The difference in the proton and neutron separation energies ( <math altimg='si2.svg'><mrow><mstyle mathvariant='normal'><mi>&#916;</mi></mstyle><mi>S</mi></mrow></math>) of the weakly bound <math altimg='si5.svg'><msup><mrow /><mn>15</mn></msup></math>C ground state is -19.86 MeV, an extreme value. Data from intermediate-energy heavy-ion induced (HI-induced) knockout reactions on nuclei spanning <math altimg='si20.svg'><mrow><mo>&#8722;</mo><mn>20</mn><mo>&#8818;</mo><mstyle mathvariant='normal'><mi>&#916;</mi></mstyle><mi>S</mi><mo>&#8818;</mo><mo>+</mo><mn>20</mn></mrow></math> MeV, suggest that the degree to which single-particle strength is quenched, <math altimg='si13.svg'><msub><mi>R</mi><mrow><mi mathvariant='normal'>s</mi></mrow></msub></math>, has a negative correlation with <math altimg='si2.svg'><mrow><mstyle mathvariant='normal'><mi>&#916;</mi></mstyle><mi>S</mi></mrow></math>, decreasing from unity around <math altimg='si21.svg'><mrow><mo>&#8722;</mo><mn>20</mn></mrow></math> MeV to around 0.2 at <math altimg='si22.svg'><mrow><mo>+</mo><mn>20</mn></mrow></math> MeV. For the <math altimg='si5.svg'><msup><mrow /><mn>15</mn></msup></math>C ground state ( <math altimg='si23.svg'><mrow><msub><mi>R</mi><mi>s</mi></msub><mo linebreak='goodbreak'>=</mo><mn>0.96</mn><mrow><mo>(</mo><mn>4</mn><mo>)</mo></mrow></mrow></math> in HI-induced knockout), contrasting results have recently been obtained via the neutron-adding transfer reaction, which reveal a value of <math altimg='si24.svg'><mrow><msub><mi>R</mi><mi>s</mi></msub><mo linebreak='goodbreak'>=</mo><mn>0.64</mn><mrow><mo>(</mo><mn>15</mn><mo>)</mo></mrow></mrow></math>, similar to the value observed at modest <math altimg='si2.svg'><mrow><mstyle mathvariant='normal'><mi>&#916;</mi></mstyle><mi>S</mi></mrow></math> and more extreme values of <math altimg='si2.svg'><mrow><mstyle mathvariant='normal'><mi>&#916;</mi></mstyle><mi>S</mi></mrow></math> with reaction probes other than HI knockout. In order to explore the any potential differences between <math altimg='si25.svg'><mrow><mi>a</mi><mi>d</mi><mi>d</mi><mi>i</mi><mi>n</mi><mi>g</mi></mrow></math> and <math altimg='si26.svg'><mrow><mi>r</mi><mi>e</mi><mi>m</mi><mi>o</mi><mi>v</mi><mi>i</mi><mi>n</mi><mi>g</mi></mrow></math> processes in transfer reactions at extreme <math altimg='si2.svg'><mrow><mstyle mathvariant='normal'><mi>&#916;</mi></mstyle><mi>S</mi></mrow></math>, single-neutron removal transfer reactions on <math altimg='si5.svg'><msup><mrow /><mn>15</mn></msup></math>C were performed at 7.1 MeV/u in inverse kinematics. The removal of a valence neutron in 2 <math altimg='si19.svg'><msub><mi>s</mi><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msub></math> orbit using both ( <math altimg='si7.svg'><mrow><mi>p</mi><mo>,</mo><mi>d</mi></mrow></math>) and ( <math altimg='si8.svg'><mrow><mi>d</mi><mo>,</mo><mi>t</mi></mrow></math>) reactions shows consistent quenching factors and agrees with those from the neutron-adding reaction. The present results, which can be compared with neutron knockout reaction, suggest that correlations, represented by the quenching factor, show limited dependence on neutron-proton asymmetry under the most extreme asymmetry conditions so far achieved in transfer reactions.

