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Accessing Individual Values

Accessing Individual Values

To evaluate kinematic quantities at a specific beam energy and kinematic variable value, use kinematics_at_beam_energy_and_angle().

This method automatically handles multi-valued solutions and always returns lists.

Syntax

from reaction_kinematics import Reaction

# or equivalently: Reaction("3H(p,n)3He")
rxn = Reaction("p", "3H", "n", "3He")

r = rxn.kinematics_at_beam_energy_and_angle(1.2, "theta3_lab", 122)
print(r)

This will return:

{'cos_theta_cm': [-0.9813047694699246], 
'theta_cm': [168.9], 
'theta3_lab': [122.0], 
'theta4_lab': [3.098], 
'energy3_lab': [0.005237930117122223], 
'energy4_lab': [0.43100601988343396], 
'velocity3_lab': [0.003338681989975168], 
'velocity4_lab': [0.017517730726598162], 
'momentum3_lab': [3.136927647029636], 
'momentum4_lab': [49.204196838704895]}

Parameters:

  • beam_energy : Beam kinetic energy (MeV by default)
  • angle_name : Independent variable (e.g. "theta3_lab", "theta4_lab", "theta_cm", "cos_theta_cm")
  • angle_value : Value at which to evaluate (degrees for angles by default)
  • angle_unit : Unit for angle_value — "deg" (default), "rad", "mrad"
  • energy_unit : Unit for beam_energy — "keV", "MeV" (default), "GeV", "TeV"

For example, to evaluate at a beam energy given in keV:

r = rxn.kinematics_at_beam_energy_and_angle(1200, "theta3_lab", 122, energy_unit="keV")