Observation of isoscalar and isovector dipole excitations in neutron-rich 20O

被引：25

作者：

Nakatsuka, N. ^{[1
,2
]}

Baba, H. ^{[2
]}

Aumann, T. ^{[3
,4
]}

Avigo, R. ^{[5
,6
]}

Banerjee, S. R. ^{[7
]}

Bracco, A. ^{[5
,6
]}

Caesar, C. ^{[3
,4
]}

Camera, F. ^{[5
,6
]}

Ceruti, S. ^{[5
,6
]}

Chen, S. ^{[2
,8
,9
]}

Derya, V. ^{[10
]}

Doornenbal, P. ^{[2
]}

Giaz, A. ^{[5
,6
]}

Horvat, A. ^{[3
,4
]}

Ieki, K. ^{[11
]}

Inakura, T. ^{[12
]}

Imai, N. ^{[13
]}

Kawabata, T. ^{[1
]}

Kobayashi, N. ^{[14
]}

Kondo, Y. ^{[15
]}

Koyama, S. ^{[14
]}

Kurata-Nishimura, M. ^{[2
]}

Masuoka, S. ^{[13
]}

Matsushita, M. ^{[13
]}

Michimasa, S. ^{[13
]}

Million, B. ^{[5
]}

Motobayashi, T. ^{[2
]}

Murakami, T. ^{[1
]}

Nakamura, T. ^{[15
]}

Ohnishi, T. ^{[2
]}

Ong, H. J. ^{[16
]}

Ota, S. ^{[13
]}

Otsu, H. ^{[2
]}

Ozaki, T. ^{[15
]}

Saito, A. ^{[15
]}

Sakurai, H. ^{[2
,14
]}

Scheit, H. ^{[3
]}

Schindler, F. ^{[3
,4
]}

Schrock, P. ^{[3
]}

Shiga, Y. ^{[2
,11
]}

Shikata, M. ^{[15
]}

Shimoura, S. ^{[13
]}

Steppenbeck, D. ^{[2
]}

Sumikama, T. ^{[2
]}

Syndikus, I. ^{[3
,4
]}

Takeda, H. ^{[2
]}

Takeuchi, S. ^{[2
]}

Tamii, A. ^{[16
]}

Taniuchi, R. ^{[14
]}

Togano, Y. ^{[15
]}

机构：

[1] Kyoto Univ, Dept Phys, Kyoto 6068502, Japan

[2] RIKEN, Nishina Ctr, Saitama 3510198, Japan

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

[4] GSI Helmholtzzentrum Schwerionenforsch GmbH, D-64291 Darmstadt, Germany

[5] Ist Nazl Fis Nucl, Sez Milano, I-20133 Milan, Italy

[6] Univ Milan, Dipartimento Fis, I-20133 Milan, Italy

[7] Variable Energy Cyclotron Ctr, 1-AF, Kolkata 700064, India

[8] Peking Univ, Sch Phys, Beijing 100871, Peoples R China

[9] Peking Univ, State Key Lab Nucl Phys & Technol, Beijing 100871, Peoples R China

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

[11] Rikkyo Univ, Dept Phys, Tokyo 1718501, Japan

[12] Niigata Univ, Dept Phys, Niigata 9502181, Japan

[13] Univ Tokyo, Ctr Nucl Study, Tokyo 1130033, Japan

[14] Univ Tokyo, Dept Phys, Tokyo 1130033, Japan

[15] Tokyo Inst Technol, Dept Phys, Tokyo 1528551, Japan

[16] Osaka Univ, Res Ctr Nucl Phys, Osaka 5670047, Japan

来源：

PHYSICS LETTERS B | 2017年 / 768卷

关键词：

O-20; Low-energy dipole excitation; Inelastic alpha scattering; Virtual-photon excitation; STRENGTH; CA-40; SPECTROSCOPY; RESONANCE; STATES; BEAMS;

D O I：

10.1016/j.physletb.2017.03.017

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

The isospin characters of low-energy dipole excitations in neutron-rich unstable nucleus O-20 were investigated, for the first time in unstable nuclei. Two spectra obtained from a dominant isovector probe (O-20 + Au) and a dominant isoscalar probe (O-20 + alpha) were compared and analyzed by the distorted-wave Born approximation to extract independently the isovector and isoscalar dipole strengths. Two known 1(-) states with large isovector dipole strengths at energies of 5.36(5) MeV (1(1)(-)) and 6.84(7) MeV (1(2)(-)) were also excited by the isoscalar probe. These two states were found to have different isoscalar dipole strengths, 2.70(32)%(1(1)(-)) and 0.67(12)%(1(2)(-)), respectively, in exhaustion of the isoscalar dipole-energy-weighted sum rule. The difference in isoscalar strength indicated that they have different underlying structures. (C) 2017 The Author(s). Published by Elsevier B.V.

