0 an extremely small piece of matter with a positive electrical charge, having the same mass as an electron -- 正電子，陽電子
Following their emission, positrons travel for a short distance that is defined by their energy and the surrounding tissue.
This effect decreases when the number of positrons increases.
When using carbon, however, the carbon 11 isotopes produced by fragmentation are positron emitters.
Planning and spatial working memory : a positron emission tomography study in humans.
Their spatial patterns are significantly modified by the presence of the positron component.
It is seen that an addition of minute quantities of positrons abruptly reduces the net negative charge of the dust grain.
After an encounter with a shock wave, some positrons are reflected and then accelerated along the magnetic field.
Further, we find that some particles in another positron bunch are accelerated by the parallel electric field.
