Recent refurbishment of the Oak Ridge Electron Linear Accelerator neutron source

Abstract
For almost 40 years the Oak Ridge Electron Linear Accelerator (ORELA) at Oak Ridge National Laboratory (ORNL) has been operational and has provided high-resolution neutron cross-section data for many isotopes in the energy range from thermal up to 60 MeV. ORELA is a four-section radiofrequency electron linear accelerator with a water-cooled tantalum neutron production target. Short (2-30 ns) electron burst widths together with available long flight paths lead to excellent time-of-flight resolution. The electron beam energy can range up to 180 MeV and at 50 kW of beam power yields a neutron production rate 10¹⁴ n/s. We report on recent refurbishment activities that included improvements to the accelerator vacuum and electron gun design and other upgrades. The current ORELA program is focused on high-resolution neutron cross-section measurements for the Nuclear Criticality Safety Program for nuclides for which deficiencies in existing data have been identified. Additionally neutron cross-section measurements for nuclear astrophysics are performed to support studies of heavy element synthesis in Asymptotic Giant Branch stars. Detection and data analysis capabilities have been developed for making highly accurate measurements of neutron capture, neutron total, and (n,α) cross sections simultaneously on different beam lines.