  The sensitivity of a THz hot-electron nanobolometer (nano-HEB) made from a
normal metal is analyzed. Johnson Noise Thermometry (JNT) is employed as a
readout technique. In contrast to its superconducting TES counterpart, the
normal-metal nano-HEB can operate at any cryogenic temperature depending on the
required radiation background limited Noise Equivalent Power (NEP). It does not
require bias lines; 100s of nano-HEBs can be read by a single low-noise X-band
amplifier via a filter bank channelizer. The modeling predicts that even with
the sensitivity penalty due to the amplifier noise, an NEP ~ 10$^{-20}$ -
10$^{-19}$ W/Hz$^{1/2}$ can be expected at 50-100 mK in 10-20 nm thin titanium
(Ti) normal metal HEBs with niobium (Nb) contacts. This NEP is fairly constant
over a range of readout frequencies ~ 10 GHz. Although materials with weaker
electron-phonon coupling (bismuth, graphene) do not improve the minimum
achievable NEP, they can be considered if a larger than 10 GHz readout
bandwidth is required.
