Measuring the ß-decay Properties of Neutron-rich Exotic Pm, Sm, Eu, and Gd Isotopes to Constrain the Nucleosynthesis Yields in the Rare-earth Region

The ß-delayed neutron-emission probabilities of 28 exotic neutron-rich isotopes of Pm, Sm, Eu, and Gd were measured for the first time at RIKEN Nishina Center using the Advanced Implantation Detector Array (AIDA) and the BRIKEN neutron detector array. The existing ß-decay half-life (T1/2) database was significantly increased toward more neutron-rich isotopes, and uncertainties for previously measured values were decreased. The new data not only constrain the theoretical predictions of half-lives and ß-delayed neutron-emission probabilities, but also allow for probing the mechanisms of formation of the high-mass wing of the rare-earth peak located at A ˜ 160 in the r-process abundance distribution through astrophysical reaction network calculations. An uncertainty quantification of the calculated abundance patterns with the new data shows a reduction of the uncertainty in the rare-earth peak region. The newly introduced variance-based sensitivity analysis method offers valuable insight into the influence of important nuclear physics inputs on the calculated abundance patterns. The analysis has identified the half-lives of 168Sm and of several gadolinium isotopes as some of the key variables among the current experimental data to understand the remaining abundance uncertainty at A = 167–172.Peer ReviewedPostprint (published version

miniBELEN: a modular neutron counter for (a, n) reactions

miniBELEN is a modular and transportable neutron moderated counter with a nearly flat neutron detection efficiency up to 10 MeV. Modularity implies that the moderator can be reassembled in different ways in order to obtain different types of response. The detector has been developed in the context of the Measurement of Alpha Neutron Yields (MANY) collaboration, which is a scientific effort aiming to carry out measurements of (a, n) production yields, reaction cross-sections and neutron energy spectra. In this work we present and discuss several configurations of the miniBELEN detector. The experimental validation of the efficiency calculations using 252Cf sources and the measurement of the 27Al(a, n) 30P reaction is also presented.This work has been supported by the Spanish Ministerio de Economía y Competitividad under grants FPA2017-83946- C2-1 & C2-2 and PID2019-104714GB-C21 & C22, the Generalitat Valenciana Grant PROMETEO/2019/007, both cofounded by FEDER (EU), and the SANDA project funded under H2020-EURATOM-1.1 Grant No. 847552. The authors acknowledge the support from Centro de Microanálisis de Materiales (CMAM) - Universidad Autónoma de Madrid, for the beam time proposal (Comissioning of neutron detector systems for (a,݊n) reaction measurements) with code P01156, and its technical staff for their contribution to the operation of the accelerator.Article signat per 41 autors/es: N. Mont-Geli, A. Tarifeño-Saldivia, L.M. Fraile, S. Viñals, A. Perea, M. Pallàs, G. Cortés, E. Nácher, J.L. Tain, V. Alcayne, A. Algora, J. Balibrea-Correa, J. Benito, M.J.G. Borge, J.A. Briz, F. Calviño, D. Cano-Ott, A. De Blas, C. Domingo-Pardo, B. Fernández, R. Garcia, G. García, J. Gómez-Camacho, E.M. González-Romero, C. Guerrero, J. Lerendegui-Marco, M. Llanos, T. Martínez, E. Mendoza, J.R. Murias, S.E.A. Orrigo, A. Pérez de Rada, V. Pesudo, J. Plaza, J.M. Quesada, A. Sánchez, V. Sánchez-Tembleque, R. Santorelli, O. Tengblad, J.M. Udías and D. Villamarín.Postprint (published version

Estudi de les propietats de desintegració de nuclis del Ba a Nd (A~160) rellevants per a la formació del pic de terres rares del procés r

