A compact detector system for simultaneous measurements of the light yield non-linearity and timing properties of scintillators.

This work presents an outline of a detection system that employs the Compton spectrometer method to assess the non-linearity of scintillator light yield. A novel approach is introduced, leading to more accurate measurements through the separate determination of the intrinsic light output parameters and the non-linearity of the scintillators. Key features of this system include the use of a portable scintillation detector with three photomultiplier tubes for precise measurement of the average number of detected photoelectrons and the incorporation of recent advancements in correction techniques for accidental coincidences.

Towards a radon-in-water primary standard at LNHB.

Despite widespread radon-in-water measurements, no primary radon-in-water standards currently exist. This work aims to bridge this gap by developing a system to produce radon-in-water reference materials. The system relies on cryogenic, loss-free transfer of radon, which is standardized through defined solid angle measurements, to a radon standard in water.

Uncertainties in TDCR measurement revisited: Contribution of optical effects.

In the Triple to Double Coincidence Ratio method in Liquid Scintillation Counting, the detection efficiency is calculated from the value of a free parameter describing the intrinsic light yield of the counting system. This model is generally based on a Poisson distribution of the number of photoelectrons detected and the detection efficiency is obtained from the complement of the non-detection efficiency. In the classical free parameter model, the mean of the Poisson distribution, m, is a constant but some variability of this mean could be expected from optical effects due to internal reflections inside the LS source or from non-homogeneity of the detection efficiency of the photomultiplier tubes.

The international reference system for beta-particle emitting radionuclides: Validation through the pilot study CCRI(II)-P1.Co-60.

The Bureau International des Poids et Mesures (BIPM) is developing a new transfer instrument to extend its centralized services for assessing the international equivalence of radioactive standards to new radionuclides. A liquid scintillation counter using the triple/double coincidence ratio method is being studied and tested in the CCRI(II)-P1.Co-60 pilot study.

A bilateral comparison between LNHB and PTB to determine the activity concentration of the same I solution.

A bilateral comparison to determine the activity concentration of the same I solution was organized. As electron-capture radionuclide with a rather high atomic number, I must be regarded as difficult to measure. The situation is partly exacerbated by the fact that some established standardization methods, like photon-photon coincidence counting, can no longer be applied due to the unavailability of appropriate equipment and expertise.

Measurement of the half-life of excited nuclear states using liquid scintillation counting.

This work presents measurements of the half-lives of excited nuclear states of Np and Fe using a liquid scintillation (LS) spectrometer and a gamma detector. A novel approach for the determination of the half-lives of some excited states is presented which uses only LS counting data from a detector with two PMTs. The lifetime of the 1st and 2nd excited states of Fe were obtained without the use of a gamma detector.

Time-domain based evaluation of detection efficiency in liquid scintillation counting.

This work explores the distribution of time intervals between signals from the photomultiplier tubes (PMTs) of a liquid scintillation counting (LSC) system when a scintillation burst caused by an ionizing particle is detected. This distribution is termed the cross-correlation distribution and it is shown that it contains information about the probability to detect a scintillation event. A theoretical model that describes the cross-correlation distribution is derived.

On the photomultiplier-tube asymmetry in TDCR systems.

The responses of the three photomultiplier tubes (PMTs) in a triple-to-double coincidence ratio (TDCR) liquid scintillation (LS) system are often not identical. Such asymmetries can have a significant influence on activity determinations. The problem is often solved by means of a minimization algorithm which can easily be applied when analytical methods are used for the efficiency calculation, as is usually done for pure beta emitters.