Ultrasound attenuation of superfluid 3He in aerogel.
We have performed longitudinal ultrasound (9.5 MHz) attenuation measurements in the B phase of superfluid 3He in 98% porosity aerogel down to the zero temperature limit for a wide range of pressures at zero magnetic field. The absolute attenuation was determined by direct transmission of sound pulses. Compared to the bulk fluid, our results revealed a drastically different behavior in attenuation, which is consistent with theoretical accounts with gapless excitations and a collision drag effect.
Microkelvin Laboratory, Department of Physics, University of Florida, Gainesville, Florida 32611-8440, USA.
H C
HC
Choi
N
N
Masuhara
B H
BH
Moon
P
P
Bhupathi
M W
MW
Meisel
Y
Y
Lee
N
N
Mulders
S
S
Higashitani
M
M
Miura
K
K
Nagai