Shape coexistence and collective low-spin states in Sn112,114 studied with the (p,p′γ) Doppler-shift attenuation coincidence technique

Spieker, M.; Petkov, P.; Litvinova, E.; Müller-Gatermann, C.; Pickstone, S.G.; Prill, S.; Scholz, P.; Zilges, A.

doi:10.1103/PhysRevC.97.054319

Shape coexistence and collective low-spin states in Sn112,114 studied with the (p,p′γ) Doppler-shift attenuation coincidence technique

May 18, 2018

21 pages

Published in:

Phys.Rev.C 97 (2018) 5, 054319

Published: May 18, 2018

e-Print:

1807.07141 [nucl-ex]

DOI:

10.1103/PhysRevC.97.054319

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Abstract: (APS)

Background: The semimagic Sn (Z=50) isotopes have been subject to many nuclear-structure studies. Signatures of shape coexistence have been observed and attributed to two-proton–two-hole (2p-2h) excitations across the Z=50 shell closure. In addition, many low-lying nuclear-structure features have been observed which have effectively constrained theoretical models in the past. One example are so-called quadrupole-octupole coupled states (QOC) caused by the coupling of the collective quadrupole and octupole phonons. Purpose: Proton-scattering experiments followed by the coincident spectroscopy of γ rays have been performed at the Institute for Nuclear Physics of the University of Cologne to excite low-spin states in Sn112 and Sn114 to determine their lifetimes and extract reduced transition strengths B(ΠL). Methods: The combined spectroscopy setup SONIC@HORUS has been used to detect the scattered protons and the emitted γ rays of excited states in coincidence. The novel (p,p′γ) Doppler-shift attenuation (DSA) coincidence technique was employed to measure sub-ps nuclear level lifetimes. Results: Seventy-four (74) level lifetimes τ of states with J=0–6 were determined. In addition, branching ratios were deduced which allowed the investigation of the intruder configuration in both nuclei. Here, sd IBM-2 mixing calculations were added which support the coexistence of the two configurations. Furthermore, members of the expected QOC quintuplet are proposed in Sn114 for the first time. The 1− candidate in Sn114 fits perfectly into the systematics observed for the other stable Sn isotopes. Conclusions: The E2 transition strengths observed for the low-spin members of the so-called intruder band support the existence of shape coexistence in Sn112,114. The collectivity in this configuration is comparable to the one observed in the Pd nuclei, i.e., the 0p-4h nuclei. Strong mixing between the 0+ states of the normal and intruder configuration might be observed in Sn114. The general existence of QOC states in Sn112,114 is supported by the observation of QOC candidates with J≠1.

Note:

Manuscript has been published in Phys. Rev. C 97, 054319 (2018). This is the preprint version

References(68)

Figures(9)

[1]

Simple Models of Complex Nuclei - The Shell Model and Interacting Boson Model, Contemporary Concepts in Physics, Vol. 7 (Hardwood / Publishers,)

I. Talmi

[2]

Spectroscopy of even Sn nuclei and generalized-seniority breaking

- Nucl.Phys.A 432 (1985) 389-410
•
DOI:
- 10.1016/0375-9474(85)90250-7

[3]

Coexistence in even-mass nuclei

- Phys.Rept. 215 (1992) 101-201
•
DOI:
- 10.1016/0370-1573(92)90095-H

[4]

Shape coexistence in atomic nuclei

- Rev.Mod.Phys. 83 (2011) 4, 1467
•
DOI:
- 10.1103/RevModPhys.83.1467

[5]

Three-phonon excitations in 124 Sn

et al.

- Nucl.Phys.A 747 (2005) 206-226
•
DOI:
- 10.1016/j.nuclphysa.2004.10.003

[6]

P.E. Garrett
,
J.L. Wood

- J.Phys.G 37 (2010) 064028

[7]

Nuclear Structure Bd. II / Singapore,)

A. Bohr
,
B.R. Mottelson

[8]

Shape coexistence at low spin in the Z = 50 region and its spectroscopic signatures

P.E. Garrett

- J.Phys.G 43 (2016) 8, 084002
•
DOI:
- 10.1088/0954-3899/43/8/084002

[9]

Uniform properties of Jpi=1- two-phonon states in the semimagic even-even tin isotopes 116, 118, 120, 122, Sn-124

J. Bryssinck
(
- Gent U.
)
,
L. Govor
(
- Kurchatov Inst., Moscow
)
,
D. Belic
(
- Stuttgart U.
)
,
F. Bauwens
(
- Gent U.
)
,
O. Beck
(
- Stuttgart U.
)

et al.

