Response of high resolution drift tubes to relativistic heavy ions

Abstract

We report the results of various tests undertaken in a program to develop a drift tube hodoscope for a cosmic ray balloon experiment intended to search for extragalactic antimatter. Included are studies of mechanical integrity, electron drift velocity, tube gain, space charge saturation effects as measured for relativistic iron nuclei, and delta ray backgrounds associated with signals from iron projectiles. Implications of the results of these studies with regard to the use of drift tubes on baloon borne experiments are discussed. It is found that a spatial resolution of [sigma] ~ 300 [mu]m can be achieved over a dynamic range from Z = 20 to 30 with little degradation from delta ray effects for suitably chosen tube gains and discriminator threshold settings.