Search for two-octupole-phonon states in 208Pb

doi:10.1016/0375-9474(83)90310-X

Nuclear Physics A

Volume 407, Issues 1–2, 3–10 October 1983, Pages 98-126

https://doi.org/10.1016/0375-9474(83)90310-X Get rights and content

Abstract

A search for two-phonon octupole vibrational states in ²⁰⁸Pb was carried out using the ²⁰⁷Pb(n_th, γ) reaction at the High Flux Reactor of the Institut Laue-Langevin.

The conversion electron spectrum was scanned with the spectrometer BILL with a sensitivity of 20 μb in the 4–6 MeV interval. Coincidence and singles γ-ray measurements were performed at the end of the thermal neutron beam guide H22-F reaching a sensitivity of 80 μb for energies above 0.511 MeV. In addition the singles spectrum was investigated with the pair spectrometer at the tangential beam facility.

Levels have been observed at (energies in keV and parenthesis for tentative level identification and spin-parity assignments): 2614.4, 3⁻; 3997, (3⁻); 4084.7, 2⁺; 4253, (2⁻, 3⁻); 4704, (2⁻, 3⁻); (4882.0), (0⁺); (4904.9), (0⁺); 4935, 2⁺; (6343), (2⁺) and the 0⁻, 1⁻ capture state at 7367.9 keV. The 4882.0 keV level probably corresponds to the known two-neutron pairing vibration. Possible candidates for two-phonon octupole excitations are the (0⁺)(4904.9) and 2⁺ 4935 keV states. The nuclear field theory formalism is used to calculate branching ratios and energies for states in ²⁰⁸Pb under several assumptions. The most inimportant result of the comparison of theory and experiment is that the experimental properties of the 2⁺ 4935 keV state favour the interpretation of this state as a two-phonon octupole vibration rather than as a one-phonon non-collective quadrupole state.

References (39)

M. Nagao et al.
Phys. Lett.
(1971)
J.F. Ziegler et al.
Phys. Rev.
(1968)
J. Alster
Phys. Lett.
(1967)
G. Vallios
thesis
(1968)
M.B. Lewis
Nucl. Data Sheets
(1971)
D.R. Bes et al.
Nucl. Phys.
(1966)
J. Blomqvist
Phys. Lett.
(1970)
A.R. Barnett et al.
Phys. Rev.
(1969)
A.R. Barnett et al.
J. Phys. Soc. Jpn. Suppl.
(1973)
D.H. Feng et al.
Phys. Rev.
(1976)
A.M.R. Joye et al.
Phys. Rev. Lett.
(1977)
C.F. Moore et al.
Phys. Rev.
(1967)
P. Richard et al.
Phys. Rev.
(1969)
R. Richard et al.
Phys. Lett.
(1967)
P.R. Christensen, J.D. Garrett, O. Hansen, D. Hillis, O. Nathan and F. Videbaek, unpublished work [quoted in ref....
S. Landowne et al.
Phys. Lett.
(1977)

H.T. Motz and A. Jurney, private communication (1967) [see ref....

V.F. Trusov

Nucl. Data Tables

(1972)

J. Bardwick et al.

Phys. Rev.

(1967)

M. Dost et al.

Phys. Lett.

(1968)

D.C. Nellis et al.

Bull. Am. Phys. Soc.

(1970)

H.R. Koch et al.

Nucl. Instr.

(1980)

D.R. Bes et al.

Phys. Lett.

(1974)

D.R. Bes et al.

Nucl. Phys.

(1976)

C.M. Lederer et al.

Table of isotopes

(1978)

P. Kleinheinz et al.

Phys. Rev. Lett.

(1982)

K. Wienhard et al.

Phys. Rev. Lett.