- Phys.Rev.C 59 (1999) 1930-1934
•
DOI:
- 10.1103/PhysRevC.59.1930

[10]

Two-phonon 1- state in Sn-112 observed in resonant photon scattering

I. Pysmenetska
(
- Darmstadt, Tech. Hochsch. and
- Stuttgart U.
)
,
S. Walter
(
- Darmstadt, Tech. Hochsch. and
- Stuttgart U.
)
,
J. Enders
(
- Darmstadt, Tech. Hochsch. and
- Stuttgart U.
)
,
H. von Garrel
(
- Darmstadt, Tech. Hochsch. and
- Stuttgart U.
)
,
O. Karg
(
- Darmstadt, Tech. Hochsch. and
- Stuttgart U.
)

et al.

- Phys.Rev.C 73 (2006) 017302
•
e-Print:
- nucl-ex/0512013
•
DOI:
- 10.1103/PhysRevC.73.017302

[11]

Heterogeneous vibrations in Sn-112

et al.

- Phys.Rev.C 72 (2005) 034313
•
DOI:
- 10.1103/PhysRevC.72.034313

[12]

21+ ---> 01+ transition strengths in Sn nuclei

et al.

- Phys.Rev.C 76 (2007) 021302,
- Phys.Rev.C 77 (2008) 029902 (erratum)
•
DOI:
- 10.1103/PhysRevC.76.021302

[12]

21+ ---> 01+ transition strengths in Sn nuclei

et al.

- Phys.Rev.C 76 (2007) 021302,
- Phys.Rev.C 77 (2008) 029902 (erratum)
•
DOI:
- 10.1103/PhysRevC.76.021302

[13]

Level lifetimes in the stable Zr nuclei: Effects of chemical properties in Doppler-shift measurements

et al.

- Phys.Rev.C 88 (2013) 2, 024317
•
DOI:
- 10.1103/PhysRevC.88.024317

[14]

Combining {\gamma}-ray and particle spectroscopy with SONIC@HORUS

et al.

- Nuclear Inst. and Methods in Physics Research A875 (2017) 104-110,
- Nucl.Instrum.Meth.A 875 (2017) 104
•
e-Print:
- 1710.07106
•
DOI:
- 10.1016/j.nima.2017.09.016

[15]

Lifetime measurement of excited low-spin states via the (p,p′γ) reaction

et al.

- Nucl.Instrum.Meth.A 794 (2015) 171-176
•
e-Print:
- 1506.05986
•
DOI:
- 10.1016/j.nima.2015.05.024

[16]

B. Hubbard-Nelson
,
M. Momayezi
,
W.K. Warburton

- Nucl.Instrum.Meth.A 422 (1999) 411

[17]

W. Skulski

- Acta Phys.Polon.B 31 (2000) 47

[18]

W. Warburton
,
P. Grudberg

- Nucl.Instrum.Meth.A 568 (2006) 350

[19]

Investigation of octupole vibrations in the rareearth region with different experimental probes and implementation of a multithreaded evaluation software for double coincidence listmode data, Ph.D. thesis, University of Cologne (Germany)

M. Elvers

[20]

Study of Proton-Neutron Mixed-Symmetry Excitations in 96 Ru by Means of Inelastic Proton Scattering and Digital Pulse Processing of Semiconductor Detector Signals, Ph.D. thesis, University of Cologne (Germany)

A. Hennig

[21]

Vollständige γ-Spektroskopie des Kerns 127 Xe, Ph.D. thesis, University of Cologne (Germany)

I. Wiedenhöver

[22]

Mixed-symmetry octupole and hexadecapole excitations in the $N=52$ isotones

et al.

- Phys.Rev.C 90 (2014) 5, 051302
•
e-Print:
- 1502.06409
•
DOI:
- 10.1103/PhysRevC.90.051302

[23]

Collective excitations of Ru96 by means of (p,p′γ) experiments

et al.

- Phys.Rev.C 92 (2015) 6, 064317
•
DOI:
- 10.1103/PhysRevC.92.064317

[24]

Mat. Fys. Med / Dan. Vid. Selsk. 33, 1

J. Lindhard
,
M. Scharff
,
H.E. Schiøtt

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