Jozef Uyttenhove

Accuracy and Precision of Loss-Free Counting in gamma-Ray Spectrometry.

Abstract The performance of a “Loss-Free Counting” (LFC) method for pulse loss compensation is tested on two HPGe detectors; one with classical RC feedback preamplifier and another with Transistor Reset Preamplifier (TRP). Results are excellent on both, though extra fine-tuning precautions are required for the latter. Pulse loss by pileup is at the origin of an increased count variance in LFC spectra. A new formula for LFC uncertainty is presented and its validity demonstrated for a HPGe detector set-up.

Radiocesium contamination in Belgium

Radiocesium contamination of air, rain, grass, milk and humans in Belgium from the late 1950s to present was measured. The main sources of fallout were atmospheric nuclear weapons tests and the Chernobyl accident; in Belgium the average impact of the first on the human body burden was more than six times higher. The geographical distribution of radiocesium fallout in Belgium was surveyed by means of in-situ gammaspectrometry with HPGe detectors.

Capabilities and limitations of high-resolution gamma spectrometry in environmental research

Publisher Summary The availability of large intrinsic germanium detectors has opened new perspectives for fast, accurate and reliable environmental measurements. Many important isotopes in the natural and the technologically enhanced radiation environment have some suitable gamma lines, allowing quantitative determination of the radionuclides by high-resolution gamma spectrometry. In this chapter, the capabilities and the limitations of a typical gamma spectrometry set-up that can be used for in situ applications and laboratory measurements on soil samples are discussed and emphasis is laid on the sensitivity of laboratory measurements as well as on the applications for systematic surveys. High-resolution spectrometry gives reliable quantitative results for all γ-emitting nuclides, natural or artificial, in one measurement. Most of the important isotopes in environmental research have suitable γ-lines with usable intensities. The in situ technique provides a fast, reliable and sensitive means for the complete characterization of the gamma radiation field at a given location, with quantitative determination of the most important radionuclides in the soil.

Statistical precision of high-rate spectrometry with a Wilkinson ADC

Nuclear counting statistics at high count rate are assessed on a γ-ray spectrometer set-up with a Wilkinson analog to digital convertor. The validity of recent theoretical formulas for the standard deviation, before and after pulse-loss compensation, is checked. The experimental counting uncertainty is well reproduced by theory. Without pulse-loss compensation (cf. real-time mode), it is dependent on the size and position of the considered region of interest in the spectrum. With pulse-loss compensation (cf. live-time correction) the relative deviation from Poisson statistics is equal for all regions of interest in the spectrum.

Einstein’s “little machine” as an example of charging by induction

Einstein, a theoretical physicist, also contributed to practical realizations, such as the little machine, his “Maschinchen.” The goal was to measure small electrical potentials. Although Einstein proposed it as “a new electrostatic method to measure small quantities of electricity”, the method was not new. As far as we know, three original copies of the Maschinschen still exist. Only one of the instruments was used in research. Because the physical principles on which the instrument is based have not been explained clearly, we discuss these principles in more detail. Simulation of the charge amplification is performed and the equilibration time of the instrument is estimated.