Speaker
Description
Neutron yields and energy spectra from ($\alpha$,xn) reactions are relevant data for several fields such as nuclear astrophysics, underground physics (low background measurements), nuclear technologies and applications like nuclear safeguards. The existing experimental data have been obtained with thin and thick targets often via activation measurements or in direct neutron measurements using proportional counters based on BF$_{3}$ and $^{3}$He as well as with organic scintillators. The data available in the EXFOR database [1] show large discrepancies with respect to the reported uncertainties. On the other hand, the only existing evaluated nuclear data library JENDL/AN-2005 [2] contains information for just 17 isotopes. The general purpose and computer driven TENDL [3] library provides data for a much larger set of isotopes, but in relevant cases it differs significantly from the JENDL/AN-2005 evaluation and from the experimental data. Therefore, the conclusion is that it is highly desirable to perform new measurements with the aim to improve our knowledge on ($\alpha$,xn) cross sections.
A collaboration for the Measurement of Alpha Neutron Yields and spectra (MANY) formed by Spanish research groups has been established with the aim to carry out measurements of ($\alpha$,xn) reactions on isotopes of interest. Two different detector types are being used: one based on $^{3}$He proportional counters moderated in a high-density polyethylene matrix, miniBELENA [4], and a second detector based on BC501/EJ301 liquid scintillator modules, MONSTER [5, 6], which can operate as a time of flight spectrometer. Both instruments are coupled to high performance digital electronics and have been commissioned at the two accelerator facilities CMAM [7] and CNA HISPANOS [8] studying the response to well-known nuclear reactions. The measurements are complemented by $\gamma$ spectroscopy measurements for ($\alpha$,xn$\gamma$) reactions using an array of fast scintillators.
The experimental program of the MANY collaboration and first results with pulsed and continuous $\alpha$ beams will be reported. A comparison with simulations carried out with the SaG4n code [9] for ($\alpha$,xn) yield calculations will also be provided.
References
[1] https://www-nds.iaea.org/exfor/endf.htm
[2] T. Murata, H. Matsunobu, K. Shibata, Technical Report, JAEA-Research 2006-052, 2006.
[3] A. Koning and D. Rochman, Nucl. Data Sheets, 113 (12) (2012), pp. 2841-2934
[4] N. Mont i Geli, A novel modular neutron detector for ($\alpha$,n) reactions: design and experimental validation, Master thesis. U. de Sevilla, 2020.
[5] A.R. Garcia et al., JINST 7 C05012 (2012).
[6] T. Martinez et al., Nuclear Data Sheets, 120 (2014), pp. 78
[7] A. Redondo-Cubero et al., Eur. Phys. J. Plus (2021) pp. 136-175
https://doi.org/10.1140/epjp/s13360-021-01085-9
[8] Gomez-Camacho, J., Garcia Lopez, J., Guerrero, C. et al. Research facilities and highlights at the Centro Nacional de Aceleradores (CNA). Eur. Phys. J. Plus 136, 273 (2021)
[9] E. Mendoza et al., Nucl. Instr. and Meth. A 960, (2020) 163659.
