Collectivity in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mrow /><mml:mn>66</mml:mn></mml:msup></mml:math>Ge and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mrow /><mml:mn>68</mml:mn></mml:msup></mml:math>Ge via lifetime measurements

Lüttke, R.; McCutchan, E. A.; Werner, V.; Aleksandrova, K.; Atwater, S.; Ai, H.; Casperson, R. J.; Casten, R. F.; Heinz, A.; Mertz, Aaron F.; Qian, J.; Shoraka, B.; Terry, J. R.; Williams, E.; Winkler, R.

doi:10.1103/physrevc.85.017301

Cited by 13 publications

(14 citation statements)

References 16 publications

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“…E x (2 Ge, which was also seen in the JUN45 calculation [7]. It was pointed out [32] 72 Ge is an interesting nucleus because its first excited 0 + state is found to be the lowest in all the Ge isotopes, which lies below 2 + 1 . As one can see from the right panel of Fig.…”

supporting

confidence: 56%

Toward a unified realistic shell-model Hamiltonian with the monopole-based universal force

et al. 2014

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We propose a unified realistic shell-model Hamiltonian employing the pairing plus multipole Hamiltonian combined with the monopole interaction constructed starting from the monopole-based universal force by Otsuka et al. (Phys. Rev. Lett. 104, 012501 (2010)). It is demonstrated that the proposed PMMU model can consistently describe a large amount of spectroscopic data as well as binding energies in the p f and p f 5/2 g 9/2 shell spaces, and could serve as a practical shell model for even heavier mass regions. PACS numbers: 21.30.Fe, 21.60.Cs, 21.10.Dr, 27.50.+e The nuclear shell-model interaction can in principle be derived microscopically from the free nucleon-nucleon force. In fact, such attempts were made in the early years for the beginning of the shell [1,2]. However, it was soon after realized that such an interaction fail to describe binding energies, excitation spectra, and transitions if many valence nucleons were considered. To reproduce experimental data, considerable efforts have been put forward to construct the so-called effective interactions, such as USD [3] and USDA/B [4] for the sd shell, KB3G [5] and GXPF1A [6] for the p f shell, and JUN45 [7] and jj4b [8] for the p f 5/2 g 9/2 model space. Each of these interactions is applicable to a given model space while mutual relations among them are obscure. On the other hand, it has been shown [9] that realistic effective interactions are dominated by the pairing plus quadrupole-quadrupole (P + QQ) terms with the monopole interaction. This finding not only makes the understanding of effective interactions in nuclei intuitive, but may also be used to unify effective interactions for different model spaces. In particular, one may begin to talk about universality for shell models.Along the lines of this thought, we have carried out shellmodel calculations using the extended P + QQ Hamiltonian combined with the monopole terms (EPQQM), which are regarded as corrections for the average monopole interaction. It has been demonstrated that despite of its simplicity, this EPQQM model works surprisingly well for different mass regions, for example, the proton-rich p f shell [10] and the p f 5/2 g 9/2 shell [11], the neutron-rich f pg shell [12], and the sd-p f shell region [13]. It has also been successfully applied to the neutron-rich nuclei around 132 Sn [14,15]. However, these calculations rely heavily on phenomenological adjustments on the monopole corrections. Consequently, the EPQQM model cannot describe binding energies or unusual structures such as the first excited 0 + state of Zn and Ge isotopes around N = 40 [16], and it essentially provides no information about the unconventional shell evolution in neutronrich nuclei.The monopole interaction is a crucial ingredient for successful shell-model calculations. It is defined as [17]where V JT ab,ab are the interaction matrix elements. The connection between the monopole interaction and the tensor force [18] was confirmed, which explains the shell evolution [19]. It was shown [20,21] shown by open and ...

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confidence: 56%

Toward a unified realistic shell-model Hamiltonian with the monopole-based universal force

et al. 2014

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“…Both interactions have successfully been used to describe the nuclear properties of N ≈ Z nuclei in the A = 64 − 80 mass region [32,66,67]. In the present calculations, the effective charges for proton and neutron have been taken as e p = 1.5e and e n = 0.5e, respectively, which provide a good agreement with the observed B(E2) values in A ∼ 70 nuclei [69,70]. Furthermore, the PMMU Hamiltonian has been modified so as to fit the higher spin states of 70 Se.…”

