First Direct Mass Measurements of Nuclides around Z=100 with a Multireflection Time-of-Flight Mass Spectrograph

Y Ito; P Schury; M Wada; F Arai; H Haba; Y Hirayama; S Ishizawa; D Kaji; S Kimura; H Koura; M MacCormick; H Miyatake; J Y Moon; K Morimoto; K Morita; M Mukai; I Murray; T Niwase; K Okada; A Ozawa; M Rosenbusch; A Takamine; T Tanaka; Y X Watanabe; H Wollnik; S Yamaki

doi:10.1103/PhysRevLett.120.152501

First Direct Mass Measurements of Nuclides around Z=100 with a Multireflection Time-of-Flight Mass Spectrograph

Phys Rev Lett. 2018 Apr 13;120(15):152501. doi: 10.1103/PhysRevLett.120.152501.

Authors

Y Ito¹, P Schury², M Wada^{1

2}, F Arai^{1

3}, H Haba¹, Y Hirayama², S Ishizawa^{1

4}, D Kaji¹, S Kimura^{1

2

3}, H Koura⁵, M MacCormick⁶, H Miyatake², J Y Moon^{2

7}, K Morimoto¹, K Morita^{1

8}, M Mukai^{2

3}, I Murray¹, T Niwase⁸, K Okada^{1

9}, A Ozawa³, M Rosenbusch¹, A Takamine¹, T Tanaka^{1

8}, Y X Watanabe², H Wollnik^{1

10}, S Yamaki^{1

11}

Affiliations

¹ RIKEN Nishina Center for Accelerator-Based Science, Wako 351-0198, Japan.
² Wako Nuclear Science Center (WNSC), Institute of Particle and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK), Wako 351-0198, Japan.
³ University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan.
⁴ Graduate School of Science and Engineering, Yamagata University, Yamagata 990-8560, Japan.
⁵ Japan Atomic Energy Agency, Tokai, Ibaraki 319-1185, Japan.
⁶ Institut de Physique Nucléaire, IN2P3-CNRS, Université Paris-Sud, Université Paris-Saclay, 91406 Orsay Cedex, France.
⁷ Rare Isotope Science Project, Institute for Basic Science (IBS), Daejeon 305-811, Korea.
⁸ Department of Physics, Kyushu University, Nishi-ku, Fukuoka 819-0395, Japan.
⁹ Sophia University, Chiyoda-ku, Tokyo 102-8554, Japan.
¹⁰ Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces, New Mexico 88003, USA.
¹¹ Department of Physics, Saitama University, Sakura-ku, Saitama 338-8570, Japan.

PMID: 29756864
DOI: 10.1103/PhysRevLett.120.152501

Abstract

The masses of ^{246}Es, ^{251}Fm, and the transfermium nuclei ^{249-252}Md and ^{254}No, produced by hot- and cold-fusion reactions, in the vicinity of the deformed N=152 neutron shell closure, have been directly measured using a multireflection time-of-flight mass spectrograph. The masses of ^{246}Es and ^{249,250,252}Md were measured for the first time. Using the masses of ^{249,250}Md as anchor points for α decay chains, the masses of heavier nuclei, up to ^{261}Bh and ^{266}Mt, were determined. These new masses were compared with theoretical global mass models and demonstrated to be in good agreement with macroscopic-microscopic models in this region. The empirical shell gap parameter δ_{2n} derived from three isotopic masses was updated with the new masses and corroborates the existence of the deformed N=152 neutron shell closure for Md and Lr.