Search

A survey of even–even nuclei in the nuclear chart showed regularities in the values of the ratio Q ( 2 1 + ) / ( B ( E 2 ) for each nucleus for which independent measurements of both the electric quadrupole moment of the 2 1 + state, Q ( 2 1 + ) , and the reduced transition probability B ( E 2 ; 0 1 + → 2 1 + ) exist. As predicted by the rotational model, this ratio was found to be close to unity for the deformed nuclei in the rare-earth region. For non-rotational nuclei the absolute value of this ratio is almost always considerably lower. This latter observation can be interpreted within different models for different classes of nuclei as illustrated by a set of schematic IBA model calculations. A general mixing model and simple geometrical models are also suitable for collective non-rotational nuclei. Near magic nuclei a mechanism within the seniority scheme is compatible with the observed small value of R Q B .

Background: The Cd isotopes are well studied, but experimental data for the rare isotopes are sparse. At energies above the Coulomb barrier, higher states become accessible.Purpose: Remeasure and supplement existing lifetimes and magnetic moments of low-lying states in $^{106}\mathrm{Cd}$.Methods: In an inverse kinematics reaction, a $^{106}\mathrm{Cd}$ beam impinging on a $^{12}\mathrm{C}$ target was used to Coulomb excite the projectiles. The high recoil velocities provide a unique opportunity to measure $g$ factors with the transient-field technique and to determine lifetimes from lineshapes by using the Doppler-shift-attenuation method. Large-scale shell-model calculations were carried out for $^{106}\mathrm{Cd}$.Results: The $g$ factors of the ${2}_{1}^{+}$ and ${4}_{1}^{+}$ states in $^{106}\mathrm{Cd}$ were measured to be $g({2}_{1}^{+})=+0.398(22)$ and $g({4}_{1}^{+})=+0.23(5)$. A lineshape analysis yielded lifetimes in disagreement with published values. The new results are $\ensuremath{\tau}(^{106}\mathrm{Cd};{2}_{1}^{+})=7.0(3)\phantom{\rule{4.pt}{0ex}}\mathrm{ps}$ and $\ensuremath{\tau}(^{106}\mathrm{Cd};{4}_{1}^{+})=2.5(2)\phantom{\rule{4.pt}{0ex}}\mathrm{ps}$. The mean life $\ensuremath{\tau}(^{106}\mathrm{Cd};{2}_{2}^{+})=0.28(2)\phantom{\rule{4.pt}{0ex}}\mathrm{ps}$ was determined from the fully-Doppler-shifted $\ensuremath{\gamma}$ line. Mean lives of $\ensuremath{\tau}(^{106}\mathrm{Cd};{4}_{3}^{+})=1.1(1)\phantom{\rule{4.pt}{0ex}}\mathrm{ps}$ and $\ensuremath{\tau}(^{106}\mathrm{Cd};{3}_{1}^{\ensuremath{-}})=0.16(1)\phantom{\rule{4.pt}{0ex}}\mathrm{ps}$ were determined for the first time.Conclusions: The newly measured $g({4}_{1}^{+})$ of $^{106}\mathrm{Cd}$ is found to be only 59% of the $g({2}_{1}^{+})$. This difference cannot be explained by either shell-model or collective-model calculations.

In this study, the structure of the semimagic Sn50 isotopes were previously studied via measurements of B(E2;21+ → 01+) and g factors of 21+ states. The values of the B(E2;21+) in the isotopes below midshell at N = 66 show an enhancement in collectivity, contrary to predictions from shell-model calculations. This work presents the first measurement of the 21+ and 41+ states' magnetic moments in the unstable neutron-deficient 110Sn. The g factors provide complementary structure information to the interpretation of the observed B(E2) values.

Both theoretical descriptions of nuclei and experimental techniques for measuring magnetic moments have become very sophisticated. Yet, in general, good agreement between calculations and measurements still eludes us. Highlights are presented of new measurements of g factors of mixedsymmetry states in 92,94Zr, of the 4 1 + state in 70Ge, and of the 2 1 + states in some S and Ar isotopes.

