The PILATUS 1M detector

Abstract

The PILATUS 1M detector is a hybrid pixel array detector with over one million pixels that operate in single photon counting mode. The detector, designed for macromolecular crystallography, is the largest pixel array detector currently in use at a synchrotron. It is a modular system consisting of 18 multichip modules covering an area of 21 cm x 24 cm. The design of the components as well as the manufacturing of the detector including the bump-bonding was performed at the Paul Scherrer Institute (PSI). The use of a single photon counting detector for protein crystallography requires detailed studies of the charge collection properties of the silicon sensor. The 18 modules are read out in parallel, leading to a full frame readout-time of 6.7 ms. This allows crystallographic data to be acquired in fine-varphi-slicing mode with continuous rotation of the sample. The detector was tested in several experiments at the protein crystallography beamline X06SA at the Swiss Light Source at PSI. Data were collected both in conventional oscillation mode using the shutter, as well as in a fine-varphi-slicing mode. After applying all the necessary corrections to data from a thaumatin crystal, the processing of the conventional data led to satisfactory merging R-factors of the order of 8.5%. This allows, for the first time, determination of a refined electron density map of a macromolecular biological crystal using a silicon pixel detector.

Quantitative biological imaging by ptychographic x-ray diffraction microscopy

“…Freeze-dried, unstained cells of the bacterium D. radiodurans were mounted onto a thin Kapton film placed 1.4 mm downstream of the pinhole. The diffracted intensity was measured at a distance of 7.22 m from the sample by using a single-photon counting PILATUS 2M array with a pixel size of 172 μm (25). An optical microscope allowing for an accurate and parallax-free positioning control was placed a few centimenters upstream of the pinhole.…”

Protein structure determination by electron diffraction using a single three-dimensional nanocrystal

“…It is possible that data from micrometresized crystals may also be measured more accurately, although it needs to be investigated further whether data accuracy is limited by detector sensitivity or the amount of dynamical diffraction for such crystals. The introduction of hybrid pixel detectors has had a major positive impact on protein X-ray crystallography owing to their high speed, increased sensitivity and high dynamic range (Broennimann et al, 2006). Based on the results that we present here, we suggest that specialized hybrid pixel detectors may have a similar impact on electron diffraction studies of protein crystals.…”

In-vacuum long-wavelength macromolecular crystallography

“…Performing the experiments in vacuum eliminates scattering from the air path to the crystal between the crystal and the beamstop, as demonstrated by Perutz in 1946 on dried protein crystals at room temperature (Perutz & Rogers, 1946). The invacuum sample environment, in combination with the singlephoton-counting detector technology (Broennimann et al, 2006), reduces the measured background to X-rays scattered only from the crystal and its mount. The optical design of the beamline provides a homogeneous beam illuminating the complete crystal volume and mount.…”

“…Only recently have several challenging crystal structures been determined employing multi-crystal averaging El Omari et al, 2014) and low-dose experiments in multiple orientations from only one crystal (Weinert et al, 2015). Aside from continuous successful efforts to reduce instrument errors introduced by the beamline hardware, the main contributing factors to these recent breakthroughs have been the introduction of pixel-array detectors (Broennimann et al, 2006) and improved software for data processing and structure solution (Kabsch, 2010;Sheldrick, 2010;Adams et al, 2010).…”