Detailed spectroscopy of quadrupole and octupole states inYb168

Abstract

The low-lying positive-and negative-parity states in l68Yb have been investigated by means of the (a,2ny) fusion evaporation reaction. Using the coincidence method, the level scheme was corrected and extended up to 3 MeV, for both the positive-and negative-parity states. Using the new branching ratios determined in the present experiment, the K quantum number was proposed for two negative-parity bands by direct comparison with the Alaga rule. Like in some other nuclei, one negative-parity band was established, decaying predominantly to the y-vibrational band. In a second experiment, the lifetimes of the low-lying excited states up to J n = 6+ in the ground-state band were measured by using the in-beam fast-timing method with the Bucharest mixed high-purity germanium (HPGe) and LaBr3:Ce detector array using the triple-y coincidence method. Reduced E2 transition probabilities were extracted from the measured lifetimes and compared with the corresponding observables in neighboring isotopes, showing a smooth behavior with increasing mass. The positive-and negative-parity states as well as E 1 and E2 transition probability ratios revealed by these experiments are compared with the interacting boson model in the sd and s p d f boson space, and with the confined beta-soft rotor model, and are found to be in good agreement.

Lifetime measurements of low-spin negative-parity levels in Gd160

“…Recent studies of quadrupole and octupole states in 168 Yb (R 4/2 = 3.27) noted a pattern of strong decay from a K π = 2 − band into the γ-vibrational band when compared to the decay into the ground-state band [42]. This is consistent with the degree of K forbiddenness.…”

“…Earlier work by Aprahamian [43] showed a difference of three orders of magnitude in E1 strength for transitions between states with the same K (∆K = 0) and for those with ∆K = 2. The authors note [42] this interesting decay pattern has also been observed in the J π = 2 − states belonging to the K π = 2 − band in the nuclei from Gd (Z = 64) to W (Z = 74). The preferred decay 168 Yb is to the is to the J π = 4 − state.…”

Investigation of transition symmetry shapes of 160-168Yb nuclei using IBM

“…, respectively) as a function of mass numbers for even -even 160-168 Yb isotopes. The effective boson charges estimated from equations ( 4) and (12) were used in and to calculate the reduced electric quadrupole transition probability that was compared with the experimental values [13][14][15][16][17][18][19][20][21][22] for [160][161][162][163][164][165][166][167][168] Yb isotopes, as listed in Tables- (2,3).…”

“…The present study investigated the medium and heavy mass isotopes of Ytterbium which are located in the rear-earth mass region and are well deformed nuclei that can be populated to very high spin. There are many studies that attempted to explain the behavior of Ytterbium nuclei [7][8][9][10][11][12]. Some of them were described as having vibrattional bound to the rotational properties, while others were described as possessing unstable characteristics and being on their way to the rotating region by increasing the neutron number.…”

Combining γ-ray and particle spectroscopy with SONIC@HORUS

“…It consists of the new particle spectrometer SONIC, which can house up to 12 ∆E-E telescopes for the identification of ejectiles and measurement of their energy; and the existing γ-ray spectrometer HORUS with its 14 HPGe detectors, which has already been used for the investigation of Nuclear Structure, e.g. by measuring fusion-evaporation reactions [1][2][3] and capture reactions for Nuclear Astrophysics [4][5][6]. The identification of the ejectile is necessary to select light-ion scattering and specific transfer reactions, since those are typically not the dominating reaction channels.…”