QtiSAS & QtiKWS

Vitaliy Pipich, 2020

Probably, small angle neutron scattering (SANS) is one of “easiest” neutron-related-method to understand technique and to interpret obtained results for a not experienced user: adjustable pinhole collimator, sample, and 2D-detector. The user could have the same illusion about SANS also after measurement and data reduction: if sample scatters well, instrument works stably, and number of instrument configurations is limited to one… But, in order to measure a sample in the full Q-range at a classical non-TOF SANS instrument, number of instrument configurations should be higher than three. This increases in geometrical progression number of calibration files; and data reduction becomes already really painful.

The aim of SANS data reduction interface “DAN-SANS” developed within the cross-compiled software package QtiSAS [ www.qtisas.com ] to keep “illusion of simplicity” for a starter and “filling of full control” for a guru of small angle scattering. “Illusion of simplicity” is saved by step-by-step definition of two script tables, namely a table of configurations and sample table. It allows proceeding of all measured datasets within “5 minutes principle”; re-treatment with changed parameters will take only few seconds.

Run-time creation/configuration of data-reduction-algorithm allows to an instrument responsible to optimize data treatment procedure correspondingly to the current status of the instrument or experiment and to control data output at every step. Extraction of needed parameters from files is controlled by universal header-reader tool. The header-reader could read free-format ASCII files with known position of parameters; find parameters by a key sequence; extract data from encoded-data-formats like XML and YAML. It allows integrating most of SANS instruments and data-treatment-procedure looks similar for all of them. “Instrument-free” approach means “independence” from data format; and “dependence” on algorithms of data treatment.

Now, this software package is standard data-reduction-tool for two classical SANS instruments KWS-1 and KWS-2 as well as for very-high resolution focusing SANS diffractometer KWS-3 of the Jülich Centre for Neutron Science (JCNS) at FRM2 reactor in Garching (Germany). Behind current version there are many years of intensive user- and instrument operation as well as source evolution.