Automatic scanning of excitation function

In measuring excitation function using an accelerator, it is advantageous to record the complete excitation function between two energy limits at the same time. This reduces the effect due to variation of background and nonuniformity of the target thickness. An automatic arrangement is installed at the 5.5 MeV Van-de-Graaff acclerator at Trombay for this purpose. The reference voltage of the analysing magnet current apply varies between two given values V and V + ΔV by a sawtooth voltage. A corresponding beam energy interval of about 100 keV can be scanned easily. The counts from upto 6 detectors and pulses from the current integrator are modulated by the sawtooth and can be displayed on the different memory groups of a multichannel analyser. In addition the energy calibration also is made on the analyser by recording the N.M.R. signal as a function of varying magnetic field. Examples of its function are presented. (author)