LAMBDA X-ray detectors

LAMBDA is a next-generation pixel detector for X-rays, based on Medipix3 technology. It is a photon-counting detector, making it effectively noise free, and it offers a high frame rate of up to 23,000 frames per second (with no readout deadtime) and a small pixel size of 55 µm. It is available in a wide variety of sizes and configurations for different applications, and can be equipped with different sensor materials to allow high detection efficiency even at high X-ray energies. The system also has “colour imaging” capabilities, where X-rays hitting the detector can be divided into two energy ranges. Developed by DESY for use at the PETRA-III synchrotron, the system is designed for high reliability, and has external triggering and gating capability for synchronisation with the rest of the experiment. It can be easily integrated into common beamline control systems.

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Technical data overview
Pixel size55 µm x 55 µm
NoisePhoton counting – noise free at 5 keV
Count rate (uncorrected)8 x 107 cts/mm²/s at 10% deviation from linear
Count rate (corrected)up to 2.5 x 108 cts/mm²/s
External trigger3.3 V TTL
Software interfaceSDK for C++ and Python, Tango and EPICS drivers available
Operating modes
Image depthFramerateReadout dead time
1 bit (1 photon)23,000 fps0
6 bit (63 photons)4,000 fps0
12 bit (4095 photons)2,000 fps0
24 bit (16,777,215 photons)up to 1,000 fps1 ms

Detector sizes

We offer a range of detector sizes, ranging from 256 by 256 pixels to up to 10 megapixels area. The systems are designed to be compact and lightweight – for example, the LAMBDA 750k weighs approximately 2 kg. As well as our standard systems listed below, larger systems (above 1 megapixel) can be custom-built with different geometries – for example, a long narrow detector, or a non-rectangular layout. In our new “Hydra” design, one or more compact sensors of 256 by 256 pixels are connected to the readout electronics by flexible cables. These sensors can be freely positioned, making them ideal for experiments with limited detector space, such as RIXS.

To reduce air scattering in experiments at lower X-ray energies, we also offer systems that can be operated in vacuum. The in-vacuum options are described in more detail on the AMBER product page.

SystemDetector pixelsSensor area
LAMBDA 60k256 x 25614 x 14 mm²
LAMBDA 250k512 x 51228 x 28 mm²
LAMBDA 350k512 x 76828 x 42 mm²
LAMBDA 750k512 x 153628 x 85 mm²
LAMBDA 2M1536 x 153685 x 85 mm²
LAMBDA 10M4608 x 2560260 x 175 mm²
HYDRA256 x 256 per sensor14 x 14 mm² per sensor

Sensor materials for hard X-ray detection

To allow efficient detection at different X-ray energies, LAMBDA systems are available with Silicon, Gallium Arsenide or Cadmium Telluride sensors. Detection efficiencies for these materials are shown in the graphics.

Colour imaging capability

The Medipix3 chip inside LAMBDA counts individual X-ray photons by comparing the signal pulses produced by photon hits to a user-defined threshold. This makes it possible to exclude lower-energy photons, for example unwanted fluorescence signal. Additionally, it can operate in a mode where two user-defined thresholds are used to divide photon hits into two energy ranges, in effect producing a “colour” image where each pixel records two colour channels. This can be used, for example, to distinguish different materials in X-ray imaging with a tube, or to exclude higher beam harmonics in synchrotron experiments.

Control PC and software

All LAMBDA systems are sold with a control PC with software installed. Different PC options are available, depending on your requirements.

The control software provides a range of options. There is a control library written in C++ which can be integrated into common beamline control systems. For example, open-source TANGO and EPICS drivers have been developed by users. There are a set of Python bindings, for convenient scripted operation of the detector. Finally, a GUI is provided for manual control.

To allow synchronisation with apparatuses such as motion stages or other detectors, there is an external trigger input which can be operated in a variety of modes. For example, this can be used to control when each image is taken, or be used as an electronic gate to switch the detector’s X-ray sensitivity on and off during image taking. The gating is sufficiently fast to select individual synchrotron X-ray bunches with 200ns spacing.

Applications

LAMBDA can be used for a wide range of X-ray scattering and imaging experiments, particularly where high speed and sensitivity are required. Here, you can find a few examples which highlight research done by our customers.

HYDRA: Flexible detector placement

The HYDRA design option to our LAMBDA detectors allows you to place several detector chips independently to acquire your images at different positions or at different angles in your experiment setup. An example of a shutter seen from different angles is shown in the video.

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