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Silicon Lithium Si(Li) Detectors for X-ray Spectroscopy

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 Si(Li) Detectors for X-ray Spectroscopy


  • 2-5 mm thick detectors providing better stopping power for high-energy X-rays compared to SDD's
  • Escape to full energy peak ratio 2-3 orders of magnitude higher compared to HPGe detectors


  • XRF, XRD
  • Synchrotron applications (EXAFS, XANES,…)
  • X-ray spectroscopy (e.g. EDS)
  • PIXE
  • Mossbauer spectroscopy
Silicon Lithium Si(Li) detectors for charged particle spectroscopy

Silicon Lithium Si(Li) detectors for charged particle spectroscopy


Wide range of detector sizes:

  • In standard – Active areas from 200 mm2 up to 1600 mm2 thickness 5 mm.
  • Upon request – Larger active areas (like 2000 mm2 circular) or thicknesses up to 10 mm.

Gold front entrance window – Nominal 2000 angstrom equivalent Silicon.

Lithium back contact:

  • Typically for LEC/LER energy detectors – 300 mm.
  • Typically for LTC/LTR transmission detectors – 50 mm.

Gold plated brass mounts:

  • Circular for LEC/LTC detectors.
  • Rectangular for LER/LTR detectors.
  • The standard dimensions are given below within the table.

In standard, with Microdot female connector located:

Axially (on the back of the detector) for LEC/LER detector type.

Radially (on the side of the detector) for LTC/LTR detector type.

Typical delivery 4-6 months for standard designs as given below within the table. All these detectors are built to order. Any special design on request.


  • Designed for highly penetrating charged particles
  • Up to 3 MeV Betas, 30 MeV protons, 140 MeV Alphas. More if detectors are stacked (LTC/LTR)
  • Wide range of active areas
  • Both circular and rectangular mount shapes available
  • Telescope arrangements with minimized thin Li back contact (LTC/LTR)

Lithium Drifted Silicon Detectors

Silicon Lithium Si(Li) Detectors for conversion electron Spectroscopy

Silicon Lithium Si(Li) Detectors for conversion electron Spectroscopy


CANBERRA offers highly-reliable Silicon Lithium drifted detectors, cooled at cryogenic temperatures, for X-ray or conversion electron spectroscopy or beta decay exploration. Two configurations are available depending on the application. The ESLB is delivered with all components required for integration into an existing vacuum chamber. The ESLB-X comes with a complete cryostat and user friendly features to create a common vacuum between the cryostat and the experiment chamber.

ESLB Detector

ESLB detector consists of:

  • Lithium drifted Silicon diode
  • Aluminum mount including the diode and the first stage of the charge sensitive preamplifier (input FET, feedback network)
  • Two feedthrough connectors (multipin and high voltage connectors)
  • Charge sensitive preamplifier Model PSC761R with a 3.5 meter cable set

The detector is to be mounted on the cold finger of the cryostat (16 mm diameter). The remaining part of the resistive preamplifier is mounted outside the experiment chamber.

NOTE: The cryostat is not included in ESLB detectors; please use ESLB-X type if a complete cryostat is required.

ESLB-X Detector

An ESLB-X is a complete detector system consisting of:

  • Lithium drifted Silicon diode
  • Flanged dipstick cryostat with horizontal output as a standard – additional cryostat configurations are available as an option
  • Flange on the cap enables a vacuum connection on the customer's vacuum chamber
  • The removable flange is equipped with a Be window for x-ray measurements
  • Charge-sensitive preamplifier with a cold input stage and resistive feed-back network – an alarm card drives the bias shut down signal in case of incorrect temperature
  • Set of cables (power supply – signal – high voltage)
  • VOP10 vacuum operator to enable easy access to the cryostat vacuum

The ESLB-X detector is a ESLB detector embedded in a dedicated cryostat.


  • Measurement of electrons from 20 keV to 3 MeV or x-rays up to 20 keV and even above with an increased detector thickness
  • Thin entrance window: gold front entrance window with nominal thikness of 2000 angstrom equivalent Silicon
  • Best performance through liquid nitrogen temperature operation
  • Storage at room temperature
  • Active thickness from 2 to 5 mm in standard and up to 10 mm on request
  • Beta resolution from 1.6 keV to 1.8 keV at 624 keV
  • Available with a cryostat as a turn key system (ESLB-X) or in kit form (ESLB)
  • Position sensitivity possible through segmentation (see ESLX-S & LTS sheet)

Silicium Lithium Si(Li) Detectors for conversion electron Spectroscopy

Silicium Lithium Si(Li) Detectors for conversion electron Spectroscopy

ESLB-X detector connected on a vacuum chamber. The ESLB-X is consisting of a portable slimline cryostat Big MAC type with a 7 liter Dewar.
By courtesy Dr. Wu – CIAE Beijing