Total-reflection high-energy positron diffractometer at NEPOMUC - Instrumentation, simulation, and first measurements

Area of Science:

• Physics
• Materials Science
• Particle Accelerators

Background:

• Positron beams are valuable tools in materials science and fundamental physics.
• Existing positron sources require advanced instrumentation for precise applications.
• The Neutron Induced Positron Source Munich (NIPS) provides a high-intensity positron beam.

Purpose of the Study:

• To report the successful instrumentation of a new positron diffractometer.
• To adapt and optimize a high-intensity positron beam for diffraction experiments.
• To achieve a coherent positron beam with a small diameter.

Main Methods:

• Designing and implementing magnetic field termination for beam control.
• Utilizing an optional transmission-type remoderator for positron brightness enhancement.
• Employing an electrostatic system for positron acceleration and beam optics.
• Simulating positron trajectories to optimize system parameters.
• Experimentally characterizing the positron beam after remoderation.

Main Results:

• The new positron diffractometer was successfully instrumented and connected to the NIPS beamline.
• Key components for positron beam adaptation, including magnetic termination and remoderation, were developed.
• Simulations predicted optimal system configurations for a coherent, small-diameter beam.
• Experimental results for the twofold remoderated beam at 10 keV showed a diameter less than 1.3 mm.
• Observed beam diameter closely matched simulation predictions.

Conclusions:

• The developed instrumentation enables precise control and enhancement of positron beams.
• The new positron diffractometer is suitable for high-resolution diffraction studies.
• The system's performance, particularly the small beam diameter, meets the requirements for advanced applications.