Multilayer Surface Detector for Ultracold Neutrons (UCN)

A multilayer surface detector for Ultracold Neutrons was created for measurements to determine neutron lifespan. This is a multilayer solid state detector which relies on a topmost Boron-10 layer to capture ultra cold neutrons. The ZnS:Ag layer below detects neutron capture charge release and a photomultiplier detects the light generated by this neutron capture.

"The multilayer 10B surface detector for UCNs consists of a thin 10B top layer supported by a luminescent layer of ZnS:Ag. At least one of the charged particles α o 7Li generated from the neutron capture slows down or stops in the ZnS:Ag layer and emits light. A light-guide or a transparent window is used to transmit the light to a photomultiplier tube (PMT). A 10B thickness of 100 nm and a ZnS:Ag thickness of a few microns are sufficient." A Multilayer Surface Detector for Ultracold Neutrons (Link below)

Left: Boron-10 coated commercial silver-doped ZnS screens are used to capture ultracold neutrons directly; Right: A large area detector prototype is being examined in a light-tight box. An array of wavelength-shifting scintillator fibers is used to collect light from a 0.5 m by 0.3 m surface. (Department of Energy)