The spectrum of elementary excitations of Hell at wave vectors q almos
t-equal-to 0.1-1.9 angstrom-1 has been studied by a neutron-scattering
method at temperatures T = 0.42-1.72 K. At q greater-than-or-equal-to
q0(T) almost-equal-to 0.48 angstrom-1 and under the condition epsilon
greater-than-or-equal-to DELTA, the spectrum has a two-branch structu
re.