arXiv : Pairing-quadrupole interplay in the neutron-deficient tin nuclei: first lifetime measurements of low-lying states in $^{106,108}$Sn

Siciliano, M.; Goasduff, A.; Goldkuhle, A.; Marchi, T.; Birkenbach, B.; Jungclaus, A.; Gadea, A.; Müller-Gatermann, C.; de France, G.; Menegazzo, R.; Theisen, Ch.; Doncel, M.; Michelagnoli, C.; Pérez-Vidal, R.M.; Boston, A.J.; Lopez-Martens, A.; Leoni, S.; Cieplicka-Oryńczak, N.; Harkness-Brennan, L.J.; Million, B.; Jakobsson, U.; Pullia, A.; Jaworski, G.; Mengoni, D.; Sayği, B.; Hess, H.; Reiter, P.; Lefevre, A.; Dudouet, J.; Nowacki, F.; Judson, D.S.; Bazzacco, D.; Désesquelles, P.; John, P.R.; Lemasson, A.; Korten, W.; Li, H.; Mijatović, T.; Stezowski, O.; Egea-Canet, F.J.; Cullen, D.M.; Domingo-Pardo, C.; Zielińska, M.; Testov, D.; Benzoni, G.; Braunroth, T.; Napoli, D.R.; Labiche, M.; Valiente-Dobón, J.J.; Salsac, M.D.; Clément, E.; Sanchis, E.; Ertürk, S.; Nyberg, J.; Maj, A.; Sohler, D.; Georgiev, G.; Recchia, F.; Cederwall, B.; Fransen, C.; Boston, H.C.; Szilner, S.; Eberth, J.; Barrientos, D.; Palacz, M.; Crespi, F.C.L.; González, V.; Zuker, A.P.; Kuti, I.; Collado, J.

doi:10.1016/j.physletb.2020.135474

Article
Report number	arXiv:1905.10313
Title	Pairing-quadrupole interplay in the neutron-deficient tin nuclei: first lifetime measurements of low-lying states in $^{106,108}$Sn
Author(s)	Siciliano, M. (INFN, Legnaro ; Padua U. ; IRFU, Saclay) ; Valiente-Dobón, J.J. (INFN, Legnaro) ; Goasduff, A. (INFN, Legnaro ; Padua U. ; INFN, Padua) ; Nowacki, F. (Strasbourg, IPHC) ; Zuker, A.P. (Strasbourg, IPHC) ; Bazzacco, D. (INFN, Padua) ; Lopez-Martens, A. (CSNSM, Orsay) ; Clément, E. (GANIL) ; Benzoni, G. (INFN, Milan) ; Braunroth, T. (Cologne U.) ; Cieplicka-Oryńczak, N. (INFN, Milan ; Cracow, INP) ; Crespi, F.C.L. (INFN, Milan ; Milan U.) ; de France, G. (GANIL) ; Doncel, M. (U. Salamanca (main)) ; Ertürk, S. (Nigde U.) ; Fransen, C. (Cologne U.) ; Gadea, A. (Valencia U., IFIC) ; Georgiev, G. (CSNSM, Orsay) ; Goldkuhle, A. (Cologne U.) ; Jakobsson, U. (Royal Inst. Tech., Stockholm) ; Jaworski, G. (INFN, Legnaro) ; John, P.R. (Padua U. ; INFN, Padua ; Darmstadt, Tech. Hochsch.) ; Kuti, I. (Debrecen, Inst. Nucl. Res.) ; Lemasson, A. (GANIL) ; Li, H. (Royal Inst. Tech., Stockholm) ; Marchi, T. (INFN, Legnaro) ; Mengoni, D. (Padua U. ; INFN, Padua) ; Michelagnoli, C. (GANIL ; Laue-Langevin Inst.) ; Mijatović, T. (Boskovic Inst., Zagreb) ; Müller-Gatermann, C. (Cologne U.) ; Napoli, D.R. (INFN, Legnaro) ; Nyberg, J. (Uppsala U.) ; Palacz, M. (Warsaw U. (main)) ; Pérez-Vidal, R.M. (Valencia U., IFIC) ; Sayği, B. (INFN, Legnaro ; Ege U.) ; Sohler, D. (Debrecen, Inst. Nucl. Res.) ; Szilner, S. (Boskovic Inst., Zagreb) ; Testov, D. (Padua U. ; INFN, Padua) ; Barrientos, D. (CERN) ; Birkenbach, B. (Cologne U.) ; Boston, H.C. (Liverpool U.) ; Boston, A.J. (Liverpool U.) ; Cederwall, B. (Royal Inst. Tech., Stockholm) ; Cullen, D.M. (U. Manchester (main)) ; Collado, J. (Valencia U., Dept. Ing. Electronica) ; Désesquelles, P. (CSNSM, Orsay) ; Dudouet, J. (CSNSM, Orsay ; Lyon, IPN) ; Domingo-Pardo, C. (Valencia U., IFIC) ; Eberth, J. (Cologne U.) ; Egea-Canet, F.J. (INFN, Legnaro) ; González, V. (Valencia U., Dept. Ing. Electronica) ; Judson, D.S. (Liverpool U.) ; Harkness-Brennan, L.J. (Liverpool U.) ; Hess, H. (Cologne U.) ; Jungclaus, A. (CSIC, Madrid) ; Korten, W. (IRFU, Saclay) ; Labiche, M. (Madrid, Inst. Estructura Materia) ; Lefevre, A. (GANIL) ; Leoni, S. (INFN, Milan ; Milan U.) ; Maj, A. (Cracow, INP) ; Menegazzo, R. (INFN, Padua) ; Million, B. (INFN, Milan) ; Pullia, A. (INFN, Milan ; Milan U.) ; Recchia, F. (Padua U. ; INFN, Padua) ; Reiter, P. (Cologne U.) ; Salsac, M.D. (IRFU, Saclay) ; Sanchis, E. (Valencia U., Dept. Ing. Electronica) ; Stezowski, O. (Lyon, IPN) ; Theisen, Ch. (IRFU, Saclay) ; Zielińska, M. (IRFU, Saclay)
Publication	2020-07-10
Imprint	2019-05-24
Number of pages	6
Note	V1: 6 pages, 3 figures, 1 table, theoretical interpretation described in detail in the arXiv paper of A.P.Zuker (cross-reference) V2: added reference to A.P. Zuker paper (arXiv:1905.11479)
In:	Phys. Lett. B 806 (2020) 135474
DOI	10.1016/j.physletb.2020.135474 (publication)
Subject category	nucl-ex ; Nuclear Physics - Experiment
Abstract	The lifetimes of the low-lying excited states $2^+$ and $4^+$ have been directly measured in the neutron-deficient $^{106,108}$Sn isotopes. The nuclei were populated via a deep-inelastic reaction and the lifetime measurement was performed employing a differential plunger device. The emitted $\gamma$ rays were detected by the AGATA array, while the reaction products were uniquely identified by the VAMOS++ magnetic spectrometer. Large-Scale Shell-Model calculations with realistic forces indicate that, independently of the pairing content of the interaction, the quadrupole force is dominant in the $B(E2; 2_1^+ \to 0_{g.s.}^+)$ values and it describes well the experimental pattern for $^{104-114}$Sn; the $B(E2; 4_1^+ \to 2_1^+)$ values, measured here for the first time, depend critically on a delicate pairing-quadrupole balance, disclosed by the very precise results in $^{108}$Sn. This result provides insight in the hitherto unexplained $B(E2; 4_1^+ \to 2_1^+)/B(E2; 2_1^+ \to 0_{g.s.}^+) < 1$ anomaly.
Copyright/License	preprint: (License: arXiv nonexclusive-distrib 1.0) publication: © 2020-2024 The Authors (License: CC-BY-4.0), sponsored by SCOAP³