Magnetic moments have in general provided substantial information on the microscopic structure of nuclear states. Advances in technology have made it possible to measure, with reasonable accuracy, magnetic moments of nuclear states with lifetimes of the order of picoseconds or less. Improvements over the last decade involve all experimental aspects ranging from the availability of a wide variety of stable and radioactive beams, to the realization of highly segmented, high resolution detector arrays. A microscopic understanding of the hyperfine interaction between the nuclear moments and the ferromagnetic environment with which they interact has not yet been reached. Nevertheless, elegant applications of the new experimental techniques have allowed the measurement of nuclear moments of many nuclear states that were not accessible previously. Such measurements have shown how these moments vary with energy, spin and temperature in specific nuclei, or across isotopic chains. New results, in turn, have placed stringent constraints on theoretical calculations. The technical advances and selected highlights of relevant measurements across the periodic table are described in this review. Recent examples of applications of transient field and recoil-in-vacuum techniques in a radioactive beam environment are presented.

The g factor of the first excited 2 + state in 46 Ca has been remeasured with better accuracy than previously obtained, g(2 + , 46 Ca) =− 0.26(6). The experiment utilized the transient field technique combined with Coulomb excitation in inverse kinematics. This result was analyzed in terms of shell model plus deformed core calculations. The positive g factors of the 2 + states in 42 Ca and 44 Ca suggest that the 2 + state wave functions require significant particle–hole excitations of the Z = 20, N = 20 core. The new data for 46 Ca show that (fp) 6 configurations dominate near the shell closure at 48 Ca and indicate that core excitation plays a lesser role than was hitherto believed.

A batch mode process has been developed to produce a 76 Kr ( T 1 / 2 = 14.8 h) radioactive ion beam at the Lawrence Berkeley National Laboratory 88-in. Cyclotron. First, a 6 particle μA α beam is run for 17 h to produce approximately 10 14 76 Kr atoms via the reaction 74 Se(α, 2n) 76 Kr. Then, the krypton is separated from the target material and injected into the AECR-U ion source. Beam intensities as high as 3×10 8 particles per second are observed with an integrated beam current of 6(2)×10 11 particles per 24-h batch cycle.

The g factor of the first 2+ state of radioactive 76Kr (T1/2=14.8 h) has been measured, extending the systematics of the previously measured stable 78, 80, 82, 84, 86Kr isotopes. The measurement was performed with a radioactive 76Kr ion beam applying projectile Coulomb excitation in inverse kinematics combined with the transient magnetic field technique. The 76Kr beam was produced and accelerated in batch mode (re-cyclotron method) at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. A total of three production and acceleration cycles yielded six hours of beam on target with peak rates of 108 particles/s. About 5.6×104 particle-γ coincidence events were recorded. The g factor g( 76 Kr ;2 + 1 )=+0.37(11) was obtained by direct comparison to the known g( 78 Kr ;2 + 1 ) value re-measured immediately after the 76Kr runs with the same setup and under almost identical kinematic conditions.

The g factors of the 2 + 1 and 3 − 1 states in 96 Zr have been measured for the first time by Coulomb excitation of 96 Zr beams in inverse kinematics using transient magnetic fields. The resulting g factors are g (2 + 1 )=+0.03(7) and g (3 − 1 )=+0.98(15). The lifetime of the 2 + 1 state, τ =0.82(10) ps, was redetermined via the Doppler Shift Attenuation Method. The 2 + 1 →0 + 1 transition rate and the g -factor data are in fair agreement with shell-model calculations involving both proton and neutron excitations. The pronounced octupole strength of the 3 − 1 →0 + 1 transition is not seen in the g factor which exceeds significantly an expected Z / A value.

The g factor of the 2 1 + state in 44 Ca has been measured using the transient field technique and Coulomb excitation in inverse kinematics. A positive value of g(2 1 + , 44 Ca )=+0.12±0.05 was deduced. The result suggests the ( fp ) 4 ν configuration competes with excitations of the 40 Ca core. A simple model which considers that the wave function for the 2 1 + state consists of approximately equal admixtures of spherical four valence neutron configurations and a deformed core configuration accounts for the experimentally observed g factor as well as the previously measured quadrupole moment.

