Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

In my textbook it is written that Tritium is an isotope of hydrogen whose nucleus Triton contains 2 neutrons and 1 proton. Free neutrons decay into p + electron + anti-neutrino . If one of the neutrons in Triton decays, it would transform into $He^3$ nucleus. This does not happen and the reason is given to be that both the neutrons in triton have to decay simultaneously resulting in a nucleus with 3 protons, which is not a $He^3$ nucleus.

But, why is necessary that both the nucleus should decay simultaneously?

share|cite|improve this question
It does. Halflife a bit over 12 years. Who told you it doesn't? – dmckee Mar 3 '14 at 16:19
@dmckee Sir can you please explain?I'm not able to understand from the given link. – Rajath Krishna R Mar 3 '14 at 16:22
That is from an on-line table of the isotopes (useful link, BTW). The symbol at the top left is $^3_1\mathrm{H}$, which is to say tritium. The table lists the decay mode b- (which means $\beta^-$) as having a 100% branching ratio and no other modes (i.e. all decays occur in that channel) and gives the halflife. For more complicated isotopes there is a lot more data in the page, but tritium is simple. – dmckee Mar 3 '14 at 16:25
There is no double beta decay mode listed as it would be energetically disfavored. – dmckee Mar 3 '14 at 16:27

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.