Precision mass measurements of $^{104}$Y, $^{106}$Zr, <math><msup><mrow></mrow><mrow><mn>104</mn><mo>,</mo><mn>104</mn><mi>m</mi><mo>,</mo><mn>109</mn></mrow></msup></math>Nb, and $^{111,112}$Mo have been performed with the JYFLTRAP double Penning trap mass spectrometer at the Ion Guide Isotope Separator On-Line facility. The order of the long-lived states in $^{104}$Nb was unambiguously established. The trend in two-neutron separation energies around the <math><mi>N</mi><mo>=</mo><mn>66</mn></math> neutron midshell appeared to be steeper with respect to the Atomic Mass Evaluation 2020 extrapolations for the $_{39}$Y and $_{40}$Zr isotopic chains and less steep for the $_{41}$Nb chain, indicating a possible gap opening around <math><mi>Z</mi><mo>=</mo><mn>40</mn></math>. The experimental results were compared to the BSkG2 model calculations performed with and without vibrational and rotational corrections. All of them predict two low-lying minima for $^{106}$Zr. While the unaltered BSkG2 model fails to predict the trend in two-neutron separation energies, selecting the more deformed minima in calculations and removing the vibrational correction, the calculations are more in line with experimental data. The same is also true for the <math><msubsup><mrow><mn>2</mn></mrow><mrow><mn>1</mn></mrow><mrow><mo>+</mo></mrow></msubsup></math> excitation energies and differences in charge radii in the Zr isotopes. The results stress the importance of improved treatment of collective corrections in large-scale models and further development of beyond-mean-field techniques.

Finland

France

M. Hukkanen

Belgium

W. Ryssens

P. Ascher

M. Bender

T. Eronen

S. Grévy

A. Kankainen

M. Stryjczyk

O. Beliuskina

Z. Ge

S. Geldhof

M. Gerbaux

W. Gins

A. Husson

D.A. Nesterenko

A. Raggio

M. Reponen

S. Rinta-Antila

United Kingdom

J. Romero

A. de Roubin

V. Virtanen

A. Zadvornaya

Precision mass measurements in the zirconium region pin down the mass surface across the neutron midshell at = 66

The multinucleon transfer (MNT) reaction approach was successfully employed for the first time to measure the isomeric ratios (IRs) of $^{211}$Po isomer (25/2$^{+}$) and its ground state (9/2$^{+}$) at the IGISOL facility using a 945 MeV $^{136}$Xe beam impinged on $^{209}$Bi and $^{nat}$Pb targets. The dominant production of isomers compared to the corresponding ground states was consistently revealed in the α-decay spectra. Deduced IR of $^{211}$Po populated through the $^{136}$Xe+$^{nat}$Pb reaction was found to have an enhancement of ≈1.8-times than that observed for the $^{136}$Xe+$^{209}$Bi. State-of-the-art Langevin-type model calculations have been utilized to estimate the spin distribution of an MNT residue. The computations qualitatively corroborate with the considerable increase in the IRs of $^{211}$Po produced from $^{136}$Xe+$^{nat}$Pb compared to $^{136}$Xe+$^{209}$Bi. Theoretical investigations indicate a weak dependence of target spin on the IRs. The enhancement of the $^{211}$Po isomer in the $^{136}$Xe+$^{nat}$Pb over $^{136}$Xe+$^{209}$Bi can be attributed to the different proton (p)-transfer production routes. Estimations demonstrate an increment in the angular momentum transfer, favorable for isomer production, with increasing projectile energy. Comparative analysis reveals the two entrance channel parameters, projectile mass and p-transfer channels, strongly influencing the population of the high-spin isomer of $^{211}$Po (25/2$^{+}$). This letter reports the first experimental and theoretical study on the IRs of nuclei formed from two different p-transfer channels via two independent MNT reactions.

