Eur. Phys. J. D 45, 99-106 (2007)
https://doi.org/10.1140/epjd/e2007-00198-1

Towards optical spectroscopy of the element nobelium (Z = 102) in a buffer gas cell

First on-line experiments on ¹⁵⁵Yb at the velocity filter SHIP with a novel ion collection and atom re-evaporation method of high efficiency

¹ Institut für Kernphysik der Universität Mainz, 55099 Mainz, Germany
² Department für Physik, Ludwig-Maximilians-Universität München, 85748 Garching, Germany
³ Gesellschaft für Schwerionenforschung, 64291 Darmstadt, Germany

Corresponding author: ^a pkunz@uni-mainz.de

Received: 18 January 2007
Revised: 11 April 2007
Published online: 20 June 2007

Abstract

For the investigation of the atomic level structure of heavy elements which can only be produced at on-line facilities such as GSI, a novel experimental procedure has been developed. It is based on Radiation Detected Resonance Ionization Spectroscopy (RADRIS) and can be applied to elements like nobelium produced at rates of a few ions per second. Fusion reaction products are separated from the primary beam by the velocity filter SHIP at GSI, stopped in a buffer gas cell, collected on a tantalum filament and then re-evaporated as atoms. The ions produced by resonance ionization with tunable laser beams are detected via their characteristic α decay. First on-line experiments on α-active ¹⁵⁵Yb, which is supposed to have an atomic level structure similar to nobelium, were performed. These test experiments focused on the optimization of the collection and re-evaporation process of the radioactive ions, the laser ionization efficiency and the detection via α decay. An overall efficiency for RADRIS of 0.8% with respect to the target production rate was measured. While further improvements of this efficiency are in progress it should already be sufficient for the search for atomic levels in nobelium.