Two-phonon1−state inSn112observed in resonant photon scattering

Systematics of the pygmy dipole resonance in stable tin isotopes from resonant photon scattering

“…2 shows the B(E1) strength of all observed ground state dipole transitions up to 9.5 MeV. The lowest transition results from the population of the two-phonon state [18,19] at 3434 keV. The strongest transitions are located between 6 and 7 MeV.…”

Low-energy dipole strength inSn112,120

“…The spin of the excited states can be determined by comparing the intensities of a given line measured simultanously at different scattering angles. Figure 3 [63] J π = 2 + states and full circles to states with unknown spin except for the quadrupole-octupole two-phonon 1 − states [64,65]. We note in passing that that for the assumed two-phonon 1 − state in 112 Sn, the four-fold segmentation of the 90 • detector [67] was used to extract the multipole character of the transition.…”

“…The corresponding centroid energies of the low-energy E1 strength are 6.74 and 6.60 MeV for 112 Sn and 120 Sn, respectively. The twophonon states [64,65] are not included in the EWSR and centroid values. A comparison with the previous NRF measurements on 116,124 Sn [38] up to 10 MeV endpoint is given in Tab.…”

Decay of quadrupole-octupole1−states inCa40andCe140Derya1, Tsoneva2, Aumann3 et al. 2016Phys. Rev. C12120View full textAdd to dashboardCite

“…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].…”