Neutron Fluence Estimates Inside the APS Storage Ring During Normal Operation

Introduction In an electron storage ring, neutrons are generated as a result of the electron beam interaction with high-Z materials, such as scrapers and collimators [1]. When the energy of the incident electron beam is sufficiently high, it can produce high-energy photons, which subsequently interact with a nucleus, resulting in the emission of nucleons. This interaction is known as a photonuclear interaction. For photons with energies above the typical binding energy of nucleons (>5-15 MeV), photonuclear interaction generally leads to emission of photoneutrons as well as photoprotons. Photonuclear interaction is mainly the result of three specific processes: giant nuclear dipole resonance, quasi-deuteron production and decay, and intranuclear cascade generated via photopion production.