China

Y.C. Jiang

United States

J. Chen

B.P. Kay

C.R. Hoffman

T.L. Tang

I.A. Tolstukhin

M.R. Xie

J.G. Li

N. Michel

M.L. Avila

Spain

Y. Ayyad

D. Bazin

United Kingdom

S. Bennett

J.A. Clark

Switzerland

S.J. Freeman

H. Jayatissa

G. Li

W.P. Liu

J.L. Lou

A. Munoz-Ramos

C. Müller-Gatermann

T. Nathan

D. Santiago-Gonzalez

D.K. Sharp

Y.P. Shen

A.H. Wuosmaa

C.X. Yuan

Quenching of single-particle strength inferred from nucleon-removal transfer reactions on <math altimg='si5.svg'><msup><mrow /><mn>15</mn></msup></math>C

The observation of a resonance structure in the opening angle of the electron-positron pairs in the $$^{7}$$ Li(p,e $$^+$$ e $$^-$$ ) $$^{8}$$ Be reaction was claimed and interpreted as the production and subsequent decay of a hypothetical particle (X17). Similar excesses, consistent with this particle, were later observed in processes involving $$^{4}$$ He and $$^{12}$$ C nuclei with the same experimental technique. The MEG II apparatus at PSI, designed to search for the $$\mu ^+ \rightarrow \textrm{e}^+ \gamma $$ decay, can be exploited to investigate the existence of this particle and study its nature. Protons from a Cockroft–Walton accelerator, with an energy up to 1.1 MeV, were delivered on a dedicated Li-based target. The $$\gamma $$ and the e $$^{+}$$ e $$^{-}$$ pair emerging from the $$^8\textrm{Be}^*$$ transitions were studied with calorimeters and a spectrometer, featuring a broader angular acceptance than previous experiments. We present in this paper the analysis of a four-week data-taking in 2023 with a beam energy of 1080 keV, resulting in the excitation of two different resonances with Q-value 17.6 and 18.1 MeV. No significant signal was found, and limits at 90% C.L. on the branching ratios (relative to the $$\gamma $$ emission) of the two resonances to X17 were set, $$R_{17.6} <{1.8}\,\times \,10^{-6}$$ and $$R_{18.1} < {1.2}\,\times \,10^{-5}$$ in the mass range between $${16.5}\hbox { MeV}/\hbox {c}^{2}$$ and $${17.1}\hbox { MeV}/\hbox {c}^{2}$$ .

Russia

K. Afanaciev

Italy

A. Baldini

Japan

S. Ban

H. Benmansour

G. Boca

P. Cattaneo

G. Cavoto

F. Cei

M. Chiappini

A. Corvaglia

G. Maso

A. Bari

M. Gerone

L. Barusso

M. Francesconi

L. Galli

G. Gallucci

F. Gatti

L. Gerritzen

F. Grancagnolo

E. Grandoni

M. Grassi

D. Grigoriev

M. Hildebrandt

F. Ignatov

F. Ikeda

T. Iwamoto

S. Karpov

P. Kettle

N. Khomutov

A. Kolesnikov

N. Kravchuk

V. Krylov

N. Kuchinskiy

F. Leonetti

W. Li

V. Malyshev

A. Matsushita

M. Meucci

S. Mihara

W. Molzon

T. Mori

D. Nicolò

H. Nishiguchi

A. Ochi

W. Ootani

A. Oya

D. Palo

M. Panareo

A. Papa

V. Pettinacci

A. Popov

F. Renga

S. Ritt

M. Rossella

A. Rozhdestvensky

S. Scarpellini

P. Schwendimann

G. Signorelli

M. Takahashi

Y. Uchiyama

A. Venturini

B. Vitali

C. Voena

K. Yamamoto

R. Yokota

T. Yonemoto

Search for the X17 particle in $$^{7}\textrm{Li}(\textrm{p},\textrm{e}^+ \textrm{e}^{-}) ^{8}\textrm{Be}$$ processes with the MEG II detector

