Isospin mixing in the electroexcitation of the Ex = 10.84 MeV, Jπ; T = 1−; 0 state in 12C at low momentum transfers

Campos, M.C.A.; Neumann-Cosel, P. von; Neumeyer, F.; Richter, A.; Schrieder, G.; Spamer, E.; Brown, B. A.; Peterson, R.J.

doi:10.1016/0370-2693(95)00252-g

Cited by 8 publications

(4 citation statements)

References 23 publications

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“…Ref. e 2 fm 2 ) (e,e ) [ 7] 1 .684 (7) 217(10) 0.027(2) (e,e ) [ 8] 1 .68 (15) 200 (20) 0.034(3) (γ ,n) [ 6] 1 .750 (10) 283(42) 0.0535(35) (e,e ) [ 11] 1 .732 270 0.0685 β decay [9] 1 .689 (10) 224 7-(e,e ) Present work 1.748 (6) 274(8) 0.027 (2) between the strengths deduced from the real photon and virtual photon experiments is unknown. Furthermore, Barker [11] reanalyzed the (e,e ) data of [7] and extracted resonance parameters that differ considerably from those quoted in the original paper (see Table I).…”

Section: Reactionmentioning

confidence: 99%

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Resonance parameters of the first1/2+state inBe9and astrophysica

et al. 2010

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Spectra of the 9 Be(e,e) reaction have been measured at the Superconducting Darmstadt Electron Linear Accelerator at an electron energy of E 0 = 73 MeV and scattering angles of 93 • and 141 • with high-energy resolution up to excitation energies of E x = 8 MeV. The astrophysically relevant resonance parameters of the first excited 1/2 + state of 9 Be have been extracted in a one-level approximation of R-matrix theory, resulting in resonance energy E R = 1.748(6) MeV and width R = 274(8) keV, which are in good agreement with the latest 9 Be(γ ,n) experiment but with considerably improved uncertainties. However, the reduced B(E1) transition strength deduced from an extrapolation of the (e,e) data to the photon point is smaller by a factor of two. Implications of the new results for possible production of 12 C in neutron-rich astrophysical scenarios are discussed.

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Section: Reactionmentioning

confidence: 99%

“…A similar calculation of an E1 longitudinal form factor for a transition in 12 C is described in Ref. [20]. Spurious states are removed with the Gloeckner-Lawson method [21].…”

Section: B Extraction Of Equivalent (γ N) Cross Sections and B(e1)mentioning

confidence: 99%

Resonance parameters of the first1/2+state inBe9and astrophysica

et al. 2010

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“…A similar calculation of an E1 longitudinal form factor for a transition in 12 C is described in Ref. [20]. Spurious states are removed with the Gloeckner-Lawson method [21].…”

Section: A One-level R-matrix Approximationmentioning

confidence: 99%

Resonance parameters of the first 1/2+ state in 9Be and astrophysical implications

Burda,

von Neumann-Cosel,

Richter

et al. 2010

Preprint

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Spectra of the 9 Be(e, e ′ ) reaction have been measured at the S-DALINAC at an electron energy E0 = 73 MeV and scattering angles of 93 • and 141 • with high energy resolution up to excitation energies Ex = 8 MeV. The astrophysically relevant resonance parameters of the first excited 1/2 + state of 9 Be have been extracted in a one-level approximation of R-matrix theory resulting in a resonance energy ER = 1.748(6) MeV and width ΓR = 274(8) keV in good agreement with the latest 9 Be(γ, n) experiment but with considerably improved uncertainties. However, the reduced B(E1) transition strength deduced from an extrapolation of the (e, e ′ ) data to the photon point is a factor of two smaller. Implications of the new results for a possible production of 12 C in neutron-rich astrophysical scenarios are discussed.

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“…Both conditions are, e.g., fulfilled at the S-DALINAC (Superconducting Darmstadt Electron Linear Accelerator) and its spectrometers LINTOTT and Q-CLAM [14]. Some selective excitations of isoscalar and isovector electric dipole transitions below the electric giant resonance region were, e.g., investigated in 12 C, 16 O, 40 Ca and 208 Pb [15,16,17,18]. Furthermore, some benchmark high-resolution (e, e x) experiments with x = p, n, α and the decay of the Giant Dipole Resonance (GDR) in the doubly magic nuclei 40 Ca and 48 Ca were also performed at the S-DALINAC [19,20,21,22,23] but in general, the information on the observation of detailed strength distributions of 1 − states in the (e, e ) reactions is very sparse.…”

Section: Introductionmentioning

confidence: 99%

Excitation of the electric pygmy dipole resonance by inelastic electron scattering⋆

et al. 2019

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To complete earlier studies of the properties of the electric pygmy dipole resonance (PDR) obtained in various nuclear reactions, the excitation of the 1 − states in 140 Ce by (e, e ) scattering for momentum transfers q = 0.1 − 1.2 fm −1 is calculated within the plane-wave and distorted-wave Born approximations. The excited states of the nucleus are described within the Quasiparticle Random Phase Approximation (QRPA), but also within the Quasiparticle-Phonon Model (QPM) by accounting for the coupling to complex configurations. It is demonstrated that the excitation mechanism of the PDR states in (e, e ) reactions is predominantly of transversal nature for scattering angles θe ≈ 90 o − 180 o . Being thus mediated by the convection and spin nuclear currents, the (e, e ) like the (γ, γ ) reaction, may provide additional information to the one obtained from Coulomb-and hadronic excitations of the PDR in (p, p ), (α, α ), and heavy-ion scattering reactions. The calculations predict that the (e, e ) cross sections for the strongest individual PDR states are in general about three orders of magnitude smaller as compared to the one of the lowest 2 + 1 state for the studied kinematics, but that they may become dominant at extreme backward angles. PACS. 25.30.Dh Inelastic electron scattering to specific statesDedicated to Pier Francesco Bortignon

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Isospin mixing in the electroexcitation of the Ex = 10.84 MeV, Jπ; T = 1−; 0 state in 12C at low momentum transfers

Cited by 8 publications

References 23 publications

Resonance parameters of the first1/2+state inBe9and astrophysica

Resonance parameters of the first1/2+state inBe9and astrophysica

Resonance parameters of the first 1/2+ state in 9Be and astrophysical implications

Excitation of the electric pygmy dipole resonance by inelastic electron scattering⋆

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