Sound amplification by stimulated emission of radiation implies that lasers should be as feasible with sound as they are with light. In the 21st century, it is easy to produce low frequency sound in the range that humans can hear (~20 kHz), in either a random or orderly form. However, at the terahertz frequencies in the regime of phonon laser applications, more difficulties arise. The problem stems from the fact that sound travels much slower than light. This means that the wavelength of sound is much shorter than light at a given frequency. Instead of resulting in orderly, coherent phonon laser structures that can produce terahertz sound,
Neutron stimulated emission computed tomography Neutron stimulated emission computed tomography Neutron stimulated emission computed tomography (NSECT) uses induced gamma emission through neutron inelastic scattering to generate images of the spatial distribution of elements in a sample. NSECT has been shown to be effective in detecting liver iron overload disorders and breast cancer. Due to its sensitivity in measuring elemental concentrations, NSECT is currently being developed for cancer staging, among other medical applications. A given atomic nucleus, defined by its proton and neutron numbers, is a quantized system with a set of characteristic higher energy levels that it can occupy as a nuclear isomer. When the