International Topical Meeting on Nuclear Research Applications and Utilization of Accelerators
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SM/EN-12 Operation of a Variable Energy RFQ Accelerator System to Produce Intense Beams of Neutrons for Cargo Interrogation C.B. Franklyn Necsa, Pretoria, South Africa Corresponding Author: chris.franklyn@necsa.co.za Two radio-frequency quadrupole (RFQ) linear accelerator systems have recently been commissioned at Necsa, near Pretoria, South Africa. These accelerator systems are unique in their design, construction and mode of operation. Although of different design, both accelerator systems can operate over the same energy range, but with different intensities and duty cycles. To extract a variable energy ion beam a system consists of two RFQ acceleration cavities, which operate at a selectable phase between one another, thus facilitating an acceleration or deceleration of the ion beam within the second cavity. Molecular hydrogen or atomic deuterium ions can be accelerated (1.9 to 2.5 MeV or 3.8 to 5.0 MeV respectively) and targets of deuterium gas or solid targets, such as a thin beryllium foil, have been used to generate a range of neutron distributions which, through appropriate selection criteria, can then be used to perform radiographic imaging of various objects. The primary focus of this work has been to set up a system producing intense (greater than ten to power ten neutrons per second) beams of neutrons of pre-determined energy and energy spread, to interrogate typical cargo containers for traces of illicit material and/or explosives. The methodology has been to develop a neutron radiography system that can be used to scan large volumes, such as cargo containers in a relatively short time span and provide an indication as to whether the contents tally with the cargo manifest. The current status of this project will be presented. |
