If the kinetic energy of the atoms in the region of dense collisions is recalculated into temperature (using the basic equation E = 3/2·N·k B T), one finds that the kinetic energy in units of temperature is initially of the order of 10,000 K. Because of this, the region can be considered to be very hot, and is therefore called a heat spike or thermal spike (the two terms are usually considered to be equivalent). The heat spike cools down to the ambient temperature in 1–100 ps, so the "temperature" here does not correspond to thermodynamic equilibrium temperature. However, it has been shown that after about 3 lattice vibrations, the kinetic energy distribution of the atoms in a heat spike has the Maxwell–Boltzmann distribution, making the use of the concept of temperature somewhat justified. Moreover, experiments have shown that a heat spike can induce a phase transition which is known to require a very high temperature, showing that the concept of a (non-equilibrium) temperature is indeed useful in describing collision cascades.