We investigate Λ production in the ( <math altimg='si146.svg'><msup><mrow><mi>&#960;</mi></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msup></math>, <math altimg='si3.svg'><msup><mrow><mi>K</mi></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msup></math>) reaction on a 6Li target at <math altimg='si4.svg'><msub><mrow><mi>p</mi></mrow><mrow><msup><mrow><mi>&#960;</mi></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msup></mrow></msub><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mn>1.05</mn></math> GeV/ <italic>c</italic>, using the distorted-wave impulse approximation (DWIA) with the Fermi-averaged <math altimg='si5.svg'><msup><mrow><mi>&#960;</mi></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msup><mi>n</mi><mo stretchy='false'>&#8594;</mo><msup><mrow><mi>K</mi></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msup><mi mathvariant='normal'>&#923;</mi></math> amplitudes. The calculated spectrum is in good agreement with the experimental data, suggesting that <math altimg='si1.svg'><mmultiscripts><mrow><mi mathvariant='normal'>He</mi></mrow><mprescripts /><mrow><mi mathvariant='normal'>&#923;</mi></mrow><mrow><mn>4</mn></mrow></mmultiscripts></math>- <italic>d</italic> configurations play a key role in describing the &#923; continuum states of <math altimg='si23.svg'><msubsup><mrow /><mrow><mi mathvariant='normal'>&#923;</mi></mrow><mrow><mn>6</mn></mrow></msubsup></math>Li near and above the <math altimg='si8.svg'><mmultiscripts><mrow><mi mathvariant='normal'>He</mi></mrow><mprescripts /><none /><mrow><mn>3</mn></mrow></mmultiscripts><mo linebreak='goodbreak' linebreakstyle='after'>+</mo><mi>d</mi><mo linebreak='goodbreak' linebreakstyle='after'>+</mo><mi mathvariant='normal'>&#923;</mi></math> threshold. Our analysis shows that the <math altimg='si1.svg'><mmultiscripts><mrow><mi mathvariant='normal'>He</mi></mrow><mprescripts /><mrow><mi mathvariant='normal'>&#923;</mi></mrow><mrow><mn>4</mn></mrow></mmultiscripts></math> hypernucleus as a hyperfragment is prominently produced through <italic>D</italic>-wave resonances with <math altimg='si9.svg'><msup><mrow><mi>J</mi></mrow><mrow><mi>P</mi></mrow></msup><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><msup><mrow><mn>3</mn></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msup></math>, <math altimg='si10.svg'><msup><mrow><mn>2</mn></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msup></math>, and <math altimg='si11.svg'><msup><mrow><mn>1</mn></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msup></math> in the <math altimg='si108.svg'><mmultiscripts><mrow><mi mathvariant='normal'>He</mi></mrow><mprescripts /><mrow><mi mathvariant='normal'>&#923;</mi></mrow><mrow><mn>4</mn></mrow></mmultiscripts><mo linebreak='goodbreak' linebreakstyle='after'>+</mo><mi>d</mi></math> channel at a large momentum transfer <math altimg='si13.svg'><mi>q</mi><mo>&#8771;</mo><mn>360</mn></math>&#8211;400 MeV/ <italic>c</italic>. These findings provide theoretical evidence for the production of a <math altimg='si1.svg'><mmultiscripts><mrow><mi mathvariant='normal'>He</mi></mrow><mprescripts /><mrow><mi mathvariant='normal'>&#923;</mi></mrow><mrow><mn>4</mn></mrow></mmultiscripts></math> hyperfragment via a cluster-like mechanism in the 6Li( <math altimg='si146.svg'><msup><mrow><mi>&#960;</mi></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msup></math>, <math altimg='si3.svg'><msup><mrow><mi>K</mi></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msup></math>) reaction.

