A. M. I. Haque

Transient-field g-factor measurement of the first 2+ states in the N=82 nuclei 140Ce, 142Nd and 144Sm

Abstract The g -factor of the first 2 + states in three stable N =82 nuclei, 140 Ce, 142 Nd and 144 Sm, have been measured using the transient magnetic field technique. The levels under study were Coulomb excited with 110–116 MeV 32 S beams and spin precession after passing a thin polarized iron foil was measured. The field strength has been checked using the first 2 + state in 148 Sm as internal calibration. The obtained values were 0.97 (9), 0.84 (7), 0.76 (11) for 140 Ce, 142 Nd and 144 Sm, respectively. These remarkably lower values with respect to shell-model predictions in a proton subspace are explained in terms of neutron core excitation by quasiparticle random-phase-approximation calculations.

g-factor measurement of the two lowest 10+ states in 140Sm

Abstract The g -factors of the two 10 + states in 140 Sm at 3172 and 3210 keV have been measured by means of the TDPAD method. The obtained values are g = −0.176(20) and g = 1.27(9), respectively. The reaction 116 Cd ( 28 Si, 4n) 140 Sm, at incident beam energy of 125 MeV, has been used. The measured values clearly show that these states can be described as rather pure (νh 11/2 ) −2 and (πh 11/2 ) 2 configurations.

g-factor measurements in stable Hg isotopes

The g-factor of the first 2+ state in198Hg,200Hg and202Hg has been measured using the thin foil Transient Field technique. The values were calibrated to the known g-factor of the first 5/2− state in199Hg. The levels were Coulomb excited by 217 MeV nickel ions with gadolinium acting as ferromagnetic medium. The obtained values are rather constant and contradict a previously observed dip at200Hg. Two other g-factors have been remeasured in199Hg.

g-factors of the lowest 2+ and 4+ states in198, 200, 202Hg

Theg-factors of the 21+ and 41+ states in198,200,202Hg were simultaneously measured by means of the transient-field perturbed angular correlation method in Coulomb excitation using multi-isotopic targets and thin polarized Gd foils as ferromagnetic host. Theg(21+) andg(41+) were found identical within errors in198, 200Hg, while in200Hg lowerg-factor values have been determined. The experimentalg-factors were compared with the predictions of the pairing-plus-quadrupole, dynamical deformation and interacting boson models.

Gryomagnetic ratios of low-lying states in 192,194,196Pt

Abstract Gyromagnetic ratios of the 2 1 + and 4 1 + states in 192,194,196 Pt and of the 2 2 + states in 192,194 Pt were simultaneously measured by the transient-field perturbed angular correlation method in Coulomb excitation using a multi-isotopic Pt target and thin polarized Fe and Gd foils as ferromagnetic hosts. The experimental g -factors were found identical within errors. These and previous existing data indicate the independence of the low-lying state g -factors in even stable Pt nuclei with respect to the spin and neutron number.

Theg factor of the lowest 7+ state in100Rh and 6− state in104Rh

Theg-factor of the 7+ state in100Rh withT1/2=140(5) ns and of the 6− state in104Rh withT1/2=47(3)ns has been measured by the time-differential perturbedγ-ray angular distribution method (TDPAD). The obtained values are +0.67(2) and +0.33(1) respectively. The two nuclei were populated with reactions induced by7Li on96,100Mo at a bombarding energy of 30 MeV. Shell model calculations using effective single particle moments show that the 7+ state in100Rh has mostly a πg9/2 ⊗ vd5/2 configuration, while the main component of the 6− state in104Rh is the πg9/2 ⊗ vh11/2.

g-factor of the first excited 4+ states in156Gd and158Gd

Relative g-factor of the first 2+ and 4+ states have been measured with the transient field technique in156Gd and158Gd. The precession of gamma rays depopulating the levels under study were observed, after passing through thin polarized gadolinium. The observed values agree with the predictions of the rotational model, i.c. g(4+)= g(2+), while contrasting the hypothesis that in156Gd the g-factor of the 4+ is reduced with respect to the 2+, because of rotational alignment.

Transient fieldg-factor measurement of the first 3− state in144Sm

The g-factor of the octupole vibrational state 3− at 1810 keV in144Sm has been measured to be 0.76(9) by means of the transient field technique. The state has been Coulomb excited by 217 MeV58Ni beam. The obtained value agrees with the predictions of RPA calculations and confirms the dominance of the proton particle-hole configuration π(1h11/2−2d5/2−1)

Theg-factor of the 8+ isomer of142Eu

Theg-factor of the 8+ isomer of142Eu with mean lifeτ=9 ns, has been measured by the time-differential perturbedγ ray angular distribution (TDPAD) method. The 8+ isomer was populated with the reaction114Cd(32S,p3n)142Eu at 155 MeV. The obtained valueg(8+)=0.51(3) agrees with shell model calculations using effective single-particle moments taken from neighbouring nuclei. A main configurationπh11/2⊗(vh11/2)−1 has been confirmed for the 8+ isomer.

Transient magnetic field for O, Ne, Mg, Si and S recoiling in Gd at low velocity

The spin precession of the lowest excited state of16O,22Ne,24Mg,28Si and32S recoiling in thin gadolinium foils has been measured. The energy of the α-beams used to excite inelastically the investigated nuclei lead to a recoil velocity of the order of 2v0. The reduction of the transient field strength observed between Mg and Si is consistent with a description of the atomic configuration of the ions in terms of a molecular orbital mechanism.