Mon·Jun 16, 2025Monday·June 16, 2025

1. 01*

   Revised $B(E2;2_1^{+}\to 0_1^{+})$ value in the semi-magic nucleus ${}^{210}$Pb

   C. M. Nickel🇩🇪 · V. Werner🇩🇪 · G. Rainovski🇧🇬 · P. R. John🇮🇹 · M. Beckers · D. Bittner · A. Blazhev🇩🇪 · A. Esmaylzadeh🇩🇪 · C. Fransen · J. Garbe · L. Gerhard🇩🇪 · K. Geusen and 16 other authors

   The lifetime of the $2_1^{+}$ state of ${}^{210}$Pb was measured in the ${}^{208}$Pb(${}^{18}$O, ${}^{16}$O)${}^{210}$Pb two-neutron transfer reaction by $\gamma$-ray spectroscopy employing the recoil-distance Doppler-shift method. The extracted absolute $B(E2)$$\downarrow$ value of $119{}_{-8}^{+9}{\text{e}}^2{\text{fm}}^4$ is consistent with previously reported measurements, but with significantly improved precision. The available experimental data for the $2_1^{+}$-$4_1^{+}$-$6_1^{+}$-$8_1^{+}$ multiplet are compared with shell-model calculations based on the well-established Kuo-Herling interaction. The new $B(E2)$$\downarrow$ value agrees well with the shell-model prediction, providing evidence that the properties of the $2_1^{+}$ and $8_1^{+}$ states of ${}^{210}$Pb can be consistently described together within the nuclear shell-model framework.

   nucl-exPRC(2026)·1 citation
2. 02*

   Charge Pickup Reaction Cross Section for Neutron-Rich p-Shell Isotopes at 900A MeV

   J.-C. Zhang · B.-H. Sun · I. Tanihata🇯🇵 · S. Terashima · F. Wang🇨🇳 · R. Kanungo🇨🇦 · C. Scheidenberger🇩🇪 · F. Ameil · J. Atkinson · Y. Ayyad🇪🇸 · S. Bagchi🇩🇪 · D. Cortina-Gil🇪🇸 and 25 other authors

   We report charge pickup reaction cross sections for 24 \textit{p}-shell isotopes, including ${}^{8,9}$Li, ${}^{10-12}$Be, ${}^{10,13-15}$B, ${}^{12,14-19}$C and ${}^{14,15,17-22}$N, measured at relativistic energies (approximately 900$A$ MeV) on both hydrogen and carbon targets. For the first time, we reveal a universal rapid increase in the charge pickup cross sections of unstable projectiles with isospin asymmetry along several isotopic chains. The cross sections can be decoupled into distinct contributions from the mass number and isospin asymmetry of the projectile, highlighting the critical role of the latter, and can be formulated empirically.

   nucl-exnucl-thPRX(2025)·4 citations
3. 03*

   Recent Results on the Tetraneutron

   Thomas Faestermann🇩🇪 · Roman Gernhäuser🇩🇪

   We describe the recent experiments which claimed an observation of a tetra-neutron signal. Production reactions like transfer, knockout, fragmentation or photodisintegration have been used at very different experiments and facilities to form systems just made of neutrons. As a possible explanation of the partly contradicting results we suggest that some observed the bound ground state and some an unbound but still correlated state of the four neutrons at different exitation energy. We also refer to some of the theoretical works.

   nucl-exnucl-th3 citations
4. 04*

   Asymmetric muon-antimuon emission from $Z^0$ decays: a clear magnetometer in relativistic heavy-ion collisions

   Alejandro Ayala🇲🇽 · Ana Julia Mizher🇧🇷 · Javier Rendón🇲🇽

   We show that a very clear signal of the presence of a strong magnetic field during the early stage of a high-energy heavy-ion collision is provided by the decay of the $Z^0$ into dimuon pairs. We find that the process is highly anisotropic, producing pairs mainly out of plane, as signaled by a negative value of $v_2$, and leads to an antimuon transverse momentum distribution which peaks at a higher value of the transverse momentum compared to the peak of the muon transverse momentum distribution. We also show that the process does not produce a significant distortion of the $Z^0$ spectral function. The signal can be identified by comparing the dimuon-invariant mass and the individual muon and antimuon spectra produced in semicentral heavy-ion collisions with the corresponding scaled spectra produced in p+p collisions at the $Z^0$ peak.

