New results with silicon pad detectors and low-noise electronics for absorption spectrometry

High-resistivity silicon diode detectors integrable in array structures have been tested for high-resolution X-ray spectroscopy at various temperatures. Using an inexpensive commercially available front-end transistor we have obtained resolutions of 19 electrons rms, or 165 eV FWHM, at −35°C and 39 electrons rms, or 320 eV FWHM, at 26°C, with 3 and 1 μs shaping times. The obtained resolution values are adequate for synchrotron light based EXAFS experiments. These reliable detectors can be suitably employed for high-performance multichannel systems in which high-rate capability is achieved by using an array of detectors operated in parallel. A 16-element detector prototype has been recently assembled, installed and successfully operated for a real EXAFS experiment at NSLS.