Section: B Comparison With Shell-model Calculationsmentioning

confidence: 52%

Simultaneous investigation of the T=1(Jπ=0+) and T=0(J

Morales¹,

Algora²,

Rubio³

et al. 2017

Phys. Rev. C

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Simultaneous investigation of the T = 1 (J π = 0 + ) and T = 0 (J π = 9 + ) β decays in The β decay of the odd-odd nucleus 70 Br has been investigated with the BigRIPS and EURICA setups at the Radioactive Ion Beam Factory (RIBF) of the RIKEN Nishina Center. The T = 0 (J π = 9 + ) and T = 1 (J π = 0 + ) isomers have both been produced in in-flight fragmentation of 78 Kr with ratios of 41.6(8)% and 58.4(8)%, respectively. A half-life of t 1/2 = 2157 +53 −49 ms has been measured for the J π = 9 + isomer from γ-ray time decay analysis. Based on this result, we provide a new value of the half-life for the J π = 0 + ground state of 70 Br, t 1/2 = 78.42 ± 0.51 ms, which is slightly more precise, and in excellent agreement, with the best measurement reported hitherto in the literature. For this decay, we provide the first estimate of the total branching fraction decaying through the 2 + 1 state in the daughter nucleus 70 Se, R(2 + 1 ) = 1.3 ± 1.1%. We also report four new low-intensity γ-ray transitions at 661, 1103, 1561, and 1749 keV following the β decay of the J π = 9 + isomer. Based on their coincidence relationships, we tentatively propose two new excited states at 3945 and 4752 keV in 70 Se with most probable spins and parities of J π = (6 + ) and (8 + ), respectively. The observed structure is interpreted with the help of shell-model calculations, which predict a complex interplay between oblate and prolate configurations at low excitation energies.

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“…The 9 Be( 70 Se, 66 Geγ), 9 Be( 70 Se, 69 Seγ), 9 Be( 70 Se,-65 Gaγ) and 9 Be( 69 As, 65 Gaγ) reactions were used in this work. These reactions occurred at a secondary target of 96 mg/cm 2 9 Be housed at the target position of the S800 spectrograph [20].…”

Section: Methodsmentioning

confidence: 99%

“…Examples of previous such studies in this region can be found in Refs. [6][7][8][9][10][11][12][13]. This paper discusses lifetime measurements of states in nuclei residing in the A ∼ 70, N ∼ Z region: 66 Ge, 69 Se and 65 Ga.…”

Section: Introductionmentioning

confidence: 99%

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Spectroscopy and lifetime measurements inGe66,Se69, and
Nichols
¹
,
Wadsworth
²
,
Bentley
³

et al. 2015
Phys. Rev. C
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Lifetimes of low-lying excited states have been measured in 66 Ge, 69 Se and 65 Ga using a γ-ray lineshape method. The results confirm the previously reported 7 − 1 state lifetime in 66 Ge. The lifetime of the yrast 5/2 − state in 65 Ga is measured for the first time. Lifetime measurements of two excited 3/2 − states in 69 Se are also reported. Two previously unobserved γ rays have been identified in 69 Se. γ-γ coincidence measurements have been used to place one of these in the level scheme. 69 Se excited state populations are compared to shell-model calculations using the GXPF1A interaction in the fp model space. Theoretical spectroscopic factors to excited states in 69 Se have identified three candidate levels for the origin of one of the new transitions.

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Collectivity in66Ge and68Ge via lifetime measurements

Cited by 13 publications

References 16 publications

Toward a unified realistic shell-model Hamiltonian with the monopole-based universal force

Toward a unified realistic shell-model Hamiltonian with the monopole-based universal force

Simultaneous investigation of the T=1(Jπ=0+) and T=0(J

Spectroscopy and lifetime measurements inGe66,Se69, and
Nichols
¹
,
Wadsworth
²
,
Bentley
³

et al. 2015
Phys. Rev. C
3
0
0
0
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Collectivity in66Ge and68Ge via lifetime measurements

Cited by 13 publications

References 16 publications

Toward a unified realistic shell-model Hamiltonian with the monopole-based universal force

Toward a unified realistic shell-model Hamiltonian with the monopole-based universal force

Simultaneous investigation of the T=1(Jπ=0+) and T=0(J

Spectroscopy and lifetime measurements inGe66,Se69, andNichols1, Wadsworth2, Bentley3 et al. 2015Phys. Rev. C3000View full textAdd to dashboardCite

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Spectroscopy and lifetime measurements inGe66,Se69, and
Nichols
¹
,
Wadsworth
²
,
Bentley
³

et al. 2015
Phys. Rev. C
3
0
0
0
View full text Add to dashboard Cite