The ROSPHERE γ-ray spectroscopy array

Bucurescu, D.; Căta-Danil, I.; Ciocan, G.; Costache, C.; Deleanu, D.; Dima, R.; Filipescu, D.; Florea, Nicoleta Mihaela; Ghiţă, D.; Glodariu, T.; Ivaşcu, M.; Lică, R.; Mărginean, N.; Mărginean, R.; Mihai, C.; Negreţ, A.; Niță, Cristina; Olacel, Adina; Pascu, S.; Sava, T.; Stroe, L.; Şerban, A.; Șuvăilă, Rareș; Toma, S.; Zamfir, N. V.; Cǎta-Danil, G.; Gheorghe, I.; Mitu, I. O.; Suliman, G.; Ur, C. A.; Braunroth, T.; Dewald, Α.; Fransen, C.; Bruce, A. M.; Podolyák, Zs.; Regan, P.H.; Roberts, O. J.

doi:10.1016/j.nima.2016.08.052

Cited by 67 publications

(21 citation statements)

References 19 publications

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“…The γ transitions of 66 Ni were measured using the ROSPHERE array [37], consisting of 14 Ge detectors and 11 LaBr 3 ðCeÞ scintillators. A first part of the experiment was carried out with a 5 mg=cm 2 thick target of 64 Ni.…”

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confidence: 99%

Multifaceted Quadruplet of Low-Lying Spin-Zero States in Ni66 : Emergence of Shape Isomerism in Light Nuclei

Leoni¹,

Fornal²,

Mărginean³

et al. 2017

Phys. Rev. Lett.

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þ states, pointing to the oblate, spherical, and prolate nature of the consecutive excitations. In addition, they account for the hindrance of the E2 decay from the prolate 0 þ 4 to the spherical 2 þ 1 state, although overestimating its value. This result makes 66 Ni a unique nuclear system, apart from 236;238 U, in which a retarded γ transition from a 0 þ deformed state to a spherical configuration is observed, resembling a shape-isomerlike behavior. DOI: 10.1103/PhysRevLett.118.162502 The concept of potential energy surface (PES) is central in many areas of physics. Usually, the PES displays the potential energy of the system as a function of its geometry. As an example, the PES of a molecule expressed in such coordinates as bond length, valence angles, etc., can be used for finding the minimum energy shape or calculating chemical reaction rates [1]. The idea of potential energy surface in deformation space has also been widely applied to the nucleus at a given spin. For an even-even nucleus at spin 0, the lowest PES minimum corresponds to the ground state (g.s.), while there may exist additional (secondary) minima in which excited 0 þ states can reside: they can be interpreted as ground states of different shapes [2][3][4][5][6]. When a secondary minimum is separated from the main minimum by a high barrier, in the extreme case a long-lived isomer, called shape isomer, can be formed [7]. Shape isomerism at spin zero, so far, has clearly been observed only in actinide nuclei -these isomers decay mainly by fission, and in two cases only, 236 U and 238 U, by very retarded γ-ray branches [8][9][10][11].The existence of shape isomers in lighter systems has been a matter of debate for a long time. Already in the 1980s, a study based on microscopic Hartree-Fock plus BCS calculations, in which a large number of nuclei was surveyed, identified ten isotopes in which a deformed 0 þ state is separated from a spherical structure by a significantly high barrier:66 Ni and 68 Ni, 190;192 Pt, 206;208;210 Os, and 194;196;214

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confidence: 99%

Multifaceted Quadruplet of Low-Lying Spin-Zero States in Ni66 : Emergence of Shape Isomerism in Light Nuclei

Leoni¹,

Fornal²,

Mărginean³

et al. 2017

Phys. Rev. Lett.

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“…Four projectile energies were studied near the Coulomb barrier of the reaction, namely 61, 63, 65 and 67 MeV. The subsequent decay was detected by the ROSPHERE array [7] using 15 HPGe detectors distributed over three rings.…”

Section: Methodsmentioning

confidence: 99%

Investigating the structure of the low-lying states in 140Ba

Khaliel

Mertzimekis²,

Bracco³

et al. 2020

hnps

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The neutron-rich 144,146Ba isotopes have been studied recently in terms of their experimental B(E3) values [1,2]. Although featuring large uncertainties, the results were found to be significantly larger than any theoretical calculation. Similar questions exist for the slightly lighter isotope 140Ba, which is particularly interesting since it is located at the onset of octupole correlations. The lifetimes of the lower-lying states are completely unknown, with the sole exception of the first 2+ state [3].In this work, we report on the outcome of a short test run, attempting to populate the states of interest using the 138Ba(18O,16O)140Ba reaction. The experiment was carried out at IFIN-HH using a specially manufactured natBa target sandwiched between two Au layers. This was considered imperative due to Barium's quick oxidation in air. Four beam energies (61,63,65,67 MeV) below the Coulomb barrier have been tested. The subsequent decay was measured using the Bucharest ROSPHERE array, consisting of 15 Ge detectors and 10 LaBr3(Ce) scintillators.The preliminary results from the test run report on the level population strengths and the limits in lifetime measurements, which are expected to provide new information on the structural effects in neutron-rich barium isotopes, especially regarding quadrupole and octupole degrees of freedom. The _ndings are also expected to act as stringent tests to theoretical modeling in this mass regime.

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“…Nuclei recoiling from the target were stopped in another gold foil of 5 mg/cm 2 thickness. The distance between the target and the stopper foils was adjusted using the Köln-Bucharest Plunger device [27], and the γ rays were measured with the ROSPHERE array [27]. Thirteen different target-to-stopper distances ranging from 7.5 to 245 μm were set during the experiment, with an average measuring time of 18 h per distance and an average beam intensity of ∼3 pnA.…”

Section: Methodsmentioning

confidence: 99%

Lifetime measurements in Nd138

Garrote¹,

Görgen²,

Mihai³

et al. 2018

Phys. Rev. C

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Lifetimes of several short-lived excited states in 138 Nd were measured with the ROSPHERE array at IFIN-HH, Bucharest, using the recoil-distance Doppler shift technique following the 123 Sb(19 F,4n) reaction. The resulting electromagnetic transition probabilities are compared to large-scale shell model calculations and to constrained Hartree-Fock-Bogoliubov calculations with the Gogny D1S interaction, configuration mixing, and a five-dimensional collective Hamiltonian formalism. The onset of collectivity in Nd isotopes below the N = 82 shell closure and the deformation induced by the alignment of protons and neutron holes in the h 11/2 orbitals are discussed.

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The ROSPHERE γ-ray spectroscopy array

Cited by 67 publications

References 19 publications

Multifaceted Quadruplet of Low-Lying Spin-Zero States in Ni66 : Emergence of Shape Isomerism in Light Nuclei

Multifaceted Quadruplet of Low-Lying Spin-Zero States in Ni66 : Emergence of Shape Isomerism in Light Nuclei

Investigating the structure of the low-lying states in 140Ba

Lifetime measurements in Nd138

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