305 research outputs found
Macroscopic manifestations of rotating triaxial superfluid nuclei
No full textInternational audienceRecently, Allmond and Wood [J. M. Allmond and J. L. Wood, Phys. Lett. B 767, 226 (2017)PYLBAJ0370-269310.1016/j.physletb.2017.01.072] were able to extract the three moments of inertia Ik of a dozen of superfluid triaxial nuclei from experimental data. The observed dependence of the Ik on the deformation parameters is rather smooth. Here we show that these moments of inertia can be surprisingly well explained by a semiclassical cranked Hartree-Fock-Bogoliubov (HFB) calculation in which the velocity field is a simple superposition of rigid and irrotational flows
Electromagnetic Moments of Radioactive Te 136 and the Emergence of Collectivity 2 p a2 n Outside of Double-Magic Sn 132
No full text<p>Radioactive Te136 has two valence protons and two valence neutrons outside of the Sn132 double shell closure, providing a simple laboratory for exploring the emergence of collectivity and nucleon-nucleon interactions. Coulomb excitation of Te136 on a titanium target was utilized to determine an extensive set of electromagnetic moments for the three lowest-lying states, including B(E2;01+→21+), Q(21+), and g(21+). The results indicate that the first-excited state, 21+, composed of the simple 2pa2n system, is prolate deformed, and its wave function is dominated by excited valence neutron configurations, but not to the extent previously suggested. It is demonstrated that extreme sensitivity of g(21+) to the proton and neutron contributions to the wave function provides unique insight into the nature of emerging collectivity, and g(21+) was used to differentiate among several state-of-the-art theoretical calculations. Our results are best described by the most recent shell model calculations.</p>
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
No full textHalf-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
Search for pair-produced vector-like leptons in final states with third-generation leptons and at least three b quark jets in proton-proton collisions at s=13TeV
No full textThe first search is presented for vector-like leptons (VLLs) in the context of the “4321 model”, an ultraviolet-complete model with the potential to explain existing B physics measurements that are in tension with standard model predictions. The analyzed data, corresponding to an integrated luminosity of 96.5fb−1, were recorded in 2017 and 2018 with the CMS detector at the LHC in proton-proton collisions at s=13TeV. Final states with ≥3 b -tagged jets and two third-generation leptons (ττ, τντ, or ντντ) are considered. Upper limits are derived on the VLL production cross section in the VLL mass range 500–1050 GeV. The maximum likelihood fit prefers the presence of signal at the level of 2.8 standard deviations, for a representative VLL mass point of 600 GeV. As a consequence, the observed upper limits are approximately double the expected limits
High-precision B(E2) measurements of semi-magic Ni 58,60,62,64 by Coulomb excitation
No full textHigh-precision reduced electric-quadrupole transition probabilities B(E2;01+→21+) have been measured from single-step Coulomb excitation of semi-magic Ni58,60,62,64 (Z=28) beams at 1.8 MeV per nucleon on a natural carbon target. The energy loss of the
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)
No full textAt 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
Evaluating the response of new pore pressure transducers for use in dynamic centrifuge tests
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E2 collectivity in shell-model calculations for odd-mass nuclei near Sn-132
No full textShell-model calculations for In-127,In-129 and Sb-129,Sb-131 are presented, and interpreted in the context of the particle-core coupling scheme, wherein proton g(9/2) holes or g(7/2) particles are added to semimagic Sn-128,Sn-130 cores. These results indicate that the particle-core coupling scheme is appropriate for the Sb isotopes, whilst less so for the In isotopes. B(E2) excitation strengths are also calculated, and show evidence of enhanced collectivity in both Sb isotopes, especially Sb-131. This observation suggests that Sb-131 would be an excellent case for an experimental study seeking to investigate the early onset of collectivity near Sn-132
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