#!/bin/env python3
"""
Modules to define useful constants
"""

import numpy as np

M = 0.938272081 # target mass
me = 0.5109989461 * 0.001 # electron mass
ebeam = 10.604 # beam energy
pbeam = np.sqrt(ebeam * ebeam - me * me) # beam electron momentum
beam = [0, 0, pbeam] # beam vector
target = [0, 0, 0] # target vector