Authors:	Krupp, Dominik
Advisor:	Düllmann, Christoph
Title:	New ways for a faster alpha spectrometry
Online publication date:	17-Nov-2023
Year of first publication:	2023
Language:	english
Abstract:	Alpha spectrometry is a key technology in many radioanalytical fields for nuclide- and activity determi­nation. Due to the very short range of a radiation in condensed matter, great care must be taken during sample preparation to avoid self-absorption of the a radiation by the measurement sample itself. However, extensive sample preparation and production efforts in conventional a spectrometric analysis are accepted, since it is often the only way to obtain information about the radionuclide(s) in question. In no other discipline is the problem of complex sample preparation as clear as in the investigation of the heaviest known elements, the transactinides (atomic number Z 2": 104), often also referred to as "superheavy el­ements" (SHE). Since these elements are only produced at accelerators with production rates of single atoms per hour or day, all steps from production to the actual chemical experiment to the detection of the characteristic a radiation must be kept as efficient as possible. A key aspect of making SHE studies efficient is the time that elapses from nuclide production until the start of the measurement to identify its nuclear decay. With the aid of automated systems, the chemical properties of the first three SHEs, namely rutherfordium, dubnium and seaborgium, could be studied in liquid phase chemistry experiments. Subsequent SHE could only be studied in the gas phase. In order to be able to investigate the chemical properties of the transseaborgium elements in the aqueous phase, new technologies for a more efficient investigation of the SHE in the aqueous phase were developed within this work. One approach was to combine various individual steps in a previous experimental setup into a single step. Here, the primary focus was on the chemical separation of a sample, followed by sample preparation and measurement with a silicon detector. These steps can be combined if the detector surface is simultaneously a stationary phase with functional groups that selectively accumulate radionuclides from the aqueous solution on the detector surface according to their chemical properties. If this extractive layer is thin enough, the emitted a radiation of the radionuclides can be measured without significant loss of kinetic energy. In the case of accelerator based experiments, the transport of produced radionuclides, the transfer of the SHE into the liquid phase and the separation of by-products of the fusion reaction are additional complex challenges with great optimization potential. To this end, a system was developed to stop recoil nuclei directly in an aqueous phase after they have passed through a physical pre-separator and are then transported along the shortest possible path to the chemical experiment, such as a Si-detector, coated with extractive functional groups. In order to be able to test such systems without access to particle accelerators, a system was also developed to continuously elute from a generator system 211Bi as an a-emitter with a 2 min half-life in a liquid phase. To better classify these new techniques for a fast a-spectrometry, the following sections give a short theoretical overview related to a-emitting radionuclides. In doing so, an overview of the origin of a-emitting radionuclides, the theory of this type of radiation, the currently most common measurement methods and the technical developments in the field of fast analysis of a-emitters will be given.
DDC:	540 Chemie 540 Chemistry and allied sciences
Institution:	Johannes Gutenberg-Universität Mainz
Department:	FB 09 Chemie, Pharmazie u. Geowissensch.
Place:	Mainz
ROR:	https://ror.org/023b0x485
DOI:	http://doi.org/10.25358/openscience-9583
URN:	urn:nbn:de:hebis:77-openscience-02c8c5a4-003f-43fc-83d2-9eba49a9c16c8
Version:	Original work
Publication type:	Dissertation
License:	In Copyright
Information on rights of use:	http://rightsstatements.org/vocab/InC/1.0/
Extent:	XVI, 138 Seiten ; Illustrationen, Diagramme
Appears in collections:	JGU-Publikationen