| 1. |
- Kishida, T., et al.
(författare)
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High-spin isomeric beam line
- 2002
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576. ; 484:03-jan, s. 45-55
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Tidskriftsartikel (refereegranskat)abstract
- A high-spin isomeric beam line has been constructed at RIKEN based on the inverse kinematics of fusion-evaporation reactions. The beam line provides high-spin isomers as secondary beams, whose intensity is more than 10(5) sec(-1). The characteristics and the present status of the beam line are described.
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| 2. |
- Gono, Y., et al.
(författare)
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Systematics of high-spin isomers in N=83 isotones and a high-spin isomer beam
- 2002
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Ingår i: European Physical Journal A. - 1434-6001 .- 1434-601X. ; 13:02-jan, s. 5-8
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Tidskriftsartikel (refereegranskat)abstract
- Isomers in N = 83 isotones of Z = 60 66 were studied systematically. Their spins and parities arc,49/2(+) and 27(+) for odd and odd-odd nuclei, respectively. Nearly constant excitation energies of these isomers indicated a decrease of a Z = 64 shell gap energy as Z decreases from 64 to 60 within the framework of a deformed independent-particle model (DIPM). Their configurations are [v(f(tau/2)h(9/2)i(13/2)), pi(h(11/2))(2)](49/2+) and [v(f(7/2)h(9/2)i(13/2)), pi(h(11/2))(2)(d(5/2))(-1)](27+) for odd and odd-odd nuclei, respectively. The shape of the yrast status changes suddenly at spin 49/2(odd) and 27(odd-odd) from a near spherical to an oblate shape. Transitions from isomers are highly hindered because of the shape changes. They may be categorized to be shape isomers. The development of a secondary beam produced by using these high-spin isomers is also described.
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| 3. |
- Ideguchi, E., et al.
(författare)
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Position sensitivity of a segmented planar Ge detector
- 2003
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576. ; 496:03-feb, s. 373-384
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Tidskriftsartikel (refereegranskat)abstract
- A method to extract depth of interaction information for gamma-rays in a segmented planar Ge detector is presented. The method is demonstrated on signals from a segmented detector which were stored by a digital oscilloscope event by event and analysed off-line. Event samples were acquired for different interaction points in the detector. A Compton scatter coincidence detection technique ensured that the event samples were highly enriched in single-interaction events. By analysing pulse shapes and the relative timing between anode pulses and the pulses from the irradiated cathode segment, a position sensitivity of 1-2 mm in the depth direction was deduced. A similar transverse position sensitivity was inferred by studying image charge pulses on neighbouring segments.
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| 4. |
- Milanović, T., et al.
(författare)
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Lifetime measurements of low-lying states in 73Ga and 70,72,74Zn isotopes
- 2020
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Ingår i: Acta Physica Polonica B. - 0587-4254. ; 51:3, s. 837-842
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Tidskriftsartikel (refereegranskat)abstract
- Lifetimes of low-lying states in 73Ga and 70,72,74Zn were measured using the Recoil Distance Doppler Shift (RDDS) method. These nuclei were produced in deep-inelastic reactions in inverse kinematics with a 208Pb beam impinging on a 76Ge target. Prompt γ rays were detected using the AGATA tracking array coupled to the VAMOS++ spectrometer. Lifetime of the 5/2- state in 73Ga, measured for the first time, provides additional evidence for the existence of a 1/2-, 3/2- ground-state doublet. The lifetimes of the 4+ states in 70,72,74Zn were remeasured in an attempt to understand the discrepancies observed between earlier measurements. Our results are in agreement with those of previous plunger experiments.
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| 5. |
- Shimoura, S., et al.
(författare)
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Lifetime of the isomeric O-2(+) state in Be-12
- 2007
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Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 654:3-4, s. 87-91
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Tidskriftsartikel (refereegranskat)abstract
- Mean lifetime tau of the isomeric O-2(+) state in Be-12 has been determined by measuring decay spectra of delayed y-rays from stopped Be-12 2 nuclei produced by the projectile fragmentation of O-18 at 100 A MeV. A consistent value of tau = 331 +/- 12 ns was obtained from the time spectra of the E2 gamma decay to the 2(1)(+) state and the positron annihilation following the E0 decay to the ground state. Based on the observed branching ratio between the E2 and E0 decays, transition strengths of the two decay modes were deduced to be B(E2; O-2(+) -> 2(1)(+)) = 7.0 +/- 0.6 e(2) fm(4) and 2 1 1 (O-2(+) Sigma(i) e(i) r(i)(2) O-1(+)), = 0.87 +/- 0.03 e fM(2), respectively. (C) 2007 Elsevier B.V. All rights reserved.
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| 6. |
- Cederwall, Bo, 1964-, et al.
