Internal polarized gas targets: systematic studies on intensity and correlated effects

The work carried out during the PhD was dedicated to the study of high-density polarized gas targets used in high-energy physics. The thesis is related to the PAX experiment, which aims to produce a beam of polarized anti-protons, by means of spin-filtering with a polarized atomic target. In order to obtain the densities required by high-energy particle physic, gaseous targets are a combination of an Atomic Beam Source and a storage cell. The possibility to improve the various components of the ABS and the storage cell has been evaluated, through dedicated systematic studies, using the facilities available in “Spinlab” of Universit´a di Ferrara. The attenuation of a collimated beam passing through the rest gas of a vacuum system has been studied; different nozzle geometries have been tested (comparing the measured data with the data calculated by simulation programs); design and tests of an new kind of injection tube with internal fins (with the aim of decreasing the conductance of the storage cell without diminishing the acceptance and thus to increase the integrated target thickness). Estimation of the attenuation coefficients and total cross sections have been derived from the measurements of the attenuation of a hydrogen or deuterium beam. This quantities are important for projecting new ABS and to improve the existing ones. A favorable nozzle geometry (called “trumpet”) that increases the beam intensity has been derived from simulations and experimental tests. Tests on the injection tubes with fins did not give positive results when applied to the PAX storage cell geometry; however a azimuthal motion of the atoms of a focused beam emerged from the measurements, a motion that until now has been completely neglected.