Choppers Research & Development

Mechanical integration, controls integration and the development of the T0 chopper for ESS.

The Chopper Integration Module (CHIM) provides both the structural support for the chopper assemblies, the means of extraction and most of the interfaces to the external features.

The CHIM consist of all components within the chopper pit apart from the chopper assemblies. It also includes the pit head box.

The CHIM’s main function is to serve as the integration layer between the chopper assemblies and the instrument. It also ensures the alignment, positioning and extraction of the equipment. Depending on the instrument, the chopper system and the position along the beam the CHIM can look differently and be used differently, but the overall structure and functions remains the same.

Neutron Chopper Group Collaboration Space (login required)

ESS Inside

Erik Nilsson of the NCG with the CHIM in development at the EMBLA workshop.

Prototype CHIC control sub-rack

The Chopper Control Integration (CHIC) is a device used at ESS to integrate neutron chopper drives into the EPICS Channel Access network.

It serves as a bridge between the communication interface of the chopper drive to the communication interface of the EPICS control box and IOC.

CHIC is situated under the standard Chopper Rack.

CHIC controls architecture

Preliminary design of a chopper control rack

Time-of-flight diagram and T0 role in removing the highly energetic particles

The unique, powerful long pulse of the ESS facility introduces new technical and scientific challenges for the facility's instruments.

The high-energy pulse of fast neutrons and gamma rays generated when protons strike the target will be both longer and more intense than at any other source. Blocking this pulse will necessitate a T0 chopper with a much thicker and angularly wider attenuator.

The main objective of this work unit is to evaluate, design, test and validate technical solutions in preparation for implementation by instrument projects.

The ESS T0 chopper in development

Rotor for the ESS T0 chopper

EMBLA Joint Mechanical Workshop Collaboration Space (login required)

ESS Inside


The Neutron Chopper Group maintains a workshop in Lund. Read more about EMBLA here.