Why Alpha Particle Decay Q Leads to Lifetime Change

[hhhmortal]

Hi,

I want to know why a small change in energy released, Q, in alpha particle decay leads to a large change in the lifetime. Also could anyone provide me with a link that shows a diagram of the energy spectrum of alpha particles.


Thanks.

 

[Astronuc]

Hi,

I want to know why a small change in energy released, Q, in alpha particle decay leads to a large change in the lifetime. Also could anyone provide me with a link that shows a diagram of the energy spectrum of alpha particles.

Please define 'small' with respect to energy, Q.

One can find details on specific radionuclides at - http://www.nndc.bnl.gov/chart/ (click on a particular area and choose a nuclide, then select Zoom 1 for a closeup). One can use various links to various other pages (In Zoom 1 mode - look for A list of levels, a level scheme and decay radiation information are available near the bottom of the page).

For example -
http://www.nndc.bnl.gov/chart/decaysearchdirect.jsp?nuc=242PU&unc=nds

http://www.nndc.bnl.gov/chart/getdecayscheme.jsp?nucleus=238U&dsid=242pu a decay&unc=nds


The general website = http://www.nndc.bnl.gov/

 

[minerva]

Hi,

I want to know why a small change in energy released, Q, in alpha particle decay leads to a large change in the lifetime. Also could anyone provide me with a link that shows a diagram of the energy spectrum of alpha particles.


Thanks.

I take it you're referring to the exponential dependence of the mean lifetime (or half-life) on the energy Q for an alpha-emitting radionuclide, as observed in the Geiger-Nuttal law?

You can derive this if you're familiar with basic quantum mechanics, and you treat the alpha particle escaping the nucleus as a basic example of a quantum mechanical tunnelling/scattering from a bound state, as Gamow originally showed. It's often shown as an example in many undergrad quantum mechanics books.