The ORELA is a powerful electron accelerator-based neutron source located in the Physics Division of Oak Ridge National Laboratory. It produces intense, nanosecond bursts of neutrons, each burst containing neutrons with energies from 10e-03 to 10e08 eV. ORELA is operated about 1200 hours per year and is an ORNL User Facility open to university, national laboratory and industrial scientists. The mission of ORELA has changed from a recent focus on applied research to nuclear astrophysics. This is an area in which ORELA has historically been very productive: most of the measurements of neutron capture cross sections necessary for understanding heavy element nucleosynthesis through the slow neutron capture process (s-process) have been made at ORELA.Click to enlarge!
Many types of neutron cross section measurements (total, capture, fission, elastic, scattering, and gamma ray and neutron production) can be made at this facility with extremely good energy resolution. The time-of-flight method is used to determine the energy of the interacting neutron. Detector calibrations and measurements of detector responses to neutrons are also performed, and with a flux peaked around 1 MeV neutron energy, ORELA is ideal for many types of radiation damage and activation studies.
The facility consists of a 180-MeV electron accelerator, neutron producing targets, buried and evacuated flight tubes up to 200 m long leading to underground detector locations, a wide variety of sophisticated detectors, and data acquisition and analysis systems. Neutrons are produced by bremsstrahlung from a tantalum radiator. Moderated or unmoderated neutrons are available, and further tailoring of the spectral shape is done with movable filters. Pulse widths from 4 - 30 nanoseconds are available at a repetition rates from 12 - 1000 pulses per second. There is one remaining facility in the world similar to ORELA, located in Belgium.
Electron energy 180 MeV maximum Peak Current 20 amps maximum Power on target 60 kW maximum Electron beam diameter 1 cm Neutron targets Ta with H2O moderator Be block (En > 1 MeV) Neutron production 10e11 neutrons/pulse (Ta target) 10e14 n/sec at 50 kW 5 X 10e18 n/sec (peak) Neutron spectrum 4 X 10e13 n/MeV/sec at 1 MeV (Ta target) 4 X 10e10 n/MeV/sec at 14 MeV Number of flight paths 10 Number of flight stations 18 Flight path lengths 9 to 200 mFor more information, contact
P. E. Koehler
Bldg 6010, MS-6354
Oak Ridge National Laboratory
Oak Ridge, TN 37831-6354
Phone: (865) 574-6133
FAX: (865) 576-8746