A description is given of the pile oscillators at DR1 (a homogeneous reactor), together with the results of some measurements performed. Two types of oscillators are in current use: a global and a local oscillator. The global oscillator is used in two positions; in the centre and at the edge of the core, in order to be able to separate the absorbing and the scattering properties of a given sample. The local oscillator is situated in the reflector of the reactor, and utilizes an annular boron-coated ionization chamber made at Risø, The main parameters of the oscillators are: A square wave movement of 70 cm stroke and 30 seconds period with a transfer time of 0.5 second. A flux of some 108 n/cm2/sec at a power of 13 w. These conditions give the least noise, corresponding to the signal from 0.03 mm absorber material (0.01 mg boron). The ratio between absorption and moderation signals is 6,3 in the core centre and 14.5 in the local oscillator. The Epithermal index r is 0.1 at the core centre and 0.05 at the local oscilliator.
|Series||Denmark. Forskningscenter Risoe. Risoe-R|