Irradiation effects in beryllium exposed to high energy protons of the NuMI neutrino source

Abstract

has been irradiated by 120GeV protons over 7 years, with a maximum integrated fluence at the window centre of 2.06 10 22 p/cm 2 corresponding to a radiation damage level of 0.48 dpa. The proton beam is pulsed at 0.5 Hz leading to an instantaneous temperature rise of 40°C per pulse. The window is cooled by natural convection and is estimated to operate at an average of around 50°C. The microstructure of this irradiated material was investigated by SEM / EBSD and Atom Probe Tomography, and compared to that of unirradiated regions of the beam window and that of stock material of the same PF-60 grade. Microstructural investigations revealed a highly inhomogeneous distribution of impurity elements in both unirradiated and irradiated conditions. Impurities were mainly localised in precipitates, and as segregations at grain boundary and dislocation lines. Low levels of Fe, Cu, Ni, C and O were also found to be homogeneously distributed in the beryllium matrix. In the irradiated materials, up to 440 appm of Li, derived from transmutation of beryllium was homogeneously distributed in solution in the beryllium matrix.

New insights into microstructure of irradiated beryllium based on experiments and computer simulations

“…*Measured before irradiation. www.nature.com/scientificreports www.nature.com/scientificreports/ previous publications 19,34 suggest that these complex structures are beryllium intermetallic compounds. The post irradiation examination of HIDOBE1 campaign also confirmed the presence of complex beryllide particles with Fe/Al/Mn or Fe/Al/Mn/Cr composition 35 .…”

Thermal shock experiment of beryllium exposed to intense high energy proton beam pulses

“…Another essential factor to consider when determining safety margins for beam-intercepting devices is the long-term radiation damage effects on material properties. Previous studies [13,21,22] have shown a significant degradation in thermal and strength properties of beryllium from high energy particle irradiation, which can have a negative impact on the structural and thermal integrity of the component over time. Therefore, careful consideration of radiation damage effects and the resulting material property degradation is needed when evaluating the thermomechanical response of beam-intercepting devices.…”

High power targets: Challenges of next-generation high-intensity neutrino beams

“…An irradiated disc of PF-60 grade beryllium was recovered from the Fermilab NuMI primary beam window assembly and sent to the University of Oxford for PIE activities [13]. The beryllium disc was exposed to a total of 1.6 × 10 21 protons (120 GeV), equivalent to about 0.5 peak DPA, with an irradiation temperature of about 50 °C.…”