Reduced transition probabilities have been extracted between excited, yrast states in the <math><mi>N</mi><mo>=</mo><mi>Z</mi><mo>+</mo><mn>2</mn></math> nucleus $^{94}$Pd. The transitions of interest were observed following decays of the <math><msup><mrow><mi>I</mi></mrow><mrow><mi>π</mi></mrow></msup><mo>=</mo><msup><mrow><mn>14</mn></mrow><mrow><mo>+</mo></mrow></msup></math>, <math><msub><mrow><mi>E</mi></mrow><mrow><mi>x</mi></mrow></msub><mo>=</mo><mn>2129</mn></math>-keV isomeric state, which was populated following the projectile fragmentation of a $^{124}$Xe primary beam at the GSI Helmholtzzentrum für Schwerionenforschung accelerator facility as part of FAIR Phase-0. Experimental information regarding the reduced E2 transition strengths for the decays of the yrast <math><msup><mrow><mn>8</mn></mrow><mrow><mo>+</mo></mrow></msup></math> and <math><msup><mrow><mn>6</mn></mrow><mrow><mo>+</mo></mrow></msup></math> states was determined following isomer-delayed <math><msub><mrow><msub><mrow><mi>E</mi></mrow><mrow><mi>γ</mi></mrow></msub></mrow><mrow><mn>1</mn></mrow></msub><mo>−</mo><msub><mrow><msub><mrow><mi>E</mi></mrow><mrow><mi>γ</mi></mrow></msub></mrow><mrow><mn>2</mn></mrow></msub><mo>−</mo><mo>△</mo><msub><mrow><mi>T</mi></mrow><mrow><mn>2</mn><mo>,</mo><mn>1</mn></mrow></msub></math> coincidence method, using the LaBr$_{3}$(Ce)-based FATIMA fast-timing coincidence gamma-ray array, which allowed direct determination of lifetimes of states in $^{94}$Pd using the Generalized Centroid Difference (GCD) method. The experimental value for the half-life of the yrast 8$^{+}$ state of 755(106) ps results in a reduced transition probability of B(E2:8<math><mmultiscripts><mrow><mo>→</mo></mrow><mprescripts></mprescripts><none></none><mrow><mo>+</mo></mrow></mmultiscripts></math>6$^{+}$) = 205<math><msubsup><mrow></mrow><mrow><mo>−</mo><mn>25</mn></mrow><mrow><mo>+</mo><mn>34</mn></mrow></msubsup></math> e$^{2}$fm$^{4}$, which enables a precise verification of shell-model calculations for this unique system, lying directly between the <math><mi>N</mi><mo>=</mo><mi>Z</mi></math> line and the <math><mi>N</mi><mo>=</mo><mn>50</mn></math> neutron shell closure. The determined <math><mi>B</mi><mo>(</mo><mi>E</mi><mn>2</mn><mo>)</mo></math> value provides an insight into the purity of <math><msup><mrow><mo>(</mo><msub><mrow><mi>g</mi></mrow><mrow><mn>9</mn><mo>/</mo><mn>2</mn></mrow></msub><mo>)</mo></mrow><mrow><mi>n</mi></mrow></msup></math> configurations in competition with admixtures from excitations between the (lower) <math><mi>N</mi><mo>=</mo><mn>3</mn><mi>p</mi><mi>f</mi></math> and (higher) <math><mi>N</mi><mo>=</mo><mn>4</mn><mi>g</mi><mi>d</mi><mi>s</mi></math> orbitals for the first time. The results indicate weak collectivity expected for near-zero quadrupole deformation and an increasing importance of the <math><mi>T</mi><mo>=</mo><mn>0</mn></math> proton-neutron interaction at <math><mi>N</mi><mo>=</mo><mn>48</mn></math>.