Germany

D. Kumar

T. Dickel

Romania

P. Constantin

S. Purushothaman

A. Spataru

L. Al Ayoubi

M. Brunet

L. Canete

C. Delafosse

R.P. de Groote

C. Hornung

Spain

A. Illana

A. Jokinen

United States

D. Kahl

B. Kindler

B. Lommel

Israel

I. Mardor

I.D. Moore

D. Nichita

S. Nikas

A. Ortiz-Cortes

H. Penttilä

Zs. Podolyák

I. Pohjalainen

J. Saren

M. Vilen

A. Weaver

J. Winfield

First investigation on the isomeric ratio in multinucleon transfer reactions: Entrance channel effects on the spin distribution

We report on a set of high-precision measurements of nuclear binding and excitation energies, as well as nuclear spins, magnetic dipole and electric quadrupole moments of neutron-rich silver isotopes, $^{113−123}$Ag. The measurements were performed using the JYFLTRAP mass spectrometer and the collinear laser spectroscopy beamline at the Ion Guide Isotope Separator On-Line (IGISOL) facility. For the first time, we can firmly establish the ordering of the long-lived <math><msup><mrow><mi>I</mi></mrow><mrow><mi>π</mi></mrow></msup><mo>=</mo><mn>1</mn><mo>/</mo><msup><mrow><mn>2</mn></mrow><mrow><mo>−</mo></mrow></msup><mo>,</mo><mspace width="0.25em"></mspace><mn>7</mn><mo>/</mo><msup><mrow><mn>2</mn></mrow><mrow><mo>+</mo></mrow></msup></math> states in these isotopes, and pin down the inversion of these two levels at either <math><mi>A</mi><mo>=</mo><mn>121</mn><mspace width="0.25em"></mspace><mo>(</mo><mi>N</mi><mo>=</mo><mn>74</mn><mo>)</mo></math> or <math><mi>A</mi><mo>=</mo><mn>123</mn><mspace width="0.25em"></mspace><mo>(</mo><mi>N</mi><mo>=</mo><mn>76</mn><mo>)</mo></math>. We compare these findings to calculations performed with density functional theory (DFT), from which we establish the crucial role that the spin-orbit strength and time-odd mean fields play in the simultaneous description of electromagnetic moments and nuclear binding.

M.L. Bissell

J. Bonnard

P. Campbell

B. Cheal

C.S. Devlin

Poland

J. Dobaczewski

CERN

R.F. Garcia Ruiz

P. Imgram

R. Mathieson

Á. Koszorús

B. van den Borne

M. Vilén

S. Zadvornaya

Measurements of binding energies and electromagnetic moments of silver isotopes – A complementary benchmark of density functional theory

We report the first high-precision mass measurements of the neutron-rich nuclei $^{74,75}$Ni and the clearly identified ground state of $^{76}$Cu, along with a more precise mass-excess value of $^{78}$Cu, performed with the double Penning trap JYFLTRAP at the Ion Guide Isotope Separator On-Line (IGISOL) facility. These new results lead to a quantitative estimation of the quenching for the <math><mi>N</mi><mo>=</mo><mn>50</mn></math> neutron shell gap. The impact of this shell quenching on core-collapse supernova dynamics is specifically tested using a dedicated statistical equilibrium approach that allows a variation of the mass model independent of the other microphysical inputs. We conclude that the impact of nuclear masses is strong when implemented using a fixed trajectory as in the previous studies, but the effect is substantially reduced when implemented self-consistently in the simulation.

S. Giraud

B. Bastin

A.F. Fantina

F. Gulminelli

V. Girard-Alcindor

A. Khanam

F. de Oliveira Santos

C. Petrone

A. De Roubin

V.A. Rubchenya

J. Äystö

Mass measurements towards doubly magic Ni: Hydrodynamics versus nuclear mass contribution in core-collapse supernovae

