T. J. M. Symons

A fragment separator at LBL for the beta-NMR experiment

Abstract The Beam 44 fragment separator was built at the Bevalac of LBL for NMR studies of beta emitting nuclei. 37K, 39Ca, and 43Ti fragments originating from 40Ca and 46Ti primary beams were separated by the separator for NMR studies on these nuclei. Nuclear spin polarization was created in 39 and 43Ti using the tilted foil technique (TFT), and the magnetic moment of 43Ti was deduced. Fragment polarization was measured for 37K and 39Ca emitted to finite deflection angles. The beam 44 fragment separator in combination with a proper polarization technique, such as TFT or fragment polarization, has been very effective for such NMR studies.

Knight shifts for short-lived beta emitters in Pt

The Knight shifts K for short-lived β emitters 12N and 27Si implanted in Pt have been measured by means of β-NMR technique. The results were K(12N in Pt)= +(5.8 ± 2.1)× 10-4 and K(27Si in Pt)= +(1.4 ± 0.8)× 10-3. The spin–lattice relaxation time T1 was measured for 12N in Pt. The result was T1(12N in Pt, T=300 K)= 66 ± 8 ms, thus, T1T= 20 ± 2 Ks. The present Knight shifts are in good agreement with the KKR band structure calculation with local lattice relaxation determined theoretically.

Production of unstable nuclei far from the stability line: its scope and limitations

Recent improvements in isotope separators can be utilized along with the availability of a wide range of nuclear species from the heavy-ion fragmentation process to study hyperfine interactions. We have measured the magnetic moments of mirror nuclei using this method at the Lawrence Berkeley Laboratorys Bevalac heavy-ion accelerator. We present the merits, applicability and limitations of the technique.