Dear All,
one more word on the reactor TOF, although by now the x-ray people will
probably be bored to death. There is no question that conventional
focussing optics (focussing monochromators) give at least one order of
magnitude more flux on the sample than TOF optics (chopper + guide),
everything else being equal. However TOF machines have been able to more
than compensate for this with much larger detector solid angles, so sample
are the same size at pulsed sources and they could be the same size at
reactor TOF instruments as well. Building large solid-angle detectors at
steady-state sources is a technical challenge which has not been completely
solved. At the workshop, Alan argued that this is purely a question of
funding, and this may be so. Nevertheless, the fact remains that
wavelength-dispersive diffraction has some distinct advantages for some (not
all) applications (very high pressure, high-resolution backscattering,
etc.), and that a truly innovative and *fast* TOF reactor-based machine can
now be built with a "realistic" budget. Not convinced? Why not fund some
Monte Carlo development? That's not very expensive.
Beside all the other arguments, this will have the merit of contributing to
the evolution of TOF neutron diffraction, which, in all likelihood, is all
we will get with the new-generation high-flux sources.
Paolo
Dr. Paolo G. Radaelli
ISIS Facility
Rutherford Appleton Laboratory, Bldg. R3
Chilton, Didcot
Oxon. OX11 0QX
United Kingdom
Phone : (+44) 1235-44 5685
FAX : (+44) 1235-44 5642
e-mail: [EMAIL PROTECTED]
[EMAIL PROTECTED]
