMENTS WITH ARADIO FREQUENCY QUADRUPOLE ACCELERATOR

A fast, effective calibration technique has been developed for future Superconducting Supercollider (SSC) calorimeters based upon the radiative capture of protons from a pulsed Radio Frequency Quadrupole (RFQ) accelerator in a fluoride target . The intense flux of low energy photons acts as a clean "pulse generator" calibration signal equivalent to 20 GeV or more . This calibration technique has been demonstrated with a bismuth germanate (BGO) detector array, as well as with several barium fluoride detector crystals, to provide a calibration accuracy of 0.5% within two minutes . The SSC calibration has resulted from the developement of this novel technique by Caltech over the past five years for the L3 BGO electromagnetic calorimeter, which uses a lithium target for the production of 17 .6 MeV low energy photons for the calibration source . Proven techniques have been developed to provide an in situ calibration for all 11000 BGO detector crystals, with an accuracy of 0.8% obtainable in 1-2 h. The result of the experimental test by using the AccSys RFQ accelerator is reported, as is the preliminary concept of a small storage ring that can be used to compress the output beam pulse from the RFQ accelerator into a target beam pulse of 100 ns or less.