pp reaction cross section

[RemDelaporteMathurin]

Hi! thanks for that great package. Very useful!

I'd like to plot cross sections with the pp reaction. Do you think there's a way of adding this to fusion_cross_sections.py ?

I've come up with that script so far but must've messed up something with the units...

import numpy as np
import matplotlib.pyplot as plt
from scipy.constants import e, atomic_mass, hbar


ev_to_joule = 1.60218e-19  # J/eV
barn_to_m2 = 1e-28  # m2/b

E = np.logspace(0, 6)  # eV


A1 = A2 = 1.0072765
mu = atomic_mass*A1*A2/(A1+A2)
vel = (2*E*ev_to_joule/mu)**0.5

eta = e**2/hbar/vel
S_0 = 4e-25*1e6  # eV b
S_prime_0 = 11.2  # b
S = S_0 + S_prime_0 * E
cross_section = S/E*np.exp(-2*np.pi*eta)
cross_section *= barn_to_m2

plt.plot(E, cross_section)
plt.xscale("log")
plt.yscale("log")
plt.show()