UPPER CRITICAL-FIELD IN SINGLE-CRYSTAL UBE13

In order to obtain information about the symmetry of the ground state, we have studied the anisotropy of H(c2)(T) in UBe13. Using sensitive mutual induction techniques, we have systematically measured chi' (H,T ) and chi''(H,T) of several single crystals in fields up to 8 T orient ed along the [100] and [110] directions, with particular emphasis on t he T/T(c) --> 1 limit. The resulting H(c2) phase diagram is presented and compared to the results of other workers.