Magnetic Trapping of Silver and Copper, and Anomalous Spin Relaxation in the Ag-He System

Abstract

We have trapped large numbers of copper (Cu) and silver (Ag) atoms using buffer-gas cooling. Up to 3×1012 Cu atoms and 4×1013 Ag atoms are trapped. Lifetimes are as long as 5 s, limited by collisions with the buffer gas. Ratios of elastic to inelastic collision rates with He are ≳106, suggesting Cu and Ag are favorable for use in ultracold applications. The temperature dependence of the Ag−He3 collision rate varies as T5.8±0.4. We find that this temperature dependence is inconsistent with the behavior predicted for relaxation arising from the spin-rotation interaction, and conclude that the Ag−He3 system displays anomalous collisional behavior in the multiple-partial wave regime. Gold (Au) was ablated into He3 buffer gas, however, atomic Au lifetimes were observed to be too short to permit trapping.