ALBERT

Notes: Abstract The g-factors of the 11/2− states in145, 147, 149Eu were measured by the TDPAD method in metallic Sm-targets. The temperature dependence of the paramagnetism in the system145EuSm follows strictly a Curie-Weiß law Beff=B0[1+¯C/(T-θ)] with C=−50(2)K and θ=−29(5)K. Extrapolation to T→∞ yields g(145Eu)=+1.356(8), g(147Eu)=+1.28(1) and g(149Eu)=+1.27(5). In addition, the quadrupole coupling constantν Q=12.5(5) MHz, and a lower limit for the paramagnetic relaxation time τ = 1 us was determined at room temperature for the 11/2− state of145Eu in Sm. Extensive studies of the anomaly of magnetic moments in the vicinity of the closed neutron shells N=50 and N=126 have unambiguously revealed an anomaly of the proton gl factor of δgl≈0.1 [1]. In the present letter we report on a similar investigation for the closed neutron shell N=82. For this purpose the g-factors of the first excited 11/2− states in the rare earth isotopes145, 147, 149Eu were measured. Due to paramagnetic effects, a measurement of nuclear g-factors in the rare earth region requires the investigation of the paramagnetic behaviour of the probe atoms in the chosen target material. The g-factors in145,147,149Eu were measured by the method of the time differential perturbed angular distribution (TDPAD) of the deexcitationγ-rays. The 11/2− states in145Eu(EX=716 keV, T1/2=0.49 gms) and in149Eu(EX=497 keV, T1/2=2.43 μs) were populated and aligned by the nuclear reaction144,148sm(d,n)145,149Eu with the pulsed deuteron beam (Ed=11 MeV) of the Erlangen tandem accelerator. Enriched metallic Sm targets of 89%144Sm and 95%148Sm were used. The 11/2− state in147Eu(EX=625 keV, T1/2=0.77 μs) was excited by the reaction147Sm(p,n)147Eu with a pulsed proton beam (Ep=10 MeV) using a 93% enriched147Sm target. A detailed description of the experimental set-up and the evaluation procedure for the present TDPAD measurements is given in ref. [2]. The deexcitation γ-rays of the isomeric Eu states were detected by two NaJ(T1) detectors encompassing an angle of Δθ=90°, and placed in a plane perpendicular to the external applied magnetic field direction. The magnetic field was calibrated by measuring the very precisely known g-factor of the isomeric 5/2+ state of19F in a BaF2 target. The Sm targets were mounted either in an oven for the high-temperature measurements or into a copper cooling-rod for temperatures down to liquid nitrogen.

Notes: Abstract Theg-factor of the first excited state in the odd-odd nucleus138La (E x=73 keV,I π,T 1/2=116 ns) was measured by the time-differential perturbed angular distribution (TDPAD) method. The result, corrected for Knight shift and diamagnetic shielding, isg=+0.962±0.016. This value can be fairly well reproduced using the additivity relation for magnetic moments, empirical values for the odd-proton and odd-neutrong-factors, and an experimentally deduced wave function for the 3+ state.

Notes: Abstract Theg-factor of the 1,275 keV 2+ state in22Ne has been measured by means of the time-differential recoil-into-vacuum (plunger) technique. An analysis including excited heliumlike electronic configuration was performed. A fit, which includes all these electronic states, provides a value of ¦g¦=0.36±0.03.