Calcium projectile ion radiation dynamics in gaseous target

Experimental investigations of the slowing-down process of calcium projectile ions traveling through the neon gas were carried out at the UNILAC facility at GSI in the frame of the project U-189 "X-ray spectroscopy of projectile ion and target radiation". The main goal was to demonstrate the influence of the target density on the charge state distribution inside matter. In order to analyze the projectile charge state distribution along the trajectory the X-ray spectroscopy of projectile ion K-shell radiation was applied. Ca projectile ion spectra were measured with high spectral (λ/δλ=3000) and spatial resolution (100µ) along the ion beam stopping path. The dependence of the characteristic ion spectrum on the ion beam penetration depth in the gaseous target was investigated. The 48Ca +10 ion beam with initial energies of 5.9 and 11.4 MeV/u was delivered to the target chamber at Z6 experi- mental area. The ion beam was well collimated by means of two 2mm carbon apertures. The typical pulsed ion beam current in gas was 0.1-0.2 µA. The macro pulse duration was 5 - 5.5ms with a frequency of 2-5 Hz. The gas target was designed as a cylindrical copper box with a length of 210 and an inner diameter of 30mm filled with Ne gas under 1.9 bar pressure. The target was separated from 10 -5 mbar vacuum in the experimental chamber by 5µm entrance Havar foil. The gas flow in the tube served for the renewal of the stopping medium. Three rectangu- lar windows 4mm x 40mm used for X-ray diagnostic were oriented along the direction of the ion beam propagation. The distance between the entrance hole and the beginning of the first diagnostic window was 20 mm. The windows were covered with a 5µm Ti foils transmitting 60% of 3-4 keV photons and effectively protecting the crystal spec- trometer from parasitic low energy radiation. After passing through the entrance Havar foil, the 48Ca +10 ion beam enters the gas having an equilibrium charge state distribution. From the first diagnostic window we observed K-shell Ca radiation dynamics along 40mm of the ion stopping path. Spectra were measured by mean of Focusing Spectrometer with Spatial Resolution (1). The mica spherically bend crystal was used as a dispersive element. An X-ray Kodak Direct Exposure Film (DEF) was exposed 10-12 hours.