Toru Harada

Yoshiharu Hirabayashi

Evidence for <math altimg='si1.svg'><mmultiscripts><mrow><mi mathvariant='normal'>He</mi></mrow><mprescripts /><mrow><mi mathvariant='normal'>&#923;</mi></mrow><mrow><mn>4</mn></mrow></mmultiscripts></math> hyperfragment production in the 6Li( <italic>&#960;</italic> +, <italic>K</italic> +) reaction

The structure of the proton-unbound nucleus <math altimg='si1.svg'><mmultiscripts><mrow><mi mathvariant='normal'>Al</mi></mrow><mprescripts /><none /><mrow><mn>21</mn></mrow></mmultiscripts></math> has been studied via proton transfer from a <math altimg='si2.svg'><mmultiscripts><mrow><mi mathvariant='normal'>Be</mi></mrow><mprescripts /><none /><mrow><mn>9</mn></mrow></mmultiscripts></math> target to a <math altimg='si3.svg'><mmultiscripts><mrow><mi mathvariant='normal'>Mg</mi></mrow><mprescripts /><none /><mrow><mn>20</mn></mrow></mmultiscripts></math> beam at <math altimg='si4.svg'><mi>E</mi><mo stretchy='false'>/</mo><mi>A</mi></math> = 103 MeV. Three resonant states in <math altimg='si1.svg'><mmultiscripts><mrow><mi mathvariant='normal'>Al</mi></mrow><mprescripts /><none /><mrow><mn>21</mn></mrow></mmultiscripts></math> are identified by the invariant-mass reconstruction of <math altimg='si5.svg'><mmultiscripts><mrow><mi mathvariant='normal'>Ne</mi></mrow><mprescripts /><none /><mrow><mn>18</mn></mrow></mmultiscripts></math> + 3 <italic>p</italic> events. The decay-energy spectra for the two subsystems of <math altimg='si1.svg'><mmultiscripts><mrow><mi mathvariant='normal'>Al</mi></mrow><mprescripts /><none /><mrow><mn>21</mn></mrow></mmultiscripts></math>, i.e. <math altimg='si5.svg'><mmultiscripts><mrow><mi mathvariant='normal'>Ne</mi></mrow><mprescripts /><none /><mrow><mn>18</mn></mrow></mmultiscripts></math> + 1 <italic>p</italic> and <math altimg='si5.svg'><mmultiscripts><mrow><mi mathvariant='normal'>Ne</mi></mrow><mprescripts /><none /><mrow><mn>18</mn></mrow></mmultiscripts></math> + 2 <italic>p</italic>, indicate that the observed resonant state with the lowest energy has decay branches consisting of three sequential steps of one-proton decay. Based on the <italic>ab initio</italic> and the distorted-wave Born approximation (DWBA) calculations, this resonant state at <math altimg='si7.svg'><msup><mrow><mi>E</mi></mrow><mrow><mo>&#8270;</mo></mrow></msup></math> = 6.09(11) MeV likely has a spin-parity of <math altimg='si8.svg'><mo stretchy='false'>(</mo><mn>1</mn><mo stretchy='false'>/</mo><msup><mrow><mn>2</mn></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msup></math>- <math altimg='si9.svg'><mn>7</mn><mo stretchy='false'>/</mo><msup><mrow><mn>2</mn></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msup><mo stretchy='false'>)</mo></math>. Meanwhile, the possibility that the observed resonant peak represents an admixture of several states cannot be ruled out. The good isospin-symmetry of the low-lying states with <math altimg='si10.svg'><msub><mrow><mi>d</mi></mrow><mrow><mn>5</mn><mo stretchy='false'>/</mo><mn>2</mn></mrow></msub></math>, <math altimg='si11.svg'><msub><mrow><mi>d</mi></mrow><mrow><mn>3</mn><mo stretchy='false'>/</mo><mn>2</mn></mrow></msub></math> configurations in the <math altimg='si1.svg'><mmultiscripts><mrow><mi mathvariant='normal'>Al</mi></mrow><mprescripts /><none /><mrow><mn>21</mn></mrow></mmultiscripts></math>- <math altimg='si12.svg'><mmultiscripts><mrow><mi mathvariant='normal'>O</mi></mrow><mprescripts /><none /><mrow><mn>21</mn></mrow></mmultiscripts></math> pair and the <italic>ab initio</italic> calculations indicate weak configuration mixing between the <italic>s</italic>- and <italic>d</italic>-orbital components. The systematics of experimental energy differences between the <math altimg='si13.svg'><mn>5</mn><mo stretchy='false'>/</mo><msup><mrow><mn>2</mn></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msup></math> ground state and lowest-lying <math altimg='si14.svg'><mn>3</mn><mo stretchy='false'>/</mo><msup><mrow><mn>2</mn></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msup></math> excited state for isotopes (isotones) of <math altimg='si15.svg'><mi>Z</mi><mo stretchy='false'>(</mo><mi>N</mi><mo stretchy='false'>)</mo></math> = 13 suggest a likely semimagic nature of <math altimg='si1.svg'><mmultiscripts><mrow><mi mathvariant='normal'>Al</mi></mrow><mprescripts /><none /><mrow><mn>21</mn></mrow></mmultiscripts></math>.

