Measurements of heavy ion beam profiles in gases

Diagnostic of the ion beam profile is a very important part of the any heavy ion beam experiment. Usually, scintillators are used for these purposes. In the HHT-experimental area of GSI, uranium beams of up to 4,5·10 particle per bunch focused in the spot side of 0,8mm x 1,6mm are used [1]. The ion beam of such intensity is capable to destroy any usual scintillator by one shot. In this case, a promising way to diagnose the beam profile is to use gas scintillation. This scintillation is induced during the propagating of an ion beam in a chamber filled with gas. The advantages of this method are that the scintillating media can not be destroyed by heavy ion beam and has no saturation effect for such intensities. In the last experiment at HHT (27.09–03.10.2004), Ar and He gaseous at different pressures were used to provide the ion beam profile diagnostic. During the propagation of the ion beam through gas each ion produce excitation and ionization processes. Excited gas atoms and ions take off the excitation by emitting the light [2]. This light was registered by high-resolution amplified CCD-cameras (DiCam Pro, PCO) installed in two perpendicular planes providing horizontal and vertical profiles. From these pictures (Figure 1) the ion beam intensity distribution in space, position of the beam focus and focal spot side could be determined.