$(Color online) (left) Doppler-corrected $\gamma$-ray energy spectra of $^{108}$Sn for different target-to-degrader distances, gated on the Total Kinetic-Energy Loss (TKEL). For each transition the \textit{unshifted} ($u$) and \textit{shifted} ($s$) centroids are indicated by a solid and a dashed line, respectively. (right) Ratio of the transition components intensity as a function of the distance, obtained by gating on the TKEL. The dashed lines represent the fitted decay curves for the two excited states.$ $(Color online) Reduced transition probability $B(E2)$ for the (a) $2_1^+ \rightarrow 0_{g.s.}^+$ and (b) $4_1^+ \rightarrow 2_1^+$ transitions along the Sn isotopic chain. The results of the present work (red squares) are compared with those from previous experiments~\cite{jonsson1981collective, radford2004nuclear, banu2005sn, vaman2007sn, cederkall2007sub, orce20072, ekstrom2008sn, doornenbal2008enhanced, kumar2010enhanced, allmond2011coulomb, jungclaus2011evidence, kumbartzki2012transient, bader2013quadrupole, guastalla2013coulomb, doornenbal2014intermediate, allmond2015investigation, kumbartzki2016z, kumar2017noevidence, spieker2018shape}. The predictions from Large-Scale Shell-Model calculations from the I.3.4 interaction are also shown (open black pentagons).$ $(Color online) Experimental and calculated (a) $B(E2;2_1^+ \to 0_{g.s.}^+)$ and (b) $B(E2;4_1^+ \to 2_1^+)$ values and (c) $B_{4/2} \equiv B(E2;4_1^+ \to 2_1^+)/B(E2;2_1^+ \to 0_{g.s.}^+)$ ratio for Sn isotopes. Effective charges are $(e_\pi, e_\nu) = (1.40, 0.72)$ throughout. For $A=112$ and $114$ the neutron effective charge $e_\nu$ should be increased to 0.75 to account for the omission of the $h_{11/2}$ shell, that plays a small but significant role. Experimental $B(E2;2_1^+ \to 0_{g.s.}^+)$ values are the weighted averages of the Fig.~\ref{fig:B(E2)} results, while the $B(E2;4_1^+ \to 2_1^+)$ data comes from Ref.~\cite{jonsson1981collective} and the present work. I.3.0s1.6 has the $s_{1/2}$ single particle energy moved up by 800 keV with respect to GEMO.$ Show more plots

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