L. Ni

Y. Jin

Z.H. Li

K.W. Brown

H. Hua

C.Y. Niu

A.K. Anthony

J. Barney

R.J. Charity

D. Dell'Aquila

J.M. Elson

J. Estee

G. Jhang

W.G. Lynch

L.G. Sobotka

S. Sweany

F.C.E. Teh

A. Thomas

C.Y. Tsang

M.B. Tsang

S.M. Wang

H.Y. Wu

K. Zhu

Observation of three-proton-decaying resonant states in 21Al

Shell evolution has been systematically investigated in neutron-rich isotopes, revealing many exotic properties such as the disappearance of traditional magic numbers and the emergence of new ones. However, research on proton-rich nuclei remains limited. In this study, we utilize <italic>ab initio</italic> valence-space in-medium similarity renormalization group approach using chiral effective field theory-derived interaction to explore shell evolution in the proton-dripline region. We first examine how the conventional shell closures at 8, 20, and 28 evolve from the stability line to the proton/neutron drip line, analyzing the average occupation, effective single-particle energy, and low-lying spectra. Our calculations reproduce the disappearance of <italic>N</italic> = 8, 20, and 28 magic numbers near 12Be, 32Mg, and 44S, respectively. Additionally, we find that the <italic>Z</italic> = 8, 20, and 28 also vanish in the mirror nuclei of these isotopes, forming the <italic>Z</italic> = 8, 20, and 28 <italic>islands of inversion</italic>, respectively. Notably, the strength of the proton shell is weaker than that of the neutron shell, which is an indication of larger deformations in proton-rich nuclei than in their neutron-rich mirror counterparts. Furthermore, we investigate the observed new magic numbers 14, 16, 32, and 34, successfully reproducing the double magicity of 22,24O and 52,54Ca, which also persist in their respective mirror nuclei. However, significant isospin symmetry breaking is observed. For example, the <math altimg='si1.svg'><msup><mrow><mn>2</mn></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msup></math> excitation energy of 22Si is approximately 800 keV lower than in its mirror nuclei, and the strength of the <math altimg='si2.svg'><mi>N</mi><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mn>32</mn></math> shell closure is stronger than that of <math altimg='si3.svg'><mi>N</mi><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mn>34</mn></math> subshell, a contrast that is reversed in their proton-rich counterparts.

H.H. Li

W. Zuo

<italic>Ab initio</italic> calculations for shell evolution in proton-dripline nuclei

The ultralight dark photon is an intriguing dark matter candidate. The interaction between visible and dark photons is introduced by the gauge kinetic mixing between the field strength tensors of the Abelian gauge groups in the Standard Model and dark sector. Relativistic electrodynamics was generalized to quantum electromagnetodynamics (QEMD) in the presence of both electric and magnetic charges. The photon is described by two four-potentials corresponding to two $ U(1) $ gauge groups and satisfying non-trivial commutation relations. In this work, we construct low-energy dark photon-photon interactions in the QEMD framework and obtain new dark photon-photon kinetic mixings. Then, we derive the consequent field and Maxwell's equations. We also investigate the detection strategies of dark photons as light dark matter and generic kinetic mixings at haloscope experiments.

