The principle and application of liquid scintillation counter

1. Introduction to Instrument Principles

The liquid scintillation counter mainly measures the occurrence ofRadionuclides that undergo beta nuclear decay are particularly effective for low-energy beta. The basic principle is to generate fluorescence effect based on the interaction between radiation and matter. Firstly, the scintillation solvent molecule absorbs radiation energy to become an excited state, and then transfers the energy to the scintillation molecule when it returns to the ground state. When the scintillation molecule returns from the excited state to the ground state, it emits fluorescent photons. Fluorescent photons are multiplied by photomultiplier tubes(PM)Received and converted into photoelectrons, then multiplied, inPMA lot of photoelectrons are collected on the anode and transmitted out in the form of pulse signals. Match, amplify, analyze, and display the signal to indicate the strength and magnitude of radioactivity in the sample solution.

2. Main functions

　 Although the liquid scintillation counter is used to measure low energyBeta radioactive isotopes are the main ones, but in recent years, with the continuous expansion of nuclear technology applications, many testing functions in other fields have also been developed. This instrument can measure once300Sample, automatic sample replacement, display, printing, with three counting tracks, for3HCounting efficiency greater than60%，14CCounting efficiency greater than95%.

2.1 Measurement of commonly used radioactive isotopes

Liquid scintillation counter can be used for3HThe14CThe32PThe33PThe35SThe45CaThe55FeThe36ClThe86RbThe65ZnThe90SrThe203HgMeasurement of animal, plant, microbial, and non biological samples containing radioactive isotopes.

2.2 H numberQuenching correction method

At the same time as measuring the radioactivity of the sample, measureH#Numerical values can intuitively determine the degree of quenching of the sample.

2.3 Two phase detection

Used to detect the phase separation problem between aqueous radioactive samples and scintillation liquids, in order to avoid the decrease in counting efficiency caused by this.

2.4 Automatic quenching compensation(AQC)

　 By setting the optimal window and other conditions, we aim to achieve high counting efficiency for quenched samples.

2.5 Random compliance monitoring(RCM)

Can be used to monitor false counts of single photon events caused by chemiluminescence during the sample preparation process, which can be deducted from the measurement results.

2.6 Spectral search and analysis

This feature applies to unknown nuclidesReliable and accurate measurement of beta spectrum localization and distribution provides a basis for channel width setting.

2.7 Single photon monitoring(SPM)

Can be used for the determination of bioluminescence and single photon events in organisms.

2.8 Half life correction

For short-lived nuclides, the relationship between radioactive intensity and time can be corrected. Provide the amount of stored radioactivity intensity.

2.9 Double label and triple label determination

By setting different channel widths and other conditions, measure the dual or triple label radioactivity in the same sample and distinguish the radioactivity intensity of each label.

3. application

Liquid scintillation counter is mainly used to detect some low-energyThe radioactive samples of beta isotopes used to trace atoms have been widely applied in scientific research in fields such as food, industry, agriculture, biomedicine, molecular biology, environmental science, archaeology, and geological structures for isotope tracing and nuclear radiation measurement. It mainly includes the following aspects:

3.1 Cell and Molecular Biology

主要利用3HThe14CThe32PUsing radioactive isotopes for in vivo or in vitro labeling to study the synthesis, degradation, metabolism, and transformation pathways of biomolecules such as nucleic acids and proteins in cellular organisms. Especially widely used in nucleic acid molecular labeling, molecular hybridization, probe preparation, and other fields.

3.2 Biomedicine

Using radioimmunoassay technology to determine trace active substances such as hormones in animals or humans, and studying endocrine and other physiological metabolic behaviors in animals and humans.

3.3 Animal and plant nutrition

By labeling and measuring a large amount or trace elements, the absorption and utilization efficiency, physiological metabolism, and nutrient deficiency of animals and plants can be studied, providing a basis for researching prevention and control strategies.

3.4 Environmental Science

Using labeled tracer atoms to study the behavior, destination, and pollution level of toxic and harmful substances in environmental systems, including research on heavy metal and pesticide pollution, as well as monitoring the natural background values of radioactivity in water bodies, atmosphere, soil, and indoor environments.

3.5 Luminescence measurement in living organisms

The study used single photon monitoring to measure the relationship between luminescence in living organisms, single photon events, and environmental changes.