RESUMEN
Hybrid pixel detectors have become indispensable at synchrotron and X-ray free-electron laser facilities thanks to their large dynamic range, high frame rate, low noise, and large area. However, at energies below 3 keV, the detector performance is often limited because of the poor quantum efficiency of the sensor and the difficulty in achieving single-photon resolution due to the low signal-to-noise ratio. In this paper, we address the quantum efficiency of silicon sensors by refining the design of the entrance window, mainly by passivating the silicon surface and optimizing the dopant profile of the n+ region. We present the measurement of the quantum efficiency in the soft X-ray energy range for silicon sensors with several process variations in the fabrication of planar sensors with thin entrance windows. The quantum efficiency for 250 eV photons is increased from almost 0.5% for a standard sensor to up to 62% as a consequence of these developments, comparable to the quantum efficiency of backside-illuminated scientific CMOS sensors. Finally, we discuss the influence of the various process parameters on quantum efficiency and present a strategy for further improvement.
RESUMEN
Boron neutron capture therapy exploits 10B(n,α)7Li reactions for targeted tumor destruction. In this work, we aimed at developing a dose monitoring system based on the detection of 478 keV gamma rays emitted by the reactions, which is very challenging due to the severe background present. We investigated a compact gamma-ray detector with a pinhole collimator and shielding housing. Experimental nuclear reactor measurements involved varying boron concentrations and artificial shifts of the sources. The system successfully resolved the 478 keV photopeak and detected 1 cm lateral displacements, confirming its suitability for precise boron dose monitoring.