Germany

A. Yaneva

United Kingdom

S. Jazrawi

Poland

M. Mikołajczuk

M. Górska

P.H. Regan

Sweden

B. Das

H.M. Albers

Saudi Arabia

S. Alhomaidhi

T. Arici

A. Banerjee

Italy

G. Benzoni

B. Cederwall

M.M.R. Chishti

France

D.D. Dao

T. Davinson

A. Gargano

J. Gerl

O. Hall

N. Hubbard

J. Jolie

I. Kojouharov

A.K. Mistry

F. Nowacki

M. Polettini

M. Rudigier

E. Şahin

H. Schaffner

India

A. Sharma

M. Armstrong

H.J. Wollersheim

P. Boutachkov

T. Dickel

E. Haettner

H. Heggen

Ch. Hornung

R. Knöbel

D. Kostyleva

N. Kurz

N. Kuzminchuk

I. Mukha

S. Pietri

W.R. Plass

Zs. Podolyák

C. Scheidenberger

Japan

Y.K. Tanaka

Slovenia

J. Vesic

H. Weick

U. Ahmed

Ö. Aktas

Spain

Hungary

A. Algora

C. Appleton

J. Benito

A. Blazhev

A. Bracco

A.M. Bruce

M. Brunet

R. Canavan

A. Esmaylzadeh

L.M. Fraile

G. Häfner

K.P. Hucka

P.R. John

D. Kahl

V. Karayonchev

R. Kern

G. Košir

R. Lozeva

P. Napiralla

B.S. Nara Singh

R. Page

C.M. Petrache

N. Pietralla

J.M. Régis

H. Rösch

Finland

P. Ruotsalainen

V. Sanchez-Temble

L. Sexton

R. Shearman

M. Si

V. Werner

J. Wiederhold

K. Wimmer

W. Witt

P. Woods

G. Zimba

The shape of the = +1 Nucleus Pd and the role of proton-neutron interactions on the structure of its excited states

Prolate-oblate shape coexistence close to the ground state in the strongly-deformed proton-rich <math><mi>A</mi><mo>≈</mo><mn>120</mn></math> nuclei is reported for the first time. One of the four reported bands in $^{119}$Cs, built on a <math><mn>11</mn><mo>/</mo><msup><mrow><mn>2</mn></mrow><mrow><mo>−</mo></mrow></msup></math> state at 670 keV, consists of nearly degenerate signature partners, and has properties which unequivocally indicate the strongly-coupled <math><mi>π</mi><msub><mrow><mi>h</mi></mrow><mrow><mn>11</mn><mo>/</mo><mn>2</mn></mrow></msub><mo>[</mo><mn>505</mn><mo>]</mo><mn>11</mn><mo>/</mo><msup><mrow><mn>2</mn></mrow><mrow><mo>−</mo></mrow></msup></math> configuration associated with oblate shape. Together with the decoupled <math><mi>π</mi><msub><mrow><mi>h</mi></mrow><mrow><mn>11</mn><mo>/</mo><mn>2</mn></mrow></msub><mo>[</mo><mn>541</mn><mo>]</mo><mn>3</mn><mo>/</mo><msup><mrow><mn>2</mn></mrow><mrow><mo>−</mo></mrow></msup></math> band built on the <math><mn>11</mn><mo>/</mo><msup><mrow><mn>2</mn></mrow><mrow><mo>−</mo></mrow></msup></math> prolate state at 110 keV, for which a half-life of <math><msub><mrow><mi>T</mi></mrow><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msub><mo>=</mo><mn>55</mn><mo>(</mo><mn>5</mn><mo>)</mo><mspace width="0.25em"></mspace><mrow><mi>μ</mi><mtext>s</mtext></mrow></math> has been measured, the new bands bring evidence of shape coexistence at low spin in the proton-rich strongly deformed <math><mi>A</mi><mo>≈</mo><mn>120</mn></math> nuclei, a phenomenon predicted since long time, but not yet observed. Calculations using the particle-number conserving cranked shell model and two dimensional tilted axis cranking covariant density functional theory support and well reproduce the observed oblate and prolate coexisting low-energy states in $^{119}$Cs.

