Information for the Limited Availability, General User Call (2021-09-14):
CoSAXS is a hard X-ray SAXS/WAXS beamline on the 3 GeV ring at MAX IV. In autumn 2019, the commissioning of the beamline optics was started. During spring 2020, the beamline installation has been completed and full commissioning begun. The photon energy available at CoSAXS during commissioning and general user experiments from autumn 2020 will be limited to 12.4 keV, with an accessible q-range from between 1×10-3 to 0.5 Å-1. Most sample environments will be in air.
A call has been opened for general users, however, there will be limited time available due to the continued commissioning of CoSAXS. Details of what will be offered in the call are below. Due to the high brilliance of CoSAXS, many samples will need to be under flow or move to avoid radiation damage. Please consider pre-characterisation of all samples, their stability and sensitivity to radiation damage, where appropriate.
Basic SAXS sample environment for liquids and solid samples (room temperature)
Autoloader and flow through capillary cell for solutions
BioSAXS with HPLC
Laser triggered, temperature jump time-resolved SAXS (2 ms time-resolution), at 12.4 keV, q-range 1×10-3 to 0.5 Å-1 and ca. 1.5 to 2.3 Å-1. Laser system: Fiber coupled (200 µm diameter fiber), 50 W, 1470 nm CW laser gated by TTL pulse to achieve pulse lengths down to 1 ms.
Multiple sample holders for either capillaries or solid samples, with thermostatic water bath
Linkam heating stage HFS-X350 for capillaries, with liquid nitrogen cooling pump LNP96, temperature range -195 to 350 oC
For further information on Sample Environment see here
- Fixed energy of 12.4 keV (DCM Si111).
- SAXS detector is the Eiger2 4M.
- Q-range will cover 1×10-3 to 0.5 Å-1 (requiring multiple detector positions).
- Most sample environments will be at ambient pressure.
- No gas handling will be available at the sample position.
Information for Users: Data Access
Data from CoSAXS is stored centrally at MAX IV and is available for further processing using MAX IV resources – or for download using either the Globus connect service or sftp. Detailed information about downloading the data can be found here: Data access
It is possible to access MAX IV computing resources by setting up a VPN connection to MAX IV. Instructions can be found here: VPN connection to MAX IV
File location and structure:
All scans at CoSAXS result in a number of files written in the HDF5 format (*.h5). The files are written to be NeXuS compatible.
The raw files are stored in /data/visitors/cosaxs/#Proposal/#Visit/raw/ while reduced files are stored in /data/visitors/cosaxs/#Proposal/#Visit/process/.
Each scan will be saved with the name scan-####.h5 where #### is a sequential number. It is important to keep track of this number and the corresponding sample/experiment, e.g. by using the elogy logbook (https://elogy.maxiv.lu.se). The scan-####.h5 file is a master file that contains the command issued to perform the scan, the scanned parameters (e.g. motor positions), experimental channels (e.g. beam intensity, position, temperature) a snapshot of the instrument at the beginning of the scan and links to the detector datafiles. The data from the detectors are located in separate files, e.g. scan-####_eiger.h5 and scan-####_pilatus.h5. The link from the master file to the detector data is relative, and thus all files must be located in the same folder.
To visualize the data and the file structure we recommend to use silx view (http://www.silx.org/doc/silx/latest/install.html) which is available on the control computers. As the area detector data is compressed using a bit-shuffle algorithm, it is necessary to install hdf5plugin (https://pypi.org/project/hdf5plugin/).