title: Unwanted birefringence in low-temperature windows.
abstract: A small residual birefringence producing a retardation of 0.05 rad has been measured in silica windows mounted in a liquid helium cryostat. The effect is due to a uniaxial stress on the windows induced by the pressure difference between the helium reservoir and the vacuum jacket.
authors.affiliation: C.N.E.N.-Centro di Frascati, Frascati, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Baldacchini
authors.forename: U M
authors.initials: UM
authors.lastname: Grassano
authors.forename: A
authors.initials: A
authors.lastname: Tanga
mesh_terms: D016477:Artifacts; D001718:Birefringence; D003080:Cold Temperature; D006371:Helium / Q000032:analysis* / Q000737:chemistry*; D008422:Materials Testing / Q000295:instrumentation*; D012031:Refractometry / Q000295:instrumentation* / Q000379:methods; D012034:Refrigeration / Q000295:instrumentation*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013048:Specimen Handling / Q000295:instrumentation*; D014618:Vacuum
chemical_list: D006371:Helium