Eur. Phys. J. A (2015) 51: 65
https://doi.org/10.1140/epja/i2015-15065-4

Regular Article - Experimental Physics

First direct high-precision energy determination for the 8.4 and 20.7 keV nuclear transitions in ¹⁶⁹Tm

¹ Laboratory of Nuclear Problems, JINR, Dubna, Moscow Region, Russian Federation
² Institute of Applied Physics, National University, Tashkent, Republic of Uzbekistan
³ Nuclear Physics Institute of the ASCR, CZ-25068, Řež near Prague, Czech Republic
⁴ National Research Nuclear University MEPhI, 115409, Moscow, Russian Federation

^* e-mail: inoyatov@jinr.ru

Received: 20 February 2015
Revised: 16 April 2015
Accepted: 26 April 2015
Published online: 1 June 2015

Abstract

Energies of 8410.1 ± 0.4, 20743.9 ± 0.3, and 63121.6 ± 1.2 eV were determined for the 8.4 keV M1 + E2, 20.7 keV M1 + E2, and 63.1 keV E1 nuclear transitions in ¹⁶⁹Tm (generated in the EC decay of ¹⁶⁹Yb, respectively, by means of the internal conversion electron spectroscopy. The ¹⁶⁹Yb sources used were prepared by vacuum evaporation deposition on polycrystalline carbon and platinum foils as well as by ion implantation at 30keV into a polycrystalline aluminum foil. The relevant conversion electron spectra were measured by a high-resolution combined electrostatic electron spectrometer at 7 eV instrumental resoluition. Values of 0.0326(14) and 0.0259(17) were derived from our experimental data for the E2 admixture parameter |δ (E2/M1)| for the 8.4 and 20.7 keV transitions, respectively. A possible effect of nuclear structure on multipolarity of the 20.7 keV transition was also investigated.