Beta Spectroscopy: Silicon Lithium Si(Li) Detectors
Silicon Lithium Si(Li) Detectors for X-ray Spectroscopy
Silicon Lithium X-Ray Detectors are the heart of solid state x-ray spectroscopy systems. These detectors, which are p-i-n devices formed by lithium compensation or drifting of p-type silicon, are the result of some of the most carefully controlled manufacturing processes in existence. These detectors are fabricated to exacting quality standards, which is essential in ensuring a product of high performance and excellent long term reliability.
The Si(Li) x-ray detector is an integral part of a detector system which includes a liquid nitrogen cryostat and a low noise Integrated Transistor Reset Preamplifier (I-TRP).
These detectors certainly have a place in the market for x-ray applications next to Silicon Drifted Detectors (SDD's), such as our X-PIPS™, and low-energy germanium detectors (LEGe's and Ultra-LEGe's). Si(Li) detectors can be made with thicknesses up to 5 mm, which means they have a much higher stopping power than SDD's (max. 500 µm) and can be used up to higher energy x-rays (see graph below). Compared to germanium, however, silicon has a lower stopping power for the same detector thickness. But the big advantage of silicon is that it has characteristic x-rays at much lower energies (around 1.7 keV) compared to germanium (10-11 keV). Therefore the generated x-rays are less likely to escape the detector volume, which makes the escape peak less prominent. This means the ratio of the full energy peak to the escape peak is 2-3 orders of magnitude higher for a Si(Li) detector compared to a HPGe detector. Additionally the germanium x-rays lie around 10 -11 keV, which is right in the region of interest for some experiments or applications. The absorption edges of germanium in the region of interest complicate the spectrum and the analysis.
Silicon Lithium (SiLi) Detectors for Charged Particles
Wide range of detector size: active areas from 200 mm² up to 1600 mm2; thickness 2 mm and 5 mm. Other dimension are available on request. Gold entrance window 0.2 μm equivalent silicon. Lithium back contact 300 μm (50 μm for transmission option). Circular or rectangular gold plated brass mounts. Microdot female connector. The detectors can be operated either under vacuum or atmospheric pressure. They must be used in darkness. Maximum count rate 100 k count per sec at 524 keV electrons