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Difference of B-10(n,2a)H-3 cross section in ENDF/B

  1. Apr 2, 2016 #1
    In the research,it is found there is significant difference of B-10(n,2a)H-3 reaction cross section between ENDF/B-V and ENDF/B-VI (http://www.nndc.bnl.gov/).The cross section in ENDF/B-V is 10 times less than ENDF/B-VI when neutron energy E<0.1MeV(https://pic3.zhimg.com/e89e6ed65208bc4bcc2aa05bc635a39e_b.jpg). Some papers provide about 3 times difference in various measurement when neutron energy is at range 5MeV~6MeV(http://isinn.jinr.ru/proceedings/isinn-20/pdf/Ivanova.pdf).
    Could someone explain these difference and recommend which version(ENDF/B) is more reliable? Thank you very much.
     
  2. jcsd
  3. Apr 2, 2016 #2

    Astronuc

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    Staff: Mentor

    Usually, the later or latest version of ENDF is considered correct, or more accurate.

    One should also check other cross-sections and the total cross-section to see if they have changed. Sometimes, it's a matter improved experimental measurement.
     
  4. Apr 2, 2016 #3
    Probably, the later the more accurate as Astronuc mentioned. Also in case you are gonna use it from a simulation software, it seems triggering to not use it in your application unless there exists some literature that validated the software for your application of interest. Otherwise, you might be interested to validate your application yourself and make it a "literature".
     
  5. Apr 2, 2016 #4
    Thanks your prompt reply. The B-10(n,2a)H-3 cross section in other nuclear datebase(e.g. JENDL-3.1, FENDL-4.0) and current ENDF/B-VII is more close to ENDF/B-VI.But it is said by someone that ENDF/B-V may be more accurate owing to military use of H-3(used in nuclear fusion weapon) and the cross section may have been revised somewhat before its released in public. I'm so confused.
     
  6. Apr 2, 2016 #5
    Thank you for quick reply. Does total cross-section you mentioned mean sum of cross-section by each reaction(not include scattering)?
     
  7. Apr 2, 2016 #6

    Astronuc

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    The total cross-section includes total absorption + total scattering, so as not count the individual reaction cross-sections more than once.
     
  8. Apr 2, 2016 #7
    Thank you very much for discussion. It is difficult to judge reliability by comparing total cross-section because total cross-section is same in the two version of datebase. In adddition, B-10(n,2a)H-3 cross section is tremendously less than other reaction, especiallly 3~4 order of magnitude less for thermal neutron(0.00056 barn of (n,2a+T)).So I think these tiny difference of B-10(n,2a)H-3 cross section in difference datebase will be hidden by other reaction of B-10.
    Total cross section of B-10 reaction for thermal neutron(v=2200m/s) listed as below(http://www.nndc.bnl.gov/exfor/servlet/E4sGetEvaluation?Pen=2&EvalID=6374&req=482):
    Reaction Sig(2200)
    Total 3.84222E+03
    Elastic 2.25043E+00
    Inelas 0.00000E+00
    n,gamma 4.99881E-01
    n,p 5.66000E-04
    n,d 0.00000E+00
    n,alpha 3.83946E+03
     
  9. Apr 8, 2016 #8
    Could you give me any more clues to further judge the reliability of nuclear database? thank you very much.
     
  10. Apr 9, 2016 #9

    Astronuc

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    Staff: Mentor

    I would not be concerned about the (n,tαα) reaction with B-10 below a neutron energy of 1 MeV. It has a very low cross-section, which is about ~6 orders of magnitude (1.82E-6) less than the cross-section of the (n,α), so it would be hard to measure.

    A common application for B-10 is as a burnable poison in LWRs, and in a thermal spectrum the (n,α) reaction dominates. The (n,tαα) reaction is only significant in a strong fast flux (E > 1 MeV), and even then, it would not be significant in an LWR environment.
     
    Last edited: Apr 9, 2016
  11. Apr 9, 2016 #10
    Thanks very much for discussion.I will provide,later, some detailed calculation after consult with colleague doing nuclear design and fuel management.
     
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