The response of an isobutane filled ion chamber to heavy ions

Abstract A gridded ion chamber with its anode split to record both total energy and rate of energy loss has been used with isobutane gas to detect ions of seventeen elements (17⩽ Z 1 ⩽92) in the velocity range 2 v / c ) Z 1 . This variation and its effect on the resolution of the rate of energy loss signal are discussed. The effective charge of the moving ion in the ion chamber window (solid polypropylene) does not oscillate with Z 1 but probably depends on the ion charge before entering the window.