Update reference particle momentum

is beta*gamma

docs/source/dataanalysis/dataanalysis.rst

@@ -28,9 +28,9 @@ Reference particle:
 * ``y_ref`` vertical position y, in meters
 * ``z_ref`` longitudinal position z, in meters
 * ``t_ref`` clock time * c in meters
-* ``px_ref`` momentum in x, normalized to proper velocity :math:`p_x = \gamma v_x`
-* ``py_ref`` momentum in y, normalized to proper velocity :math:`p_y = \gamma v_y`
-* ``pz_ref`` momentum in z, normalized to proper velocity :math:`p_z = \gamma v_z`
+* ``px_ref`` momentum in x, normalized to mass*c :math:`p_x = \gamma \beta_x`
+* ``py_ref`` momentum in y, normalized to mass*c :math:`p_y = \gamma \beta_y`
+* ``pz_ref`` momentum in z, normalized to mass*c :math:`p_z = \gamma \beta_z`
 * ``pt_ref`` energy deviation, normalized by rest energy
 * ``mass`` reference rest mass, in kg
 * ``charge`` reference charge, in C

src/particles/ReferenceParticle.H

@@ -33,9 +33,9 @@ namespace impactx
         amrex::ParticleReal y = 0.0;  ///< vertical position y, in meters
         amrex::ParticleReal z = 0.0;  ///< longitudinal position z, in meters
         amrex::ParticleReal t = 0.0;  ///< clock time * c in meters
-        amrex::ParticleReal px = 0.0; ///< momentum in x, normalized to proper velocity
-        amrex::ParticleReal py = 0.0; ///< momentum in y, normalized to proper velocity
-        amrex::ParticleReal pz = 0.0; ///< momentum in z, normalized to proper velocity
+        amrex::ParticleReal px = 0.0; ///< momentum in x, normalized by mass*c
+        amrex::ParticleReal py = 0.0; ///< momentum in y, normalized by mass*c
+        amrex::ParticleReal pz = 0.0; ///< momentum in z, normalized by mass*c
         amrex::ParticleReal pt = 0.0; ///< energy deviation, normalized by rest energy
         amrex::ParticleReal mass = 0.0; ///< reference rest mass, in kg
         amrex::ParticleReal charge = 0.0; ///< reference charge, in C