In view of the puzzlingly small g factor, obtained for the 20 Ne(4 1 + ) state in previous measurements, in contradiction to all existing theoretical calculations, we have performed a new set of experiments that rigorously test the former results. Besides employing the same nuclear reaction for populating the nuclear states, new experimental features were introduced to exert strict control on the relevant parameters of the transient magnetic hyperfine field technique. The new result, g (4 1 + )=+0.38(8), is close to theoretical predictions.

The evolution of shell structure and the fragility of the benchmark magic numbers is a topic of major interest in nuclear-structure physics. The authors measured the structure-sensitive $g$ factors of states in unstable even-even strontium isotopes, following $\ensuremath{\alpha}$-pickup reactions by krypton beams from a carbon target. The results help elucidate how protons and neutrons contribute to the evolution of nuclear structure in this important mass region where rapid structural changes occur.

The $g$ factor and $B(E2)$ of the first excited ${2}^{+}$ state have been measured following Coulomb excitation of the neutron-rich semimagic nuclide ${}^{134}$Te (two protons outside ${}^{132}$Sn) produced as a radioactive beam. The precision achieved matches related $g$-factor measurements on stable beams and distinguishes between alternative models. The $B(E2)$ measurement exposes quadrupole strength in the ${2}_{1}^{+}$ state beyond that predicted by current large-basis shell-model calculations. This additional quadrupole strength can be attributed to coupling between the two valence protons and excitations of the ${}^{132}$Sn core. However, the wave functions of the low-excitation positive-parity states in ${}^{134}$Te up to ${6}_{1}^{+}$ remain dominated by the $\ensuremath{\pi}{({g}_{7/2})}^{2}$ configuration.

Background: Single-particle and collective modes of nuclear excitation compete in the isotopes of the elements ${}_{30}$Zn, ${}_{32}$Ge, ${}_{34}$Se, ${}_{36}$Kr, and ${}_{38}$Sr.Purpose: To study the factors which determine the onset of collectivity in this region.Methods: Data obtained from National Nuclear Data Center compilations supplemented by recent measurements of excitation energies and $B(E2)$ reduced transition probabilities between the low-lying states in these elements were examined. The data were analyzed as a function of the neutron number $N$ as well as the parameter $P={N}_{p}{N}_{n}/({N}_{p}+{N}_{n})$ related to the number of valence protons and neutrons, ${N}_{p}$ and ${N}_{n}$, in the $28\ensuremath{\le}Z,N\ensuremath{\le}50$ shell.Results: The systematics of the data show variations ranging from mostly single-particle to collective excitations.Conclusions: Collectivity sets in when the number of both protons and neutrons lie near the middle of the shell $30\ensuremath{\le}Z,N\ensuremath{\le}50$. Backbends appear in the data showing that particles and holes in the major shell behave differently. The ${2}_{2}^{+}$ states exhibit single particle behavior. The transition probabilities of the ${2}_{2}^{+}$ states in the Kr isotopes differ significantly from the systematics.

Recent experiments have shown that the technique of Coulomb excitation of beam ions in inverse kinematics, where the target nuclei are lighter than the beam, combined with transient magnetic fields, provides a powerful method to measure magnetic moments of short-lived nuclear states with high precision and efficiency. The method is directly applicable to measurements on radioactive beams. In the conventional experiments, the beam and the Coulomb excited projectiles are stopped in a multi-layered target, while the lighter target nuclei traverse the whole target and are detected around 0∘ in coincidence with projectile γ-rays. But even for low intensity radioactive beams, this technique would lead to an excessive accumulation of activity in the target. A method is presented here, in which the beam passes through the target and a hole in the particle detector and is stopped in a downstream beam dump shielded from the detectors. A test was carried out on the g factor of the 2+1 state of 50 Ti .

The g factors of the 4 + 1 and 6 + 1 states in 144,148 Nd, the 4 + 1 state in 146 Nd and the 4 + 1 , 6 + 1 , 8 + 1 and 10 + 1 states in 150 Nd have been measured for the first time by projectile Coulomb excitation combined with the transient field technique. The g factors of the 2 + 1 states in 144,146,148,150 Nd have been remeasured with very high precision. A pronounced transition in the structure of these isotopes occurs as neutrons are removed from the rotational 150 Nd and shell closure at N =82 is approached. The g factors unambiguously reflect the increasing strength of the (2 f 7/2 ) ν n configuration.

