When an accelerating detector moves through empty space it will detect a gas of particle with a temperature linear in the acceleration. The acceleration can be easily estimated from dimensional analysis. Since this is a quantum effect, the relevant constants are Planck's constant $ h $ and the speed of light $ c $. In order to convert energy to temperature we also need the Boltzmann constant $ k $. The relation between the acceleration $ a $ and the temperature $ T \, $ is, up to a numerical constant,

$ k T = h \frac{a}{c} $

The acceleration that corresponds to 1 kelvin is 6e18 m/s^2