Measurement of the temperature dependence of the shear modulus of solid He4

The elastic modulus G' and damping constant deltasub(He) are measured at temperatures between 0.40 and 1.75 K in crystalline helium samples grown under a pressure of appro ximately 35 atm. By continuously recording G and deltasub(He) it is possible to study the effect of the growth conditions and heat shock and to select samples with the temperature. This is interpreted as being due to an increase of the defect mobility with decrease of temperature. The G'(T) and deltasub(He)(T) dependences are analyzed in accordance with the Granato-Lukke theory. The internal friction dislocation parameters are obtained