The β-asymmetry parameter A for the Gamow-Teller decay of
60Co was measured by polarizing the radioactive nuclei with the brute
force low-temperature nuclear-orientation method. The 60Co activity was
cooled down to milliKelvin temperatures in a 3He-4He dilution
refrigerator in an external 13 T magnetic field. The β particles were
observed by a 500 μm thick Si PIN diode operating at a temperature of
about 10 K in a magnetic field of 0.6 T. Extensive GEANT4 Monte-Carlo
simulations were performed to gain control over the systematic effects. Our
result, A=−1.014(12)stat(16)syst, is in agreement with
the Standard-Model value of −0.987(9), which includes recoil-order
corrections that were addressed for the first time for this isotope. Further,
it enables limits to be placed on possible tensor-type charged weak currents as
well as other physics beyond the Standard Model