A source of polarized protons

Abstract

The design, construction and test of a source of polarized protons for the Minnesota linear accelerator will be described. The principle used is to separate the spin states m J = + 1 2 and m J = − 1 2 in a hydrogen atomic beam by deflection in a strong inhomogeneous magnetic field. The selected component (m J = + 1 2 ) passes adiabatically into a weak field region (forming states F = 1, m F = 1, 0), where it is ionized by electron bombardment. Protons are extracted, accelerated and scattered from various targets. The asymmetry after a single scattering is measured and allows a determination of the beam polarization, if the analyzing power of the scatterer is known. The source itself produces a direct current of 3 × 10 −8 A of protons with a polarisation of 15% ∗∗∗ 2 Improvements during the last two years have increased the polarization to 35%).