Reflex diode Bremsstrahlung improvement for SYRINX project

Abstract

In the Bremsstrahlung field, the Reflex diode principle is a good way to increase the efficiency of low energy photons (<50 keV) compared with a thick converter. To reach their goal, the authors use both numerical and experimental simulations. Their work conditions are low accelerating voltage domain (200 kV on average) and a diode with a thin gold foil and two cathodes which allow an improvement of the component of soft transmitted X-rays while working in a backscattered geometry. The interest in a gold converter is the possibility to obtain easily a thin foil material with high atomic number. In order to define the optimal converter thickness, giving the best fit between production and attenuation of X-rays, some Monte Carlo simulations have been carried out. The code used was specially improved to take the reflex effect and fluorescence X-rays into account. Some simulations with a PIC code allow one to design the diode geometry and verify the reflex effect across thin foils. The geometry defined for the Reflex diode includes two cathodes, which also allows a doubling of the current for the same anode surface. These previous computations concerning geometry and anode thickness permit one to prepare experiments with a view to optimize this Bremsstrahlung source-type for the SYRINX project. The photonic spectrum, voltage and diode current were measured for each shot in order to compare them with various simulations. The authors are confident in the first results to increase the total fluence.