The ground-state-to-ground-state <math><msup><mrow><mi>β</mi></mrow><mrow><mo>−</mo></mrow></msup></math>-decay $^{131}$I (7/2$^{+}$) → $^{131}$Xe (3/2$^{+}$) Q value was determined with high precision utilizing the double Penning trap mass spectrometer JYFLTRAP at the IGISOL facility. The Q value of this <math><msup><mrow><mi>β</mi></mrow><mrow><mo>−</mo></mrow></msup></math>-decay was found to be Q = 972.25(19) keV through a cyclotron frequency ratio measurement with a relative precision of 1.6 × 10$^{−9}$. This was realized using the phase-imaging ion-cyclotron-resonance technique. The new Q value is more than 3 times more precise and 2.3σ higher (1.45 keV) than the value extracted from the Atomic Mass Evaluation 2020. Our measurement confirms that the <math><msup><mrow><mi>β</mi></mrow><mrow><mo>−</mo></mrow></msup></math>-decay to the <math><mn>9</mn><mo>/</mo><msup><mrow><mn>2</mn></mrow><mrow><mo>+</mo></mrow></msup></math> excited state at 971.22(13) keV in $^{131}$Xe is energetically allowed with a Q value of 1.03(23) keV while the decay to the <math><mn>7</mn><mo>/</mo><msup><mrow><mn>2</mn></mrow><mrow><mo>+</mo></mrow></msup></math> state at 973.11(14) keV was found to be energetically forbidden. Nuclear shell-model calculations with established two-body interactions, alongside an accurate phase-space factor and a statistical analysis of the logft values of known allowed β decays, were used to estimate the partial half-life for the low-Q-value transition to the <math><mn>9</mn><mo>/</mo><msup><mrow><mn>2</mn></mrow><mrow><mo>+</mo></mrow></msup></math> state. The half-life was found to be (<math><msubsup><mrow><mn>1.97</mn></mrow><mrow><mo>−</mo><mn>0.89</mn></mrow><mrow><mo>+</mo><mn>2.24</mn></mrow></msubsup></math>) <math><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mn>7</mn></mrow></msup></math> years, which makes this candidate feasible for neutrino mass searches.

M. Ramalho

J. Kostensalo

J. Kotila

O. Beliushkina

J. Suhonen

High-precision measurement of a low Value for Allowed -decay of I related to neutrino mass determination

A precise determination of the ground state $^{111}$In (<math><mn>9</mn><mo>/</mo><msup><mrow><mn>2</mn></mrow><mrow><mo>+</mo></mrow></msup></math>) electron capture to ground state of $^{111}$Cd (<math><mn>1</mn><mo>/</mo><msup><mrow><mn>2</mn></mrow><mrow><mo>+</mo></mrow></msup></math>) Q value has been performed utilizing the double Penning trap mass spectrometer, JYFLTRAP. A value of 857.63(17) keV was obtained, which is nearly a factor of 20 more precise than the value extracted from the Atomic Mass Evaluation 2020 (AME2020). The high-precision electron-capture Q value measurement along with the nuclear energy level data of 866.60(6) keV, 864.8(3) keV, 855.6(10) keV, and 853.94(7) keV for $^{111}$Cd was used to determine whether the four states are energetically allowed for a potential ultra-low Q-value β decay or electron-capture decay. Our results confirm that the excited states of 866.60(6) keV with spin-parity (<math><msup><mrow><mi>J</mi></mrow><mrow><mi>π</mi></mrow></msup></math>) of 3/2$^{+}$ and 864.8(3) keV with <math><msup><mrow><mi>J</mi></mrow><mrow><mi>π</mi></mrow></msup><mo>=</mo><mn>3</mn><mo>/</mo><msup><mrow><mn>2</mn></mrow><mrow><mo>+</mo></mrow></msup></math> are ruled out due to their deduced electron-capture Q value being smaller than 0 keV at the level of around 20σ and 50σ, respectively. Electron-capture decays to the excited states at 853.94(7) keV (<math><msup><mrow><mi>J</mi></mrow><mrow><mi>π</mi></mrow></msup><mo>=</mo><mn>7</mn><mo>/</mo><msup><mrow><mn>2</mn></mrow><mrow><mo>+</mo></mrow></msup></math>) and 855.6(10) keV (<math><msup><mrow><mi>J</mi></mrow><mrow><mi>π</mi></mrow></msup><mo>=</mo><mn>3</mn><mo>/</mo><msup><mrow><mn>2</mn></mrow><mrow><mo>+</mo></mrow></msup></math>), are energetically allowed with Q values of 3.69(19) keV and 2.0(10) keV, respectively. The allowed decay transition $^{111}$In (9/2$^{+}$) → $^{111}$Cd (7/2$^{+}$), with a Q value of 3.69(19) keV, is a potential new candidate for neutrino-mass measurements by future EC experiments featuring new powerful detection technologies. The results show that the indium level <math><mn>2</mn><msub><mrow><mi>p</mi></mrow><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msub></math> for this decay branch leads to a significant increase in the number of EC events in the energy region sensitive to the electron neutrino mass.