引用

页码：387 / 392

页数：6

共 37 条

[1] GEANT4-a simulation toolkit
Agostinelli, S
Allison, J
Amako, K
Apostolakis, J
Araujo, H
Arce, P
Asai, M
Axen, D
Banerjee, S
Barrand, G
Behner, F
Bellagamba, L
Boudreau, J
Broglia, L
Brunengo, A
Burkhardt, H
Chauvie, S
Chuma, J
Chytracek, R
Cooperman, G
Cosmo, G
Degtyarenko, P
Dell'Acqua, A
Depaola, G
Dietrich, D
Enami, R
Feliciello, A
Ferguson, C
Fesefeldt, H
Folger, G
Foppiano, F
Forti, A
Garelli, S
Giani, S
Giannitrapani, R
Gibin, D
Cadenas, JJG
González, I
Abril, GG
Greeniaus, G
Greiner, W
Grichine, V
Grossheim, A
Guatelli, S
Gumplinger, P
Hamatsu, R
Hashimoto, K
Hasui, H
Heikkinen, A
Howard, A
[J]. NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, 2003, 506 (03) : 250 - 303
[2] A self-consistent study of multipole response in neutron-rich nuclei using a modified realistic potential
Bianco, D.
Knapp, F.
Lo Iudice, N.
Vesely, P.
Andreozzi, F.
De Gregorio, G.
Porrino, A.
[J]. JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS, 2014, 41 (02)
[3] Gamma decay of pygmy states from inelastic scattering of ions
Bracco, A.
Crespi, F. C. L.
Lanza, E. G.
[J]. EUROPEAN PHYSICAL JOURNAL A, 2015, 51 (08)
[4] Pygmy and giant electric dipole responses of medium-heavy nuclei in a self-consistent random-phase approximation approach with a finite-range interaction
Co', G.
De Donno, V.
Anguiano, M.
Lallena, A. M.
[J]. PHYSICAL REVIEW C, 2013, 87 (03):
[5] Isospin properties of electric dipole excitations in 48Ca
Derya, V.
Savran, D.
Endres, J.
Harakeh, M. N.
Hergert, H.
Kelley, J. H.
Papakonstantinou, P.
Pietralla, N.
Ponomarev, V. Yu.
Roth, R.
Rusev, G.
Tonchev, A. P.
Tornow, W.
Wortche, H. J.
Zilges, A.
[J]. PHYSICS LETTERS B, 2014, 730 : 288 - 292
[6] Isospin Character of the Pygmy Dipole Resonance in 124Sn
Endres, J.
Litvinova, E.
Savran, D.
Butler, P. A.
Harakeh, M. N.
Harissopulos, S.
Herzberg, R. -D.
Kruecken, R.
Lagoyannis, A.
Pietralla, N.
Ponomarev, V. Yu
Popescu, L.
Ring, P.
Scheck, M.
Sonnabend, K.
Stoica, V. I.
Wortche, H. J.
Zilges, A.
[J]. PHYSICAL REVIEW LETTERS, 2010, 105 (21)
[7] Splitting of the pygmy dipole resonance in 138Ba and 140Ce observed in the (α,α′γ) reaction
Endres, J.
Savran, D.
van den Berg, A. M.
Dendooven, P.
Fritzsche, M.
Harakeh, M. N.
Hasper, J.
Wortche, H. J.
Zilges, A.
[J]. PHYSICAL REVIEW C, 2009, 80 (03):
[8] Identification and separation of radioactive isotope beams by the BigRIPS separator at the RIKEN RI Beam Factory
Fukuda, N.
Kubo, T.
Ohnishi, T.
Inabe, N.
Takeda, H.
Kameda, D.
Suzuki, H.
[J]. NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS, 2013, 317 : 323 - 332
[9] Global optical potential for nucleus-nucleus systems from 50 MeV/u to 400 MeV/u
Furumoto, T.
Horiuchi, W.
Takashina, M.
Yamamoto, Y.
Sakuragi, Y.
[J]. PHYSICAL REVIEW C, 2012, 85 (04):
[10] Effect of repulsive and attractive three-body forces on nucleus-nucleus elastic scattering
Furumoto, T.
Sakuragi, Y.
Yamamoto, Y.
[J]. PHYSICAL REVIEW C, 2009, 80 (04):

← 1 2 3 4 →