THE INFLUENCE OF HIGH PRESSURES ON THE MOSSBAUER EFFECT IN DYSPROSIUM-161
Nuclear resonance absorption of the 25.6-kev gamma ray of /sup 161/Dy was studied experimentally at pressures up to 100 kbar by using sources situated in gadolinium metal together with thin methllic dysprosium absorbers. Velocity spectra taken at 30 and 50 kbar show complex hyperfine structure. Increasing the pressure leads to both greater recoil-free fractions and greater overall hyperfine splitting. The effect of pressure on the recoil-free fraction is satisfactorily explained with a modification of Hanks' theoretical treatment. It is proposed that the hyperfine splitting is predominantiy due to electric quadrupole interactions, with the electric field gradient at the nucleus increasing with increasing pressure. By fitting theoretical spectra to the velocity spectrum at 30 kbar, a value of 1.30 is derived for the ratio of the quadrupole moments of the 91/Nb), A the optical model of the nucleus with the complex Woodsn/ < > 3 Mev n reported data concerning their cross sections in the 12- to 14-Mev range, the value of their differentinl cross sections under an angle of 0 deg at deuteron energies ranging from 3 to 19 Mev was determined, using the extracted beam of the 1.5-m cyclotron of the Kurchatov Institute for the measurements. The cyclotron was operated at deuteron energies of 10 and 20 Mev; deuterons with lower energies were obtained by slowing down in Pt foils placed directiy on the targets, consisting of solid Zr--T supported by W boats and of gaseous T. The time-of-flight type fast reactor spectrometer was used, determining simultaneously the pulse amplitude spectrum of the recoil protons in the stilbene crystal of the scintillation detector. The angular distribution curve of the neutrons was found to be strongly extended in the forward direction. Slowing down of the deuterons in the Pt foil caused scattering and widening of the maximum of the neutrons' angular distribution. The absolute cross section values of the D(d,n)/sup 4/He reaction, determined with an accuracy of plus or minus 10%, agreed well with previously published data. The corresponding values of the T(d,n) reaction were less accurate because the T content of the solid target is known only within plus or minus 30%. (TTT)
- Research Organization:
- California. Univ., Berkeley. Lawrence Radiation Lab.; and California. Univ., Berkeley. Dept. of Chemistry
- DOE Contract Number:
- W-7405-ENG-48
- NSA Number:
- NSA-18-021214
- OSTI ID:
- 4009192
- Report Number(s):
- UCRL-10630(Rev.)
- Resource Relation:
- Other Information: Orig. Receipt Date: 31-DEC-64
- Country of Publication:
- United States
- Language:
- English
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