Russia

K.S. Tyrin

M.I. Krivoruchenko

High-precision electron-capture Value Measurement of In for electron-neutrino mass determination

Isomeric states in $^{128}$In and $^{130}$In have been studied with the JYFLTRAP Penning trap at the IGISOL facility. By employing state-of-the-art ion manipulation techniques, three different beta-decaying states in $^{128}$In and $^{130}$In have been separated and their masses measured. JYFLTRAP was also used to select the ions of interest for identification at a post-trap decay spectroscopy station. A new beta-decaying high-spin isomer feeding the <math><msup><mrow><mn>15</mn></mrow><mrow><mo>−</mo></mrow></msup></math> isomer in $^{128}$Sn has been discovered in $^{128}$In at <math><mn>1797.6</mn><mo>(</mo><mn>20</mn><mo>)</mo></math> keV. Shell-model calculations employing a CD-Bonn potential re-normalized with the perturbative G-matrix approach suggest this new isomer to be a <math><msup><mrow><mn>16</mn></mrow><mrow><mo>+</mo></mrow></msup></math> spin-trap isomer. In $^{130}$In, the lowest-lying <math><mo>(</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo></mrow></msup><mo>)</mo></math> isomeric state at <math><mn>58.6</mn><mo>(</mo><mn>82</mn><mo>)</mo></math> keV was resolved for the first time using the phase-imaging ion cyclotron resonance technique. The energy difference between the <math><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo></mrow></msup></math> and <math><msup><mrow><mn>1</mn></mrow><mrow><mo>−</mo></mrow></msup></math> states in $^{130}$In, stemming from parallel/antiparallel coupling of <math><mo>(</mo><mi>π</mi><mn>0</mn><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><mo>⊗</mo><mo>(</mo><mi>ν</mi><mn>0</mn><msubsup><mrow><mi>h</mi></mrow><mrow><mn>11</mn><mo>/</mo><mn>2</mn></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msubsup><mo>)</mo></math>, has been found to be around 200 keV lower than predicted by the shell model. Precise information on the energies of the excited states determined in this work is crucial for producing new improved effective interactions for the nuclear shell model description of nuclei near $^{132}$Sn.

C.R. Nobs

A.M. Bruce

E.R. Gamba

R. de Groote

J. Kurpeta

L. Morrison

M. Rudigier

Three beta-decaying states in In and In resolved for the first time using Penning-trap techniques

The next generation neutrino observatory proposed by the LBNO collaboration will address fundamental questions in particle and astroparticle physics. The experiment consists of a far detector, in its first stage a 20 kt LAr double phase TPC and a magnetised iron calorimeter, situated at 2300 km from CERN and a near detector based on a highpressure argon gas TPC. The long baseline provides a unique opportunity to study neutrino flavour oscillations over their 1st and 2nd oscillation maxima exploring the L/E behaviour, and distinguishing effects arising from δ CP and matter.

India

S.K. Agarwalla

L. Agostino

M. Aittola

A. Alekou

B. Andrieu

D. Angus

F. Antoniou

Switzerland

A. Ariga

T. Ariga

R. Asfandiyarov

D. Autiero

P. Ballett

I. Bandac

D. Banerjee

G. Barker

G. Barr

W. Bartmann

F. Bay

Italy

V. Berardi

I. Bertram

O. Bésida

A.M. Blebea-Apostu

A. Blondel

Bulgaria

M. Bogomilov

E. Borriello

S. Boyd

I. Brancus

A. Bravar

M. Buizza-Avanzini

F. Cafagna

M. Calin

M. Calviani

M. Campanelli

C. Cantini

O. Caretta

Japan

G. Cata-Danil

M.G. Catanesi

A. Cervera

S. Chakraborty

L. Chaussard

D. Chesneanu

F. Chipesiu

G. Christodoulou

J. Coleman

P. Crivelli

T. Davenne

J. Dawson

I. Bonis

J. Jong

Y. Déclais

P. Amo Sanchez

A. Delbart

C. Densham

F. Lodovico

S. Luise

D. Duchesneau

J. Dumarchez

I. Efthymiopoulos

A. Eliseev

S. Emery

K. Enqvist

T. Enqvist

L. Epprecht

A. Ereditato

A.N. Erykalov

T. Esanu

A.J. Finch

M.D. Fitton

D. Franco

V. Galymov

G. Gavrilov

A. Gendotti

C. Giganti

B. Goddard

J.J. Gomez

C.M. Gomoiu

JINR

Y.A. Gornushkin

P. Gorodetzky

N. Grant

A. Haesler

The mass-hierarchy and CP-violation discovery reach of the LBNO long-baseline neutrino experiment