The pygmy quadrupole resonance and neutron-skin modes in Sn-124

M. Spieker, N. Tsoneva, V. Derya, J. Endres, D. Savran, M. N. Harakeh, S. Harissopulos, R. -D. Herzberg, A. Lagoyannis, H. Lenske, N. Pietralla, L. Popescu, M. Scheck, F. Schlüter, K. Sonnabend, V. I. Stoica, H. J. Wörtche, A. Zilges

Research output: Contribution to journalArticle

Abstract

We present an extensive experimental study of the recently predicted pygmy quadrupole resonance (PQR) in Sn isotopes, where complementary probes were used. In this study, (α, α'γ) and (γ, γ') experiments were performed on 124Sn. In both reactions, Jπ = 2+ states below an excitation energy of 5 MeV were populated. The E2 strength integrated over the full transition densities could be extracted from the (γ, γ') experiment, while the (α, α'γ) experiment at the chosen kinematics strongly favors the excitation of surface modes because of the strong α-particle absorption in the nuclear interior. The excitation of such modes is in accordance with the quadrupole-type oscillation of the neutron skin predicted by a microscopic approach based on self-consistent density functional theory and the quasiparticle-phonon model (QPM). The newly determined γ-decay branching ratios hint at a non-statistical character of the E2 strength, as it has also been recently pointed out for the case of the pygmy dipole resonance (PDR). This allows us to distinguish between PQR-type and multiphonon excitations and, consequently, supports the recent first experimental indications of a PQR in 124Sn.
Original languageEnglish
Pages (from-to)102-107
JournalPhysics Letters B
Volume752
Early online date10 Nov 2015
DOIs
Publication statusPublished - 10 Jan 2016

Keywords

  • Atomic nuclei
  • Collective quadrupole excitations
  • Pygmy quadrupole resonance
  • Sn-124

Cite this

Spieker, M., Tsoneva, N., Derya, V., Endres, J., Savran, D., Harakeh, M. N., ... Zilges, A. (2016). The pygmy quadrupole resonance and neutron-skin modes in Sn-124. Physics Letters B, 752, 102-107. https://doi.org/10.1016/j.physletb.2015.11.004
Spieker, M. ; Tsoneva, N. ; Derya, V. ; Endres, J. ; Savran, D. ; Harakeh, M. N. ; Harissopulos, S. ; Herzberg, R. -D. ; Lagoyannis, A. ; Lenske, H. ; Pietralla, N. ; Popescu, L. ; Scheck, M. ; Schlüter, F. ; Sonnabend, K. ; Stoica, V. I. ; Wörtche, H. J. ; Zilges, A. / The pygmy quadrupole resonance and neutron-skin modes in Sn-124. In: Physics Letters B. 2016 ; Vol. 752. pp. 102-107.
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Spieker, M, Tsoneva, N, Derya, V, Endres, J, Savran, D, Harakeh, MN, Harissopulos, S, Herzberg, R-D, Lagoyannis, A, Lenske, H, Pietralla, N, Popescu, L, Scheck, M, Schlüter, F, Sonnabend, K, Stoica, VI, Wörtche, HJ & Zilges, A 2016, 'The pygmy quadrupole resonance and neutron-skin modes in Sn-124' Physics Letters B, vol. 752, pp. 102-107. https://doi.org/10.1016/j.physletb.2015.11.004

The pygmy quadrupole resonance and neutron-skin modes in Sn-124. / Spieker, M.; Tsoneva, N.; Derya, V.; Endres, J.; Savran, D.; Harakeh, M. N.; Harissopulos, S.; Herzberg, R. -D.; Lagoyannis, A.; Lenske, H.; Pietralla, N.; Popescu, L.; Scheck, M.; Schlüter, F.; Sonnabend, K.; Stoica, V. I.; Wörtche, H. J.; Zilges, A.

In: Physics Letters B, Vol. 752, 10.01.2016, p. 102-107.

Research output: Contribution to journalArticle

TY - JOUR

T1 - The pygmy quadrupole resonance and neutron-skin modes in Sn-124

AU - Spieker, M.

AU - Tsoneva, N.

AU - Derya, V.

AU - Endres, J.

AU - Savran, D.

AU - Harakeh, M. N.

AU - Harissopulos, S.

AU - Herzberg, R. -D.

AU - Lagoyannis, A.

AU - Lenske, H.

AU - Pietralla, N.

AU - Popescu, L.

AU - Scheck, M.

AU - Schlüter, F.

AU - Sonnabend, K.

AU - Stoica, V. I.

AU - Wörtche, H. J.

AU - Zilges, A.

PY - 2016/1/10

Y1 - 2016/1/10

N2 - We present an extensive experimental study of the recently predicted pygmy quadrupole resonance (PQR) in Sn isotopes, where complementary probes were used. In this study, (α, α'γ) and (γ, γ') experiments were performed on 124Sn. In both reactions, Jπ = 2+ states below an excitation energy of 5 MeV were populated. The E2 strength integrated over the full transition densities could be extracted from the (γ, γ') experiment, while the (α, α'γ) experiment at the chosen kinematics strongly favors the excitation of surface modes because of the strong α-particle absorption in the nuclear interior. The excitation of such modes is in accordance with the quadrupole-type oscillation of the neutron skin predicted by a microscopic approach based on self-consistent density functional theory and the quasiparticle-phonon model (QPM). The newly determined γ-decay branching ratios hint at a non-statistical character of the E2 strength, as it has also been recently pointed out for the case of the pygmy dipole resonance (PDR). This allows us to distinguish between PQR-type and multiphonon excitations and, consequently, supports the recent first experimental indications of a PQR in 124Sn.

AB - We present an extensive experimental study of the recently predicted pygmy quadrupole resonance (PQR) in Sn isotopes, where complementary probes were used. In this study, (α, α'γ) and (γ, γ') experiments were performed on 124Sn. In both reactions, Jπ = 2+ states below an excitation energy of 5 MeV were populated. The E2 strength integrated over the full transition densities could be extracted from the (γ, γ') experiment, while the (α, α'γ) experiment at the chosen kinematics strongly favors the excitation of surface modes because of the strong α-particle absorption in the nuclear interior. The excitation of such modes is in accordance with the quadrupole-type oscillation of the neutron skin predicted by a microscopic approach based on self-consistent density functional theory and the quasiparticle-phonon model (QPM). The newly determined γ-decay branching ratios hint at a non-statistical character of the E2 strength, as it has also been recently pointed out for the case of the pygmy dipole resonance (PDR). This allows us to distinguish between PQR-type and multiphonon excitations and, consequently, supports the recent first experimental indications of a PQR in 124Sn.

KW - Atomic nuclei

KW - Collective quadrupole excitations

KW - Pygmy quadrupole resonance

KW - Sn-124

U2 - 10.1016/j.physletb.2015.11.004

DO - 10.1016/j.physletb.2015.11.004

M3 - Article

VL - 752

SP - 102

EP - 107

JO - Physics Letters B

JF - Physics Letters B

SN - 0370-2693

ER -

Spieker M, Tsoneva N, Derya V, Endres J, Savran D, Harakeh MN et al. The pygmy quadrupole resonance and neutron-skin modes in Sn-124. Physics Letters B. 2016 Jan 10;752:102-107. https://doi.org/10.1016/j.physletb.2015.11.004