Beam formation at the Munich atomic beam source

Abstract

A Stern–Gerlach atomic-beam ion source (ABS) with an electron cyclotron resonance (ECR) ionizer and a Cs gas target as charge exchange units will replace the Munich Lamb–Shift polarized hydrogen source. The goal is to achieve intense negative beams of polarized H− and D− of high brightness for injection into the 14 MV MP tandem accelerator and beam intensity of about 2 μA on the target. At the entrance of the ECR ionizer the observed intensity of the neutral beam of polarized atoms is 6.4±0.4×1016 H/s, equivalent to 10 particle/mA before ionization. Comparing beam transport calculations with beam intensity measurements under various conditions allows a consistent description of the beam formation in the ABS with respect to the degree of dissociation (≃80%), peaking (≃1.6), beam absorption (≃40%), and pumping speeds to be made.