(författare)
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Lifetime Measurements of Excited States in Pt-172 and the Variation of Quadrupole Transition Strength with Angular Momentum
- 2018
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 121:2
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Tidskriftsartikel (refereegranskat)abstract
- Lifetimes of the first excited 2(+) and 4(+) states in the extremely neutron -deficient nuclide Pt-172 have been measured for the first time using the recoil-distance Doppler shift and recoil-decay tagging techniques. An unusually low value of the ratio B(E2: 4(1)(+) -> 2(1)(+)/B(E2: 2(1)(+) -> 0(gs)(+)) = 0.55(19) was found, similar to a handful of other such anomalous cases observed in the entire Segre chart. The observation adds to a cluster of a few extremely neutron -deficient nuclides of the heavy transition metals with neutron numbers N approximate to 90-94 featuring the effect. No theoretical model calculations reported to date have been able to explain the anomalously low B(E2: 4(1)(+) -> 2(1)(+)/B(E2: 2(1)(+) -> 0(gs)(+)) ratios observed in these cases. Such low values cannot, e.g., be explained within the framework of the geometrical collective model or by algebraic approaches within the interacting boson model framework. It is proposed that the group of B(E2: 4(1)(+) -> 2(1)(+)/B(E2: 2(1)(+) -> 0(gs)(+)) ratios in the extremely neutron-deficient even-even W, Os, and Pt nuclei around neutron numbers N approximate to 90-94 reveal a quantum phase transition from a seniority-conserving structure to a collective regime as a function of neutron number. Although a system governed by seniority symmetry is the only theoretical framework for which such an effect may naturally occur, the phenomenon is highly unexpected for these nuclei that are not situated near closed shells.
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| 7. |
- Ertoprak, Aysegul, et al.
(författare)
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Evidence for octupole collectivity in 172Pt
- 2020
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Ingår i: European Physical Journal A. - : Springer. - 1434-6001 .- 1434-601X. ; 56:2
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Tidskriftsartikel (refereegranskat)abstract
- Excited states in the extremely neutron-deficient nucleus 172Pt were populated via 96Ru(78Kr,2p) and 92Mo(83Kr,3n) reactions. The level scheme has been extended up to an excitation energy of ~ 5 MeV and tentative spin-parity assignments up to Iπ = 18+. Linear polarization and angular distribution measurements were used to determine the electromagnetic E1 character of the dipole transitions connecting the positive-parity ground-state band with an excited side-band, firmly establishing it as a negative-parity band. The lowest member of this negative-parity structure was firmly assigned spin-parity 3-. In addition, we observed an E3 transition from this 3- state to the ground state, providing direct evidence for octupole collectivity in 172Pt. Large-scale shell model (LSSM) and total Routhian surface (TRS) calculations have been performed, supporting the interpretation of the 3- state as a collective octupole-vibrational state.
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| 8. |
- Ideguchi, E., et al.
(författare)
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Orbifold projection in supersymmetric QCD at N(f) ≤ N(c)
- 2000
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Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 492:3-4, s. 369-375
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Tidskriftsartikel (refereegranskat)abstract
- Supersymmetric orbifold projection of N = 1 SQCD with relatively small number of flavors (N(f) ≤ N(c)) is considered. The purpose is to check whether orbifolding commutes with the infrared limit. On the one hand, one considers the orbifold projection of SQCD and obtains the low-energy description of the resulting theory. On the other hand, one starts with the low-energy effective theory of the original SQCD, and only then performs orbifolding. It is shown that at finite N(c) the two low-energy theories obtained in these ways are different. However, in the case of stabilized run-away vacuum these two theories are shown to coincide in the large N(c) limit. In the case of quantum modified moduli space, topological solitons carrying baryonic charges are present in the orbifolded low-energy theory. These solitons may restore the correspondence between the two theories provided that the soliton mass tends to zero in the large N(c) limit. (C) 2000 Elsevier Science B.V.
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| 9. |
- Ideguchi, E., et al.
(författare)
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Study of high-spin states in 48Ca region induced by secondary fusion reactions
- 2005
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Konferensbidrag (refereegranskat)abstract
- A new method of in-beam gamma-ray spectroscopy induced by secondary fusion reactions, 37P+9Be and 46Ar+9Be is presented. Low-energy secondary beams of 37P and 46Ar ions of ∼5 MeV/A were developed in order to induce fusion evaporation reactions. Excited states of nuclei in the vicinity of 48Ca, 49-52Ti and 46Ca, were studied by the method as well as β decay of the secondary beam 46Ar. Gamma-gamma coincidence and excitation function analysis were performed to study high-spin states of Ti isotopes.
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| 10. |
- Ideguchi, E, et al.
(författare)
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Study of high-spin states in the Ca-48 region by using secondary fusion reactions
- 2005
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Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 25, s. 429-430
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Tidskriftsartikel (refereegranskat)abstract
- An in-beam gamma-ray spectroscopy study, following a fusion reaction induced by a neutronrich secondary beam, Ar-46 + Be-9, is presented. A low-energy secondary beam of Ar-46 at similar to 5 MeV/A was developed in order to induce fusion reactions. Gamma-gamma coincidence and excitation function analysis was performed to study high-spin states in the vicinity of Ca-48, Ti49-52.
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