New evidence for the E1 core polarization in spherical nuclei

Andrejtscheff, W.; Kohstall, C.; Brentano, P. von; Fransen, C.; Kneißl, U.; Pietralla, N.; Pitz, H. H.

doi:10.1016/s0370-2693(01)00340-9

Cited by 60 publications

(36 citation statements)

References 48 publications

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“…the photoproduction threshold can be produced: first, via photon absorption to the excitation level of the nuclei (Hanna & Meyer-Schützmeister 1959;Axel 1962;Hayward 1977) and, second, via the photon capture into the so-called "pygmy" dipole resonance (PDR) (Bohr & Mottelson 1975;Suzuki et al 1990;Van Isacker et al 1992;Enders et al 1998;Bauwens et al 2000;Kaiser et al 2000;Andrejscheff et al 2001;Babilon et al 2002;Hartmann et al 2002;Pietralla et al 2002;Zilges et al 2002). The integrated cross section for the level excited by a γ-ray with energy E = hc/λ is usually expressed in terms of the ground state width Γ 0 :…”

Section: A2 Total Absorption Cross Section In the Giant Dipole Resomentioning

confidence: 99%

Resonant absorption troughs in the gamma-ray spectra of QSO

Iyudin

Reimer

Burwitz

et al. 2005

A&A

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Abstract. We report the very first evidence of the possible detection of γ-ray resonant absorption along the line of sight towards γ-ray bright quasars (QSOs), like 3C 279, 3C 273, PKS 0528+0134, and BL Lacertae. These detections resulted from the analysis of COMPTEL and EGRET data that were collected either during monitoring campaigns of the Virgo and galactic anticenter regions by the Compton Gamma Ray Observatory (CGRO) or during ToO observations of QSOs flares. We discuss three resonant absorption mechanisms that affect the γ-ray spectrum of point-like sources when crossing the surrounding warm and cold absorbers, as well as the potential of this γ-ray photon absorption method to constrain the abundance of the absorber. We detected two absorbers along the line of sight towards γ-ray bright QSOs, one at the QSO rest frame redshift and another at approximately zero redshift. We tentatively identify the latter with an absorber in the Galactic halo, while the former is undoubtedly caused by photon absorption in the host galaxy of the QSO. We discuss the advantages and drawbacks of this method in studies of absorbers in different astrophysical environments and compare this new method to absorber studies at X-ray or other wavelengths. We applied this γ-ray absorption method to identify a few of the EGRET unidentified (EUID) sources as QSOs, and determine their redshifts.

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Section: A2 Total Absorption Cross Section In the Giant Dipole Resomentioning

confidence: 99%

Resonant absorption troughs in the gamma-ray spectra of QSO

Iyudin

Reimer

Burwitz

et al. 2005

A&A

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“…In the last years, the B(E1) strength distributions of many nuclei were measured using this method. The evaluated data serve as a systematic basis for the discussion of two-phonon E1 excitations like, e.g., in the Sn isotopes [7,47], for N = 82 isotones [48] and in the compilation of Andrejtscheff et al [49] for A = 48 − 148 nuclei. An alternative way to determine B(E1) strengths in particular for states of rare isotopes, for which NRF measurements are difficult, are lifetime measurements using the Doppler-shift attenuation method (DSAM) in particle-γ coincidence measurements [50].…”

Section: Introductionmentioning

confidence: 99%

Decay of quadrupole-octupole1−states inCa40andCe140
Derya
¹
,
Tsoneva
²
,
Aumann
³

et al. 2016
Phys. Rev. C
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“…is obtained which results in a similar value for the B(E1) ratio. Nevertheless, for most even-even nuclei where candidates for the J π = 1 − member of the quintuplet have been proposed, the excitation energy has been found to be systematically lower by about 5-10% compared to the sum energy of the constituent phonons [57,58]. Thus, it is more likely that the state at E x = 3282 keV represents the main fragment of the (2…”

Section: Table I: Levels Inmentioning

confidence: 99%

Collective excitations ofRu96by means of(p,p′γ)experiments

et al. 2015

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Background: One-phonon mixed-symmetry quadrupole excitations are a well-known feature of near-spherical, vibrational nuclei. Their interpretation as a fundamental building block of vibrational structures is supported by the identification of multi-phonon states resulting from a coupling of fullysymmetric and mixed-symmetric quadrupole phonons. In addition, the observation of strong M 1 transitions between low-lying 3 − and 4 + states has been interpreted as an evidence for one-phonon mixed-symmetry excitations of octupole and hexadecapole character. Purpose: The aim of the present study is to identify collective one-and two-phonon excitations in the heaviest stable N = 52 isotone 96 Ru based on a measurement of absolute M 1, E1, and E2 transition strengths. Methods: Inelastic proton-scattering experiments have been performed at the Wright Nuclear Structure Laboratory (WNSL), Yale University, and the Institute for Nuclear Physics (IKP), University of Cologne. From the acquired proton-γ and γγ coincidence data we deduced spins of excited states, γ-decay branching ratios, and multipole mixing ratios, as well as lifetimes of excited states via the Doppler-shift attenuation method (DSAM). Results: Based on the new experimental data on absolute transition strengths, we identified the 2 + and 3 + members of the two-phonon mixed-symmetry quintuplet (2 + 1,ms ⊗ 2 + 1,s ). Furthermore, we observed strong M 1 transitions between low-lying 3 − and 4 + states suggesting one-phonon symmetric and mixed-symmetric octupole and hexadecapole components in their wave functions, respectively. The experimental results are compared to sdg-IBM-2 and shell-model calculations. Conclusions: Both, the sdg-IBM-2 and the shell-model calculations, are able to describe key features of mixed-symmetry excitations of 96 Ru. Moreover, they support the one-phonon mixedsymmetry hexadecapole assignment of the experimental 4 + 2 state.

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New evidence for the E1 core polarization in spherical nuclei

Cited by 60 publications

References 48 publications

Resonant absorption troughs in the gamma-ray spectra of QSO

Resonant absorption troughs in the gamma-ray spectra of QSO

Decay of quadrupole-octupole1−states inCa40andCe140
Derya
¹
,
Tsoneva
²
,
Aumann
³

et al. 2016
Phys. Rev. C
Self Cite
12
1
2
0
View full text Add to dashboard Cite

Collective excitations ofRu96by means of(p,p′γ)experiments

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New evidence for the E1 core polarization in spherical nuclei

Cited by 60 publications

References 48 publications

Resonant absorption troughs in the gamma-ray spectra of QSO

Resonant absorption troughs in the gamma-ray spectra of QSO

Decay of quadrupole-octupole1−states inCa40andCe140Derya1, Tsoneva2, Aumann3 et al. 2016Phys. Rev. CSelf Cite12120View full textAdd to dashboardCite

Collective excitations ofRu96by means of(p,p′γ)experiments

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Decay of quadrupole-octupole1−states inCa40andCe140
Derya
¹
,
Tsoneva
²
,
Aumann
³

et al. 2016
Phys. Rev. C
Self Cite
12
1
2
0
View full text Add to dashboard Cite