### Author Topic: Radioactive nuclei decay law  (Read 71171 times)

#### Fu-Kwun Hwang

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##### Radioactive nuclei decay law
« on: June 07, 2005, 04:36:02 pm »
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Assume the number of radioactive nucleus is N(t) --- not yet decayed into daugheter product.
Each nucleus has the same probability p (p<1) decayed into daughter product.
It means that dN(t)/dt= -p*N(t) , where dN(t) is the number of nucleus decayed into daughter product at time t.
The solution is N(t)=N(0) e -pt, where N(0) is total number of nucleus at time t.

Each box represent a nucleus.
This applet let you set the probability for a nucleus to decay and watch how the number of decayed nuclei (color changed to RED)  increased with time t.

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#### line17341

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##### Storage
« Reply #1 on: November 30, 2005, 09:28:17 am »
[quote:a56ebe29b0="hwang"]This applet let you set the probability for a nuclei to decay and watch how the number of decayed nuclei change with time.[/quote:a56ebe29b0]

Where can i keep something like that? :X

#### Fu-Kwun Hwang

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##### Decay series
« Reply #2 on: November 30, 2005, 09:52:17 am »
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Get click the above "GET APPLET FILE" button (at the end of the first message)!

Here is another simulation I have created many years ago (not with EJS).
It shows a series of radioactive nuclei decay: different color represent different nucleus.
The radioactive nuclei will decay into daughter product, and the daughter nucleus will decay another nucleus.
The original nuclei are color code in BLACK.
It will decay into RED -> GREEN -> YELLOW -> BLUE (and become stable nuclei).

You can change decay time (unit: second) for each stage (from black -> red -> green -> yellow -> blue),
click start and watch how the number of different nuclei changed with time -- colored traces.

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#### bunia

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##### something p?
« Reply #3 on: September 29, 2006, 05:32:17 am »
What means p?

#### lookang

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##### Re: Radioactive nuclei decay law
« Reply #4 on: May 13, 2009, 11:22:08 am »
p is Nuclear Decay Probability
http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/halfli2.html

i am trying to make n variable into a dynamically selectable slider.
but i can't seems to do it quickly.

my thoughts:
data is an array [n]*[n].
when n is changed in the slider, the data is not changed. why? what must be done to make an applet that allows of changes of number of atoms?
« Last Edit: May 13, 2009, 12:19:31 pm by lookang »

#### lookang

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##### Re: Radioactive nuclei decay law
« Reply #5 on: May 18, 2009, 01:46:42 pm »
i am exploring remixing this applet into
http://66.7.205.91/~lookangc/index.php?topic=707.msg1442#msg1442

radioactive decay of parent isotope to daughter D to further daughter S.

u can download all 3 files n run the html to see my applet made in Netlogo 3.0.2.

thinking of using Ejs to improve the version

#### lookang

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##### Re: Radioactive nuclei decay law
« Reply #6 on: May 21, 2009, 08:25:46 pm »
http://66.7.205.91/~lookangc/netlogo/Decay01.html
can
see ?
i wish to redo it in EJs, using your existing code here, is it ok?

#### lookang

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##### Re: Radioactive nuclei decay law
« Reply #7 on: May 22, 2009, 08:43:56 am »
hope to get some pointers how to get the EJs version "n" to be selectable by the slider, like mentioned in my early posts

Just figure out how to embed Netlogo applets
« Last Edit: May 22, 2009, 09:06:32 am by lookang »

#### Fu-Kwun Hwang

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##### Re: Radioactive nuclei decay law
« Reply #8 on: May 22, 2009, 10:41:01 am »
I downloaded your attached xml files from previous message.
It seems that you want to be able to modify the nxn array from 40-400.
This will need a lot of memory when you have 400*400 cells.
I modified it and it can be chaged from 40-200.
1. You need to allocate the maximum number of cells needed.
2. The lattice GUI has been replaced with particleSet.

I did not understand why you want to modify range so I removed it.
Please check out the following modified version.

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• Please feel free to post your ideas about how to use the simulation for better teaching and learning.
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Let's work together. We can help more users understand physics conceptually and enjoy the fun of learning physics!

#### lookang

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##### Re: Radioactive nuclei decay law
« Reply #9 on: May 22, 2009, 12:00:38 pm »
nice! thx for solving the n problem.

i will explore more when time permits.

That is what i need to figure out but couldnt!
Quote
1. You need to allocate the maximum number of cells needed.
2. The lattice GUI has been replaced with particleSet.

The range thing was my attempt by trial and error of how to control the size of the view, i was confused by n*n and range. Lucky u solved it so i can continue to learn by constructing a model with support from u. will seek guidance after finding out more whether can remix in my netlogo version.

Thanks a million boss!

#### NagySandorIstvan

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##### Re: Radioactive nuclei decay law
« Reply #10 on: August 15, 2009, 12:46:25 am »
Dear Prof. Hwang,
I have found a version of your simulation at http://www.phy.ntnu.edu.tw/oldjava/decay/decay.html
I am working on a web-based nuclear glossary for my students in Hungarian: http://www.chem.elte.hu/Sandor.Nagy/NewClearGlossy/index.html.
Is it possible to get the source code of that program?
The reason I am asking it, because the color scheme could be better. I think e.g. that a gray background would make the green text easier to read than the present background. I have also realized that the parameter "tau" is actually the half-life which should be denoted by T1/2, or at least by T, because tau is used for denoting mean life in nuclear chemistry and physics.
Otherwise I like the applet very much. I am adding a supporting page to my glossary with an introductory page to your program. As soon as I upload it to the server, I will send you the link to it.
Best regards,
Sandor
PS: here is my home address if you want to react:
nasa@enternet.hu

#### Fu-Kwun Hwang

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##### Re: Radioactive nuclei decay law
« Reply #11 on: August 15, 2009, 10:42:41 am »
You can find the source code decay.java as attachement file of the third message.
Those labels can be modified as parameters for applet tag.

You need to modified the source code for the background color.

<applet width="600" height="340" codebase="/java/decay/" code="decay.class"><param value="reset" name="Reset" /><param value="start" name="Start" /><param value="time=" name="Time" /><param value="decay time ?1" name="tau1" /><param value="?2" name="tau2" /><param value="?3" name="tau3" /><param value="?4" name="tau4" /></applet>

#### NagySandorIstvan

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##### Re: Radioactive nuclei decay law
« Reply #12 on: August 25, 2009, 11:11:52 pm »
Dear Prof. Hwang,
Thank you for the instructions you gave me. Here is the link where you can find the Hungarian version of your great simulation:
http://www.chem.elte.hu/Sandor.Nagy/NewClearGlossy/Java/4StepSeries_Hwang/index.html
Attached please find the java with the new color scheme. I hope you will like it.
Very best regards,
Sandor

#### diinxcom

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##### Re: Radioactive nuclei decay law
« Reply #13 on: December 14, 2014, 06:26:58 pm »
-*-
Content on this thread so help me. Thanks