Neutron Optics Upgrades to the Residual Stress Diffractometer, KOWARI

Abstract

Abstract. In the last 5 years a number of significant enhancements have been implemented on the neutron beam strain scanner Kowari at the OPAL reactor in Sydney Australia. These changes have resulted in reduced beam time losses when conducting experiments due to sample and stage alignment, and optics and sample changes. There have been 3 projects, starting in 2011 with a new manual slit system design and collision recovery system, in 2013 with a series of radial collimators and finally with the delivery of a 6 axis robot capable of texture measurements and of running up to 20 samples automatically. IntroductionThe thermal neutron residual strain scanner, Kowari, has been operational since 2007. On the residual strain stress scanning instrument KOWARI the spatial resolution ranges from 0.2 to 1000 mm 3 . The resolution in lattice strain is of the order 0.01% giving a stress resolution in steels of ~ 20 MPa. The instrument has been operated accordingly to ISO/TS 21432-2005 to achieve reproducible and reliable stress measurements [1,2]. Initially sample alignment and changes to the neutron optics were both slow and ergonomically challenging.A project commenced in 2011 to design and manufacture a new neutron optics exchange system, to improve the slit system through improved collision protection and appature control and to allow much faster change over between configurations of the neutron optics (currently, three options are available: slit system, radial collimator, open detector). The new system allows for rectangular gauge volumes of quite a large size range, and has extended toolkit for accurate alignment and built-in anticollision system. After a successfully series of tests with collimators borrowed from the JRR-3M reactor a project commenced in 2013 to design and purchase a series of collimators.Texture measurements have been undertaken for many years using a standard Euler cradle. Sample changes were thus manually made every 4-8 hours depending on sample and conditions. To increase productivity and lower exposures for users a 6 axis robotic sample changer began operating on KOWARI in 2015 which allows automated testing of 20 (in some cases more) samples.