Speaker
Description
Purpose: Small-angle Bhabha scattering of e+e- → e+e-(nγ) has a very large cross-section and is a favorable process for measuring e+e- collision luminosity. The theoretical precision is approaching 10-4. The experimental measurements of radiative Bhabha interactions have been achieved at the 1 % level. We present Monte Carlo simulations using BHLUMI and BHWIDE programs to estimate the detection of radiative photons for higher-order contributions.
Methods: Future collider projects are proposed for flavor facilities and Higgs factories of the FCC-ee and the CEPC. Luminosity detectors are proposed as precision luminometers for detection of the well-predicted Bhabha scattering events. The LumiCal is designed within the Machine-Detector Interface (MDI) region on both sides of the Interaction Point surrounding the beam-pipe before the quadrupole magnets. Bhabha scattering events are simulated for center-of-mass energies of 91 to 360 GeV for Higgs factories. The Bhabha cross-sections and the distributions of radiative photons are compared.
Results: Radiative photons are generated with the Yennie–Frautschi–Suura (YFS) exclusive exponentiation method. The event rates of photons with energies near zero are compatible independent of the electron energies. Photons are populated surrounding the incident or scattered electrons. The e/gamma identification is conducted with silicon sensors to detect electrons and LYSO arrays for shower clusters of electrons and photons. The segmentation of LYSO arrays separating shower clusters can distinguish e/gamma with an opening angle of more than 2 cells (~10 mrad). The photon event rates and angular distributions can be measured for higher-order terms in QED.
Conclusion:
The exclusive measurement of radiative photons in Bhabha events. The goal is for 10-4 precision on Bhabha event counting at future collider projects.