(1982)

Cited by (20)

Evidence of octupole-phonons at high spin in 207Pb
2019, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
A lifetime measurement of the $19 / 2^{-}$ state in ²⁰⁷Pb has been performed using the Recoil Distance Doppler-Shift (RDDS) method. The nuclei of interest were produced in multi-nucleon transfer reactions induced by a ²⁰⁸Pb beam impinging on a ¹⁰⁰Mo enriched target. The beam-like nuclei were detected and identified in terms of their atomic mass number in the VAMOS++ spectrometer while the prompt γ rays were detected by the AGATA tracking array. The measured large reduced transition probability $B (E 3, 19 / 2^{-} \to 13 / 2^{+}) = 40 (8)$ W.u. is the first indication of the octupole phonon at high spin in ²⁰⁷Pb. An analysis in terms of a particle-octupole-vibration coupling model indicates that the measured $B (E 3)$ value in ²⁰⁷Pb is compatible with the contributions from single-phonon and single particle E3 as well as E3 strength arising from the double-octupole-phonon $6^{+}$ state, all adding coherently. A crucial aspect of the coupling model, namely the strong mixing between single-hole and the phonon-hole states, is confirmed in a realistic shell-model calculation.
Nuclear Data Sheets for A = 208
2007, Nuclear Data Sheets
Detailed level schemes, decay schemes, and the experimental data on which they are based are presented for all nuclei with mass number A = 208. The experimental data are evaluated; inconsistencies and discrepancies are noted; and adopted values for level and γ-ray energies, γ intensities, as well as for other nuclear properties are given. This evaluation replaces the A = 208 evaluation published by M.J. Martin in Nuclear Data Sheets 47, 797 (1986).
New experimental access to the two-phonon octupole vibration in 208Pb
1997, Nuclear Physics A
The feasibility of a new experimental method to identify two-phonon octupole vibrations is investigated for the example of ²⁰⁸Pb. The 2⁺ member of the 3_I⁻ ⊗ 3_I⁻ multiplet can be excited with the (γ, γ′) reaction and a sizable E1 decay to the 3_I⁻ level serves as a signature of the two-phonon character. Numerical estimates within the quasiparticle-phonon model indicate that such an experiment should be possible with state-of-the-art large volume Ge detectors like the EUROBALL cluster module.
Two-octupole-phonon states in 208Pb
1991, Nuclear Physics, Section A
The so-called “two-octupole-phonon states” in ²⁰⁸Pb are theoretically analyzed by using the Dyson boson mapping method for the collective multi-phonon space consisting of collective octupole phonons, collective quadrupole phonons and collective monopole pairing phonons. The effective hamiltonian used is constituted by a Woods-Saxon-type single-particle potential, monopole pairing forces for neutrons and protons, a quadrupole-quadrupole force and an octupole-octupole force. The numerical calculation reasonably reproduces the experimental low-energy spectrum and E2 and E3 transitions in ²⁰⁸Pb, and we can get a good understanding on the low-energy collective properties in ²⁰⁸Pb.
On the states 3-⊗3- in 208Pb
1988, Physics Letters B
Nuclear Data Sheets for A = 208
1986, Nuclear Data Sheets

View all citing articles on Scopus

^∗: Fellow of the Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina.

^∗∗: Present address: Department of Physics, Technische Universität München, Garching D-8046, West Germany.

^∗∗∗: Present address: Department of Physics, Brookhaven National Laboratory, Upton, NY 11973, USA.

View full text

Article preview

Nuclear Physics A

Abstract

References (39)

Phys. Lett.

Phys. Rev.

Phys. Lett.

thesis

Nucl. Data Sheets

Nucl. Phys.

Phys. Lett.

Phys. Rev.

J. Phys. Soc. Jpn. Suppl.

Phys. Rev.

Phys. Rev. Lett.

Phys. Rev.

Phys. Rev.

Phys. Lett.

Phys. Lett.

Nucl. Data Tables

Phys. Rev.

Phys. Lett.

Bull. Am. Phys. Soc.

Nucl. Instr.

Phys. Lett.

Nucl. Phys.

Table of isotopes

Phys. Rev. Lett.

Phys. Rev. Lett.

Cited by (20)

Evidence of octupole-phonons at high spin in <sup>207</sup>Pb

Nuclear Data Sheets for A = 208

New experimental access to the two-phonon octupole vibration in <sup>208</sup>Pb

Two-octupole-phonon states in <sup>208</sup>Pb

On the states 3<sup>-</sup>⊗3<sup>-</sup> in <sup>208</sup>Pb

Nuclear Data Sheets for A = 208