China

K.K. Zheng

Z.H. Zhang

P.W. Zhao

Y.K. Wang

A. Astier

B.F. Lv

P.T. Greenlees

T. Grahn

R. Julin

S. Juutinen

M. Luoma

J. Ojala

J. Pakarinen

J. Partanen

P. Rahkila

M. Sandzelius

J. Sarén

H. Tann

J. Uusitalo

A. Ertoprak

W. Zhang

S. Guo

M.L. Liu

I. Kuti

B.M. Nyakó

D. Sohler

J. Timár

Canada

C. Andreoiu

M. Doncel

D.T. Joss

R.D. Page

Evidence of oblate-prolate shape coexistence in the strongly-deformed nucleus Cs

Lifetimes of low-lying excited states in the <math><mi>ν</mi><msub><mrow><mi>i</mi></mrow><mrow><mn>13</mn><mo>/</mo><msup><mrow><mn>2</mn></mrow><mrow><mo>+</mo></mrow></msup></mrow></msub></math> bands of the neutron-deficient osmium isotopes $^{169,171,173}$Os have been measured for the first time using the recoil-distance Doppler shift and recoil-isomer tagging techniques. An unusually low value is observed for the ratio <math><mi>B</mi><mo>(</mo><mi>E</mi><mn>2</mn><mo>;</mo><mn>21</mn><mo>/</mo><msup><mrow><mn>2</mn></mrow><mrow><mo>+</mo></mrow></msup><mo>→</mo><mn>17</mn><mo>/</mo><msup><mrow><mn>2</mn></mrow><mrow><mo>+</mo></mrow></msup><mo>)</mo><mo>/</mo><mi>B</mi><mo>(</mo><mi>E</mi><mn>2</mn><mo>;</mo><mn>17</mn><mo>/</mo><msup><mrow><mn>2</mn></mrow><mrow><mo>+</mo></mrow></msup><mo>→</mo><mn>13</mn><mo>/</mo><msup><mrow><mn>2</mn></mrow><mrow><mo>+</mo></mrow></msup><mo>)</mo></math> in $^{169}$Os, similar to the “anomalously” low values of the ratio <math><mi>B</mi><mo>(</mo><mi>E</mi><mn>2</mn><mo>;</mo><msubsup><mrow><mn>4</mn></mrow><mrow><mn>1</mn></mrow><mrow><mo>+</mo></mrow></msubsup><mo>→</mo><msubsup><mrow><mn>2</mn></mrow><mrow><mn>1</mn></mrow><mrow><mo>+</mo></mrow></msubsup><mo>)</mo><mo>/</mo><mi>B</mi><mo>(</mo><mi>E</mi><mn>2</mn><mo>;</mo><msubsup><mrow><mn>2</mn></mrow><mrow><mn>1</mn></mrow><mrow><mo>+</mo></mrow></msubsup><mo>→</mo><msubsup><mrow><mn>0</mn></mrow><mrow><mi>gs</mi></mrow><mrow><mo>+</mo></mrow></msubsup><mo>)</mo></math> previously observed in several transitional rare-earth nuclides with even numbers of neutrons and protons, including the neighbouring $^{168,170}$Os. Furthermore, the evolution of <math><mi>B</mi><mo>(</mo><mi>E</mi><mn>2</mn><mo>;</mo><mn>21</mn><mo>/</mo><msup><mrow><mn>2</mn></mrow><mrow><mo>+</mo></mrow></msup><mo>→</mo><mn>17</mn><mo>/</mo><msup><mrow><mn>2</mn></mrow><mrow><mo>+</mo></mrow></msup><mo>)</mo><mo>/</mo><mi>B</mi><mo>(</mo><mi>E</mi><mn>2</mn><mo>;</mo><mn>17</mn><mo>/</mo><msup><mrow><mn>2</mn></mrow><mrow><mo>+</mo></mrow></msup><mo>→</mo><mn>13</mn><mo>/</mo><msup><mrow><mn>2</mn></mrow><mrow><mo>+</mo></mrow></msup><mo>)</mo></math> with increasing neutron number in the odd-mass isotopic chain $^{169,171,173}$Os is observed to follow the same trend as observed previously in the even-even Os isotopes. These findings indicate that the possible quantum phase transition from a seniority conserving structure to a collective regime as a function of neutron number suggested for the even-even systems is maintained in these odd-mass osmium nuclei, with the odd valence neutron merely acting as a “spectator”. As for the even-even nuclei, the phenomenon is highly unexpected for nuclei that are not situated near closed shells.

Türkiye

R. Liotta

C. Qi

D.M. Cullen

D. Hodge

M. Giles

S. Stolze

H. Badran

T. Braunroth

T. Calverley

D.M. Cox

Y.D. Fang

J. Hilton

E. Ideguchi

M. Kumar Raju

H. Li

H. Liu

S. Matta

P. Subramaniam

Norway

V. Modamio

P. Papadakis

C. Scholey

J. Sorri

M.J. Taylor

J.J. Valiente-Dobón

Lifetime measurements of excited states in Os: Persistence of anomalous ( 2) Ratios in Transitional Rare Earth Nuclei in the Presence of a Decoupled Valence Neutron