Universal calibration of a scintillation spectrometer with a NaI(Tl) detector when measuring 137Cs activity in counting samples of arbitrary density and volume

The article proposes an empirical method for constructing a universal calibration for a scintillation gamma spectrometer, which allows determining the activity and specific activity of 137Cs with an accuracy of no more than 15% in counting samples of arbitrary density and volume in cylindrical containers with a volume of 250 ml and 500 ml. To construct calibration ratios, measurements of 137Cs sample media prepared on the basis of materials of different densities (quartz sand, plastic granules and sawdust) were performed. The calibration was carried out by preparing samples from the listed materials with a volume of 50 to 250 ml in increments of 50 ml for a 250 ml container and 100-500 ml in increments of 100 ml for a 500 ml container. Along with taking into account the volume of the counting sample, its weighing was also carried out. The result of the measurements performed for each material was the ratio of the activity of the counting sample to the counting intensity in the 137Cs window, depending on the volume. The universal calibration factor is obtained by taking into account the counting rate from the mass and volume of the sample for the corresponding measuring vessel.

Analysis of the affect of fluid container sizes on readings of Brookfield viscometer

Brookfield viscometers provide measurements viscosity directly in vessels with controlled liquids without transfer into a special measuring vessel. However, information on the degree and nature of the influence of these vessels dimensions on the measurement results is not presented in the literature. To increase the accuracy of viscosity measurements in vessels of arbitrary shape and size we conducted the experimental and theoretical studies of the LVF Brookfield viscometer sensitivity to the influencing quantities: the diameter of the vessel with a liquid, the distance from a spindle to the bottom of the vessel, and the level of immersion of the spindle. According to the technical documentation for Brookfield viscometers, viscosity measurements must be carried out in a Griffin beaker with a diameter of 83 mm and a volume of 600 ml or in a large vessel. The aim of this work is to determine the correction factors necessary for measuring viscosity in vessels whose sizes differ from those recommended. The general characteristic of factors influencing the accuracy of viscosity measurements is given. To determine the dependence of the viscometer readings on the vessel diameter a set of glass vessels with different diameters was used. To determine the dependence of the readings on the distance to the bottom of the vessel the liquid level in it was changed. When performing experiments, the temperature of the liquids was kept constant with an error of not more than 0,1 °C. Based on the known equations for rotational viscometers, expressions for approximating the dependences of the viscometer readings on the diameter of the vessel and the distance between its bottom and the end of the spindle are obtained. Formulas allowing to make corrections to the measurement results during the changing the mentioned influencing quantities are obtained. It was found that the distance from the spindle to the bottom of the vessel with the liquid affects the measurement results only when using the LV1 spindle and the immersion level affects only when using the LV4 spindle. The results of the viscometer calibration using the viscosity standards REV-100, REV-300, REV-1000, Brookfield 12500, Brookfield 100000 are presented. A correction factor of 1,04 for the case of using the LV3 spindle without a guardleg was obtained. The research results presented in the article allow applying a Brookfield viscometer for viscosity measurements in vessels with diameters up to 40, 30, 23, 10 mm for spindles LV1, LV2, LV3, LV4, respectively.

Stories from the Frontier: Bridging Past and Present at Hadrian’s Wall

A corn modius, excavated in 1915 at Carvoran Roman fort, survives as an enduring testament to the memory sanctions applied to the emperor Domitian after his death. Domitian’s name has been hammered out, even though the rest of the engraved text – which reveals the capacity of this measuring vessel – has been preserved. Taking this case study as its springboard, this article reflects on how artefacts act as battlegrounds for the parallel processes of commemoration and censorship. It exemplifies, moreover, how a modern video-game for school-aged children which Stocks co-designed about Vindolanda, an Imperial-era Roman fort at Hadrian’s Wall, can serve a similar function. By translating the physical realities of that site into virtual images, and challenging players to solve a fictional murder mystery within this simulated environment, the game creates a new means through which students might be led into the past: it allows them to co-create history by selecting narrative paths and engaging intermedially with ancient Vindolanda. Far from being all ‘fun and games’, this process is especially effective as a pedagogical tool: players experience history not as readers, spectators, or listeners, but as visitors, endowed with first-person access to the stories and places of Britain’s Roman past.