High-spin states in neutron-rich indium isotope $^{116}$In have been observed for the first time by using incomplete fusion of $^{7}$Li on a $^{116}$Cd target at a beam energy of 42 MeV. A negative-parity band with <math><mi>π</mi><msubsup><mrow><mi>g</mi></mrow><mrow><mn>9</mn><mo>/</mo><mn>2</mn></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msubsup><mo>⊗</mo><mi>ν</mi><msub><mrow><mi>h</mi></mrow><mrow><mn>11</mn><mo>/</mo><mn>2</mn></mrow></msub></math> configuration and a pair of positive-parity doublet bands with <math><mi>π</mi><msubsup><mrow><mi>g</mi></mrow><mrow><mn>9</mn><mo>/</mo><mn>2</mn></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msubsup><mo>⊗</mo><mi>ν</mi><mo>(</mo><msub><mrow><mi>g</mi></mrow><mrow><mn>7</mn><mo>/</mo><mn>2</mn></mrow></msub><mo>/</mo><msub><mrow><mi>d</mi></mrow><mrow><mn>5</mn><mo>/</mo><mn>2</mn></mrow></msub><mo>)</mo><msubsup><mrow><mi>h</mi></mrow><mrow><mn>11</mn><mo>/</mo><mn>2</mn></mrow><mrow><mn>2</mn></mrow></msubsup></math> configurations have been identified. The positive-parity doublet bands are tentatively interpreted as chiral doublet bands, which is supported by the adiabatic and configuration-fixed constrained triaxial relativistic-mean-field and multiparticle plus rotor model calculations. This observation reports a possible new region of chirality in neutron-rich A≈ 120 mass region.

China

W.Z. Xu

S.Y. Wang

X.G. Wu

H. Jia

C. Liu

H.F. Bai

Y.J. Li

B. Qi

H.Y. Zhang

G.S. Li

Y. Zheng

C.B. Li

L. Mu

A. Rohilla

S. Wang

D.P. Sun

Z.Q. Li

N.B. Zhang

R.J. Guo

X.C. Han

X. Xiao

First observation of high-spin states in In and possible new region of chirality

Level lifetimes for the candidate chiral doublet bands of $^{80}$Br were extracted by means of the Doppler-shift attenuation method. The absolute transition probabilities derived from the lifetimes agree well with the M1 and E2 chiral electromagnetic selection rules, and are well reproduced by the triaxial particle rotor model calculations. Such good agreements among the experimental data, selection rules of chiral doublet bands and theoretical calculations are rare and outstanding in researches of nuclear chirality. Besides odd-odd Cs isotopes, odd-odd Br isotopes in the A≈ 80 mass region represent another territory that exhibits the ideal selection rules expected for chiral doublet bands.

Germany

R. Schwengner

F. Dönau

T. Servene

H. Schnare

J. Reif

G. Winter

L. Käubler

H. Prade

S. Skoda

J. Eberth

H.G. Thomas

F. Becker

B. Fiedler

S. Freund

Austria

S. Kasemann

T. Steinhardt

O. Thelen

T. Härtlein

C. Ender

F. Köck

P. Reiter

D. Schwalm

Lifetime measurements in Br and a new region for observation of chiral electromagnetic selection rules

Nearly degenerate positive-parity doublet bands and several E1 transitions between positive- and negative-parity bands have been identified in $^{76}$Br. These experimental observations are interpreted as the coexistence of chirality and octupole correlations, based on the analysis of detailed γ-ray spectroscopy with the precise lifetime measurements and theoretical calculations, and play a key role to explore the simultaneous breaking of chiral and reflection symmetry and their interplay. The present work provides the first test for chirality in the <math><mi>A</mi><mo>≈</mo><mn>80</mn></math> mass region by lifetime measurements, and firstly elucidates the formation of chiral geometry in the presence of the octupole correlations in Br isotopes, leading to the conclusion that the reflection symmetry breaking catalyzes rather than destroys chiral symmetry breaking in nuclear systems.

J. Zhao

Y.M. Zhang

C.L. Wang

Y. Li

Interplay between nuclear chiral and reflection symmetry breakings revealed by the lifetime measurements in Br

