Shape coexistence in Hg-178

Lifetime measurements of excited states in Hg-178 have been performed using the Rh-103(Kr-78, p2n) reaction at a beam energy of 354 MeV. The recoil-decay tagging (RDT) technique was applied to select the Hg-178 nuclei and associate the prompt gamma rays with the correlated characteristic ground-state alpha decay. Lifetimes of the four lowest yrast states of Hg-178 have been determined using the recoil distance Doppler-shift (RDDS) method. The experimental data are compared to theoretical predictions with focus on shape coexistence. The results confirm the shift of the deformed prolate structures to higher lying states but also indicate their increasing deformation with decreasing neutron number.Peer reviewe

Lifetime measurements in the even-even isotopes

Background: The heaviest doubly-magic nucleus, , and the neighboring nuclei offer unique opportunities to investigate the properties of nuclear interaction. For instance, the structure of light-Sn nuclei has been shown to be affected by the delicate balance between nuclear-interaction components, such as pairing and quadrupole correlations. From Cd to Te, many common features and phenomena have been observed experimentally along the isotopic chains, leading to theoretical studies devoted to a more general and comprehensive study of the region. In this context, having only two proton holes in the shell, the Cd isotopes are expected to present properties similar to those found in the Sn isotopic chain. Purpose: The aim of this work was to measure lifetimes of excited states in neutron-deficient nuclei in the vicinity of . Results: Lifetimes of low-lying states were measured in the even-mass isotopes. In particular, multiple states with excitation energy up to MeV, belonging to various bands, were populated in via inelastic scattering. The transition strengths corresponding to the measured lifetimes were compared with those resulting from state-of-the-art beyond-mean-field calculations using the symmetry-conserving configuration-mixing approach. Methods: The neutron-deficient nuclei in the region were populated using a multinucleon transfer reaction with a beam and a target. The beamlike products were identified by the VAMOS spectrometer, while the rays were detected using the AGATA array. Lifetimes of excited states were determined using the recoil distance Doppler-shift method, employing the Cologne differential plunger. Conclusions: Despite the similarities in the electromagnetic properties of the low-lying states, there is a fundamental structural difference between the ground-state bands in the and isotopes. The comparison between experimental and theoretical results revealed a rotational character of the Cd nuclei, which have prolate-deformed ground states with . At this deformation becomes a closed-shell configuration, which is favored with respect to the spherical one

Study of quadrupole correlations in N = Z = 50 region via lifetime measurements

During the AGATA campaign at GANIL, the neutron-deficient Sn region was populated via a multi-nucleon transfer reaction in order to directly measure the lifetime of the first excited states with a plunger device, providing complementary information to previous results obtained with Coulomb excitation experiments. The AGATA? -ray array was used together with the VAMOS++ spectrometer to study the nuclei of interest

Lifetime measurements in the even-even Cd102-108 isotopes

Background: The heaviest T-z = 0 doubly-magic nucleus, Sn-100, and the neighboring nuclei offer unique opportunities to investigate the properties of nuclear interaction. For instance, the structure of light-Sn nuclei has been shown to be affected by the delicate balance between nuclear-interaction components, such as pairing and quadrupole correlations. From Cd to Te, many common features and phenomena have been observed experimentally along the isotopic chains, leading to theoretical studies devoted to a more general and comprehensive study of the region. In this context, having only two proton holes in the Z = 50 shell, the Cd isotopes are expected to present properties similar to those found in the Sn isotopic chain. Purpose: The aim of this work was to measure lifetimes of excited states in neutron-deficient nuclei in the vicinity of Sn-100. Methods: The neutron-deficient nuclei in the N approximate to Z approximate to 50 region were populated using a multinucleon transfer reaction with a Cd-106 beam and a Mo-92 target. The beamlike products were identified by the VAMOS++ spectrometer, while the gamma rays were detected using the AGATA array. Lifetimes of excited states were determined using the recoil distance Doppler-shift method, employing the Cologne differential plunger. Results: Lifetimes of low-lying states were measured in the even-mass Cd-102-(108) isotopes. In particular, multiple states with excitation energy up to MeV, belonging to various bands, were populated in approximate to 3 Cd-106 via inelastic scattering. The transition strengths corresponding to the measured lifetimes were compared with those resulting from state-of-the-art beyond-mean-field calculations using the symmetry-conserving configuration-mixing approach. Conclusions: Despite the similarities in the electromagnetic properties of the low-lying states, there is a fundamental structural difference between the ground-state bands in the Z = 48 and Z = 50 isotopes. The comparison between experimental and theoretical results revealed a rotational character of the Cd nuclei, which have prolate-deformed ground states with beta(2) approximate to 0.2. At this deformation Z = 48 becomes a closed-shell configuration, which is favored with respect to the spherical one

