Can you tell me what units are used for radiation length in FairRadLenPoint?

When I do GetRadLength(), I get numbers up to 3000 * 10^(30)! I thought that units are cm instead of g/(cm^2), but even if I multiply it by density, which I get via GetDensity(), I get numbers up to 100*10^(15).

Thanks in advance.]]>

In case somebody else has such a problem:

Values of radiation length are in

One may need not the radiation length itself, but the

Thus, assuming you have your FairRadLenPoint

as RadLenP:

TVector3 PosIn=RadLenP->GetPosition();

TVector3 PosOut=RadLenP->GetPositionOut();

TVector3 InOut=PosOut-PosIn;

Double_t Distance=InOut.Mag();

Double_t RadLen=RadLenP->GetRadLength();

Double_t RadLenEffective=Distance/RadLen;

There is a detailed example:

materialana.C

And an example of simulation:

materialsim.C]]>

Usually, the radiation length is given in units of g/cm^2, so to arrive at the unit cm you would have to divide by the density in g/cm^3. It is unclear which value FairRadLenPoint::GetRadLength() returns. It would be nice if at least the unit of the return value could be specified in the class documentation.

Assuming the unit is cm, then what you calculate is the material budget along the trajectory step described by the FairRadLenPoint, in units of the radiation length of the material. Since this is a measure of the energy loss of electrons by Bremsstrahlung and also for multiple scattering, it makes sense tu sum up this value along the trajectory, even if different materials are involved.]]>