A simple method for measuring transition efficiencies of weak-field radio frequency transition units for polarized atomic hydrogen sources

A weak magnetic field radio frequency transition unit (RFT) was developed and installed in a compact atomic-beam type polarized ion source. A simple experimental method was devised to determine the transition efficiency of the RFT without ionizing and/or accelerating of the atomic beam. This method is based on the switching operation of the RFT generating the difference in the atomic beam intensity. The measurement of the atomic beam intensity and the calculation of the acceptance for each state of the atom in the atomic beam system allow us to determine the transition efficiency of the RFT. The experimental transition efficiency of the RFT for hydrogen atoms was 0.88. For studying the validity of this method, the transition efficiency was calculated by solving a time-dependent Schrodinger equation by considering the actual magnetic field distribution in the RFT. The calculation results reproduced the experimental data within about 10% error.