1. Unit of physical quantities

The unit is based on SI. The following units are used internally and users will obtain outputs from COSMOS in those units in principle. It is also very important to note that all real variables are given in the double precision; users are recommended to output them in the single precision to save the disk space if necessary.

• Length : m.

• Energy : GeV. Note, however, users can specify the energy of primary particles in a variety of units, such as MeV, MeV/n, TeV etc., or in momentum.

• Magnetic field strength : Tesla. Note that 1 Gauss is \(10^{-4}\) T.

• Thickness of air : \(\mathrm{kg/m}^2\) . \(1\mathrm{g/cm}^2\) is \(10\mathrm{kg/m}^2\) ( \(1000\mathrm{g/cm}^2 = 10,000\mathrm{kg/m}^2\) ). The air density is in \(\mathrm{kg/m}^3\) .

• Time : sec. However, time in the chookObs routine is already converted to nsec. The default Cerenkov output contains time factor in (length in cm)/beta for saving output space.

• Angle : Angles in degree are used to specify the latitude and longitude of the observation place. The declination angle is also in degree.