Delayed neutron energy spectrum

  • Thread starter snorkack
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  • #1
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Main Question or Discussion Point

First: what precisely is the shape of delayed neutron energy spectrum for each single emitter, generally?
Second: what are the delayed neutron energy parameters for the common isotopes producing them?
The attested list seems to be:
  1. Br-87 55,65 s 2,52 %
  2. Cs-141 24,8 s 0,035 %
  3. I-137 24,13 s 7,14 %
  4. Br-88 16,3 s 6,48 %
  5. I-138 6,23 s 5,46 %
  6. Rb-93 5,84 s 1,35 %
  7. Rb-92 4,49 s 0,011 %
  8. Br-89 4,4 s 13,8 %
  9. As-84 4 s 0,28 %
  10. Rb-94 2,7 s 10 %
  11. I-139 2,28 s 10 %
  12. Br-90 1,91 s 25,2 %
  13. Kr-92 1,84 s 0,03 %
  14. Cs-143 1,79 s 1,62 %
  15. Xe-141 1,73 s 0,04 %
  16. Cs-142 1,69 s 0,09 %
  17. Kr-93 1,29 s 1,95 %
  18. Xe-142 1,22 s 0,41 %
  19. Cs-144 1 s 3,2 %
  20. I-140 0,86 s 9,3 %
  21. Cs-145 0,58 s 14,3 %
  22. Br-91 0,54 s 20 %
  23. Rb-95 0,38 s 8,73 %
  24. Br-92 0,34 s 33 %
  25. Kr-94 0,21 s 5,7 %
Any others, or other corrections?
Which of the above provide the highest energy delayed neutrons?
 

Answers and Replies

  • #2
Astronuc
Staff Emeritus
Science Advisor
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One will have to look at each nuclide. I can readily find some data on one nuclide Kr-87 for which Br-87 is a precursor. Br-87 undergoes beta decay to several excited states of Kr-87. Looking at the binding energy of the last neutron in Kr-87, it has an energy of ~5.1 MeV. With a intermediate state of 5.4 MeV, Kr-87 can emit a neutron of 0.3 MeV, and there are apparently levels slightly above 5.4 MeV.
Ref: John R. Lamarsh, Introduction to Nuclear Reactor Theory, Addison-Wesley Publishing Co. , 1972, p. 98

Two papers (Online purchase) - energy spectra plots/data
R.C. Greenwood, A.J. Caffrey, "Delayed-Neutron Energy Spectra of 93-97Rb and 143-145Cs,"
Nuclear Science and Engineering, Volume 91, 1985 - Issue 3, ANS (Taylor and Francis Online), 1985
https://www.tandfonline.com/doi/abs/10.13182/NSE85-A17307

R.C. Greenwood, K.D. Watts, "Delayed Neutron Energy Spectra of 87Br, 88Br, 89Br, 90Br, 137I, 138I, 139I, and 136Te," Nuclear Science and Engineering, Volume 126, 1997 - Issue 3, ANS (Taylor and Francis Online), 1997
https://www.tandfonline.com/doi/abs/10.13182/NSE97-A24484

Open Access
http://inspirehep.net/record/1364634/files/v46p0717.pdf

Michaele Clarice Brady, Evaluation and Application of Delayed Neutron Precursor Data, 1988
https://www.osti.gov/servlets/purl/6187550
 
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