# Multi-decay chains

Hi guys,

I'm taking a first year bridging course lab and so the labs are really simple, but the students have no Physics knowledge. They are dealing with radiation mainly, but some are struggling with the concept of Multi-Decay chains. They have a lab that has to do with Parent decaying to the daughter, which then decays to a stable grandaughter (the program draws graphs of vairous half-life situations). Anyway even after I explain it to them I feel that they are still lost. As a result I realise I'm probably not the best teacher, but I'd appreciate it if any of you guys knew of any good sites that give a real basic description of multi-decay chains, with diagrams illustrating transient, secular and no equilibrium.

I feel bad that I haven't been able to make them understand this too well and I really want to help them as much as possible.

mjsd
Homework Helper
to fix the problem you must work out why your students don't understand. what concepts do they find hard, and how are they trying to visualize it... it is often a matter of knowing their "line of thoughts" that solves the problem.

Astronuc
Staff Emeritus
In order to understand decay chains, one has to understand first order differential equations.

Try this -

http://jnm.snmjournals.org/cgi/reprint/20/2/162 (pdf)

This is pretty decent - decay chains toward the end

Health Physics Society is generally a good site
[URL]http://www.hps.org/publicinformation/ate/cat47.html[/URL]

And the IAEA
[PLAIN]http://www.iaea.org/programmes/ripc/ih/volumes/vol_one/cht_i_06.pdf [Broken]

Last edited by a moderator:
Yeah mjsd you are right. That is what I have to do to fix the problem, but it is hard to get that out of a person. Most people don't want to feel stupid so they lie to you. But I should try harder to find out how they are thinking and what they are finding so difficult. This is the first time I've done something like this so I guess I'm not as efficient and good at communicating the theory to the students as I should be.

Thanks for the links Astronuc!! There are some very good resources there that I'm sure will be of some help.

One of my instructors had a great demo of what multi decay chains were. He gave one person a pile of small pebbles and had that person give Person #2 a peblle at a specified rate. Person #2 then gave pebbles to person #3 at a different specified rate. He then went through various scenarios where person 1 transferred pebbles quickle but person 2 transferred slowly, and then another where it was the opposite. This demo (albeit simple for a graduate level course I felt) is a great visual for those who don't understand multi-decay systems.