in the same axis as the beam) is preferred whenever possible, as the characteristics are best (maximum energy and flux, minimal contribution of scattered neutrons, optimal homogeneity of the field on the detector's surface). This property is used to extend the energy domain of the available monoenergetic neutron fields: it is sufficient to place the detector to be calibrated at a given emission angle. The neutrons' energy also varies with their emission angle in relation to the direction of the ion beam. To generate neutrons with a specific energy, the energy of the ion beam is adjusted: a 15° bending magnet located after the source selects the type of ion - proton or deuteron - to be accelerated, and a 90° analysis magnet located at the accelerator's output defines the desired ion beam energy. Multiple target thicknesses are therefore used. The resolution of the monoenergetic peak depends mainly on the type and thickness of the deposit chosen for the target.
The energy of the neutrons emitted from the target depends not only on the type of particles used (protons or deuterons) and its energy, but also on the reaction used. stable nucleus formed of one proton and one neutron) and these now-positive ions are accelerated again by the same voltage. They are thereby transformed onto protons or deuterons (i.e. First, negatively-charged hydrogen and deuterium ions (H- and D-) are accelerated by a voltage until they reach the centre of the accelerator tube, where their charge is reversed by passing through a nitrogen flow, which strips two electrons from them. The ion beam hitting the target is achieved in two steps. The deposit is made of scandium, lithium, or titanium, with tritium or deuterium trapped inside. The accelerated ions interact with the target reactive layer nuclei, thereby producing neutrons. These particles are accelerated to a given energy and directed onto a target formed of a few microns thick reactive layer deposited on a metallic backing.
Monoenergetic neutrons are obtained using ion beams (protons or deuterons). Principle and description of the facility those that have a single energy (within a degree of uncertainty) this makes it easier to conduct tests and interpret them, and makes it possible to study the variation of an instrument's response with neutron energy.
perform various types of calibration on radiation protection instruments (routine calibration, calibration in "realistic" fields, determination of the energy variation with neutron energy).ĪMANDE is beneficial in that it provides monoenergetic neutron fields, i.e.in terms of the number of neutrons per surface area unit) or dose equivalents references (ambient or personal) related to neutrons, define national fluence references (i.e.Through LMDN, IRSN is Designated Laboratory of the LNE (French National Metrology Institute), and in that context develops and operates facilities that produce neutron reference fields. testing and calibrating neutron sensitive devices at multiple specific energies over a broad range (between 2 keV and 20 MeV).ĪMANDE is one of the facilities of IRSN's Neutron Metrology and Dosimetry Laboratory (LMDN).metrology related to neutron fluence and dose equivalents quantities.
The AMANDE facility (AMANDE = "Accelerator for metrology and neutron applications for external dosimetry"), commissioned in 2005, produces monoenergetic neutron reference fields, with two objectives:
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