Background and muon counting rates in underground muon measurements with a plastic scintillator counter based on a wavelength shifting fibre and a multi-pixel avalanche photodiode readout

In this short note we present results of background measurements carried out with polystyrene based cast plastic 12.0×12.0×3.0 cm3 size scintillator counter with a wavelength shifting fibre and a multi-pixel Geiger mode avalanche photodiode readout in the Baksan underground laboratory at a depth of 200 metres of water equivalent. The total counting rate of the scintillator counter measured at this depth and at a threshold corresponding to ∼0.37 of a minimum ionizing particle is approximately 1.3 Hz.

A Standard Collimator for Thyroid Radioiodine Uptake Measurements

SummaryA standard collimator for thyroid radioiodine uptake measurements is described. The characteristics of this collimator comply with the requirements stated in a set of recommendations made by an expert group to the IAEA.Reducing the contribution of scattered radiation to the total counting rate by raising the discriminator level results in a widening of the visual field and a sharpening of the cut-off of the collimator. Increasing the working distance reduces the sharpness of cut-off slightly.