Positron Systems, Inc - IPA Technology

Introduction

Earlier detection of material degradation Lifetime health monitoring Failure prediction Component life extension Primarily used for metals	3 - 4 mm below surface	3 - 184 mm below surface

There are two types of test. The first is a surface level test which can find defects up to 4mm in depth. This is the IPA application being deployed now. There is a volumetric version that can find defects up to 184mm from the surface - this test requires a linear accelerator and is therefore limited to a specialized service center.	*all before a fracture occurs*
	All the uses listed above are for metals - and for testing before the fracture occurs - not just when we can detect it today. To the right is a sample crystal lattice structure of a given material. Consider what happens when there is a dislocation in the lattice structure. Using a technique in physics called positron annihilation, we can induce a positron into new material and it will find its anti-matter - a free electron - and the two will disappear and turn into a gamma ray. The same is true for damaged material, except that the gamma ray emitted has a different energy level. We detect the gamma ray response and we can determine where the component is on the lifetime degradation chart.

Basic Theory

positron is anti-matter of electron mass of positron and electron are equal charge of positron and electron is opposite positron and electron attarct	Year 1930 1932 1934 1949	Researcher Dirac Anderson Klemperer DeBenedetti et. al.	Event positron predicted positron discovered 2γ annihilation θ not 180°
positron - electron annihilation produces γ rays positron or electron velosity change γ rays electron velocity causes energy shift in γ rays positrons live in matter for ≈ 200 pico seconds
positron diffuses - until annihilation or trap increase in trap density increases annihilations positron traps - open volume defects (monovacancy, divacancy, etc) positron traps - negatively charged defects
positrons in defects annihilate with low velocity electrons defects causes narrower annihilation spectrum no defect causes broader spectrum measure the shape or sharpness of response sharpness of response is the "S" parameter