The g factors of the 2 + 1 and 3 − 1 states in semi-magic 90 Zr have been measured for the first time with the technique of Coulomb excitation of 90 Zr beams in inverse kinematics in combination with transient magnetic fields. The resulting g factors, g (2 + 1 )=+1.25(21) and g (3 − 1 )=+0.986(56), are both consistent with a dominant g 9/2 proton configuration and a closed N =50 neutron shell. The lifetime of the 2 + 1 state was measured by the Doppler shift attenuation method, τ =0.126(3) ps.

Measurements of magnetic moments and lifetimes of ${2}_{1}^{+}$ and ${4}_{1}^{+}$ states of ${}^{46,48}\mathrm{Ti}$ and ${}^{50,52}\mathrm{Cr}$ were performed with high accuracy via projectile Coulomb excitation and the technique of transient magnetic fields. The high quality of the data allows for the first time to establish stringent constraints on large scale shell model calculations. Whereas the global behavior of the data is well explained by full $\mathrm{fp}$ shell model calculations, distinct deviations in the $g$ factors and $B(E2)$ values of ${}^{46,48}\mathrm{Ti}$ from theoretical predictions can be attributed to excitations of the ${}^{40}\mathrm{Ca}$ core. This suggestion is supported by recent Monte Carlo calculations which provide evidence that ${}^{48}\mathrm{Ca}$ is a better inert core.

g factors of the 2 + 1 and 4 + 1 states in 92,94 Zr have been measured via Coulomb excitation of isotopically pure 92,94 Zr beams in inverse kinematics in combination with the transient field technique. The high precision results, g ( 92 Zr; 2 + 1 ) = −0.180(10) and g ( 94 Zr; 2 + 1 ) = −0.329(15) as well as the new data on the 4 + 1 state, g ( 92 Zr; 4 + 1 ) = −0.50(11), provide, for the first time, clear evidence of the dominant role of d 5/2 neutrons in the wave functions of these nuclei just above the N =50 shell closure. Moreover, the data imply increased purity of the d 5/2 neutron component in the wave function with increasing spin.

The magnetic moment of the ${2}_{1}^{+}$ and ${4}_{1}^{+}$ states in ${}^{152}\mathrm{Gd}$ have been measured by the transient field technique. Heavy ion beams of ${}^{58}\mathrm{Ni}$ and ${}^{32}\mathrm{S}$ were used to Coulomb excite the ${2}_{1}^{+},{0}_{2}^{+},{4}_{1}^{+},{2}_{2}^{+}$, and ${6}_{1}^{+}$ states in ${}^{152}\mathrm{Gd}.$ A ratio of g factors, ${g(4}_{1}^{+}{)/g(2}_{1}^{+})=1.10(24)$ was obtained. This result is consistent with a collective model description and does not support large single particle contributions to the wave function of low-lying states as were found for the isotone ${}^{150}\mathrm{Sm}.$

The time evolution of the decay of high-spin, normal deformed structures in 193,194 Hg was studied by measuring, in the Gammasphere array, the Doppler shift attenuation of selected transitions depopulating various bands. The data suggest that a fraction of states feeding selective yrast levels is non-collective in nature and show resemblance to A = 150 nuclei where shape polarizing effects have been linked to particles occupying high- j orbitals.

The average g factors of high spin, high-excitation energy, quasicontinuum structures in {sup 194,193}Hg were measured by observing the precessions of the angular distributions of {gamma}-ray transitions in several normal-deformation bands that coalesce in the decay of the entry distribution of states. The average g factors of the states leading to the three main bands in the {sup 193,194}Hg isotopes were: {l_angle}g({sup 193}Hg){r_angle}=+0.19(1) and {l_angle}g({sup 194}Hg){r_angle}=+0.26(1), respectively. These average g factors are smaller than the average of the g factors of the high energy states in the three superdeformed bands of {sup 194}Hg, {l_angle}g(SD; {sup 194}Hg){r_angle}=+0.41(8). While the nucleus in the superdeformed well behaves like a rigid rotor, the present results demonstrate the important role played by multiple, quasiparticle neutron configurations in the structure of normal-deformation, highly-excited nuclear states.

