TATAKI-Pro

Nuclear structure and nucleosynthesis of the heaviest elements in nature

Ref: CISEJI/2022/25

The Project

How were the actinides created in nature? The genesis of the chemical elements in the universe is one of the most relevant questions of modern Science. Of the two main nucleosynthesis mechanisms synthesizing nuclei beyond Fe, only the rapid neutron-capture process (also called r process) is able to create highly unstable nuclei near the neutron-drip line, reach the trans-bismuth fissile elements and produce the nuclear cosmo-chronometers 238U and 232Th. The later, of great interest to measure the age of stars or identify r-process events, are expected to be very sensitive to the β-decay properties of nuclei beyond the third r-process peak. While significant progress has been made in the last decade in measuring β-decay properties of relevant r-process progenitor nuclei, the region of heavy neutron-rich nuclei spanning across the Z=82 shell closure remains largely unexplored due to the difficulties in synthesizing, identifying, and investigating N~126 nuclei in the laboratory.

The first and foremost aim of the TATAKI-Pro project is to perform cutting-edge basic research on highly unstable, thus far unexplored nuclei at both sides of the N=126 closed shell, of relevance to provide robust nuclear-structure theoretical frames to understand the synthesis of the heaviest chemical elements.

Scientific activity

How does the nuclear structure impact on the reaction and decay rates of heavy neutron-rich r-process nuclei? To help answering this general question, the AGATA group is carrying out an extensive experimental program at the forefront facilities RIBF, in RIKEN (Japan), and GSI-FAIR (Germany). The experiments address different systematic measurements of nuclear properties to answer more specific questions and, more generally, to help better modeling the  structure of r-process nucleosynthetic nuclei out of experimental reach.

The experiment was successfully completed in November 2024. About xxx nuclear species between Au and Ra were produced in relativistic fragmentation reactions of 238U. These were identified in the BigRIPS magnetic spectrometer. The experimental setup comprised the new WAS3ABi active stopper, consisting of a stack of two Double Sided Silicon Strip Detectors (DSSSD) of 1-mm thickness and 128 strips –64 vertical and 64 horizontal– and the DTAS spectrometer, made of 16 square-shaped NaI(Tl) detectors of big dimensions. The versatile setup will allow us to measure a variety of nuclear properties such as isomeric transitions, β-decay half-lives, Meitner-Ellis electrons, or β-strength functions. The new information will help us better understanding which is the role of first-forbidden transitions in the β decay of N~126 nuclei, to which extent the seniority scheme holds southeast of 208Pb, or which is the role of collective nuclear vibrations in the region.

The experiment was carried out in June 2024. More than 50 nuclear species between 198Ir and 229Fr were produced by fragmentation reactions of a 238U beam at 1GeV/nucleon on a 2.5 m/cm2 Be target, and were subsequently identified in the FRS magnetic spectrometer. At the final focal plane, the exotic nuclei were stopped in the implantation stack, comprising two AIDA DSSSDs with dimensions 24×8 cm2 and divided in 382 horizontal and 128 vertical strips, two βPlast plastic scintillators of similar dimensions sandwiching AIDA, and the DINTESPEC demonstrator, consisting of two BB7 DSSSD detectors from MICRON STD with 64 2-mm pitch strips each –32 vertical and 32 horizontal–. Both AIDA and DINTESPEC were 1-mm thick. The implantation stack was surrounded by the DESPEC hybrid γ array, comprising 36 FATIMA LaBr3 crystals arranged in three backward rings and 12 DEGAS triple-cluster HPGe detectors in the forward hemisphere. The setup was intended for the measurement of  β-decay half-lives, high-resolution γ-ray spectroscopy, and nuclear lifetimes through fast-timing measurements.

  1. First observation of isomeric states in 111Zr, 113Nb, and 115Mo. J. Wu […] A.I. Morales et al. Phys. Rev. C 106, 064328 (12/2022)

  2. Beta-Delayed One and Two Neutron Emission Probabilities Southeast of 132Sn and the Odd-Even Systematics in r-Process Nuclide Abundances. V.H. Phong […] A.I. Morales et al. (46/65). Phys. Rev. Lett. 129, 172701 (10/2022)

  3. Measuring the β-decay Properties of Neutron-rich Exotic Pm, Sm, Eu, and Gd Isotopes to Constrain the Nucleosynthesis Yields in the Rare-earth Region. G.G. Kiss […] A.I. Morales et al. (45/72). The Astrophysical Journal 936, 107 (09/2022)

  4. Evidence of nonstatistical neutron emission following beta decay near doubly magic 132Sn. J. Heideman […] A.I. Morales et al. (34/49) Phys. Rev. C 108, 024311 (08/2023)

  5. 133In: A Rosetta Stone for Decays of r-Process Nuclei. Z.X. Xu […] A.I. Morales et al. (34/49). Phys. Rev. Lett. 131, 022501 (07/2023)

