Laser preparation of bunched ion beams

Laser ionization at ISOLDE is performed with high repetition laser beams in the ion source unit and for daughter elements with low repetition lasers synchronized with laser desorption from a secondary target. We are preparing an implementation of thermal adsorption followed by laser desorption and laser ionization in the target ion source unit of ISOLDE. The combination of resonance ionization with thermal bunching allows the preparation of bunched and chemically pure ion beams. Bunched ion beams of Mg or Ca are prepared for post-acceleration at REX-ISOLDE, In order to investigate the process of adsorption and pulsed laser desorption, experiments are performed with Ba vapour. In a test setup Ba is effusing from an oven and adsorbed on a cooled surface, which can be heated by a pulsed Nd:YAG laser beam, The adsorption and bunched release of Ba atoms is detected via resonance absorption of the 6s(2 1)S(0) --> 6s6p(1)P(1) atomic line at lambda = 553 nm with a single mode dye laser.