Study of the production and decay properties of neutron-deficient nobelium isotopes

M. S. Tezekbayeva; A. V. Yeremin; A. I. Svirikhin; A. Lopez-Martens; M. L. Chelnokov; V. I. Chepigin; A. V. Isaev; I. N. Izosimov; A. V. Karpov; A. A. Kuznetsova; O. N. Malyshev; R. S. Mukhin; A. G. Popeko; Yu. A. Popov; V. A. Rachkov; B. S. Sailaubekov; E. A. Sokol; K. Hauschild; H. Jacob; R. Chakma; O. Dorvaux; M. Forge; B. Gall; K. Kessaci; B. Andel; S. Antalic; A. Bronis; P. Mosat

doi:10.1140/epja/s10050-022-00707-9

2023 Impact factor 2.6

Hadrons and Nuclei

Eur. Phys. J. A (2022) 58: 52
https://doi.org/10.1140/epja/s10050-022-00707-9

Letter

Study of the production and decay properties of neutron-deficient nobelium isotopes

M. S. Tezekbayeva¹^,2^a, A. V. Yeremin¹^,3, A. I. Svirikhin¹^,3, A. Lopez-Martens⁴, M. L. Chelnokov¹, V. I. Chepigin¹, A. V. Isaev¹, I. N. Izosimov¹, A. V. Karpov¹^,3, A. A. Kuznetsova¹, O. N. Malyshev¹^,3, R. S. Mukhin¹, A. G. Popeko¹^,3, Yu. A. Popov¹^,3, V. A. Rachkov¹^,3, B. S. Sailaubekov¹^,2^,5, E. A. Sokol¹, K. Hauschild⁴, H. Jacob⁴, R. Chakma⁶, O. Dorvaux⁷, M. Forge⁷, B. Gall⁷, K. Kessaci⁷, B. Andel⁸, S. Antalic⁸, A. Bronis⁸ and P. Mosat⁸

¹ Flerov Laboratory of Nuclear Reactions, JINR, Dubna, Russia
² The Institute of Nuclear Physics, 050032, Almaty, Republic of Kazakhstan
³ Dubna State University, Dubna, Russia
⁴ IJCLAb, IN2P3-CNRS, Université Paris Saclay, 91405, Orsay, France
⁵ L.N. Gumilyov Eurasian National University, Nur-Sultan, Kazakhstan
⁶ GANIL, 14076, Caen Cedex 5, France
⁷ Université de Strasbourg, CNRS, IPHC UMR 7178, 67000, Strasbourg, France
⁸ Comenius University in Bratislava, 84248, Bratislava, Slovakia

^a tezekbaeva@jinr.ru

Received: 7 December 2021
Accepted: 14 March 2022
Published online: 24 March 2022

Abstract

The new neutron-deficient isotope $^{249}$ $^{249}$ No was synthesized for the first time in the fusion-evaporation reaction $^{204}$ $^{204}$ Pb( $^{48}$ $^{48}$ Ca,3n) $^{249}$ $^{249}$ No. After separation, using the kinematic separator SHELS, the new isotope was identified with the GABRIELA detection system through genetic correlations with the known daughter and granddaughter nuclei $^{245}$ $^{245}$ Fm and $^{241}$ $^{241}$ Cf. The alpha-decay activity of $^{249}$ $^{249}$ No has an energy of 9129(22) keV and half-life 38.3(2.8) ms. An upper limit of 0.2% was measured for the fission branch of $^{249}$ $^{249}$ No. Based on the present data and recent information on the decay properties of $^{253}$ $^{253}$ Rf and aided by Geant4 simulations, the ground state of $^{249}$ $^{249}$ No is assigned the 5/2 $^{+}$ $$^+$$ [622] neutron configuration and a partial decay scheme from $^{253}$ $^{253}$ Rf to $^{245}$ $^{245}$ Fm could be established. The production cross-section was found to be $σ$ $\sigma$ (3n)=0.47(4) nb at a mid-target beam energy of 225.4 MeV, which corresponds to the maximum of the calculated excitation function. Correlations of the $^{249}$ $^{249}$ No alpha activity with subsequent alpha decays of energy 7728(20) keV and half-life $1 . 2_{- 0.4}^{+ 1.0}$ $1.2_{-0.4}^{+1.0}$ min provided a firm measurement of the electron-capture or $β^{+}$ $\beta ^{+}$ branch of $^{245}$ $^{245}$ Fm to $^{245}$ $^{245}$ Es. The excitation function for the 1n, 2n and 3n evaporation channels was measured. In the case of the 2n-evaporation channel $^{250}$ $^{250}$ No, a strong variation of the ground state and isomeric state populations as a function of bombarding energy could be evidenced.