Chang-Jie Dai

Tong Li

Rui-Jia Zhang

Dark photon dark matter in quantum electromagnetodynamics and detection at haloscope experiments * Li Tong is supported by the National Natural Science Foundation of China (12375096, 12035008, 11975129)

Cryogenic calorimetric experiments to search for neutrinoless double-beta decay ( $$0\nu \beta \beta $$ ) are highly competitive, scalable and versatile in isotope. The largest planned detector array, CUPID, is comprised of about 1500 individual Li $$_{2}$$ $$^{100}$$ MoO $$_4$$ detector modules with a further scale up envisioned for a follow up experiment (CUPID-1T). In this article, we present a novel detector concept targeting this second stage with a low impedance TES based readout for the Li $$_2$$ MoO $$_4$$ absorber that is easily mass-produced and lends itself to a multiplexed readout. We present the detector design and results from a first prototype detector operated at the NEXUS shallow underground facility at Fermilab. The detector is a 2-cm-side cube with 21 g mass that is strongly thermally coupled to its readout chip to allow rise-times of $$\sim $$ 0.5 ms. This design is more than one order of magnitude faster than present NTD based detectors and is hence expected to effectively mitigate backgrounds generated through the pile-up of two independent two neutrino decay events coinciding close in time. Together with a baseline resolution of 1.95 keV (FWHM) these performance parameters extrapolate to a background index from pile-up as low as $$5\cdot 10^{-6}$$ counts/keV/kg/yr in CUPID size crystals. The detector was calibrated up to the MeV region showing sufficient dynamic range for $$0\nu \beta \beta $$ searches. In combination with a SuperCDMS HVeV detector this setup also allowed us to perform a precision measurement of the scintillation time constants of Li $$_2$$ MoO $$_4$$ , which showed a primary component with a fast O(20 $$\upmu $$ s) time scale.

G. Bratrud

C. Chang

R. Chen

Canada

E. Cudmore

E. Figueroa-Feliciano

Z. Hong

K. Kennard

S. Lewis

M. Lisovenko

L. Mateo

V. Novati

V. Novosad

France

E. Oliveri

R. Ren

J. Scarpaci

B. Schmidt

G. Wang

L. Winslow

V. Yefremenko

J. Zhang

D. Baxter

M. Hollister

C. James

P. Lukens

D. Temples

First demonstration of a TES based cryogenic Li $$_2$$ MoO $$_4$$ detector for neutrinoless double beta decay search

Two-proton (2 <italic>p</italic>) radioactivity represents a rare decay mode that has been experimentally observed only in a selected few nuclei. The exploration of 2 <italic>p</italic> emission is crucial for elucidating the structure, mass, and nucleon-nucleon interactions within exotic proton-rich nuclei. 39Ti has long been postulated as a potential candidate for 2 <italic>p</italic> emission; however, experimental investigations have yet to confirm its 2 <italic>p</italic> decay. To provide more accurate information for further studies, we utilize the Gamow shell model (GSM) and the Gamow coupled channel (GCC) method to analyze the prospective 2 <italic>p</italic> radioactivity of isotopes 38,39Ti. Our calculations suggest that 39Ti is indeed a viable candidate for 2 <italic>p</italic> emission. Notably, the estimated partial 2 <italic>p</italic> decay width for 39Ti, predicted from the three-body GCC method, suggests that its 2 <italic>p</italic> decay could rival its <italic>&#946;</italic> decay in likelihood, although this is highly dependent on the specific 2 <italic>p</italic> decay energy. Additionally, our analysis indicates a propensity for pairing between the valence protons in 39Ti. A similar investigative approach reveals that 38Ti exhibits a higher 2 <italic>p</italic> decay energy and a broader decay width than 39Ti, positioning it as a more promising candidate for 2 <italic>p</italic> decay.

B. Huang

F.P. Bai

D.Q. Fang

Exploring the possible two-proton radioactivity of 38,39Ti

In this work we investigate the two-neutron decay of $^{13}$Li and of the excited states of $^{11}$Li populated via one-proton removal from $^{14}$Be and $^{12}$Be, respectively. A phenomenological model is used to describe the decay of $^{11}$Li and $^{13}$Li. While the first one displays important sequential components, the second one appears dominated by the direct two-neutron decay. A microscopic three-body model is used to extract information on the spatial configuration of the emitted neutrons before the decay and shows that the average distance between the neutrons increases going from $^{11}$Li to $^{13}$Li.