R. D. Taylor

A multipurpose miniature diamond anvil cell

A new multipurpose miniature diamond anvil high‐pressure cell (DAC) has been constructed. The circular DAC has an overall 22‐mm diam. and 15‐mm height and is comprised of a gasket, opposing diamond anvils each mounted on backing plates, and force rings (platens). The pressure is generated by six Allen‐type screws. Pressures up to 38 GPa were achieved with this miniature cell. Design features, mode of operation, and performance are described. A particular application to cryogenic and room temperature 119Sn Mossbauer spectroscopy is presented.

Temperature-dependent isomer shift and anharmonic binding of Sn119 in Nb3Sn

Abstract We have studied the temperature dependence of the Mossbauer recoil-free fraction and the line shift of Sn119 in Nb3Sn. The results indicate anharmonic binding and a temperature-dependent band structure.

Internal conversion from resonance absorption

The Mossbauer re-emission spectrum in Fe/sup 57/ is studied. A Co/sup 57/ gamma source is mounted on a speaker, which is driven at 11 cps. The re- emission of these rays is measured by a NaI scintillation crystal. Since internal conversion in Fe/sup 57/ competes with gamma re-emission, a proportional counter is provided for measuring the 6.3 ksv x-rays which are emitted by Fe/sup 57/ following K-conversion. The spectra of gamma- and x-ray transmission are given as functions of relative source-abaorber velocities. The use of this method in investigation of Mossbauer spectra of highly converted gamma rays is suggested. (T.F.H.)

Localized magnetic moments on very dilute Fe impurities in copper

Abstract The magnetic behavior of very dilute Fe impurities in Cu has been studied as a function of temperature between 1.1° and 310°K in applied magnetic fields up to 61 kOe by means of the Mossbauer hyperfine spectra of Fe 57 . The temperature dependence of the negative internal field is explained in terms of a localized moment on Fe which is coupled to the host lattice.

High Vacuum Brass‐to‐Aluminum Seal for Use at Cryogenic Temperatures

A seal is designed for the thin Al windows in a helium cryostat made from brass. The seal comprises a brass collar soldered into the cryostat bottom, an O-ring made from a soft alloy and fitting loosely around the collar, and an Al retainer on the thin window. The retainer is slipped over the collar and 0-ring and compressed by means of a brass or phosphorus bronze clamp ring. The retainer is formed with a lip to transfer thermal stresses from tae window to the neck of the retainer. The seal improves at low temperatures owing to differential contraction of Al with respect to brass. The window is preferably made out of Type 6061 Dural and should be annealed after machining.