Electroexcitation of the M1 scissors mode in 154Gd and the systematics of the M1 strength distributions in 154,156,158,160Gd

Hartmann, U.; Bohle, D.; Humbert, F.; Richter, A.

doi:10.1016/0375-9474(89)90270-4

Cited by 25 publications

(11 citation statements)

References 17 publications

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“…The measured branching ratios lie in between the values of 0.5 and 2 as expected from the Alaga rules for pure K = 1 and K = 0 states. Since [28,31].In the case of the odd nucleus ' Gd, because of the unknown spins of the excited states, the products of the ground state decay widths I 0 and the spin factor g = (21+ I )/(2JO+ I ) are plotted.…”

Section: B Resuits For Gdmentioning

confidence: 99%

“…5 the ground state transition widths I 0 and gI 0 are plotted. For marked transitions in even Gd isotopes the positive parities are known from electron scattering experiments (open symbols[28,31]) and NRF polarization mesurements (full symbols[30]). The dipole strength in ' Gd is distributed over more than 90 transitions in the whole energy range2 -4 MeV where the present NRF experiments have a good sensitivity.…”

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Systematics of low-lying dipole strengths in odd and even Dy and Gd isotopes

et al. 1995

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Photon scattering experiments on the odd, deformed nuclei ' " Dy and ' Gd provided detailed information on the excitation energies and transition probabilities of low-lying dipole excitations. In the case of the even-even nuclei ' ' Dy in addition spins and parities of the excited states could be determined model independently by measuring the angular distributions and the linear polarization of the scattered photons using a Compton polarimeter. The results are compared with the systematics obtained for the neighboring even-even isotopes ' Dy and ' ' ' Gd in previous photon scattering experiments. Whereas in the odd Dy isotopes a concentration of dipole strength is observed, which fits nicely into the systematics of the orbital M1 mode, the dipole strength in ' Gd is completely fragmented into about 90 transitions.

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Section: B Resuits For Gdmentioning

confidence: 99%

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confidence: 99%

Systematics of low-lying dipole strengths in odd and even Dy and Gd isotopes

et al. 1995

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“…NRF measurements using a Compton polarimeter have been performed [6,29 -31] for the nuclei ' 2' 6' Nd, 606d, and ' ' Dy. For some nuclei additional information about the parities has come from high resolution electron scattering experiments (see e.g., [2,32,33]). …”

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confidence: 99%

Correlation between low-lyingM1 andE2 strength in heavy rare earth nuclei

et al. 1995

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Magnetic dipole excitation strengths attributable to the scissors mode in even-A rare earth nuclei between A=140 -190 are collected and presented assuming the excitation energy as an additional signature for the fragments of this mode. In this whole mass region the total M1 strength is found to be proportional to the quantity B(E2;0, + -+2, +)/Z as has been known before for the Nd and the Sm nuclei. In the upper half of the N= 82 -126 major shell the M1 and the E2 strengths do not saturate. Both quantities exhibit a rather monotonous increase towards midshell.PACS number(s): 21.10. Re, 23.20.g, 25.20.Dc, 27.70.+q One of the most exciting findings in nuclear spectroscopy in the last decade is the observation of strong low-lying magnetic dipole excitations in deformed nuclei which are frequently referred to as a scissors mode [1,2]. A crucial proof of the "scissors" character of this M1 mode was the discovery of the so-called "8 law" by Ziegler et al. [3] and its confirmation in Refs. [4 -6]. In various nuclear models such as microscopical, algebraical, geometrical, and phenomenological models a large effort has been made to predict the energy and the excitation strength of the scissors mode. Nearly all of these models are consistent with a quadratic dependence of its excitation strength on the deformation parameter 8 [7 -18].Thus the 8' law implies a saturation of the excitation strength of the scissors mode in light rare earth nuclei toward midshell as the deformation 8 saturates. This effect is actually observed.Contrary to the prediction of simple collective models such as the axially symmetric two rotor model which predicts a single scissors mode state, in real nuclei the scissors mode turns out to be fragmented into several states. This fragmentation considerably complicates the detection and identification of the scissors mode.Since the prediction of the scissors mode [1] in the late seventies and its discovery [2] in 1984 in a high resolution electron scattering experiment the nuclei of the rare earth region have been systematically investigated by means of the nuclear resonance fiuorescence (NRF) technique [19 -21] which is particularly well suited to study dipole excitations from the ground state. Recent NRF experiments have provided (y, y') data on heavier nuclei [22 -25]. It is the purpose of this paper to collect and discuss the available data for the even-A rare earth nuclei focusing on their dependence on the nuclear deformation and the numbers of nucleons.We will first discuss how one can obtain information on the scissors mode from a (y, y') NRF experiment. Observables in NRF experiments on even-A nuclei are the excitation energy F, the spin J of the excited level, the branching ratio R,"~=B(ml; I;~2+, )/B(ml; I; -+0t+), and the absolute dipole transition strengths B(m1;0, +~1;). If a Compton polarimeter is used as is discussed in Refs. [26 -28] information about the parities m of the excited states can be obtained. NRF measurements using a Compton polarimeter have been performed [6,29 -31] f...

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“…For an experimental investigation of the pn degree of freedom at the shape phase transitional point X(5) [11] the study of the evolution of the scissors mode around the transitional point is an ideal test case. Therefore, the N = 90 nucleus 154 Gd a e-mail: beller@ikp.tu-darmstadt.de The data were obtained in electron scattering [12][13][14] and nuclear resonance fluorescence experiments [15]. These transitions are usually asumed to be of M1 character.…”

Section: Introductionmentioning

confidence: 99%

“…was chosen. It was one of the first nuclei in which the scissors mode was observed [14]. In deformed nuclei a decay of the scissors mode to the β-band would annihilate the scissors-like oscillation while simultaneously exciting a β-vibration.…”

Section: Introductionmentioning

confidence: 99%

A novel decay channel of the 1⁺scissors mode: coupling to the vibrationalβ-excitation

Beller

Fransen

Kotila

et al. 2012

EPJ Web of Conferences

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Abstract. The transitional nucleus 154 Gd was investigated using a combination of a photon scattering experiment and a γγ-coincidence study following the β decay of 154 Tb. A novel decay channel from the scissors mode to the band head of the β-band was observed. Its transition strength B(M1; 1 + sc → 0 + β ) was determined. An IBM-2 calculation reveals a correlation of this decay channel and the shape phase transition between spherical and deformed nuclei.

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Electroexcitation of the M1 scissors mode in 154Gd and the systematics of the M1 strength distributions in 154,156,158,160Gd

Cited by 25 publications

References 17 publications

Systematics of low-lying dipole strengths in odd and even Dy and Gd isotopes

Systematics of low-lying dipole strengths in odd and even Dy and Gd isotopes

Correlation between low-lyingM1 andE2 strength in heavy rare earth nuclei

A novel decay channel of the 1⁺scissors mode: coupling to the vibrationalβ-excitation

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Electroexcitation of the M1 scissors mode in 154Gd and the systematics of the M1 strength distributions in 154,156,158,160Gd

Cited by 25 publications

References 17 publications

Systematics of low-lying dipole strengths in odd and even Dy and Gd isotopes

Systematics of low-lying dipole strengths in odd and even Dy and Gd isotopes

Correlation between low-lyingM1 andE2 strength in heavy rare earth nuclei

A novel decay channel of the 1+scissors mode: coupling to the vibrationalβ-excitation

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A novel decay channel of the 1⁺scissors mode: coupling to the vibrationalβ-excitation