How to find neutron capture and fission cross section


by henxan
Tags: capture, cross, fission, neutron
henxan
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#1
Oct24-07, 11:05 AM
P: 49
I'm writing a paper on Thorium utilization in nuclear reactors.
In this connection I'm looking for figures which describe the neutron capture and neutron fission cross sections over a wide energy range (not only thermal). There are probably some online resources unbeknown to me, any hints?
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theCandyman
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#2
Oct24-07, 11:57 AM
P: 395
I think ENDF VII came out recently, you can check that.

http://www.nndc.bnl.gov/exfor7/endf00.htm

I looked up Th-232 quickly, and I found a small part that gave cross sections for 1 eV to 4 keV range. I couldn't find info on higher energies than that in th file though.
Azael
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#3
Oct24-07, 12:05 PM
P: 324
Click on the sigma retrival in canydmans link or go straight here
http://www.nndc.bnl.gov/sigma/index.jsp

there you can find plots of capture and fission cross section and many other cross sections.

henxan
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#4
Oct25-07, 04:53 AM
P: 49

How to find neutron capture and fission cross section


Superb!!! This was really helpful!!

Thanks a lot people!! :D
henxan
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#5
Oct25-07, 05:22 AM
P: 49
I'm having some difficulties in interpreting the data on NNDC database. I'm trying to figure out how to use the database.
Ive got a table from IAEA's tecdoc 1450 attached to this message.

Specifically: Table gives data for 233U at 0.05eV:
sigma(f)=332
alfa=sigma(c)/sigma(f)=0.096

Straight forward calculation gives sigma(c)=32, which quite elegantly corresponds to the Sigma Plot of sigma(n,gamma) on NNDC.

But this is not the case in the table, which gives the sigma(c)=54

The second anomaly occurs for when I look at the data for sigma(n, total fission) at NNDC's site, which gives the value 377. In the table this value is 332 as earlier described.

Anyone got a hunch what errors I may be making?
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vanesch
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#6
Oct25-07, 09:36 AM
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P: 6,238
Quote Quote by henxan View Post
I'm having some difficulties in interpreting the data on NNDC database. I'm trying to figure out how to use the database.
Ive got a table from IAEA's tecdoc 1450 attached to this message.

Specifically: Table gives data for 233U at 0.05eV:
sigma(f)=332
alfa=sigma(c)/sigma(f)=0.096

Straight forward calculation gives sigma(c)=32, which quite elegantly corresponds to the Sigma Plot of sigma(n,gamma) on NNDC.
I don't see your problem: the absorption is 364, of which there is 332 fission, so there is 32 capture in the table, no ?

Also, these values are INTEGRATED values over a thermal SPECTRUM at 300 degrees (corresponding to about 0.05 eV average), but 32 is actually pretty close to the cross section in the table at 0.05 eV if you check, while 54 is the value at one single energy (0.0253 eV).
2200 m/s corresponds to 0.0253 eV.

But this is not the case in the table, which gives the sigma(c)=54

The second anomaly occurs for when I look at the data for sigma(n, total fission) at NNDC's site, which gives the value 377. In the table this value is 332 as earlier described.

Anyone got a hunch what errors I may be making?
I've checked this, and I don't know either why this is so. Maybe the cross section is not strictly 1/nu and the maxwell integral doesn't give the same as the value at the average energy...
yasaman
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#7
Feb6-08, 02:55 PM
P: 2
i like to solve more problem in chapter 5(lamarsh),please tell me how find new problem?


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