GIWAXS @ D-line: Procedures

Switch to Line-up Mode

• disable garage door (switch on garage door controller)
  
• disable ccd macros  >  ccdoff
• go into hutch, move CCD back, put ion chamber in, and change samples
  
• new data file  >  newfile
• open CCD shutter  >  shopen
• direct beam line-up
  
• switch video to sample position; the horizontal cross hair indicates the beam position at the sample
  
• move sample positions back  >  wsam; mv samth 0; mv samz 0; mv samx 0; mv samaz 0
• move beamstop out of the direct beam  >  wbs; mv bsx 2; mv bsz -1
• if there is no signal on Idet yet, move sample down 1 mm   >  mvr samz -1; wsam; wbs
  
• height line-up >  dscan samz -1 1 20 1; mv samz CEN
  
• make sample parallel to beam >  dscan samth -1 1 20 1; mv samth CEN
  
• redo height line-up  >  dscan samz -.5 .5 20 1; mv samz CEN
  
• reflectivity line-up 
  
• block direct beam  >  mv bsz 0.1
  
• find reflectivity  >  dscan samth -.5 .5 50 1; laser
  
• determine ZERO of samth from print-out  >  mv samth [ZERO]; set samth 0
• fine-tune sample height  >  mv samth 0.1; dscan samz -.3 .3 30 1; mv samz CEN
• measure specular reflectivity  >  ascan samth 0 1 100 1
• (optional: determine electronic offset of Idet  >  shclose; tseries 1 10; shopen)
• (optional: measure reflectivity between critical angles of film and substrate  >  ascan samth .1 .25 150 1)

Switch to CCD mode

• verify that rod beamstop is in the reflected beam  >  mv samth 0.1; mv bsx 0  >  Idet should read low
• remove blade  >  mv bsz -.5  >  Idet should still read low
  
• close shutter  >  shclose
• enable ccd macros  >  ccdon
• go into hutch and remove ion chamber
• switch video to detector camera
  
• enable and open garage door; watch on video
  
• take a test image for 0.1 sec  > corr 1 0.1
• check test image with fit2d; make sure that image is set to log scale and range 1 to 15,000 (z-scaling > user min/max)
  
• look for hot spots, in particular close to beam stop - use the zoom!
  
• if necessary, finetune beamstop position
  
• step of +/- 0.1 mm in bsx  >  mvr bsx 0.1  or mvr bsx -0.1
  
• take test images > corr 1 0.1
• take images at various incident angles and samx positions
• check out some characteristic points first (maximum of reflectivity, samx or samaz min & max)  >  corr 1 1
• determine at what exposure the most intense features will saturate - maximum CCD intensity before overexposure is 15,000
• check whether corresponding dark image exists  >  ls dark
• if not, create new dark image for exposure time EXPT by  >  dark [EXPT]
• take image with best exposure time EXPT  >  corr 2 [EXPT]
  

Set-up notes

• create a terminal; home directory is "/home/specuser"
• check that "images" directory is cleaned up  >  ls images
• make user directory [USER] from LINUX prompt  >  mkdir [USER]; mkdir [USER]/data
  
• goto the user directory  >  cd [USER]
• start SAXS version of SPEC  >  saxs
• create CCD image directories from within SPEC  >  ccdroot [USER]
• goto a new LINUX desk top, make a window, and goto the user image directory  >  cd [USER]/corr
• start fit2d* program  >  fit2d
• go back to SPEC desk top - you are ready to roll!