What is the life span of an accelerated particle? e.g. positron?

Question

In a particle accelerator, an electron beam can be shot at particles of elements that are speeding at near the speed of light. These particles usually become two gamma ray photons...but, how long do those newly formed particles last?

Answer 1

A positron is a stable particle just like the electron, which can last the life span of the Universe or longer. As long as the positron do not collide with ordinay matter like an electron, it can live as long as an electron. It is very difficult and costly to isolate anti-matter; however, it is done through magnetic field confinement in high energy particle accelerators.

As for lifespan of particles formed through high energy collisions in a particle accelerator, it totally depends on the type of particles formed. But most of the exotic and heavy particles are very short-lived and usually decay immediately after they are created. Typically physicsts look at the "decayed products" to deduce what particles were originally the result of the collision.

Just to give you some examples: free neutrons are actually unstable and decay with a lifespan of just under 15 minutes, W and bosons, which are involved in the Weak force interactions have a mean lifespan of about 3 × 10^−25 seconds, a Delta particle has a mean lifespan of 6×10^-24 sec, Omega particle has a mean lifespan of 8.2×10^-11 sec, and a J/Psi paricle has a mean lifespan of 7.2×10-^21 sec.