Taking a Single Frame
From marccd GUI select 'Acquire'
menu and then Single Frame.
A new window will appear:
On this window the user can select:
- The exposure time or dose. Use the mouse to choose either time (in seconds) or dose (in KHz) for the unit to define the exposure per rotation angle. Experience so far indicated that exposures longer that a minute are rarely needed.
- Scan widt17/02/06ong>Multiread. This is used to remove "zingers" (cosmic rays causing spots on the frames that are not diffraction spots from the crystals). The number of sections are typed into the box to the right of this button. This option is usually desired for long exposure times (over 4 minutes).
- Starting phi value
(the current value will picked up by pressing the
button) - 2-Theta value
(the current value will picked up by pressing the button)
- Crystal to detector
distance (the current value will picked up by pressing the button)
- Root Filename. The typical format is anything_###.img where the hashes '###' are filled with the image number.
- Next Frame Number. The first frame is usually 1 and then it increments itself.
- Acquire Background. A background image is always subtracted from the collected data frame. If this button in clicked to show a check mark, a new background image will be collected prior to the exposure. If no current background image is available, one will be collected, no matter how this button is set.
- Disk Directory. This button should be ticked, and then the path for the directory to write data frames should be typed into the box. Alternatively the left mouse button can be used to select the proper directory via the browse feature.
- Archive Command. If the data is not to be processed soon, or to be stored for transport, this button can be clicked to show a tick, and an archive command can be typed into the adjacent box. Use the left mouse button can be used to select the proper directory via the browse feature. An example archive command would be tar ...
- Auto Save. Given the option, the user should be click this button to show a checkmark, since there is ususally no reason to collect a frame but not save the data. The data file will be written to disk, they are flat-field and spatially corrected and the background subtracted. They can generally read by any popular software.
If in doubt call your station scientist.
