  We report on our investigations into density fluctuations in electron
bunches. Noise and density fluctuations in relativistic electron bunches,
accelerated in a linac, are of critical importance to various Coherent Electron
Cooling (CEC) [1-5] concepts as well as to free-electron lasers (FELs). For
CEC, the beam noise results in additional diffusion that counteracts cooling.
In SASE FELs, a micro-wave instability starts from the initial noise in the
beam and eventually leads to the beam microbunching yielding coherent
radiation, and the initial noise in the FEL bandwidth plays a useful role. In
seeded FELs, in contrast, such noise interferes with the seed signal, so that
reducing noise at the initial seed wavelength would lower the seed laser power
requirement [6-8]. Status of the project will be presented.
