Results

I will present cross section results for 6 \((\text{n},~\text{n}')\) and \((\text{n},~2\text{n})\) transitions, extracted using the code described previously. The transitions can be seen in blue in the level scheme in Figure 4.

The experimental values are compared to Talys calculations . (The level scheme used by Talys is shown in the appendix) We compare to default computations using version 1.96 (2021), P. Romain’s own calculations [1], and M. Dupuis’s calculations [2].

The values will also be compared to very preliminary results obtained from the data recorded with Grapheme and a natural tungsten target, analyzed by Pol Scholtes in 2011 [3]. He extracted two \((\text{n},~\text{n}'~\gamma)\) cross sections related to reaction on ¹⁸³W.

At the time, the natural tungsten target mass was underestimated. Thanks to comparisons with the data from isotopically enriched targets [4], the natural target was re-characterized at JRC-Geel and the mass was reevaluated to be 6.35 % more than first considered, leading to a corresponding scaling down of the cross sections extracted from the natural tungsten dataset. This scaling down as been applied to the P. Scholtes’ values shown here.

Note

The data from P. Scholtes was extracted from his report’s figures using WebPlotDigitizer online, because the values (whether they were stored initially in root files or excel spreadsheet) could not be found again in the archives. This is a good example of bad practice in file tracking and data management that has to be avoided [5].

The uncertainties associated with the cross section values extracted from the figures use a flat relative uncertainty value of 20 %, extracted from the graph for a few points and generalized to all. There is no uncertainty on the neutron energy part.

Finally, the values are also compared for 4 transitions (two \((\text{n},~2\text{n}~\gamma)\) and two \((\text{n},~\text{n}'~\gamma)\)) to values obtained by using the old full Monte Carlo Code on the same data.

The raw values of the experimental points are given in the appendix.

• Convergence
• Flux
• Experimental (n, n’ \(\gamma\)) and (n, 2n \(\gamma\)) cross sections
  • Check of angular cross section
  • Inelastic reactions results
  • (n, 2n) results

Footnotes

[1]

Done by Pascal Romain (CEA/DAM/DIF) in 2016, private communication.

[2]

Done by Marc Dupuis (CEA/DAM/DIF) in 2024, private communication.

[3]

“Mesure des sections efficaces des réactions \((\text{n},~x\text{n}~\gamma)\) sur les isotopes ¹⁸⁶W, ¹⁸⁶W et ¹⁸⁶W” Pol Scholtes. Internship report (2011).

[4]

“Improving the accuracy of 182,184,186W(n, n’\(\gamma\)) cross sections calculations” G. Henning, M. Dupuis, M. Kerveno, R. Capote, Ph. Dessagne, S. Hilaire, T. Kawano, P. Romain, C. de Saint Jean, P. Scholtes, P. Tamagno. In preparation for Physical Review C. (2024)

[5]

I’m not blaming anyone, it was not possible at the time to anticipate that it would be so long before someone looked into the data again. Also, the technical solution to centralized data did not exists at the time.