Forgot Password | New Account

Reflectometer D17

D17 is the first ILL dedicated reflectometer and it has been designed to be as flexible as possible in resolution and modes of operation. The instrument is suitable for the analysis of surface structures in solids and solid/liquid interfaces. Horizontal surface experiments, such as free liquids, will suffer from a severe restriction in Q-range and flux and are thus not recommended for this instrument.

Back to ILL Homepage
www > Instruments & Support > Instruments & groups > D17 > Documentation > D17 LAMP Book > COSMOS > Data Table

D17 LAMP Book

The Data Table is a spreadsheet-like interface that allows you to enter the relevant file names and to force certain calculation constraints on COSMOS.

Each row corresponds to a separate reflectivity calculation.

The Direct columns are for the main beam measurements. 

You can put multiple file numbers in here,

     separate consecutive files by ','                    (e.g. 12345,12347 will load 12345, 12346 and 12347)

     separate non-consecutive files by a '+'.       (e.g. 12345+12347 will load 12345 and 12347)

The Reflect columns are for the file numbers referring to the reflected beams.  The post scripts '1' and '2' must correspond to the appropriate Direct post scripts.

You can put multiple file numbers in here,

     separate consecutive files by ','                    (e.g. 12345,12347 will load 12345, 12346 and 12347)

     separate non-consecutive files by a '+'.       (e.g. 12345+12347 will load 12345 and 12347)


The Normalise column can contain a constant, which will be used to multiply the calculated reflectivity. 

This is useful if the sample is over-illuminated, in which case the reflectivity below the critical edge will be less than unity.

The Factor column can contain a constant, which is a relative scale factor between the first and second angles.

Because the oscillating slit is often used to measure the main beam at the second angle position, the calculated second angle reflectivity will be larger than reality.  COSMOS will calculate a scale factor based on the reflectivities that overlap between the first and the second angles, however you can use this column to force the scale factor if you wish.

The Theta columns allow you to force the incident angles for the calculations of Q for the reflectivity.

You can enter a number here, or you can insert 'san' (where COSMOS takes the sample angle value from the data file), or 'dan' (where COSMOS calculates the value of theta based on the position of the reflected beam on the detector). 

Probably the best thing to insert here is 'dan'.

The Out File column allows you to specify a name for the output data.

If nothing is chosen, the output will be saved under a name using the  first run number in column 'Reflect 1'.

The Out LAMP column allows you to choose a LAMP workspace to output and view the calculated reflectivity.