The high‐intensity option of the SANS diffractometer KWS‐2 at JCNS – characterization and performance of the new multi‐megahertz detection system. Issue 2 (30th March 2018)

• Record Type: Journal Article
• Authors: Houston, Judith Elizabeth; Brandl, Georg; Drochner, Matthias; Kemmerling, Günter; Engels, Ralf; Papagiannopoulos, Aristeidis; Sarter, Mona; Stadler, Andreas; Radulescu, Aurel
• Is Part Of: Journal of applied crystallography. Volume 51:Issue 2(2018)
• Page Start: 323
• Page End: 336
• Publication Date: 2018-03-30
• Subjects: small‐angle neutron scattering (SANS) -- neutron detectors -- mesoscale structures -- event‐mode capability; Crystallography -- Periodicals; 548.05
• DOI: 10.1107/S1600576718004132
• Languages: English
• ISSNs: 0021-8898

Abstract

Abstract : A new detection system based on an array of 3 He tubes and innovative fast detection electronics has been installed on the small‐angle neutron scattering (SANS) diffractometer KWS‐2 at the Jülich Centre for Neutron Science (JCNS), Germany. The high counting rates that can be detected and the event‐mode capability will enable new scientific opportunities in the field of structural investigation of small soft‐matter and biological systems. Abstract : A new detection system based on an array of 3 He tubes and innovative fast detection electronics has been installed on the high‐intensity small‐angle neutron scattering (SANS) diffractometer KWS‐2 operated by the Jülich Centre for Neutron Science (JCNS) at the Heinz Meier‐Leibnitz Zentrum in Garching, Germany. The new detection system is composed of 18 eight‐pack modules of 3 He tubes that work independently of one another (each unit has its own processor and electronics). To improve the read‐out characteristics and reduce the noise, the detection electronics are mounted in a closed case on the rear of the 3 He tubes' frame. The tubes' efficiency is about 85% (for λ = 5 Å) and the resolution slightly better than 8 mm. The new detection system is characterized by a dead‐time constant of 3.3 µs per tube and an overall count rate as high as 6 MHz at 10% dead‐time loss. Compared with the old detector this is an improvement by a factor of 60. The much higher count rate will shorten the measurement times and thus increase the number of experiments possible in a given time period by the optimal use of the high flux of up to 2 × 10 8 n cm −2 s −1 at the sample position. Combined with the event‐mode operation capability, this will enable new scientific opportunities in the field of structural investigations of small soft‐matter and biological systems. The implementation of the detector in the high‐intensity concept on KWS‐2, its characterization and its performance based on test experiments are reported in this paper.