Effect of the boundary condition on the Kapitza resistance between superfluid <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mmultiscripts><mml:mi>He</mml:mi><mml:mprescripts /><mml:none /><mml:mn>3</mml:mn></mml:mmultiscripts><mml:mtext>−</mml:mtext><mml:mi>B</mml:mi></mml:mrow></mml:math> and sintered metal

Understanding the temperature dependence of thermal boundary resistance, or Kapitza resistance, between liquid helium and sintered metal has posed a problem in low-temperature physics for decades. In the ballistic regime of superfluid ^{3}\mathrm{He}\text{\ensuremath{-}}B we find the Kapitza resistance can be described via scattering of thermal excitations (quasiparticles) with a macroscopic geometric area, rather than the sintered metal's...