Measurements of magnetic dipole moments of excited states in sd-shell nuclei

The magnetic dipole moment and thus the spin precess about the direction of the magnetic induction. One can observe such a precession through a rotation of the gamma-ray distribution (or correlation) pattern. To measure g-factors of sd-shell nuclei one has to have fields greater than 105G. As static hyperfine fields of those nuclei in an Fe lattice do not exceed this value it is not possible to measure their g-factors by usual techniques. However, it was discovered that nuclei slowing down in magnetically polarised Fe feel a very strong magnetic field during flight-transient magnetic field. This field is in a MG region and consequently is well fitted for g-factors measurements. In the experiment the 24Mg (α,α,γ) 24Mg reaction is studied. Alpha particles are detected in Si detectors and gamma-ray by Nal(T1) detectors. A completely different approach to nuclear g-factors measurements is - the deorientation method. An unpaired 1s electron will create through its own magnetic moment very strong magnetic field at the nuclear site of a heavily stripped atom. Classicaly, each nucleus will precess about the magnetic field direction which belongs to the nucleus. Consequently, the angular correlation will be attenuated. In the first experiment the 20Ne first excited 2+ state was populated by the 12C(12C,α)20Ne reaction. It was concluded that mostly the 9+ ground state was responsible for the measured deorientation. In the second experiment described the 12C(180,180)12C reaction was studied. Angular correlations were measured with 8+,7+ and 6+ oxygen ions and the g-factor was calculated. (S.B.)