  The properties expected of "hot" non-flaring plasmas due to nanoflare heating
in active regions are investigated using hydrodynamic modeling tools, including
a two-fluid development of the EBTEL code. Here we study a single nanoflare and
show that while simple models predict an emission measure distribution
extending well above 10 MK that is consistent with cooling by thermal
conduction, many other effects are likely to limit the existence and
detectability of such plasmas. These include: differential heating between
electrons and ions, ionization non-equilibrium and, for short nanoflares, the
time taken for the coronal density to increase. The most useful temperature
range to look for this plasma, often called the "smoking gun" of nanoflare
heating, lies between $10^{6.6}$ and $10^7$ K. Signatures of the actual heating
may be detectable in some instances.

Solar and Stellar Astrophysics