Calibrate

Brief Description

Command to perform wavelength calibration for triple axis instruments. Given the user's selection of the standard to be used, the calibration routine calculates the expected peak positions of the Bragg peaks from known d-spacings and the approximate wavelengths. The detector arm is then driven to each estimated position TwoTheta_i and the short scan is performed there to locate the Bragg peak. The system will determine the A4 offset and the wavelength correction based on the peak data set.

Full Command Path

Usage: Calibrate [std] [twotheta_lo] [twotheta_hi] -COLL [alpha_mi, alpha_mf, alpha_ai, eta_m] -STEPSIZE [s] -TIME [t] -ACCEPT -SIM [A2offset, A4offset]

Positional Arguments

[std] specifies calibration standard. The following standards are valid: AL203, CU, SIFILT, SILAM2.

[twotheta_lo] specifies the minimum value that A4 will be moved to during the scan. By default, twotheta_lo is equal to the A4 lower limit if it is greater than zero, zero otherwise.

[twotheta_hi] specifies the maximum value that A4 will be moved to during the scan. By default, twotheta_hi is equal to the A4 upper limit.

Keyword Arguments

-COLL [alpha_mi, alpha_mf, alpha_ai, eta_m] specifies working monochromator incident, monochromator final, analyzer incident collimations and monochromator mosaic, resprectively.

-STEPSIZE [s] provides an A4 step size. If this parameter is not specified by the user, the system uses Cooper-Nathans resolution function to automatically estimate the step size at each TwoTheta_i such that there will be at least five points traversing the peak. (Optional)

-TIME [t] specifies a count time. [t] must be an integer. By default, the value of t=1 is used. (Optional)

-ACCEPT ensures that adjustments of the current scattering angle and the current wavelength are applied to the instrument. (Optional)

-SIM [A2offset, A4offset] creates fake data for testing using the A2offset and A4offset simulation offsets.