Design and Optimization of a Non-Adiabatic Zero-Field Passage for a Source of Polarized Ions

摘要

The present work was carried out within the framework of the design of a source of a polarized protons and deuterons according to Lambshift procedure. In this procedure, protons with the energy of 500 eV and deuterons of 1000 eV are converted into the metastable 2S/sub 1/2/ state through charge exchange reactions in caesium vapor. The intensive beam of metastable hydrogen or deuterium atoms passes along a longitudinal magnetic field of a solenoid, which achieves a maximum field strength of 575 Oe. When a transverse electrical field (Stark effect) with a field strength of approx. 10 V/cm is additionally applied, a length of stay of 10 exp -7 sec. (corresponding to a trajectory of several cm) is sufficient in this region to convert more than 99% of one of the two hull spin components (m/sub J/ = -1/2) into the basic state, while simultaneously more than 99% of the other components (m/sub J/ = +1/2) remain in the metastable state (selective quenching). By means of an adiabatic passage in a weak magnetic field (the nuclear spin is then coupled with the hull spin) a partial nuclear spin polarization can be achieved. On the basis of the works of P.G. Sona, an arrangement was constructed, consisting essentially in two solenoids and making possible a double selective quenching of the metastable atoms. Between the first and the second quenching process, a rapid, non-adiabatic direction reversal of the magnetic field occurs, effecting a reallocation of the hyperfine structure states (Sona transition) and thereby increasing the nuclear spin polarization. The quality of a polarized beam can be characterized by the quality measure; this is the product from the beam intensity and the square of polarization (the polarization is included in measurements of asymmetry at the power of 2 due to the error reproduction of the statistical error for particles polarized both by vector and by tensor methods). (ERA citation 06:003077)