SPATIAL ORIENTATION OF NUCLEI - MASS DEFORMATION IN 165-HOLMIUM

Measurements of neutron transmission through a rotating, cryogenically aligned holmium target are reported. From the variation in the transm ission yield as a function of alignment angle we obtain holmium deform ation cross sections of -548+/-42, -354+/-17, -283+/-23, and 248+/-23 mb at neutron energies 1.5, 1.8, 1.9, and 3.9 MeV, respectively. Coupl ed channels calculations using deformed optical model parameters give a quadrupole mass deformation length beta2r0 = 0.38+/-0.03, consistent with the literature. In contrast to a recent result from analysis of pion single-charge-exchange scattering, the data imply similar deforma tion lengths for the proton and neutron distributions in holmium.