Splitting of the pygmy dipole resonance in 138Ba and 140Ce observed in the (α,α′γ) reaction

被引：80

作者：

Endres, J. ^{[1
]}

Savran, D. ^{[2
,3
]}

van den Berg, A. M. ^{[3
]}

Dendooven, P. ^{[3
]}

Fritzsche, M. ^{[2
]}

Harakeh, M. N. ^{[3
,4
]}

Hasper, J. ^{[1
]}

Wortche, H. J. ^{[3
]}

Zilges, A. ^{[1
]}

机构：

[1] Univ Cologne, Inst Kernphys, D-50937 Cologne, Germany

[2] Tech Univ Darmstadt, Inst Kernphys, D-64289 Darmstadt, Germany

[3] Univ Groningen, Kernfys Versneller Inst, NL-9747 AA Groningen, Netherlands

[4] CNRS IN2P3, CEA DSM, GANIL, F-14076 Caen, France

来源：

PHYSICAL REVIEW C | 2009年 / 80卷 / 03期

关键词：

STRENGTH; ENERGY; ALPHA; MODES; EXCITATION; NUCLEI;

D O I：

10.1103/PhysRevC.80.034302

中图分类号：

O57 [原子核物理学、高能物理学];

学科分类号：

070202 ;

摘要：

The N = 82 nuclei Ce-140 and Ba-138 have been investigated by means of the (alpha,alpha',gamma) coincidence method to study the pygmy dipole resonance (PDR). The experiments have been performed at the AGOR cyclotron at KVI, Groningen, at a primary beam energy of E-alpha = 136 MeV. The Big-Bite Spectrometer and seven large-volume high-purity germanium detectors were used in coincidence to perform a simultaneous spectroscopy of the scattered alpha particles and the gamma decay. The comparison with results of nuclear resonance fluorescence experiments reveals a splitting of the PDR into two components. Up to about 6 MeV the same states that could be observed in (gamma,gamma') are also excited in alpha-scattering experiments, whereas the higher-lying states are missing in the (alpha,alpha',gamma) reaction. This indicates a structural splitting of the PDR into two modes with different underlying structure.

引用

页数：8

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