Polarization measurements following the beam-foil interaction

Abstract

Induced nuclear spin polarization P I by hyperfine interaction following the passage of 0.5 μA, 300 keV beams of 15N and 13C through single tilted carbon foils yields P I=(5.7±0.9)% and (3.2±0.6)%, respectively. The nuclear polarizations were enhanced to (9.5±1.4)% and (4.1±0.8)% by passage through two tilted foils, and the sign of the polarization flipped by a simple flip of the foil direction with respect to the beam direction. Polarization transfer from the electrons to the nucleus was observed by a single frequency quantum beat pattern for the 5667 Å line in 15N downstream after a single tilted foil. This greatly simplifies determinations of the beat frequencies involved and in this case an experimental magnetic hyperfine constant A(5667)=(7.5±0.7)×10 −6 eV was deduced. The atomic and nuclear polarization measurements are discussed in detail.