Half-lifes (T1/2) of exotic neutron-rich isotopes of Ba, La, Ce, Pr, and Nd were measured at the RIKEN Nishina Center. The experimental setup consisted of the BigRIPS in-flight separator for ion selection identification, the Advance Implantation Detector Array (AIDA) for ions and ß detection, and the BRIKEN detector for neutron counting. Using this setup, 4 new T1/2 have been measured for the first time, and 38 T1/2 have been remeasured with improved precision in several cases. These new experimental data should help to constrain theoretical models for calculations of T1/2. The status of the experimental analysis and preliminary results are provided in this contribution.This work has been supported by the Spanish Ministerio de Economía y Competitividad under Grants. FPA2014- 52823-C2-1-P, FPA2014-52823-C2-2-P, FPA2017-83946- C2-1-P, FPA2017-83946-C2-2-P and grants from Ministerio de Ciencia e Innovacion PID2019-104714GB-C21, PID2019-104714GB-C22. Supported by Generalitat Valenciana regional grant PROMETEO/2019/007. Supported by European Union FEDER funds. It also has been supported by NKFIH (NN128072).Article signat per 61 autors/es: M. Pallàs, A. Tarifeño-Saldivia, G. G. Kiss, J. L. Tain, A. Tolosa-Delgado, A. Vitéz- Sveiczer, F. Calviño, J. Agramunt, P. Aguilera, A. Algora, J. M. Allmond, H. Baba, N. T. Brewer, R. Caballero-Folch, P. J. Coleman-Smith, G. Cortes, T. Davinson, I. Dillmann, C. Domingo-Pardo, A. Estrade, N. Fukuda, S. Go, C. J. Griffin, R. K. Grzywacz, O. Hall, L. J. Harkness-Brennan, T. Isobe, D. Kahl, T. T. King, A. Korgul, S. Kovács, S. Kubono, M. Labiche, J. Liu, M. Madurga, K. Miernik, F. Molina, N. Mont-Geli, A. I. Morales, E. Nácher, A. Navarro, N. Nepal, S. Nishimura, M. Piersa-Silkowska, V. Phong, B. C. Rasco, J. Romero-Barrientos, B. Rubio, K. P. Rykaczewski, Y. Saito, H. Sakurai, Y. Shimizu, M. Singh, T. Sumikama, H. Suzuki, T. N. Szegedi, H. Takeda, K. Wang, M. Woli´nska-Cichocka, P. J. Woods, and R. Yokoyama for the BRIKEN collaboration.Postprint (published version

Estudi de les propietats de desintegració de nuclis del Ba a Nd rellevants per a la formació del pic de les terres rares del procés r (A~160)

At the RIKEN Nishina Center, exotic neutron-rich isotopes of Ba, La, Ce, Pr, and Nd were measured. This work reports their half-lives (T1/2) and ß-delayed neutron-emission probabilities (Pxn). The setup consisted of the BigRIPS in-flight separator for particle identification, the Advanced Implanta- tion Detector Array (AIDA) for ions and ß detection, and the BRIKEN neutron counter for neutron detection. Using this arrangement, 4 new T1/2 and 14 new P1n were measured. Furthermore, 38 T1/2 and 2 P1n values were remeasured, decreasing the uncertainties for some of them. In addition to improving predic- tions of nucleosynthesis models that describe the production of the rare-earth peak at A~160 via the r-process, these additional experimental data should help to constrain theoretical models for calculations of T1/2 and Pxn in this region.This work has been supported by the Spanish Ministerio de Economía y Competitividad un- der Grants nos. FPA2014-52823-C2-1-P, FPA2014-52823-C2-2-P, FPA2017-83946-C2-1-P, FPA2017-83946-C2-2-P and grants from Ministerio de Ciencia e Innovacion nos PID2019- 104714GB-C21, PID2019-104714GB-C22. It was also supported by NKFIH (NN128072) and by the ÚNKP-22-2 and ÚNKP-22-3 New National Excellence Program of the Ministry for Culture and Innovation from the source of the National Research, Development and In- novation Fund (Project numbers: ÚNKP-22-2-I-DE-75; ÚNKP-22-3-II- DE-132).Article signat per 61 autors/es: M. Pallàs, A. Tarifeño-Saldivia, G. G. Kiss, J. L. Tain, A. Tolosa- Delgado, A. Vitéz-Sveiczer, F. Calviño, J. Agramunt, P. Aguilera, A. Algora, J. M. Allmond, H. Baba, N. T. Brewer, R. Caballero-Folch, P. J. Coleman-Smith, G. Cortes, T. Davinson, I. Dillmann, C. Domingo-Pardo, A. Estrade, N. Fukuda, S. Go, C. J. Griffin, R. K. Grzywacz, O. Hall, L. J. Harkness-Brennan, T. Isobe, D. Kahl, T. T. King, A. Korgul, S. Kovács, S. Kubono, M. Labiche, J. Liu, M. Madurga, K. Miernik, F. Molina, N. Mont-Geli, A. I. Morales, E. Nácher, A. Navarro, N. Nepal, S. Nishimura, M. Piersa- Silkowska, V. Phong, B. C. Rasco, J. Romero-Barrientos, B. Rubio, K. P. Rykaczewski, Y. Saito, H. Sakurai, Y. Shimizu, M. Singh, T. Sumikama, H. Suzuki, T. N. Szegedi, H. Takeda, K. Wang, M. Woli´nska-Cichocka, P. J. Woods, and R. Yokoyama for the BRIKEN collaboration.Postprint (published version