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n_TOF Collaboration(Alcayne, V. et al), Babiano-Suarez, V., Caballero-Ontanaya, L., Domingo-Pardo, C., Ladarescu, I., & Tain, J. L. (2026). Measurement of the 244Cm neutron capture cross section at the n_TOF facility at CERN. Ann. Nucl. Energy, 227, 111977–14pp.
Abstract: Accurate neutron capture cross section data for minor actinides are essential for the safe and efficient management of high level radioactive waste produced during the operation of nuclear reactors. In particular, Cm-244, with a half-life of 18.11 years, dominates neutron emission in spent fuel and also contributes significantly to the decay heat and radiotoxicity. Furthermore, neutron capture on Cm-244 opens the pathway for the formation of heavier isotopes such as Bk, Cf, and other Cm isotopes. Sensitivity studies for present and future nuclear reactors have highlighted the need to reduce the uncertainties in the Cm-244 capture cross section. Experimental data on the capture cross section of this isotope are scarce due to the challenges associated with its measurements. Prior to the presented measurement and two recent measurements conducted at J-PARC, only one set of data for the Cm-244 capture cross section existed, obtained in 1969 during an underground nuclear explosion experiment. The capture cross section of Cm-244 has been measured at the nTOF facility at CERN with three different experimental setups: one at Experimental Area 1 (EAR1) using the Total Absorption Calorimeter and two measurements at Experimental Area 2 (EAR2) with C6D6 detectors, employing two different samples. The results from these three measurements were found to be compatible and then combined. In total, 17 resonances of Cm-244 were measured at nTOF below 300 eV. The radiative kernels obtained in this measurement are in good agreement with JENDL-4.0 for the majority of the resonances. Additionally, they are compatible with the recent JENDL-5 library below 50 eV, while at higher energies, the majority of radiative kernels from this evaluation based on the recent measurement by Kawase et al., are not compatible. Additionally, the Cm-244 samples also contained Pu-240. Resonances of this isotope were analyzed in the energy range between 20 and 180 eV, and the results were found to be consistent with previous measurements and evaluations, that enhances confidence in the Cm-244 results.
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Kruzsicz, B. et al, & Algora, A. (2025). Negative-parity high-spin structure of 105Pd. Phys. Rev. C, 112(6), 064316–13pp.
Abstract: Negative-parity medium-and high-spin structure of the nucleus 105Pd was studied through the 96Zr(13C, 4n) 105Pd reaction at incident energies of 51 and 58 MeV, using the EUROBALL IV gamma-ray spectrometer in conjunction with the DIAMANT charged particle array. New bands have been observed and the previously reported bands have been extended to higher energies and spins. Altogether six decoupled bands with E2 transitions and one strongly coupled band with M1 + E2 transitions have been observed. The observed energy spectra and B(M1)/B(E2) ratios are compared with results of quantum particle rotor model calculations. Based on these comparisons, quasiparticle configurations can be assigned to two newly observed decoupled bands as well as to the strongly coupled band. The previously emerged possible interpretation for the third decoupled band as a two-phonon wobbling excitation lacks support. The observations indicate possible gamma-band nature for this band. The strongly coupled band, consistently with the absence of another observed strongly coupled band in this experiment, does not exhibit chirality.
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IDS Collaboration(Dyszel, P. et al), Algora, A., & Nacher, E. (2025). First β-Delayed Two-Neutron Spectroscopy of the r-Process Nucleus 134In and Observation of the i13/2 Single-Particle Neutron State in 133Sn. Phys. Rev. Lett., 135(15), 152501–8pp.
Abstract: This manuscript reports on the direct observation of a beta-delayed two-neutron emission in a study of In-134 at the ISOLDE Decay Station using neutron spectroscopy. We also report on the first measurement in beta(-) decay of the long-sought 13/2(+) excited state in Sn-133, attributed to be the neutron single-particle i(13/2) orbital. The observation of sequential neutron emission is used to extract the relative population of the i(13/2) state, which was found to be much smaller than the predictions of the statistical model. The experiment was possible because of the innovative use of a neutron array with neutron discrimination and interaction tracking capabilities. This is the first study of the details of the two-neutron emission for a nucleus, which belongs to the r-process path. Understanding beta-delayed two-neutron emission probabilities is essential to validate models used in astrophysical r-process nucleosynthesis calculations. Observing two-neutron emissions in beta(-) decay paves the way for new experiments to study energy and angular correlations for ssdelayed multineutron emitters.
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Gomez Dumm, D., Noguera, S., & Scoccola, N. N. (2025). Charged pion decay in a laser field. Phys. Rev. D, 112(11), 114035–23pp.
Abstract: We study the decays n+ -> l+vl in the presence of a background electromagnetic plane wave with circular polarization. We find that, in the presence of this background, the number of hadronic form factors required to describe the pion-to-vacuum amplitude increases from one to four. Three of these form factors are associated with the axial vector current and one with the vector piece, which is in general different from zero. We obtain analytical expressions for the corresponding contributions to the decay width, considering in particular some range of values of interest for the frequency and amplitude of the external wave. For laser frequencies ri of the order of the eV, it is seen that the main correction to the result obtained in absence of the external field is proportional to the vector form factor, carrying a suppression factor of order similar to(ri/mn)4/3. In addition, we show that our expressions can be connected with the Kroll-Watson formula, which provides the differential cross section for the scattering of a charged particle by some potential in the presence of a strong external electromagnetic wave. Our analytical results are also compatible with previous numerical calculations obtained in the limit of low amplitude laser fields, offering new insight on some characteristics of these results.
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ISOLDE Collaboration(Parra, S. et al), Nacher, E., Rubio, B., Agramunt, J., Algora, A., Morales, A. I., et al. (2025). Isospin mixing in 64,66Ga reexamined via total absorption spectroscopy. Phys. Rev. C, 112(6), 064328–9pp.
Abstract: New measurements of the ,B decay of 64Ga and 66Ga have been carried out using total absorption spectroscopy at CERN-ISOLDE. The purpose of the study was to determine whether systemic effects such as Pandemonium have affected previous measurements and also determine the degree of isospin mixing in these proton-rich nuclei. Our results show that the ,B strength distribution of 64Ga was previously underestimated, while that of 66Ga agrees well with previous high-resolution measurements. The results allowed us to determine the amount of isospin mixing in the 0+ -> 0+ transitions to the ground states of the daughter nuclei. From the extracted log ft values, we determined the isospin mixing parameter a for the two cases. They were found to be consistent with values for similar transitions in other nuclei. 64Ga exhibits the largest amount of isospin mixing in such nuclei. These findings improve our understanding of beta decay and have implications for nuclear structure models and medical applications of 66Ga in PET imaging.
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