Dependence of the number-weighted angular distribution of Compton-scattered photon beams on the laser intensity

Inverse Compton scattering of ultra-relativistic electron beams in the field of a high-intensity laser produces photon beams with angular and spectral distributions that are strongly dependent on the laser intensity. Here we show that the laser intensity at the interaction point can be accurately inferred from the measurement of the angular number-density distribution of Compton-scattered photon beams. The theoretical expressions, supported by numerical simulations, are accurate to within 10%–15% in a wide range of laser intensities (dimensionless intensity <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mrow><a:mn>5</a:mn><a:mo>≤</a:mo><a:msub><a:mi>a</a:mi><a:mn>0</a:mn></a:msub><a:mo>≤</a:mo><a:mn>50</a:mn></a:mrow></a:math>) and electron energies (<b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:mrow><b:mn>250</b:mn><b:mspace width="3.33333pt"/><b:mi>MeV</b:mi><b:mo>≤</b:mo><b:mi>E</b:mi><b:mo>≤</b:mo><b:mn>15</b:mn><b:mspace width="3.33333pt"/><b:mi>GeV</b:mi></b:mrow></b:math>), and accounts for experimental features such as the finite transverse size of the electron beam, low-energy cutoffs in the photon detector, and the possibility of a transverse misalignment between the electron beam and the laser focus. Published by the American Physical Society 2024