  6. Beta-delayed neutron spectroscopy of 133In. Z.X. Xu […] A.I. Morales et al. (34/49). Phys. Rev. C 108, 014314 (07/2023)

  7. Experimental level scheme of 78Cu. L.G. Pedersen […] A.I. Morales et al. (40/67) Acta Physica Polonica B, Proceedings Supplement. 14 – 6, 2023

  8. Half-life measurements using implant-(beta-gamma) time correlations in the region of neutron-rich lanthanides. A. Vitez-Sveiczer […] A.I. Morales et al. (45/72) Acta Physica Polonica B, Proceedings Supplement. 14 – 6, 2023

  9. First Full Beta-Strength Measurement With DTAS Across N=126 at Fair Phase-0. D. Rodríguez-García, J.L. Tain, A.I. Morales et al. (3/77) EPJ Web of Conferences. 290, 02006 (2023)

  10. Study of decay properties of Ba to Nd nuclei (A~160) relevant to the formation of the r-process rare-earth peak. M. Pallàs […] A.I. Morales et al. (39/61) EPJ Web of Conferences. 284, pp. 02005 – 02005. EDP Sciences, 2023

  11. The beta-decay of 71Kr: Precise measurement of the half-life. A. Vitez-Sveiczer […] A.I. Morales et al. (5/67) EPJ Web of Conferences. 290, pp. 02021 – 02021. EDP Sciences, 2023

  12. First spectroscopic study of odd-odd 78Cu. L.G. Pedersen […] A.I. Morales et al. (40/67) Phys. Rev. C 107, 044301 (04/2023)

  13. Beta-decay studies across N = 126. A.I. Morales (1/1) Journal of Physics: Conference Series. 2586 – 1, 2023

  14. Project Meitner. Contributions of the pioneer women of radioactivity. A.I. Morales et al. (1/19) Journal of Physics: Conference Series. 2586 – 1, 2023

  15. Beta-delayed neutron emissions from N>50 gallium isotopes. R. Yokoyama […] A.I. Morales et al. (39/62) Physical Review C. 108 – 064307 (12/2023)

  16. Beta decay along the N=Z line and its relevance in rp-process and X-Ray bursts. E. Nacher […] A.I. Morales et al. (19/28) NUCLEAR PHYSICS IN ASTROPHYSICS – X, NPA-X 2022. 279, 2023

  17. Study of decay properties for Ba to Nd nuclei relevant for the formation of the r-process rare-earth peak (A~160). M. Pallàs […] A.I. Morales et al. (39/61) NUCLEAR PHYSICS IN ASTROPHYSICS – X, NPA-X 2022. 279, 2023

  18. Collectivity at the prolate-oblate shape transition: The 2+ lifetime of 190W. E. Sahin […] A.I. Morales et al. (62/89) Phys. Lett. B 857, 138976 (10/2024)

  19. First exploration of monopole-driven shell evolution above the N=126 shell closure: New milliseciond isomers in 213Tl and 215Tl. T.T. yeung, A.I. Morales et al. (2/58), Phys. Rev. Lett. 133, 072501 (08/2024)

  20. Compound nucleus and doorway-state decays of beta-delayed neutron emitters 51,52,53K. Z.Y. Xu […] A.I. Morales et al. (37/51), Phys. Rev. Lett. 133, 042501 (07/2024)

  21. Commissioning and performance of IDATEN: A large fast-timing gamma-ray detector array at the RIBF. B. Moon […] A.I. Morales et al. (29/41) Nucl. Inst. And Methods A 1084, 171239 (01/2026)

  22. Shell evolution beyond 208Pb: Isomer and beta-decay spectroscopy of neutron-rich N>126 nuclei. A.I. Morales et al. (1/37), RIKEN Accel. Prog. Rep. 58, 14 (2025)

  23. Isospin mixing in 64,66Ga reexamined via total absorption spectroscopy. S. Parra […] A.I. Morales et al. (20/31), Phys. Rev. C. 112, 064328 (12/2025)

  24. Beta decay of the Tz=-2 nucleus 64Se and its descendants: The T=2 isobaric multiplet. P. Aguilera […] A.I. Morales et al. (11/52), Phys. Rev. C. 112, 054319 (11/2025)

  25. Beta-decay half-lives of neutron-rich sulfur to titanium: Evolution of the N=32 and 34 subshell closures below calcium. Q.B. Zeng […] A.I. Morales et al. (14/49), Phys. Rev. Lett. 135, 232501 (12/2025)

  26. Impact of Newly Measured β-Delayed Neutron Emitters around Ni78 on Light Element Nucleosynthesis in the Neutrino Wind Following a Neutron Star Merger. A. Tolosa-Delgado […] A.I. Morales et al. (49/74), Phys. Rev. Lett. 134, 172701 (05/2025)