The recent availability of large γ-ray arrays has opened new domains in experiments for measurements of magnetic moments. The study of oblate structures in heavy nuclei as well as of superdeformed bands are good examples of the new nuclear regions that have become amenable to the transient field magnetic moment measurements. These measurements are very difficult to perform even with the modern ‘4π’ Ge arrays due to the weak transitions of interest and severe background conditions. Thus, it is very important to utilize the entire power of the 4π detector in the analysis of precession measurements. We propose here a new method for analyzing such measurements in the form of a ‘global fit’ procedure. Results are presented for three high-spin transitions of interest in 193Hg.

The average g factors of the high-energy states of the three superdeformed bands in ${}^{194}\mathrm{Hg}$ were determined directly in a transient field experiment. The reaction ${}^{150}\mathrm{Nd}{(}^{48}\mathrm{Ca}{,4n)}^{194}\mathrm{Hg}$ at a beam energy of 203 MeV was used to provide recoiling reaction product nuclei with sufficient velocity to traverse a gadolinium ferromagnetic layer. The resulting g factors $g(\mathrm{SD}1)=0.36(10),$ $g(\mathrm{SD}2)=0.41(20),$ and $g(\mathrm{SD}3)=0.71(26)$ are in agreement with cranked Hartree-Fock calculations as well as with the picture of a rigid rotation for which $g=Z/A.$

Precessions of the angular distribution of numerous transitions in three normal deformation bands in194,193Hg, as well as of high-excitationM1/E2 transitions, were determined in a transient field experiment conducted at the Berkeley 88″ Cyclotron with the Gammasphere array. The reaction150Nd(48Ca,4n-5n)194,193Hg at a beam energy of 203 MeV was used to populate high-spin levels and to provide recoiling reaction-product nuclei with sufficient velocity to traverse a gadolinium ferromagnetic layer. The average precession of the observed γ-ray transitions reflects the precession of the magnetic moment of higher, unobservable quasicontinuum states which feed these states. The resulting averageg-factors obtained for the three main decay paths in each of the193,194Hg isotopes are: 〈g(193Hg)〉 = 0.19(1) and 〈g(194Hg)〉 = 0.26(1). For theM1/E2 transitions the results are: 〈g(193Hg)〉 = 0.24(5) and 〈g(194Hg)〉 = 0.26(4), respectively. The reduction of the averageg-factors in even isotopes compared to the naiveZ/A value, and the further reduction in odd isotopes, is evident. These results are discussed in terms of a neutron particle contribution and are compared to similar data in lighter Hf nuclei.

Background: The interplay between single-particle and collective excitations in the 30 ≤Z≤ 40 and 30 ≤N≤ 50 even-even isotopes has been examined in light of recent new measurements of magnetic moments of 41+, 22+, and 21+ states. Purpose: The g factors of the 41+ and 22+ states in the 72,74,76Ge isotopes have been measured for the first time and the g(21+) values have been remeasured. Methods: The transient field (TF) technique in inverse kinematics with a variety of targets has been applied, following Coulomb excitation of the relevant states. The data have been analyzed within the framework of the IBA-II model. Large-scale shell-model calculations have been performed within the p3/2,p1/2,f 5/2,g9/2 orbital space for both protons and neutrons with the JUN45 and JJ4B interactions. Results: The measured Ge g factors were compared to the g factors of the low-lying states of the neighboring Zn, Ge, Se, Kr, and Sr isotopes. The results were evaluated in the context of the systematics of g factors in the A∼80 region. Conclusions: The predictions based on the classic collective model and the interacting boson model IBA-II agree with the experimental results. No evidence for shell closure was found for neutrons at N=38 or N=40. © 2013 American Physical Society.

Studies at the interface between nuclear, atomic and condensed matter physics have revealed new phenomena in all three areas. In this review, a few examples taken from observed interactions between moving ions and ferromagnetic materials or tilted foils, are discussed and future directions are indicated.

