Extend MCC to accurately treat relativistic particles (#3118)

* initial commit for MCC to support relativistic particles

* proper calculation of collision energy when target mass is not much greater than projectile mass

* fix bug with scattered velocity rotation to lab frame

* refactor the MCC sequence for clarity

* use cross-section input to determine energy limits when calculating the maximum collision frequency

* code cleanup

* updated CI tests

* added Collisions section to Implementation Details in docs

* reset benchmark for mixed precision MCC test and other more code cleanup

* fix issue with single precision and simplified implementation

* use `double` for particle mass and energy calculations in MCC

* added comment to ImpactIonization.H explaining why `double`s are used for `energy` and `mass`

* switch to round off safe version of energy calculation and switched to using u instead of v for gamma*v in ParticleUtils.H

* update documentation

* simplified expression for collision energy, updated docs

* Add comment that the direct solver can be replaced for the MLMG solver once the issue with that solver is fixed (in the 1d MCC test)

1 files changed, 0 insertions, 4 deletions

diff --git a/Source/Particles/Collision/BackgroundMCC/MCCProcess.cpp b/Source/Particles/Collision/BackgroundMCC/MCCProcess.cpp
index 4fa0bc744..b9e6f12e6 100644
--- a/Source/Particles/Collision/BackgroundMCC/MCCProcess.cpp
+++ b/Source/Particles/Collision/BackgroundMCC/MCCProcess.cpp
@@ -14,10 +14,6 @@ MCCProcess::MCCProcess (
                         const std::string& cross_section_file,
                         const amrex::Real energy )
 {
-    amrex::Print() << Utils::TextMsg::Info(
-        "Reading file " + cross_section_file + " for "
-        + scattering_process + " scattering cross-sections.");
-
     // read the cross-section data file into memory
     readCrossSectionFile(cross_section_file, m_energies, m_sigmas_h);