Date of Award

3-1973

Degree Type

Thesis

Degree Name

Doctor of Philosophy (PhD)

Department

Physics

Supervisor

R.G. Summers-Gill

Abstract

Atomic beam magnetic resonance has been used to study the 14.6 min isomer and the 19.2 hr ground state in ¹⁴²Pr. For the isomeric state the results are:

I = 5

J = 9/2: A = 245(10) MHz,

B = 100(450) MHz,

μ = 2.2(1) nuclear magnetons.

Re-interpretation of previous results for the ground state hyperfine structure, together with some new data, yield the following interaction constants:

J = 9/2: A = 65.6(2) MHz,

B = 22(2) MHz.

The effect on μ is of minor consequence but the quadrupole moment is tripled in value. With the sign of the moment determined to be positive, the results are:

μ = 0.234(1) nuclear magnetons,

Q = 0.110(25) barns.

In addition, the combination of a high-resolution ¹⁴¹Pr(d,p) experiment and the analysis of singles and coincidence gamma ray data has been used to reveal two new states at 89.7 and 358.1 KeVi these are tentatively assigned spins 6⁻ and 7⁻ respectively.

The results have been interpreted in terms of configuration- mixing between π2d₅/₂ν2f₇/₂ and π1g₇/₂ν2f₇/₂. The resulting wave functions for both the ground state and the isomeric state, as determined from the (d,p) spectroscopic factors, are quite different from those required to fit the measured magnetic moments. In view of this discrepancy, a possible mixing of higher configurations into the low-lying states cannot be ruled out.

Finally, a mixed-configuration shell model calculation using Surface Delta Interaction has been carried out, and its predictions are compared with the experimental results.

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