Another question about beta decay (stupid ones)

[vertices]

A couple of really stupid questions:(

In beta minus decay, an atom release and electron (and an antineutrino). The electron, does this happen spontaneously? Doesn't the another particle have to collide or interact with the atom (be give it some momentum, or energy), to trigger the atom to release an electron.

And in beta plus decay, an atom releases a positron. Where does this positron actually come from? The atom can liberate electrons, sure, but not positrons!

 

[mathman]

In beta decay (either one), the particle release is spontaneous. The particle is emitted by the nucleus - it has nothing to do with the electrons in the atom. The essential process is neutron to proton conversion (electron emission) or proton to neutron (positron emission), within the nucleus.

 

[tiny-tim]

Hi vertices!

Most atomic nuclei are "neutron-heavy", so they naturally decay to emit electrons, but a few (cobalt-something, for example, I think) are "proton-heavy", so they naturally decay to emit positrons.

 

[Vanadium 50]

True positron emitters are rare and short-lived. (I think Na-22 is the longest lived, at about 3 years) More common is something called K-capture, when a proton absorbs an electron, turns into a neutron and emits a neutrino.

There are even rare nuclei that can beta decay in either direction. One is even mentioned somewhere on this page.

 

[vertices]

thanks for the replies guys:)