Electromagnetic transition strengths in155Dy (original) (raw)
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Lifetimes and electromagnetic transition strengths in ^{155}Dy
Physical Review C, 2013
Lifetimes of excited states of 157 Dy were measured by Recoil distance Doppler-shift (RDDS) and Doppler-shift attenuation (DSAM) methods. The γ-ray coincidence data were analysed by the Differential decay curve method. The level scheme and the newly deduced transition strengths were simultaneously described in the framework of the Particle plus triaxial rotor model (PTRM) and the rigid-rotor model.
Low-lying bands with different quadrupole deformation in155Dy
EPJ Web of Conferences, 2014
To investigate the interplay between collective and single particle degrees of freedom in odd nuclei, Recoil distance Doppler-shift and Doppler-shift attenuation lifetime measurements were carried out for levels in 155 Dy in coincidence detection of gamma-rays. 26 lifetimes were determined using the Differential decay curve method. Particle plus triaxial rotor model (PTRM) calculations were performed to compare the experimental level scheme and transition strengths with theoretical ones in order to get information on the quadrupole deformation (ǫ,γ) of the bands. As a result, different quadrupole deformations for the one-quasineutron bands at low and medium spins are deduced.
Lifetime measurements and shape coexistence in ^{144}Dy
Physical Review C, 2010
The known level scheme of 144 Dy has been extended and lifetime measurements have been made with the recoil-distance Doppler-shift method. Reduced transition probabilities and deformations have been determined for four low-lying transitions. These states form part of the first observed band crossing, giving information on the change in nuclear deformation resulting from the rearrangement of h 11/2 protons in the nucleus. Two bands built upon excited 10 + states have been assigned π (h 11/2) 2 prolate and ν(h 11/2) −2 oblate configurations with τ = 12(2) ps and 0.01 < τ 16 ns, respectively. These long lifetimes are reasoned to be a result of shape coexistence at low energy and moderate spin. A known four-quasiparticle dipole band has been extended to higher spin and lifetime measurements suggest a long-lived bandhead state. In this case, the excited states in the band may be consistent with a shears model interpretation of a magnetic dipole rotor. However, the measured B(M1)/B(E2) branching ratios reveal a larger than expected deformed rotational component compared with that in the analogous band in the lower mass isotone 142 Gd.
Electromagnetic transition probabilities in 130Ce
Nuclear Physics A, 1992
Lifetimes of excited nuclear states have been measured in 131 'Ce using the coincidence-plunger technique. The employed nuclear reaction was`'NMO(;`'S, 4n)"'Ce at a beam energy of 150 MeV. The measurement has been performed at the NSF Daresbury using the ESSA 30 setup. It was possible to determine lifetimes for the 4+ to 16' states in "'Ce. The experimental B(E2) values could be well reproduced by calculations using the triaxial rotor model with ß = 0.26 and y = 21°a s well as the rotation vibration model (0 = 0.25) .
Lifetimes measurements for 134Nd and neighboring nuclei with the coincidence-plunger technique
Physical Review C, 1999
The lifetimes of 12 excited states in 134 Nd were measured with a high precision by means of the GASP spectrometer applying the coincidence recoil-distance Doppler-shift method. The 110 Pd( 28 Si,xny p) reaction was used at a beam energy of 125 MeV. The data were analyzed with the differential decay curve method and the derived lifetimes were used for a sensitive test of various nuclear models. The transition quadrupole moments (Q t ) in the ground state band agree nicely with the predictions of both the rotor model and the O͑6͒ symmetry of the interacting boson approximation up to the 4 g ϩ state of 134 Nd. The Q t values for the 8 g ϩ , 10 S1 ϩ , and 12 S1 ϩ states, however, give evidence for a strong change of the nuclear deformation. The lifetimes of 12 low lying yrast states in the 130,131,132 Ce, 133,134 Pr, and 135 Nd nuclei have been also determined.
Transition probability studies in175Au
Journal of Physics: Conference Series, 2013
Transition probabilities have been measured between the low-lying yrast states in 175 Au by employing the recoil distance Doppler-shift method combined with the selective recoil-decay tagging technique. Reduced transition probabilities and magnitudes of transition quadrupole moments have been extracted from measured lifetimes allowing dramatic changes in nuclear structure within a low excitation-energy range to probed. The transition quadrupole moment data are discussed in terms of available systematics as a function of atomic number and aligned angular momentum.
Nuclear Instruments and Methods, 1974
A method is described in which the observation of conversionelectron Doppler shifts is used to measure nuclear lifetimes in the picosecond range. The isomeric nuclei recoil into the vacuum chamber of an orange-type fl-spectrometer following a-emission. The recoil velocity is measured directly by a time-of-flight technique. For the lifetime measurements the recoil distance is limited by a stopper foil, the position of which is varied in a reproducible way using the thermal expansion of a metal holder rod. Since the distances are in the micrometer region, an optical interference method can be applied to measure directly the variation in distance. The fraction of conversion electrons in the unshifted conversion line represents the fraction of isomeric nuclei which do not decay in flight. The nuclear lifetime is derived directly from the variation of this quantity with the recoil distance. This method should be applicable to many excited states of nuclei in the Z > 82 region, where common techniques fail. Lifetimes are accessible in the range 1 ps < Ta/2 < 100 ps. An application to three excited states in 219Rn gave the following results: T1/2(159 keV) = (17.74-2.6) × 10-12 s, T1/2(269 keV) = (4.44-1.0) × 10-12 s, and TI/2(339 keV) = (8.1 4-2.8) × 10 12 s.
Lifetimes of yrast and near-yrast states of159,160,161Yb
Physical Review C, 1988
Lifetimes of high-spin states of "' ' 'Yb, populated by fusion-evaporation reactions, have been measured by the recoil-distance technique. The data were collected in coincidence with a total-energy filter to provide some discrimination on reaction channel. The principal feature of the resulting transition quadrupole moments is a frequency-dependent reduction which is displayed by those bands with aligned quasiparticles. This seems to be mainly due to the influence of the favored i&3/2 quasineutron. Additional available data are surveyed and support this conclusion. Calculations using the cranked shell model and the cranked Hartree-Fock-Bogoliubov and cranked Nilsson-Strutinsky methods provide a qualitative description of the experimental observations. In addition, a satisfactory account is provided by recent calculations based on a fermion dynamical-symmetry model.