  27. Isospin Symmetry Breaking in the 71Kr and 71Br Mirror System. A. Algora […] A.I. Morales et al. (14/68), Phys. Rev. Lett. 134, 162502 (04/2025)

  1. A.I. Morales. «Beta-decay studies across N = 126». Invited talk. INPC 2022. 11-16 September 2022. Capetown (Southafrica)

  2. A.I. Morales. «Project Meitner: science-and-gender outreach to recover the contributions of the pioneer women of radioactivity». Invited talk. INPC 2022. 11-16 September 2022. Capetown (Southafrica)

  3. A.I. Morales. «Persistence of the Z = 28 shell gap in A = 75 isobars». Poster. INPC 2022. 11-16 September 2022. Capetown (Southafrica)

  4. A.I. Morales. «Spectroscopy of heavy neutron-rich N > 126 nuclei at RIKEN». Contributed talk. Advances in Radioactive Isotope Science (ARIS 2023). 04-09 April 2023. Avignon (France)

  5. A.I. Morales. «Detectors for HISPEC-DESPEC». Invited talk. NuPECC LRP2024-TWG-Detectors and Exp. Techniques, kick-off meeting. 17-18 April 2024. Frascati (Italy)

  6. A.I. Morales. «Discovery of new ms-isomers in 213Tl and 215Tl at RIBF-RIKEN». Contributed talk. Exploring the heavy exotic neutron-rich nuclides via multinucleon transfer reactions (MNT2024). 02-05 July 2024. RIKEN-Wako (Japan)

  7. A.I. Morales. «Decay Spectroscopy of heavy nuclei at RIBF». Invited talk. NUSTAR Week 2025. 29/09/2025-02/10/2025. Prague (Czech Republic)

  8. A.I. Morales. «Decay Spectroscopy experiments across N=126 at RIBF and GSI». Invited talk. Nuclear Astrophysics Experiments with HIAF. 3-5 September 2025. Huizhou (China)

  9. A.I. Morales. «Opportunities with TAGS spectrometers at RIBF». Invited talk. HYPATIA Workshop – Science Opportunities. 20-21 March 2025. London (UK)

  10. M. Kundu. «Exploring isomers and beta decay in neutron-rich heavy nuclei beyond N=126». Contributed talk. Active Stoppers for Decay Experiments. 24-26 March 2025. Valencia (Spain)

  11. M. Kundu. «Investigation of nuclei beyond N=126 at the DESPEC Phase-0 campaign». Poster presentation. Euroschool on Exotic beams. 25-30 August 2024. Jyväskylä (Finland)

  12. M. Kundu. «Isomer and beta-decay studies of neutron-rich heavy nuclei above N=126». Poster presentation. Basic Concepts in Nuclear Physics: theory, experiments and applications. 16-20 June 2025. La Rábida (Spain)

  13. A.I. Morales. «S181 Extending the quest towards the N=126 r-process waiting point». Contributed talk. HISPEC/DESPEC Collaboration Meeting. 13-14 November 2023. GSI-Darmstadt (Germany)

  14. A.I. Morales. «The DINTESPEC Project». Contributed talk. HISPEC/DESPEC Collaboration Meeting. 26-27 February 2024. GSI-Darmstadt (Germany)

  15. A.I. Morales. «Research opportunities of heavy neutron-rich nuclei with DTAS at RIBF: TATAKI-Pro». Contributed talk. Structure of neutron-rich matter revealed by beta decay. 29-30 July 2024. RIKEN-Wako (Japan)

  16. M. Kundu. «Investigation of nuclei beyond N=126 at the DESPEC Phase-0 campaign». Contributed talk. HISPEC/DESPEC Collaboration Meeting. 25-26 November 2024. GSI-Darmstadt (Germany)

  17. A.I. Morales. «Decay spectroscopy experiments at RIBF: Study of nuclei at the edge of experimental synthesis with BRIKEN and DTAS». Invited talk. RIBF Users Meeting. 21 January 2025. RIKEN-Wako (Japan)

  18. M. Kundu. «Isomers and beta decay in neutron-rich nuclei beyond N=126: Update of S181 analysis». Contributed talk. HISPEC/DESPEC Collaboration Meeting. 2 June 2025. GSI-Darmstadt (Germany)

Team

News

Experiment NP2112-RIBF208 finished!

October 14, 2024
Our team has successfully finished the TATAKI-Pro experiment at RIBF. The preliminary analysis confirms the excellent performance of the WAS3ABi and DTAS detectors. The offline analysis will start soon!

Talk of Mallicka Kundu in the H/D collaboration meeting 2024

October 14, 2024
Mallicka Kundu has given a talk on the analysis status of experiment S181 at the HISPEC/DESPEC collaboration meeting held in November at GSI (Germany). Preliminary results on calibrations and α-decay