The transient-field technique has been used to measure the [ital g] factors of yrast states in [sup 86]Zr over the spin region [ital I]=8[h bar]--14[h bar] in order to ascertain the nature of the alignments at the first and second backbends. The states of interest were populated in the reaction [sup 12]C([sup 77]Se,3[ital n]) at 260 MeV. The results demonstrate that the first crossing at the 8[sub 1][sup +] state involves the alignment of neutron [ital g][sub 9/2] quasiparticles, and that proton [ital g][sub 9/2] quasiparticles align at higher spin.

Background: The $g$ factors and lifetimes of the 2${}_{1}^{+}$ states in the stable, proton-rich Sn isotopes have been measured, but there is scant information on neutron-rich Sn isotopes.Purpose: Measurement of the $g$ factor and the lifetime of the 2${}_{1}^{+}$ state at 1.141 MeV in neutron-rich ${}^{126}$Sn (${T}_{1/2}=2.3\ifmmode\times\else\texttimes\fi{}{10}^{5}y$).Method: Coulomb excitation in inverse kinematics together with the transient field and the Doppler shift attenuation techniques were applied to a radioactive beam of ${}^{126}$Sn at the Holifield Radioactive Ion Beam Facility.Results: $g({2}_{1}^{+})=\ensuremath{-}0.25(21)$ and $\ensuremath{\tau}({2}_{1}^{+})=1.5(2)$ ps were obtained.Conclusions: The data are compared to large-scale shell-model and quasiparticle random-phase calculations. Neutrons in the ${h}_{11/2}$ and ${d}_{3/2}$ orbitals play an important role in the structure of the 2${}_{1}^{+}$ state of ${}^{126}$Sn. Challenges, limitations, and implications for such experiments at future rare isotope beam facilities are discussed.

Background: The evolution of and interplay between single-particle and collective excitations in the 40 $\ensuremath{\leqslant}N\ensuremath{\leqslant}$ 50 range for ${}_{38}$Sr and ${}_{40}$Zr isotopes have been studied.Purpose: Measurement of the $g$ factor of the 2${}_{1}^{+}$ and 4${}_{1}^{+}$ states in radioactive ${}^{88}$Zr while simultaneously remeasuring the $g({2}_{1}^{+})$ factors in the Sr isotopes and extention of the measurements to higher energy states in the Sr isotopes. Lifetimes of states in these nuclei are determined.Methods: The transient field technique in inverse kinematics and line-shape analysis using the Doppler-shift attenuation method are applied. The ${}^{88}$Zr nuclei were produced by the transfer of an $\ensuremath{\alpha}$ particle from the ${}^{12}$C nuclei of the target to ${}^{84}$Sr nuclei in the beam. The excited states in the stable ${}^{84}$Sr isotopes were simultaneously populated via Coulomb excitation by ${}^{12}$C in the same target. Coulomb excitation measurements on ${}^{86,88}$Sr were carried out with the same apparatus.Results: The resulting $g$ factors and $B(E2)$ values of these nuclei reveal similarities between the two chains of Zr and Sr isotopes. Large-scale shell-model calculations were performed within the ${p}_{3/2},{f}_{5/2},{p}_{1/2},{g}_{9/2}$ orbital space for both protons and neutrons and yielded results in agreement with the experimental data.Conclusions: In this paper the magnetic moments and lifetimes of several low-lying states in ${}^{88}$Zr and ${}^{84.86,88}$Sr have been measured and compared to large-scale shell-model calculations.

