feat: polish CSV header format with improved metadata and column naming

beta_spectrum/spectrum.py

@@ -15,6 +15,7 @@ from beta_spectrum.components.screening import ScreeningCorrection
 from beta_spectrum.components.exchange import ExchangeCorrection
 from beta_spectrum.components.radiative import RadiativeCorrection
 from beta_spectrum.utils import T_to_W
+from beta_spectrum.constants import ME_MEV
 
 
 @dataclass
@@ -250,11 +251,13 @@ class BetaSpectrum:
         W0 = float(T_to_W(config.endpoint_MeV))
 
         if config.use_phase_space:
+            # Convert neutrino mass from MeV to natural units
+            m_nu_natural = config.neutrino_mass_MeV / ME_MEV
             components.append(
                 PhaseSpace(
                     W0=W0,
                     transition_type=config.transition_type,
-                    m_nu=config.neutrino_mass_MeV,
+                    m_nu=m_nu_natural,
                     logger=logger,
                 )
             )