B24 is the transmission cryo-soft X-ray tomography beamline at Diamond Light Source aiming to satisfy the growing need for biologically relevant X-ray tomography on unstained biological samples under near physiological conditions. The operational energy range for B24 is 200eV-2.6keV, which allows imaging via absorption contrast within the water window as well as phase contrast at higher energies.
Beamline acceptance: 2x2mrad
Energy range: 200eV-2600eV
Single torroidal focusing 1:1 magnification
Plain grating monochromator (2x VLS gratings, 1x plain mirror)
Absorption- and Phase-contrast modes
Resolving power > 1000
Beam size at sample: 20um
Photon flux: ~108 photons/um2
Time to collect single tomographic series < 5 mins
Detector: Direct detection CCD (Pixis)
B24 uses bending magnet radiation and comprises a horizontally deflection torroidal mirror (located within the synchrotron machine vault) which focuses and directs the beam through a Variable Line Spacing - Plain Grating Monochromator (VLS-PGM) to a focal point at the PGM's exit slits. Diagnostics after the exit slits allow the beam to be characterised before it enters the Endstation (a commercial in-vacuum cryo X-ray microscope). There, the beam is focused onto the sample by a single-bounce Capillary condenser, and the resulting image is refocused by a (40nm or 25nm) Zone Plate onto a direct detection CCD.
The Endstation, supplied by Xradia (now Zeiss), is designed to allow the colleection of 3D tomographic data on vitrified biological samples mounted on electron microscopy grods. An automated sample loading system allows up to four samples to be loaded into the chamber at a single time. Samples are maintained at cryo-temperatures throughout data collection.
Basic laboratory equipment
Zeiss Axioimager with Linkam cryostage for grid preliminary analysis and mapping (max resolution 50x, variable filters)
Leica EM GP plunge freezer
B24 has also invested in the development of a bespoke super resolution light microscope located at the beamline which will allow correlative light/X-ray microscopy (CLXM) techniques to be explored on site.
Diamond Light Source is the UK's national synchrotron science facility, located at the Harwell Science and Innovation Campus in Oxfordshire.
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