Added flexibility in triple axis spectrometers: the two RITAs at Riso

The cold-neutron triple-axis spectrometer RITA-I at Rise has been operation al for about three years, and in the near future an improved version, RITA- 2 will replace the existing triple-axis instrument TAS7. We review the perf ormance of RITA-1 and the operation modes of its flexible secondary spectro meter, giving examples of a few key experiments, and describe the software developed for running it. Further, the design of the new RITA-2 instrument is presented. The two RITA spectrometers are compared with their sister ins trument SPINS at NIST and with similar instruments planned elsewhere. (C) 2 000 Elsevier Science B.V. All rights reserved.