Technical & Chemical Improvements for Short-Time Activation

Short time activation analysis (STNAA) is, in general, a non-destructive, fast, accurate, and sensitive technique to investigate up to 19 elements (Ag, Al, Br, Ca, Cl, Cu, Dy, F, Hf, I, In, K, Mg, Mn, Na, Sc, Se, Ti and V) in environmental matrices. The number of elements eligible for investigation in actual samples by means of STNAA can, in fact, be increased up to 35 (e.g., Ba, Cd, Ce, Er, Ga, Gd, Ge, Ir, Mo, Nb, Nd, Os, Pd, Pt, Rb, Rh, Ru, Sb, Sm, Sn, W, Y, ect.,), by increasing the effort to determine their short-lived nuclides. Indeed, both non-destructive and post-separation (radiochemical) techniques are not able to investigate up to 35 nuclides (half life < 30 min.). This means that, beside the 19 nuclides usually analysed by means of STNAA non-destructively, there are approx. 10-15 further nuclides which can be investigated by pre-concentration technique. This project will shed light on which of those nuclides can actually be investigated in different matrices. The question is whether it is really necessary to investigate 35 nuclides by means of STNAA. Furthermore, is the quality of the pre-concentration comparative to that of non-destructive procedures at high count rates measurements? These are, in fact, the main points to be answered by this project. Unfortunately, many scientists are doubtful about pre-chemical treatment technique. In contrast, we believe that the total error occurring at high count rates measurments, non-destructively, is at least as high as the total error occurring at destructive procedures. This project will clarify this point in detail and according to statistic evaluation, something which is currently not documented in literature. The aim of this project is therefore to realise the following points: 1. Constructing a moveable fast pneumatic system for irradiating small samples (~ 0.5 ml) at the central irradiation position (high neutron flux) of the TRIGA-Mark II Reactor. The moveable system should facilitate the general use of this sole irradiation position for different experiments. 2. Constructing a rotating fast pneumatic system for irradiating large samples (up to 8 ml). 3. Constructing a fast pneumatic system for irradiating small samples (up to 2 ml) which can be fitted within a moveable Cd filter for thermal / epithermal irradiation at the same position. 4. The counting chambers of the new systems will be constructed as a moveable chamber to change the sample- detector distances between 4 positions fully automatic within a series of measurements. Furthermore, the construction should faciliate the cyclic activation analysis 5. Constructing a device for removing an irradiation container fully automatically before reaching the counting chamber within a few seconds (2-3s). 6. Constructing and implementing a sample exchanger for each system 7. Developing a software which is able to manage the irradiation and counting procedures . 8. Optimising the non-destructive analysis technique according to sample matrices, weight, and type of the investigated nuclides, using a fully digital gamma spectrometer with loss free counting mode. 9. Optimising a pre-concentration technique which is based on adsorption of the desired metals complex on activated carbon, to investigate the short-lived nuclides in water, biological, and other matrices.