Abstract: A double crystal based moderate resolution small-angle neutron scattering instrument has been built and commissioned at the guide tube laboratory of Dhruva reactor, Bhabha Atomic Research Centre, Trombay, India. The instrument consists of a non-dispersive ( 1, −1) setting of 111 reflections of silicon single crystals with sample between the two crystals. The neutron wavelength used is 0.312 nm. The analyser crystal rotates with smallest step size of 0.0012°. At 65 MW of reactor power, the peak count rate of the blank rocking curve is about 55 counts per second at the detector position and the ratio of integrated signal to integrated noise is 450 for a typical experiment with sintered alumina. Experiments with sintered alumina specimens reveal that the accessible range of wave vector transfer q is 0.003–0.173 nm−1. The instrument is calibrated with respect to the high resolution ultra small-angle neutron scattering instrument S18 at the Institute Laue-Langevin in Grenoble, France.
