Winkelkorrelationsmessungen an Hf¹⁸⁰ und Bestimmung derg _R-Faktoren des 2⁺- und des 4⁺-Rotationsniveaus

Abstract

The following angular correlations in the decay of Hf^180m have been measured: 215 keV-93 keVγγ-cascade:

$$W(\Theta ) = 1 + (0 \cdot 093 \pm 0 \cdot 007) P_2 + (0 \cdot 014 \pm 0 \cdot 009) P_4 $$

332 keV-215 keVγγ-cascade:

$$W(\Theta ) = 1 + (0 \cdot 090 \pm 0 \cdot 010) P_2 + (0 \cdot 006 \pm 0 \cdot 010) P_4 $$

501 keV-332 keVγγ-cascade:

$$W(\Theta ) = 1 + (0 \cdot 004 \pm 0 \cdot 007) P_2 - (0 \cdot 002 \pm 0 \cdot 012) P_4 .$$

Liquid sources of HfF₄ solved in concentric HF were used for these experiments. The angular correlation of the 215 keV-93 keV-cascade was found to be slightly attenuated by internal fields. A measurement of the differential angular correlation for different delays gave:

$$\lambda _2 = (0 \cdot 073 \pm 0 \cdot 036) \cdot 10^9 \sec ^{ - 1} assuming A_2 (t) = A_2 (0) \cdot e^{ - \lambda _2 t} .$$

The above correlation functions agree with the interpretation of the low lying states of Hf¹⁸⁰ as a (0⁺, 2⁺, 4⁺, 6⁺)-rotational band.

The 501 keV-332 keV angular correlation shows that the multipolarity of the 501 keV-γ-transition is a mixture of (3.5±0.5)%M2 and (96.5±0.5)%E3.

The rotation of angular correlations in a strong external magnetic field has been observed and the gyromagnetic ratios of the 2⁺ and the 4⁺ rotational states were determined as:

$$g_R (2^ + level) = + 0 \cdot 371 \pm 0 \cdot 032$$

and

$$g_R (4^ + level) = + 0 \cdot 5 \pm 0 \cdot 1.$$