diff --git a/Framework/Particles/ParticleProperties.h b/Framework/Particles/ParticleProperties.h
index 2f5365eb0525183b2810da96e3c7b85fe9766570..7b2b6f7e5594efa6aa4c5014f002bcc78d328701 100644
--- a/Framework/Particles/ParticleProperties.h
+++ b/Framework/Particles/ParticleProperties.h
@@ -23,13 +23,12 @@
 #include <iosfwd>
 #include <type_traits>
 
-#include <corsika/units/PhysicalConstants.h>
 #include <corsika/units/PhysicalUnits.h>
 
 /**
  *
  * The properties of all elementary particles is stored here. The data
- * is taken from the Pythia ParticleData.xml file.
+ * are taken from the Pythia ParticleData.xml file.
  *
  */
 
diff --git a/Framework/Particles/testParticles.cc b/Framework/Particles/testParticles.cc
index 0603ea03575cb7668bed8e3e276b5c81f60e27c3..cba91b476f42e6ee540ebfbf64b5990c4e03ea81 100644
--- a/Framework/Particles/testParticles.cc
+++ b/Framework/Particles/testParticles.cc
@@ -34,6 +34,8 @@ TEST_CASE("ParticleProperties", "[Particles]") {
   SECTION("Masses") {
     REQUIRE(Electron::GetMass() / (511_keV) == Approx(1));
     REQUIRE(Electron::GetMass() / GetMass(Code::Electron) == Approx(1));
+    
+    REQUIRE((Proton::GetMass() + Neutron::GetMass()) / corsika::units::constants::nucleonMass == Approx(2));
   }
 
   SECTION("Charges") {
diff --git a/Framework/Units/PhysicalConstants.h b/Framework/Units/PhysicalConstants.h
index 38c59992fe928228754e3a16658043308e71ab68..1bf9872a03ed3abee9bcb03ef93fd24250f14a50 100644
--- a/Framework/Units/PhysicalConstants.h
+++ b/Framework/Units/PhysicalConstants.h
@@ -61,7 +61,9 @@ namespace corsika::units::constants {
 
   // unified atomic mass unit
   constexpr quantity<mass_d> u{Rep(1.6605402e-27L) * kilogram};
-
+  
+  auto constexpr nucleonMass = 0.5 * (0.93827 + 0.93957) * 1e9 * electronvolt;
+  
   // etc.
 
 } // namespace corsika::units::constants
diff --git a/Framework/Units/PhysicalUnits.h b/Framework/Units/PhysicalUnits.h
index 90b98e170f2a912018e1486cac26b7da1c85f3ff..af4dbb966aaaf5dfe5bfe7ace9619c9d299e94c7 100644
--- a/Framework/Units/PhysicalUnits.h
+++ b/Framework/Units/PhysicalUnits.h
@@ -18,28 +18,11 @@ namespace phys::units {
 /**
  * @file PhysicalUnits
  *
- * Add new units and types we need. Units are compile-time. We support
- * different system of units in parallel. Literals are used for
- * optimal coding style.
+ * Add new units and types we need. Units are compile-time. Literals are
+ * used for optimal coding style.
  *
  */
-/*
-namespace corsika::units::hep {
-  using namespace phys::units;
-  using namespace phys::units::literals;
-  using namespace phys::units::io;
-
-  /// defining HEP energy, mass, momentum
-  using energy_hep_d = phys::units::energy_d;
-  constexpr phys::units::quantity<energy_hep_d> GeV{corsika::units::constants::eV};
-  // corsika::units::constants::e / phys::units::coulomb * phys::units::joule };
-
-  using MassType = phys::units::quantity<energy_hep_d, double>;
-  using MomentumType = phys::units::quantity<energy_hep_d, double>;
-  using EnergyType = phys::units::quantity<energy_hep_d, double>;
 
-} // namespace corsika::units::hep
-*/
 namespace corsika::units::si {
   using namespace phys::units;
   using namespace phys::units::literals;