The Upstream Detectors of the FIRST Experiment at GSI

Abstract FIRST (FragmentationofIonsRelevantforSpaceandTherapy)isanexperimentdevotedtoaprecise measurementofion fragmentation for space radiation protection and hadron therapyapplications. Afirst run dedicated to the fragmentation of fully stripped 12 Cions on a thin graphite target has been already performed during August 2011 at GSI. The experiment is composed of already existing detectors complemented by a newly designed interaction region, including the so -called Upstream Detectors: a Start Counter and a Beam Monitor. The Start Counter is used to trigger the beam and to give a precise time reference for time of flight measurements, while the Beam Monitor is needed to track ions before their interaction in the target. In this paper we present their description and the results of the tests performed on different beams to validate their performances before the installation at GSI.