THERMOCOAX rhodium SPND sensitivity dispersion and validation of the sensitivity calculation model

This paper describes the neutron irradiation tests of 7 THERMOCOAX Self-Powered Neutron detectors (SPNDs) in the BR1 reactor at SCK•CEN. The SPNDs were fabricated according to the same specifications, but from different fabrication batches. The SPND signals were recorded during stepwise power-up of the reactor, proving the linearity of the SPND response within a wide thermal neutron flux range: from as low as 0.8·109 n/(cm2) to 2.6·1011 n/(cm2s). Intercomparison of the SPND signals shows a very small spread, confirming the repeatability of the THERMOCOAX fabrication processes. The overall neutron sensitivities of the seven SPNDs agreed within a 1% margin. The experimental data were analyzed in terms of prompt and various delayed responses. Prompt contributions to the signal are due to external gamma induced processes and to processes involving gamma rays emitted instantaneously upon neutron capture. The main contribution in a rhodium SPND is due to activation of the rhodium emitter and beta emission during decay of the activated rhodium and leads to a delayed response with a characteristic time of a few minutes. Activation and subsequent beta decay in other materials present in the SPND lead to additional minor delayed signal contributions. The partial SPND sensitivities due to all these processes were calculated using an MCNPX based model and were compared with experimental sensitivities based on the recorded data. The results were in fair agreement; for the overall SPND neutron sensitivity an agreement within a 1% margin was achieved.

Radionuclide therapy with alpha-emitters

In this review the main streams of using alpha-emitters radium-223, actinium-225, bismuth-213, astatine-211 in complex treatment of malignant tumors are reviewed. The features of radiobiological actions of alpha-emission make its more effective in hundred times than beta-emission. The efficacy of this kind of radionuclide therapy does not dependent from chemoresistance and radioresistance to beta-emitters. The results of experimental and initial clinical investigation, which indicate on promising further investigations in this direction, were revealed. Key words: radionuclide therapy of malignant tumors, alpha-emitters, radium-223, actinium-225, bismuth-213, astatine-211.

Synthesis, Radiochemical Purity Control and Stability of Scandium-46-1,4,7-triazacyclononane-1,4,7-triacetic acid (46Sc-NOTA)

Radiotherapy is one of healing method of cancer using radionuclide elements. The radionuclide scandium-46 (46Sc) has a half-life of 83.8 days, beta emission 0.35 MeV and gamma emission 899 and 1120 keV is suitable for studying the chemical aspects, synthesis and stability of scandium complex for radiotherapy. The purposes of this research are synthesis of scandium-46-1,4,7-triazacyclononane-1,4,7-triacetic acid (46Sc-NOTA) labeled compound based on formation of a complex bonding in stoichiometry between radioisotope 46Sc and 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA) ligand, and radiochemical purity and stability assay of 46Sc-NOTA. In this research, conducted that optimum moles several variables, namely moles comparison and pH effect was used. The result are optimum conclusion of mole comparison between radioisotope and ligand was 1:2 (46Sc : NOTA) and environment at pH 5. The radiochemical purity and stability assay of 46Sc-NOTA was carried out by paper chromatography and the result showed that 46Sc-NOTA has radiochemical purity of 99.09 ± 0.2% and remained stable for 9 days.

A spectral re-examination of the Markarian AGN

The recently published ZORROASTER catalogue is being expanded into what will eventually be a complete list of known ‘nearby’ (z < 0.1) AGN, with optical spectral images, detailed spectral descriptors and waveband-specific flux ratios included where available. The first version of ZORROASTER contained 2843 entries characterised by confirmed or previously suspected broad H-beta emission, and 1000 spectral images. The 2nd version of ZORROASTER was released during the conference, and (in addition to serendipitous updates) includes all z < 0.1 objects from the list of Markarian. Activity classes and spectral descriptions of Markarian objects have been reviewed, and comparisons of flux ratios derived from the 100 ZORROASTER wavelength-specific pass bands are presented for those Markarian AGN for which Sloan Digital Sky Survey spectra exist. The value of the improved parameterizations and classifications of the Markarian objects on AGN studies, and the implications on some past investigations based on the Markarian lists, are briefly discussed.