The Geel electron linear accelerator GELINA

The Geel Electron Linear Accelerator (GELINA) is a 150 MeV pulsed-beam electron accelerator in combination with a metallic uranium target, serving as a neutron source for time-of-flight measurements. The facility is one of the most powerful white spectrum neutron sources available in the world, especially designed for high-resolution neutron cross-section measurements. The accelerator consists of three S-band accelerator sections operating at 3 GHz. The first section is a standing-wave buncher, while the two other sections are of the travelling-wave type. The electron source is a Pierce-type thermionic gun. The RF power is produced with three pulsed klystrons, powered with pulse-line type modulators. The facility has been designed for maximum peak currents in very short pulses. A pulse length between 10 ns and 2 ps at repetition rates between 1 and 800 Hz may be selected. Using a unique post acceleration pulse-compression system, electron pulses with a 10 ns width can be further reduced to approx. 1 ns (FWHM) with peak currents up to 100 A. Accelerated electrons produce Bremsstrahlung in a uranium target which in turn, by photo-nuclear reactions, produces neutrons. Within a 1 ns pulse a peak neutron production of up to 4.3 χ 10¹⁰ neutrons is achieved (average flux of 3.4 χ 10¹³ neutrons/s at 800 Hz). The neutron energy ranges from sub-thermal to about 20 MeV. Neutron time-of-flight measurements can be carried out simultaneously at 12 flight-paths with lengths between 8 m and 400 m. The facility is operated on a continuous 24 h shift from Monday morning to Friday.