   ↳ hep-phhep-exnucl-exnucl-thPRC(2026)·3 citations
5. 05*

   Impact of particle production mechanisms on pseudorapidity distribution and directed flow in Au+Au and Cu+Cu collisions at $\sqrt{s_{NN}}$ = 19.6 GeV using AMPT model

   Muhammad Farhan Taseer🇨🇳 · Subhash Singha🇨🇳

   The STAR experiment at the top RHIC energy has observed that the directed flow ($v_1$) of inclusive light hadrons is independent of the collision system size at a given centrality~\cite{STAR:2008jgm}. However, recent STAR measurements indicate a system-size dependence in the $v_1(y)$-slope ($d{v}_1/dy$) of protons, antiprotons, and their differences ($\Delta d{v}_1/dy$) at a given centrality, suggesting a potential influence of baryon production and transport mechanisms~\cite{Taseer:SQM2024talk}. We have studied pseudorapidity ($dN/dy$) distributions and directed flow ($v_1$ and $d{v}_1/dy$) for pions, kaons, and protons in Au+Au and Cu+Cu collisions at $\sqrt{s_{NN}}=19.6$ GeV using the A Multi-Phase Transport (AMPT) model. Specifically, we investigated the influence of string junction parameters in AMPT via the PYTHIA/JETSET routines, focusing on the popcorn mechanism and string-splitting parameters, on $dN/dy$, $d{v}_1/dy$, and their charge-dependent splittings ($\Delta dN/dy$ and $\Delta d{v}_1/dy$). We observe that string junction parameters can affect $dN/dy$, $d{v}_1/dy$, $\Delta dN/dy$, and $\Delta d{v}_1/dy$ for $\pi$, K, and p, and influence their system-size dependence. The effect is most prominent on the $v_1$ of protons, non-trivial for kaons, while the pions $v_1$ remain largely unchanged. These findings provide insights into the interplay between particle production mechanisms, baryon transport, and directed flow in heavy-ion collisions.

   ↳ nucl-thhep-exhep-phnucl-exCPC(2025)·0 citations
6. 06*

   Discrimination of neutron-$\gamma$ in the low energy regime using machine learning for an EJ-276D plastic scintillator

   S. Panda (a and b)🇮🇳 · P. K. Netrakanti (a)🇮🇳 · S. P. Behera (a and b)🇮🇳 · R. R. Sahu (a)🇮🇳 · K. Kumar (a and b)🇺🇸 · R. Sehgal (a)🇮🇳 · D. K. Mishra (a and b)🇮🇳 · V. Jha (a and b) ((a) Nuclear Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai, India, (b) Homi Bhabha National Institute, Anushakti Nagar, Mumbai, India)🇮🇳

   In this work, we present results for discrimination of neutron and $\gamma$ events using a plastic scintillator detector with pulse shape discrimination capabilities. Machine learning (ML) algorithms are used to improve the discriminatory power between neutron and $\gamma$ events at lower energy ranges which otherwise are not addressed by the conventional pulse shape discrimination techniques. The use of a multilayer perceptron with Bayesian inference (MLPBNN) and support vector machine (SVM) algorithms are studied using the recorded waveforms from the detector. Input variables are constructed for the ML algorithms, which captures the essence of the differences in the head and tail part of the neutron and $\gamma$ waveforms. A new variable, which utilizes the product of kurtosis and variance calculated from the waveform gives better ranking in terms of separation of neutron and $\gamma$ events. The training and the testing of the ML algorithms are done using an AmBe neutron source. In the lower energy region, the results obtained from the ML predictions are compared with the results obtained from a time of flight (ToF) technique to benchmark the overall performance of the ML algorithms. A reasonable agreement is observed between the results obtained from ML algorithm and the ToF experiment in the studied energy range. The MLPBNN gives better discriminatory power for the neutron and $\gamma$ events than the SVM algorithm.

   ↳ physics.ins-dethep-exnucl-exNucl.Instrum.Meth.A(2026)·1 citation

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.