Background: The experimental study of $g(Ig2)$ factors of nuclear states can provide information about the evolution of collectivity in certain regions of the nuclear chart, and assist in obtaining a microscopic description of the nuclear wave functions. The measurements and explanations of $g(Ig2)$ factors are still a challenge for experiments and theory.Purpose: Measurement of the $g({2}_{1}^{+})$ and $g({4}_{1}^{+})$ factors, the latter for the first time, in the ${\phantom{\rule{0.16em}{0ex}}}_{44}^{96}$Ru nucleus. Comparison of the experimental results with calculations using the shell model and collective models.Methods: The experiments made use of the transient field technique, using a Coulomb-excitation reaction in inverse kinematics. Large scale shell model calculations were performed; comparisons with previous theoretical predictions, using the tidal-wave model and the hydrodynamical model, were carried out.Results: The values of $g({2}_{1}^{+})=+0.46(2)$ and $g({4}_{1}^{+})=+0.58(8)$ were experimentally obtained. While the $g({2}_{1}^{+})$ value agrees with the hydrodynamical model prediction of $g=Z/A=+0.46$, the $g({4}_{1}^{+})$ is in agreement with the shell model predictions. The trend of the experimental $g$ factors, as a function of nuclear spin, is not reproduced by the theoretical models discussed.Conclusions: Measurements of $g({2}_{1}^{+})$ and $g({4}_{1}^{+})$ in ${}^{96}$Ru were performed. Further theoretical efforts are necessary to explain the trend of the $g$ factors as a function of nuclear spin for the ${}^{96}$Ru nucleus. Future measurements of $g({4}_{1}^{+})$ should reduce the uncertainty of the result.

The transient-field-perturbed angular correlation technique was used with Coulomb excitation in inverse kinematics to perform a systematic measurement of the $g$ factors of the first excited ${2}_{1}^{+}$ states in the stable even-$A$ isotopes $^{96\ensuremath{-}104}\mathrm{Ru}$. The measurements have been made relative to one another under matched kinematic conditions and include a measurement of $g({2}_{1}^{+})=+0.47(3)$ in $^{96}\mathrm{Ru}$.

The magnetic moments of the 4[sub 1][sup +] and 6[sub 1][sup +] states in [sup 150]Sm relative to that of the 2[sub 1][sup +] state have been measured by the transient field technique. The resulting [ital g]-factor ratios are [ital g](4[sub 1][sup +])/[ital g](2[sub 1][sup +])=1.60(12) and [ital g](6[sub 1][sup +])/[ital g](2[sub 1][sup +])=1.14(34). The [ital g](4[sub 1][sup +])/[ital g](2[sub 1][sup +]) ratio is larger than expected for a collective band. To confirm this result a variety of measurements were conducted with both [sup 32]S and [sup 58]Ni beams at energies ranging from 80 to 230 MeV incident on targets with both iron and gadolinium ferromagnetic layers.

The precession of the angular distribution of gamma rays deexciting the 2[sub 1][sup +] states of [sup 194,196,198]Pt and [sup 148]Nd nuclei have been measured by the transient field method. Average values of the transient field acting at Pt and Nd ions recoiling through gadolinium have been obtained from these data, and are shown to validate the Rutgers parametrization in the recoil velocity range 1.9[le]([ital v]/[ital v][sub 0])[lt]=4.6. The [ital g](2[sub 1][sup +]) factors of [sup 196,198]Pt relative to [ital g]([sup 194]Pt)=0.302(16) have also been deduced: [ital g]([sup 196]Pt)=0.302(24) and [ital g]([sup 198]Pt)=0.350(30), in good agreement with other transient field measurements.

The transient field (TF) technique in inverse kinematics was used to measure the g factors of the low lying 2{sub 1}{sup +}, 4{sub 1}{sup +}, and 2{sub 2}{sup +} states in {sup 106}Pd. The g factor of the 4{sub 1}{sup +} state was determined and the g(2{sub 1}{sup +}) and g(2{sub 2}{sup +}) factors were remeasured. The values of g(2{sub 1}{sup +}) and g(2{sub 2}{sup +}) had been determined earlier in integral perturbed angular correlation (IPAC) experiments and the value of the former served to calibrate the TF. The three g factors, g(2{sub 1}{sup +}), g(2{sub 2}{sup +}), and g(4{sub 1}{sup +}), agree with each other and with the collective Z/A value. The uncertainties in the g(2{sub 2}{sup +}) and g(4{sub 1}{sup +}) factors remain fairly large in spite of long measuring times because of the weak excitation of the two-phonon states. The lifetimes of the 2{sub 2}{sup +} and 4{sub 1}{sup +} states were newly determined from line-shape fits.

