Preparation of samples for alpha-spectrometry by direct evaporation of extracted species Kamila S ˇ t ˇ astna ´ • Vı ´t Fiala • Jan John Received: 16 July 2010 / Published online: 19 August 2010 Ó Akade ´miai Kiado ´, Budapest, Hungary 2010 Abstract Because of the energy loss of a-particles by self-absorption, a-spectrometry requires thin, uniform, and nearly weightless samples. Several methods exist for sample preparation, e.g., electrodeposition or co-precipi- tation. Unfortunately, the methods yielding the best energy resolution are not always quantitative and are usually relatively demanding and time-consuming. This fact makes application of a-spectrometry for screening tests with radiotracers complicated. For its simplicity and fastness, the possibility to prepare samples for a-spectrometry by direct evaporation of simple aliquots of aqueous or organic solutions and the influence of the presence of volatile organic diluent or tensioactive agent was investigated. Also, the influence of coating the samples with Mylar film was evaluated. The sample preparation techniques were compared based on the counting efficiency and energy resolution achieved. The performance of the selected method was tested on assessment of the efficiency of americium extraction by BTBP (bis-triazine-bipyridine) extractant. Keywords Alpha spectrometry Á Sample preparation Á Evaporation Á Americium Introduction Alpha spectrometry is a very useful method for analyzing alpha-emitting radionuclides mainly because of its rela- tively high efficiency and very low background resulting in high sensitivity. Alpha-particle spectrometry is usually performed after a radiochemical separation and deposition of alpha-emitting radionuclides onto a counting surface [1]. In order to obtain the best possible resolution, it is neces- sary to produce thin, flat, and uniform samples. Techniques for the preparation of sources suitable for alpha spectro- metric measurements are reviewed e.g., in Lally and Glover [2]. There are three basic methods of alpha-sample preparation: evaporation, co-precipitation, and electrode- position. In electrodeposition, radioactive material is electrochemically plated from an electrolyte solution onto a polished metal (stainless steel, copper, or other material) cathode planchet, anode being typically platinum wire or gauze. Co-precipitation of actinoids with rare-earth fluo- rides, followed by filtration on a smooth surface membrane filter of small pore size (0.1–0.2 lm) produces good- quality alpha sources [3]. Direct solution evaporation per- forms well for small volumes of dilute or electrolyte/carrier free solutions. In this case, the solution is spread uniformly over counting planchet and solvent is evaporated taking care to prevent splattering and consequent contamination of surrounding work area [4]. However, these samples tend to be less uniform. Spreading agents can be added to the solution, but the organics must be removed by firing before measurement. The way of drying the deposited drop of radioactive solution significantly affects the quality of the resulting source. Several drying methods can be used: in open air, in a laminar flow or fume hood, at room tem- perature or heated under infrared lamp. It is important to carry out the operation in a dust-free environment to avoid K. S ˇ t ˇ astna ´(&) Á J. John Centre for Radiochemistry and Radiation Chemistry, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Br ˇehova ´ 7, 115 19 Prague 1, Czech Republic e-mail: kamila.stastna@fjfi.cvut.cz K. S ˇ t ˇ astna ´ Á V. Fiala Á J. John Department of Nuclear Chemistry, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Brˇehova ´ 7, 115 19 Prague 1, Czech Republic 123 J Radioanal Nucl Chem (2010) 286:735–739 DOI 10.1007/s10967-010-0733-z