Newman, Bonna K.Brahms, NathanAu, Yat ShanJohnson, CortConnolly, ColinDoyle, JohnKleppner, DanielGreytak, Thomas J.2013-10-022011Newman, Bonna K., Nathan Brahms, Yat Shan Au, Cort Johnson, Colin B. Connolly, John M. Doyle, Daniel Kleppner, and Thomas J. Greytak. 2011. Magnetic relaxation in dysprosium-dysprosium collisions. Physical Review A 83, no. 1: 012713.1050-2947http://nrs.harvard.edu/urn-3:HUL.InstRepos:11130338The collisional magnetic reorientation rate constant \(\vartheta_{\mathbb{R}}\) is measured for magnetically trapped atomic dysprosium (Dy), an atom with large magnetic dipole moments. Using buffer gas cooling with cold helium, large numbers (>10\(^{11}\)) of Dy are loaded into a magnetic trap and the buffer gas is subsequently removed. The decay of the trapped sample is governed by collisional reorientation of the atomic magnetic moments. We find \(\vartheta_{\mathbb{R}} = 1.9 \pm 0.5 \times 10^{-11} \, \text{cm}^{3} \, \text{s}^{-1}\) at 390 mK. We also measure the magnetic reorientation rate constant of holmium (Ho), another highly magnetic atom, and find \(\vartheta_{\mathbb{R}} = 5 \pm 2 \times 10^{-12} \, \text{cm}^3\, \text{s}^{-1}\) at 690 mK. The Zeeman relaxation rates of these atoms are greater than expected for the magnetic dipole-dipole interaction, suggesting that another mechanism, such as an anisotropic electrostatic interaction, is responsible. Comparison with estimated elastic collision rates suggests that Dy is a poor candidate for evaporative cooling in a magnetic trap.en-USJournal Article2013-10-0210.1103/PhysRevA.83.012713