Level densities and gamma-ray strength functions in 170,171,172-Yb

Agvaanluvsan, U ; Schiller, A ; Becker, J ; Bernstein, L ; Garrett, P ; Guttormsen, M ; Mitchell, G ; Rekstad, J ; Siem, S ; Voinov, A ; Younes, W

Lawrence Livermore National Laboratory

关键词: Nuclei;    Neutrons;    Even-Even Nuclei;    Strength Functions;    Resonance;   

DOI  :  10.2172/15014599
RP-ID  :  UCRL-TR-205726
RP-ID  :  W-7405-ENG-48
RP-ID  :  15014599

美国|英语

来源: UNT Digital Library

【 摘 要 】

Level densities and radiative strength functions in {sup 171}Yb and {sup 170}Yb nuclei have been measured using the {sup 171}Yb({sup 3}He{sup 3}He{gamma}){sup 171}Yb and {sup 171}Yb({sup 3}He,{alpha}{gamma}){sup 170}Yb reactions. New data on {sup 171}Yb are compared to a previous measurement for {sup 171}Yb from the {sup 172}Yb({sup 3}He,{alpha}{gamma}){sup 171}Yb reaction. Systematics of level densities and radiative strength functions in {sup 170,171,172}Yb are established. The entropy excess in {sup 171}Yb relative to the even-even nuclei {sup 170,172}Yb due to the unpaired neutron quasiparticle is found to be approximately 2k{sub B}. Results for the radiative strength function from the two reactions lead to consistent parameters characterizing the ''pygmy'' resonances. Pygmy resonances in the {sup 170,172}Yb populated by the ({sup 3}He,{alpha}) reaction appear to be split into two components for both of which a complete set of resonance parameters are obtained.