The back-scattering part (phase I) of the new incoherent inelastic neutron
spectrometer, TOSCA, replacing the old TFXA, has been successfully installe
d at the ISIS pulsed neutron spallation source. The results, owing to the m
uch larger detector area. show a significant enhancement of the counting ra
te and an improvement of the resolution. In spring 2000, the forward scatte
ring bank (phase II) will be completed and, during the final installation,
the whole instrument will be moved; from the present 12 m primary flight pa
th to 17 m. This will result in a large improvement of the overall resoluti
on (fram 2-3% to 1-1.5% of the energy transfer). A chopper will be added in
order to avoid neutron frame overlap and to reduce the fast neutron backgr
ound. In addition, TOSCA will have a diffraction capability. (C) 2000 Elsev
ier Science B.V. All rights reserved.