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Orrigo, S. E. A. et al, Rubio, B., Agramunt, J., Algora, A., & Molina, F. (2014). Observation of the beta-Delayed gamma-Proton Decay of Zn-56 and its Impact on the Gamow-Teller Strength Evaluation. Phys. Rev. Lett., 112(22), 222501–5pp.
Abstract: We report the observation of a very exotic decay mode at the proton drip line, the beta-delayed gamma-proton decay, clearly seen in the beta decay of the T-z = -2 nucleus Zn-56. Three gamma-proton sequences have been observed after the beta decay. Here this decay mode, already observed in the sd shell, is seen for the first time in the f p shell. Both. and proton decays have been taken into account in the estimation of the Fermi and Gamow-Teller strengths. Evidence for fragmentation of the Fermi strength due to strong isospin mixing is found.
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Fallot, M., Cormon, S., Estienne, M., Algora, A., Bui, V. M., Cucoanes, A., et al. (2012). New Antineutrino Energy Spectra Predictions from the Summation of Beta Decay Branches of the Fission Products. Phys. Rev. Lett., 109(20), 202504–5pp.
Abstract: In this Letter, we study the impact of the inclusion of the recently measured beta decay properties of the Tc-102;104;105;106;107, Mo-105, and Nb-101 nuclei in an updated calculation of the antineutrino energy spectra of the four fissible isotopes U-235,U-238 and Pu-239,Pu-241. These actinides are the main contributors to the fission processes in pressurized water reactors. The beta feeding probabilities of the above-mentioned Tc, Mo, and Nb isotopes have been found to play a major role in the gamma component of the decay heat of Pu-239, solving a large part of the gamma discrepancy in the 4-3000 s range. They have been measured by using the total absorption technique, insensitive to the pandemonium effect. The calculations are performed by using the information available nowadays in the nuclear databases, summing all the contributions of the beta decay branches of the fission products. Our results provide a new prediction of the antineutrino energy spectra of U-235, Pu-239,Pu-241, and, in particular, U-238 for which no measurement has been published yet. We conclude that new total absorption technique measurements are mandatory to improve the reliability of the predicted spectra.
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Algora, A. et al, Jordan, D., Tain, J. L., Rubio, B., Agramunt, J., Perez-Cerdan, A. B., et al. (2010). Reactor Decay Heat in Pu-239: Solving the gamma Discrepancy in the 4-3000-s Cooling Period. Phys. Rev. Lett., 105(20), 202501–4pp.
Abstract: The beta feeding probability of Tc-102,Tc- 104,Tc- 105,Tc- 106,Tc- 107, Mo-105, and Nb-101 nuclei, which are important contributors to the decay heat in nuclear reactors, has been measured using the total absorption technique. We have coupled for the first time a total absorption spectrometer to a Penning trap in order to obtain sources of very high isobaric purity. Our results solve a significant part of a long-standing discrepancy in the gamma component of the decay heat for Pu-239 in the 4-3000 s range.
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Phong, V. H. et al, Agramunt, J., Algora, A., Domingo-Pardo, C., Morales, A. I., Rubio, B., et al. (2022). Beta-Delayed One and Two Neutron Emission Probabilities South-East of Sn-132 and the Odd-Even Systematics in r-Process Nuclide Abundances. Phys. Rev. Lett., 129(18), 172701–7pp.
Abstract: The beta-delayed one- and two-neutron emission probabilities (P-1n and P-2n) of 20 neutron-rich nuclei with N >= 82 have been measured at the RIBF facility of the RIKEN Nishina Center. P-1n of Ag-130;131, Cd-133;134, In-135;136, and (138;13)9Sn were determined for the first time, and stringent upper limits were placed on P-2n for nearly all cases. beta-delayed two-neutron emission (beta 2n) was unambiguously identified in Cd-133 and In-135;136, and their P-2n were measured. Weak beta 2n was also detected from Sn-137;138. Our results highlight the effect of the N = 82 and Z = 50 shell closures on beta-delayed neutron emission probability and provide stringent benchmarks for newly developed macroscopic-microscopic and self-consistent global models with the inclusion of a statistical treatment of neutron and. emission. The impact of our measurements on r-process nucleosynthesis was studied in a neutron star merger scenario. Our P-1n and P-2n have a direct impact on the
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Guastalla, G. et al, Algora, A., & Domingo-Pardo, C. (2013). Coulomb Excitation of Sn-104 and the Strength of the Sn-100 Shell Closure. Phys. Rev. Lett., 110(17), 172501–5pp.
Abstract: A measurement of the reduced transition probability for the excitation of the ground state to the first 2(+) state in Sn-104 has been performed using relativistic Coulomb excitation at GSI. Sn-104 is the lightest isotope in the Sn chain for which this quantity has been measured. The result is a key point in the discussion of the evolution of nuclear structure in the proximity of the doubly magic nucleus Sn-100. The value B(E2; 0(+) -> 2(+)) = 0.10(4) e(2)b(2) is significantly lower than earlier results for Sn-106 and heavier isotopes. The result is well reproduced by shell model predictions and therefore indicates a robust N = Z = 50 shell closure.
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