The $g$ factors and mean lifetimes of several short-lived low-lying states in ${}_{30}^{70}$${\mathrm{Zn}}_{40}$ have been measured using the techniques of projectile Coulomb excitation in inverse kinematics combined with transient magnetic fields and the Doppler-shift attenuation method. The present results have been interpreted within the framework of large-scale shell-model calculations that include the ${g}_{9/2}$ orbital.

Lifetimes and g‐factors have been measured for short‐lived low‐lying states in 70Zn using the techniques of projectile Coulomb excitation in inverse kinematics combined with transient magnetic fields and the Doppler‐Shift‐Attenuation‐Method (DSAM). While the g(21+) value was redetermined and found to be consistent with the literature values, all other data are new. The main goal is a better understanding of the influence of the v(g9/2) orbital in this region of the nuclear chart.

Average magnetic moments as well as information on the time evolution of the continuum structure of {sup 152}Dy at high spin have been obtained using the transient hyperfine magnetic field acting on fast ions traversing a thin, magnetized gadolinium foil. {sup 152}Dy nuclei were populated by the {sup 76}Ge({sup 80}Se,4{ital n}){sup 152}Dy fusion-evaporation reaction at {ital E}({sup 80}Se)=326.5 MeV. The target-ferromagnet arrangement corresponds to a time window of about 70{lt}{ital t}{lt}1100 fs, during which the excited nuclei experience the transient field interaction. The statistical {gamma} rays, as well as the high-energy, {ital E}{sub {gamma}}{gt}1200 keV, {gamma} rays contributing to the collective {ital E}2 bump,'' exhibit a negligible precession, in accordance with the very short lifetimes of these states. The precession of the angular distribution of discrete yrast {gamma} rays deexciting the nucleus from spin {ital I}{similar to}35{h bar} down yields an average magnetic moment for states with 43{h bar}{ge}{ital I}{ge}31{h bar}. The resulting {l angle}{ital g}{r angle}=0.21(2) is considerably lower than the collective value {ital Z}/{ital A}{similar to}0.43 and indicates an appreciable contribution from aligned neutrons to the lower-spin region populated within the above time frame. The results are discussed in the framework of model calculations of the {gamma}-ray cascade.

Using the transient field technique, the magnetic moments of the second excited ${2}^{+}$ states in $^{92,94}\mathrm{Zr}$ have been measured for the first time. The large positive $g$ factors, $g({2}_{2}^{+};{}^{92}\mathrm{Zr})=+0.76(50)$ and $g({2}_{2}^{+};{}^{94}\mathrm{Zr})=+0.88(27)$, which are in contrast to the known negative $g$ factors of the ${2}_{1}^{+}$ states, are found to be a consequence of weak proton-neutron coupling combined with the $Z=40$ subshell closure. From their large $M1$ transition strengths to the ${2}_{1}^{+}$ states, in earlier works an assignment to the ${2}_{2}^{+}$ states as proton-neutron symmetric and mixed-symmetry states has been made, which are now found to be polarized in their proton-neutron content. This fact allows to identify the underlying microscopic main configurations in the wave functions, which form the building blocks of symmetric and mixed-symmetry states in this region as valence nucleons are added and shell structure changes.

The g factor of the 2 1 + state in 132 52 Te, E ( 2 1 + ) = 0.9739 MeV , τ = 2.6 ps , was measured by the transient field technique applied to a radioactive beam. The development of an experimental approach necessary for work in radioactive beam environments is described. The result g = 0.28 ( 15 ) agrees with the previous measurement by the recoil-in-vacuum technique, but here the sign of the g factor is measured as well.

The last three years have seen developments in both experimental technology and theoretical capabilities. Thus it has become possible to measure the magnetic properties of weakly excited nuclear states with shorter half-lives and in nuclei further away from stability. In particular, two examples will be given concerning the structure of 4+ states in the mass 70 nuclei and the nature of the excitation of mixed-symmetry states in Zr nuclei. In addition, progress has been made in experiments involving radioactive beams. While these experiments are very difficult, successful experiments have been carried out in light Ar and S nuclei as well as in heavier isotopes in the A=132 region. The experiments will be described and the latest theoretical approaches will be discussed.