Photon scattering off 52Cr: Two-phonon E1 strength at the N = 28 shell closure?

Enders, J.; Brentano, P. von; Eberth, J.; Herzberg, R.‐D.; Huxel, N.; Lenske, H.; Neumann-Cosel, P. von; Nicolay, N.; Pietralla, N.; Prade, H.; Reif, J.; Richter, A.; Schlegel, C.; Schwengner, R.; Skoda, S.; Thomas, H. G.; Wiedenhöver, I.; Winter, G.; Zilges, A.

doi:10.1016/s0375-9474(98)00213-9

Cited by 37 publications

(14 citation statements)

References 60 publications

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“…In addition to the previously known dipole states, Pai et al, have added fourteen new dipole states in their investigation with much improved decay-characteristic values [12]. For some of these states, parity assignments were available from earlier measurements [19][20][21][22]. Because of the incomplete parity information, only limited conclusions could be drawn in this recent work [12].…”

Section: Data Analysis and Resultsmentioning

confidence: 99%

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Polarized photon scattering offCr52: Determining the parity ofJ=1states

et al. 2015

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The photoresponse of 52 Cr has been investigated in the energy range of 5.0 -9.5 MeV using the photon scattering technique at the HIγS facility of TUNL to complement previous work with unpolarized bremsstrahlung photon beams at the Darmstadt linear electron accelerator. The unambiguous parity determinations of the observed J = 1 states provides the basis needed to better understand the structure of the E1 and M 1 excitations. Theoretical calculations using the Quasiparticle Phonon Model incorporating self-consistent energy-density functional theory were performed to investigate the fragmentation pattern of the dipole strength below and around the neutron-emission threshold. These results compare very well with the experimental values.

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Section: Data Analysis and Resultsmentioning

confidence: 99%

“…This level has been investigated as a potential candidate for quadrupole-octupole two-phonon character [22]. The major part of the observed B(E1) ↑ in 52 Cr is distributed at ∼ 8 MeV excitation energy, with the strongest E1 transition at E x = 7897.4 keV.…”

Section: Data Analysis and Resultsmentioning

confidence: 99%

Polarized photon scattering offCr52: Determining the parity ofJ=1states

et al. 2015

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“…Figure 4 illustrates the strength distribution of the "pygmy" dipole resonances (E1) for heavy nuclei, like 138 Ba, 140 Ce, and 144 Sm (Zilges et al 2002). Lighter nuclei like 51 V, 52 Cr, 40 Ca, 48 Ca, and 56 Fe also show this type of concentration of electric dipole strength in the region of 6-7 MeV of photon energy (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).…”

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

confidence: 85%

“…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

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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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“…In addition, a tool which is very selective to its excitation, namely nuclear resonance fluorescence (NRF), is available. The main conclusion from systematic studies [2,3,[6][7][8] of this 1 − state in even spherical nuclei in different mass regions is that anharmonicity effects are rather weak, supporting a harmonic treatment of nuclear excitations. The next step in these studies should be the extension to spherical odd-mass nuclei.…”

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confidence: 82%

Strong Fragmentation of Low-Energy Electromagnetic Excitation Strength in117Sn

et al. 1999

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Results of nuclear resonance fluorescence experiments on117 Sn are reported. More than 50 γ transitions with Eγ < 4 MeV were detected indicating a strong fragmentation of the electromagnetic excitation strength. For the first time microscopic calculations making use of a complete configuration space for low-lying states are performed in heavy odd-mass spherical nuclei. The theoretical predictions are in good agreement with the data. It is concluded that although the E1 transitions are the strongest ones also M 1 and E2 decays contribute substantially to the observed spectra. During the last years the study of the properties of multi-phonon excitations in atomic nuclei has been one of the key topics in nuclear structure research. The main motivation for these studies is to gain insight into the applicability of a picture of harmonic excitations to a finite strongly interacting fermion system, like an atomic nucleus. At present, systematic experimental information on the properties of low-lying two-phonon states [1-3] as well as on two-phonon giant resonances [4,5] in even-even spherical nuclei is available.The 1 − component of a two-phonon quintuplet built up of collective quadrupole and octupole phonons, [2, is a very good candidate for the investigation of anharmonic properties of low-lying excited states. This state is practically a pure two-phonon state with very weak admixtures of other configurations [3]. In addition, a tool which is very selective to its excitation, namely nuclear resonance fluorescence (NRF), is available. The main conclusion from systematic studies [2,3,[6][7][8] [11] have been reported. From very general arguments one expects rather weak changes in the properties of collective vibrations when they are coupled to an odd quasiparticle. However, even the first NRF experiments indicate a rather strong fragmentation of the excitation strength. To minimize the number of possible excited levels it is imperative to consider this coupling of collective vibrations to an odd quasiparticle in a nucleus with ground state spin 1/2.In the present letter we report on NRF experiments on 117 Sn (J π g.s. = 1/2 + ) in which 59 transitions with E γ < 4.05 MeV have been observed. It is clear that a detailed theoretical analysis which provides information on the structure of the excited states, is necessary to explain the results of this experiment. For this reason a full microscopic calculation of the properties of multi-phonon states in heavy odd-mass spherical nuclei has been performed for the first time.Experimental results have been obtained at the bremsstrahlung NRF-facility at the 4.3 MV Dynamitron accelerator of the Stuttgart University [1]. The electron energy was 4

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Photon scattering off 52Cr: Two-phonon E1 strength at the N = 28 shell closure?

Cited by 37 publications

References 60 publications

Polarized photon scattering offCr52: Determining the parity ofJ=1states

Polarized photon scattering offCr52: Determining the parity ofJ=1states

Resonant absorption troughs in the gamma-ray spectra of QSO

Strong Fragmentation of Low-Energy Electromagnetic Excitation Strength in117Sn

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