Thermal Neutron Demagnetization of NdFeB Magnets

Published

July 30, 2006

Author(s)

R Klaffky, Richard M. Lindstrom, Brian B. Maranville, Robert D. Shull, B Micklich, J Vacca

Abstract

To isolate the effect that thermal neutrons have on Nd2Fe14B permanent magnets, the magnetization and coercivity were studied as a function of dose. The changes in remanent magnetization are substantial and are attributed to boron thermal neutron capture through the 10B(n,alpha)7Li reaction, which generates MeV energy alpha particles and lithium ions. MCNPX Monte Carlo calculations were used to simulate energy deposition in the APS Sector 3 insertion device magnets and the predicted gamma and neutron fluxes are compared to Au and Ti foil dosimetry. These calculations indicate that high linear energy transfer (LET) alpha particles coming from fast neutron (10 keV to 10 MeV) reactions with the boron and with materials close to the magnets (aluminum and vanadium permendur) are primarily responsible for the demagnetization. There will also be Li ion contributions in connection with the boron reactions. The MCNPX calculations predict that the thermal neutron fluxes are low, which is confirmed by Au foil dosimetry

Proceedings Title

European Particle Accelerator Conference | 10th | Joint Accelerator Conferences | European Physical Society Accelerator Group

Conference Dates

June 26-30, 2006

Conference Location

Edinburgh, 1, UK

Conference Title

European Particle Accelerator Conference Proceedings

Pub Type

Conferences

Citation

Klaffky, R. , Lindstrom, R. , Maranville, B. , Shull, R. , Micklich, B. and Vacca, J. (2006), Thermal Neutron Demagnetization of NdFeB Magnets, European Particle Accelerator Conference | 10th | Joint Accelerator Conferences | European Physical Society Accelerator Group, Edinburgh, 1, UK (Accessed April 19, 2024)