Positron Annihilation Spectroscopy Method

Positron Annihilation Spectroscopy (PAS) is a non-destructive testing technique used for determining the moisture content of materials. It is based on the principle that when positrons (the antiparticles of electrons) are implanted into a material, they annihilate with electrons, releasing energy in the form of gamma rays. The energy distribution of these gamma rays is sensitive to the electronic structure of the material, which in turn is influenced by the presence of moisture.

How does PAS work?

• A positron source is placed on the surface of the material to be tested.
• Positrons are emitted from the source and implant into the material.
• Positrons annihilate with electrons in the material, releasing energy in the form of gamma rays.
• The energy distribution of the gamma rays is measured using a spectrometer.
• The energy distribution of the gamma rays is then used to calculate the moisture content of the material.

Advantages of PAS

• Non-destructive: PAS is a non-destructive testing technique, meaning that it does not damage the material being tested.
• Accurate: PAS can accurately measure the moisture content of materials with a high degree of accuracy.
• Fast: PAS is a relatively fast testing method, with measurements typically taking only a few minutes.
• Versatile: PAS can be used to measure the moisture content of a wide variety of materials, including plastics, ceramics, and metals.

Applications of PAS

PAS is used in a variety of applications, including:

• Moisture content measurement: PAS is used to measure the moisture content of materials in a variety of industries, including the food, pharmaceutical, and construction industries.
• Quality control: PAS can be used to ensure that the moisture content of materials meets specifications.
• Research and development: PAS can be used to study the relationship between moisture content and the properties of materials.