Design of the time-of-flight small-angle-neutron scattering instrument at CPHS

The time-of-flight (TOF) small-angle neutron scattering (SANS) di_ractometer is one of the first instruments to be built at the Compact Pulsed Hadron Source (CPHS) of Tsinghua University, China. This SANS project strives to serve two purposes: its instrumental design, fabrication and optimization will help glean valuable scientific and engineering experiences; and its utilization will help promote fruitful domestic user programs on research of large structures inadvanced materials using neutrons. The design draws experiences from other TOF SANS instruments, particularly that of the long-pulse LENS of Indiana University and also considers the space constraint at CPHS and the user priority in China. The collection of one data set covering a wide Q-range (∼6x10-3 < Q < 0:5 Å-1) with reasonable Q-resolution and e_ciency is achieved by making use of a broad wavelength bandwidth (2–10 Å) of neutrons within each time frame and a large area detector (1 x 1 m2). It also pays attention to possible use of optical devices such as focusing lenses and novel detectors.