Automated construction of detector models for efficiency interpolation in gamma-ray spectrometry.
A method was developed for automated construction of detector models in gamma-ray spectrometry, which can be used in Monte Carlo calculations of efficiency calibration curves. Full-energy peak efficiencies were first measured for different gamma-ray energies and for a given sample-detector arrangement and then calculated by the Monte Carlo method. For these calculations a detector model was employed along with a computer algorithm, which seeks agreement between the experimental efficiencies and the calculated ones by automatically determining the parameters of the model. The resulting agreement of the calculated data with the experimental one was within the relative uncertainty of the latter (3-4%) and the parameters of the detector models obtained were close to the values specified by the manufacturers. The detector models thus constructed can then be used for interpolation of calibration curves.
The first experimental test of the MEFFTRAN software on HPGe detector calibration for environmental samples.
The gamma spectrometry of environmental samples poses a series of specific problems for the practitioner. The determination of full energy peak efficiencies is, in the case of environmental samples, one of the greatest challenges. In this paper, the calibration of two HPGe detectors for environmental samples in Marinelli beakers was performed using the newly developed MEFFTRAN software. The results obtained with MEFFTRAN were compared to the experimental efficiencies measured using the calibration sample produced at the Laboratory for Radiation and Environment Protection, Institute for Nuclear Sciences Vinca, Belgrade, in order to confirm the validity of the calculation. It is shown that calculated and experimental efficiencies are in good agreement with the discrepancies from -3.9% to +1.5%. The results were also validated by measuring secondary reference materials provided by the IAEA within several interlaboratory proficiency tests. The activity concentration of the radionuclides in the secondary reference materials was determined using the efficiency obtained by MEFFTRAN and compared with the target value given by the IAEA. All the results in materials provided by the IAEA were acceptable except one, proving that MEFFTRAN produces satisfactory results.
Integrated land degradation monitoring and assessment: Horizontal knowledge management at the national and international levels
The need for improved horizontal knowledge management at the national and international levels is essential for monitoring and assessment of land degradation and desertification. At the national level, governments utilise scientific, socio‐economic and technical data and information for strategic planning, priority setting and national environment and development planning. However, challenges including the lack of capacity and lack of collaboration and sharing of information across governments affect responses to and the effectiveness of monitoring and knowledge exchange, along with the ability to effectively implement treaties. At the international level, a number of Multilateral Environmental Agreements (MEAs) share cross‐sectoral themes related to research and monitoring, information exchange, technology transfer, capacity building and financial resources. The need for increased synergies stems from the similarities between the issues they address. Challenges for improving knowledge management at the international level include insufficient interaction between the scientific bodies of the various MEAs; duplication of reporting, monitoring and assessment efforts; limited knowledge management between the various assessments addressing ecosystems and biological diversity during the past decade; and insufficient collaboration between the United Nations Convention to Combat Desertification (UNCCD), the UN system and the international non‐governmental organisation (NGO) community. This paper examines these challenges and offers recommendations on how monitoring and assessment knowledge can be better managed at the national and international levels. Copyright © 2011 John Wiley & Sons, Ltd.