Two nearly degenerate positive-parity bands with the <math><mi>π</mi><msubsup><mrow><mi>g</mi></mrow><mrow><mn>9</mn><mo>/</mo><mn>2</mn></mrow><mrow><mn>2</mn></mrow></msubsup><mo>⊗</mo><mi>ν</mi><msubsup><mrow><mi>g</mi></mrow><mrow><mn>9</mn><mo>/</mo><mn>2</mn></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msubsup></math> configuration and three nearly degenerate negative-parity bands with the <math><mi>π</mi><msub><mrow><mi>g</mi></mrow><mrow><mn>9</mn><mo>/</mo><mn>2</mn></mrow></msub><mo>(</mo><msub><mrow><mi>p</mi></mrow><mrow><mn>3</mn><mo>/</mo><mn>2</mn></mrow></msub><mo>,</mo><msub><mrow><mi>f</mi></mrow><mrow><mn>5</mn><mo>/</mo><mn>2</mn></mrow></msub><mo>)</mo><mo>⊗</mo><mi>ν</mi><msubsup><mrow><mi>g</mi></mrow><mrow><mn>9</mn><mo>/</mo><mn>2</mn></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msubsup></math> configuration have been identified in $^{81}$Kr. They are interpreted as chiral doublet bands and pseudospin-chiral triplet bands, which is supported by the constrained covariant density functional theory and the multiparticle plus rotor model calculations. The present work reports two new chiral configurations <math><mi>π</mi><msubsup><mrow><mi>g</mi></mrow><mrow><mn>9</mn><mo>/</mo><mn>2</mn></mrow><mrow><mn>2</mn></mrow></msubsup><mo>⊗</mo><mi>ν</mi><msubsup><mrow><mi>g</mi></mrow><mrow><mn>9</mn><mo>/</mo><mn>2</mn></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msubsup></math> and <math><mi>π</mi><msub><mrow><mi>g</mi></mrow><mrow><mn>9</mn><mo>/</mo><mn>2</mn></mrow></msub><mo>(</mo><msub><mrow><mi>p</mi></mrow><mrow><mn>3</mn><mo>/</mo><mn>2</mn></mrow></msub><mo>,</mo><msub><mrow><mi>f</mi></mrow><mrow><mn>5</mn><mo>/</mo><mn>2</mn></mrow></msub><mo>)</mo><mo>⊗</mo><mi>ν</mi><msubsup><mrow><mi>g</mi></mrow><mrow><mn>9</mn><mo>/</mo><mn>2</mn></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msubsup></math>, and the first example of pseudospin-chiral triplet bands involving the <math><mi>π</mi><mo>(</mo><msub><mrow><mi>p</mi></mrow><mrow><mn>3</mn><mo>/</mo><mn>2</mn></mrow></msub><mo>,</mo><msub><mrow><mi>f</mi></mrow><mrow><mn>5</mn><mo>/</mo><mn>2</mn></mrow></msub><mo>)</mo></math> pseudospin doublet.

South Africa

R.A. Bark

Japan

J. Meng

S.Q. Zhang

P. Jones

S.M. Wyngaardt

Q.B. Chen

P.Y. Zhu

H.W. Li

H. Hua

X.Q. Li

C.G. Li

R. Han

B.H. Sun

L.H. Zhu

T.D. Bucher

B.V. Kheswa

N. Khumalo

E.A. Lawrie

J.J. Lawrie

K.L. Malatji

L. Msebi

J. Ndayishimye

J.F. Sharpey-Schafer

O. Shirinda

M. Wiedeking

T. Dinoko

S.S. Ntshangase

First observation of the coexistence of multiple chiral doublet bands and pseudospin doublet bands in the ≈ 80 Mass Region

The existence of light sterile neutrinos is a long-standing question in particle physics. Several experimental “anomalies” might be explained by introducing eV mass scaled light sterile neutrinos. Many experiments are actively searching for such light sterile neutrinos through neutrino oscillation. For long baseline experiments, the matter effect should be treated carefully for precise calculation of the neutrino oscillation probabilities. However, this is usually time-consuming or analytically complex. In this manuscript, we adopt a Jacobi-like method to diagonalize the Hermitian Hamiltonian matrix and derive analytically simplified neutrino oscillation probabilities for 3 (active) + 1 (sterile)-neutrino mixing for a constant matter density. These approximations can reach a considerably high numerical accuracy while retaining their analytical simplicity and fast computing speed. This would be useful for current and future long baseline neutrino oscillation experiments.

Bao-Biao Yue

Wei Li

Jia-Jie Ling

Fan-Rong Xu

A compact analytical approximation for a light sterile neutrino oscillation in matter Jiajie Ling acknowledges the support from National Key R&D program of China (2018YFA0404103) and National Natural Science Foundation of China (11775315). F. Xu is supported partially by NSFC (11605076), as well as the FRFCU (Fundamental Research Funds for the Central Universities in China) (21616309)

The decay of $^{218}$Pa was investigated by means of α and γ spectroscopy. The nucleus was produced in the fusion reaction $^{40}$Ar+$^{182}$W and separated in flight by the gas-filled recoil separator SHANS (Spectrometer for Heavy Atoms and Nuclear Structure). The known α decays of $^{218}$Pa were measured with improved precision and newly assigned to be originating from the ground state, which clarified the ambiguities in their previous assignments. In addition, a new isomeric state in $^{218}$Pa decaying with α-particle energies of 9691(15) keV, 9595(21) keV and a half-life of <math><msubsup><mrow><mn>135</mn></mrow><mrow><mo>−</mo><mn>32</mn></mrow><mrow><mo>+</mo><mn>62</mn></mrow></msubsup></math> μs was identified. The spins and parities of the involved states were tentatively assigned on the basis of the systematic α-decay properties of the odd-proton <math><mi>N</mi><mo>=</mo><mn>127</mn></math> isotones and shell model calculations.