New spallation neutron sources, their performance and applications

Pulsed spallation sources now operating in the world are at the KEK Laboratory in Japan (the KENS source), at Los Alamos National Laboratory (WNR) and at Argonne National Laboratory (IPNS), both the latter being in the USA. The Intense Pulsed Neutron Source (IPNS) is currently the world's most intense source with a peak neutron flux of 4x1014 n.cm-2.s-1 at a repetition rate of 30 Hz, and globally producing approx. 1.5x1015 n/s. Present pulsed sources are still relatively weak compared to their potential. In 1985 the Rutherford Spallation Neutron Source will come on line, and eventually be about 30 times more intense than the present IPNS. Later, in 1986 the WNR/PSR option at Los Alamos will make that facility of comparable intensity, while a subcritical fission 'booster' at IPNS will keep IPNS competitive. Those new sources will expand the applications of pulsed neutrons but are still based on accelerators built for other scientific purposes, usually nuclear or high-energy physics. Accelerator physicists are now designing machines expressly for spallation neutron research, and the proton currents attainable are in the milliamps range. (IPNS now runs at 0.5 GeV and 14 μA). Such design teams are at the KFA Laboratory Juelich, Argonne National Laboratory and KEK. Characteristics, particularly the different time structure of the pulses, of these new sources are discussed. Such machines will be expensive and require national, if not international, collaboration across a wide spectrum of scientific disciplines. The new opportunities for neutron research will, of course, be dramatic with these new sources. (author)