STUDY OF QUADRUPOLE CORRELATIONS IN N = Z=5 0 REGION VIA LIFETIME MEASUREMENTS

Zakopane Conference on Nuclear Physics - Extremes of the Nuclear Landscape -- AUG 28-SEP 04, 2016 -- Zakopane, POLANDWOS: 000398717500014During the AGATA campaign at GANIL, the neutron-deficient Sn region was populated via a multi-nucleon transfer reaction in order to directly measure the lifetime of the first excited states with a plunger device, providing complementary information to previous results obtained with Coulomb excitation experiments. The AGATA gamma-ray array was used together with the VAMOS++ spectrometer to study the nuclei of interest

Shape coexistence in ¹⁷⁸Hg

Abstract Lifetime measurements of excited states in ¹⁷⁸Hg have been performed using the ¹⁰³Rh(⁷⁸Kr,p2n) reaction at a beam energy of 354 MeV. The recoil-decay tagging (RDT) technique was applied to select the ¹⁷⁸Hg nuclei and associate the prompt γ rays with the correlated characteristic ground-state α decay. Lifetimes of the four lowest yrast states of ¹⁷⁸Hg have been determined using the recoil distance Doppler-shift (RDDS) method. The experimental data are compared to theoretical predictions with focus on shape coexistence. The results confirm the shift of the deformed prolate structures to higher lying states but also indicate their increasing deformation with decreasing neutron number

Pairing-quadrupole interplay in the neutron-deficient tin nuclei: First lifetime measurements of low-lying states in 106,108Sn

The lifetimes of the low-lying excited states 2+ and 4+ have been directly measured in the neutron-deficient 106,108Sn isotopes. The nuclei were populated via a deep-inelastic reaction and the lifetime measurement was performed employing a differential plunger device. The emitted γ rays were detected by the AGATA array, while the reaction products were uniquely identified by the VAMOS++ magnetic spectrometer. Large-Scale Shell-Model calculations with realistic forces indicate that, independently of the pairing content of the interaction, the quadrupole force is dominant in the B(E2;21+→0g.s.+) values and it describes well the experimental pattern for 104−114Sn; the B(E2;41+→21+) values, measured here for the first time, depend critically on a delicate pairing-quadrupole balance, disclosed by the very precise results in 108Sn

Pairing-quadrupole interplay in the neutron-deficient tin nuclei: First lifetime measurements of low-lying states in Sn-106,Sn-108

The lifetimes of the low-lying excited states 2(+) and 4(+) have been directly measured in the neutron-deficient Sn-106,Sn-108 isotopes. The nuclei were populated via a deep-inelastic reaction and the lifetime measurement was performed employing a differential plunger device. The emitted gamma rays were detected by the AGATA array, while the reaction products were uniquely identified by the VAMOS++ magnetic spectrometer. Large-Scale Shell-Model calculations with realistic forces indicate that, independently of the pairing content of the interaction, the quadrupole force is dominant in the B(E2; 2(1)(+) -> 0(g.s)(+)) values and it describes well the experimental pattern for Sn104-114 ; the B(E2;(+)(4) -> 2(1)(+)) values, measured here for the first time, depend critically on a delicate pairing-quadrupole balance, disclosed by the very precise results in Sn-108. (C) 2020 The Authors. Published by Elsevier B.V