A neutron spin-echo instrument has been developed and tested at the ST-1 beam port of the
High-flux Advanced Neutron Application Reactor (HANARO). The phase evolution of a neutron
spin was directly observed with this neutron spin-echo instrument. Polarized thermal neutrons
(¥ë = 1.2 ¢ªA, polarization ¡= 0.37) were produced by the (200) reflection plane of a Co0.92Fe0.08
ferromagnetic single crystal and were then transported to the experiment area of the ST-1 beam
port. The efficiency of the developed spin flipper was estimated to be 0.98 ¡¾ 0.01, and the spin
flipping ratio of the instrument was measured to be 1.26. The measured spin echo point was in
agreement with the expected value. The spin-echo time of our instrument was estimated to be in
the range of a few picoseconds