Ponente
Descripción
Neutron emitted in nuclear reactions following the absorption of alpha particles play a key role in several fields of research: acting as neutron source in the s-process, affecting the production of elements in the r-process occurring in the neutron driven winds of core-collapse supernova, inducing background signals in underground dark matter search experiments, or being a proxy for active interrogation of nuclear materials. Accordingly, there is a renewed interest in measuring the yields and energy spectra of (alpha,n) reactions on many isotopes (see. Ref. [1] for a recent overview of the scientific cases and a summary of the reactions of interest in the mentioned fields of research). In this context, the Spanish experimental nuclear physics community has established the MANY (Measurements of Alpha-N Yields) Collaboration to measure (alpha,n) reactions at two different accelerator facilities (CNA HiSPANoS [2,3] and CMAM [4]) using three complementary detectors for assessing the corresponding neutron yields (miniBELEN [5] and GARY [6]) and energy spectra (MONSTER [7]).
The CNA HiSPANoS facility is driven by a 3 MV tandem accelerator delivering both continuous and pulsed (2% duty cycle) beams of proton/deuteron up to 6 MeV and alphas up to 9 MeV. The current source of alphas is a NEC-ALPHATROSS model delivering a maximum current of only 2 uA, and the pulsing systems is only designed and optimized for protons and deuterons, hence performing poorly for alpha beams. This configuration is well suited for activation and neutron counting experiments with miniBELEN, which shall start in early 2025, and the results from preliminary measurements on 27Al(alpha,n) by ToF using the pulsed beam and a single MONSTER neutron detector module are promising. However, the limitations in beam current and pulsing performance have called for a major upgrade. First, a more versatile buncher system is currently being designed by NEC and <2 ns bunches of alpha particles will be available by Fall 2025. Furthermore, the necessary funds have been secured to purchase and install a NEC-TORVIS ion source capable of delivering alpha beam currents one order of magnitude higher, i.e. 20 uA.
[1] D. Cano-Ott et al., arXiv:2405.07952 (2024)
[2] J. Gómez-Camacho et al., Eur. Phys. J. Plus, 136:273 (2021)
[3] M.A. Millán-Callado et al., Rad. Phys. and Chem. 217 (2024) 111464
[4] A. Redondo-Cubero et al., Eur. Phys. J. Plus 136:175 (2021)
[5] N. Mont-Geli et al., Eur. Phys. J. Web of Conf., 284 (2023) 06004
[6] L.M. Fraile et al., “Measurement of Al(,n) P thick-target yields and total Al(α,n) yields by activation”, IAEA 2nd TM on (,n) Reaction Nuclear Data Evaluations and Data Needs (2023)
[7] T. Martínez et al., Nucl. Data Sheets 120 (2014) 78-80
[8] G. J. H. Jacobs and H. Liskien, Annals of Nucl. Energy 10, 541 (1983)
Abstract
Neutron emitted in nuclear reactions following the absorption of alpha particles play a key role in several fields of research: acting as neutron source in the s-process, affecting the production of elements in the r-process occurring in the neutron driven winds of core-collapse supernova, inducing background signals in underground dark matter search experiments, or being a proxy for active interrogation of nuclear materials. Accordingly, there is a renewed interest in measuring the yields and energy spectra of (alpha,n) reactions on many isotopes (see. Ref. [1] for a recent overview of the scientific cases and a summary of the reactions of interest in the mentioned fields of research). In this context, the Spanish experimental nuclear physics community has established the MANY (Measurements of Alpha-N Yields) Collaboration to measure (alpha,n) reactions at two different accelerator facilities (CNA HiSPANoS [2,3] and CMAM [4]) using three complementary detectors for assessing the corresponding neutron yields (miniBELEN [5] and GARY [6]) and energy spectra (MONSTER [7]).
The CNA HiSPANoS facility is driven by a 3 MV tandem accelerator delivering both continuous and pulsed (2% duty cycle) beams of proton/deuteron up to 6 MeV and alphas up to 9 MeV. The current source of alphas is a NEC-ALPHATROSS model delivering a maximum current of only 2 uA, and the pulsing systems is only designed and optimized for protons and deuterons, hence performing poorly for alpha beams. This configuration is well suited for activation and neutron counting experiments with miniBELEN, which shall start in early 2025, and the results from preliminary measurements on 27Al(alpha,n) by ToF using the pulsed beam and a single MONSTER neutron detector module are promising. However, the limitations in beam current and pulsing performance have called for a major upgrade. First, a more versatile buncher system is currently being designed by NEC and <2 ns bunches of alpha particles will be available by Fall 2025. Furthermore, the necessary funds have been secured to purchase and install a NEC-TORVIS ion source capable of delivering alpha beam currents one order of magnitude higher, i.e. 20 uA.
[1] D. Cano-Ott et al., arXiv:2405.07952 (2024)
[2] J. Gómez-Camacho et al., Eur. Phys. J. Plus, 136:273 (2021)
[3] M.A. Millán-Callado et al., Rad. Phys. and Chem. 217 (2024) 111464
[4] A. Redondo-Cubero et al., Eur. Phys. J. Plus 136:175 (2021)
[5] N. Mont-Geli et al., Eur. Phys. J. Web of Conf., 284 (2023) 06004
[6] L.M. Fraile et al., “Measurement of Al(,n) P thick-target yields and total Al(α,n) yields by activation”, IAEA 2nd TM on (,n) Reaction Nuclear Data Evaluations and Data Needs (2023)
[7] T. Martínez et al., Nucl. Data Sheets 120 (2014) 78-80
[8] G. J. H. Jacobs and H. Liskien, Annals of Nucl. Energy 10, 541 (1983)
