Gamma-ray spectra and absorbed doses measured at EuXFEL undulator system

Area of Science:

• Particle physics
• Accelerator physics
• Radiation physics

Background:

• Stray radiation in undulator systems poses risks to sensitive equipment at facilities like the European XFEL (EuXFEL).
• Understanding the energy profile and sources of this radiation is vital for mitigating potential damage.

Purpose of the Study:

• To characterize the stray radiation field in the EuXFEL undulator systems.
• To investigate the influence of machine operation settings on radiation intensity.
• To compare experimental measurements with Monte Carlo simulations.

Main Methods:

• Measurements of gamma-ray energy spectra (30 keV to 1.5 MeV) using a CZT spectrometer and RADFETs.
• Geant4 Monte Carlo simulations for comparison.
• Analysis of radiation intensity in relation to charge, electron energy, and undulator gap.

Main Results:

• Upstream stray radiation is linked to high-energy electrons hitting the beam pipe, with intensity correlating linearly with charge and electron energy, and inversely with the undulator gap.
• Accelerator settings can mitigate upstream stray radiation levels.
• Downstream stray radiation is dominated by low-energy synchrotron radiation (<200 keV), comprising ~99% of the field.

Conclusions:

• Stray radiation characteristics differ significantly between upstream and downstream undulator sections.
• Effective mitigation strategies can be implemented through careful control of accelerator parameters.
• The findings provide crucial data for protecting EuXFEL infrastructure from radiation damage.