Spectacular decay of K+
Picture from CERN 2-metre hydrogen bubble chamber exposed to a beam of positive
kaons ( 
) with energy
10GeV entering from the bottom of the picture.
Spectacular examples of a knock-on electron and a lone spirialling 'Compton' electron shows that negative particles turns to the left.
In the middle of the picture a decays
into 
.
Each pion 
then
stops before decaying into a muon 
.
The two positive muons 
move
a short distance before
stopping and decaying into spiralling positrons
.
The negative muon 
fails
to produce an electron 
because
it has gone into the glass window of the bubble chamber!
The decay scheme which includes the various unseen neutrinos 
produced in the
decays is:
