MEASUREMENT OF THE PROFILE OF HYDROGEN-ATOMS SCATTERED FROM A GAS-TARGET

A method is proposed, with the corresponding electronic instrumentatio n and a narrow-slit (10 mu m) detector, for the measurement of profile s of ribbon-shaped beams of hydrogen atoms with 0.7-15 MeV energies, s cattered in a thin (below 1 mu g/cm(2)) gas target. The measurements a re performed by moving the detector across the beam with the aid of a step motor and counting particles at each point of the profile. The co mposite collimator design allows the measuring detector to also be use d in the beam monitoring regime. For a minimum step of 1.6 mu m and a drift base of scattered particles about 10 m, information on the beam profile is obtained with an angular resolution better than 3 x 10(-6) rad. Various factors affecting the accuracy of measurements of the par ticle beam profile are considered, and selection of the optimum condit ions is discussed. The method was used for the profiling of both neutr al and charged beam components in order to determine the cross-section s and characteristic angles of scattering.