Application of a Spiral Resonator for Bunching Picosecond Heavy-Ion Pulses

A normal conducting spiral resonator (design ??o = vo/c = 0.06) with a maximum effective voltage of 0.33 MV at 20 kW CW input power has been used to bunch 156 MeV 58Ni and 96 MeV 32S ions. For an injected DC beam of 32S13+ of 96 MeV a pulse width of ??tFWHM = 70ps was measured behind a drift length of 3.4 m. Phase locked to the 6.78/13.56 MHz nanosecond beam pulsing system of the MP tandem, pulse widths in the range of 200ps were obtained. In this case the pulse spacing is 147.5 ns with a background to pulse ratio of about 10-5. This spiral resonator is a standard section of the Heidelberg postaccelerator. It will also be used to match the pulsed heavy-ion beam to the postaccelerator over the whole mass range of interest A = 12-80. Furthermore it is installed in a normal beam line for heavy-ion time-of-flight experiments allowing a mass resolution of A < 1 for relatively heavy reaction products.