A Cost-effective High-configurable Iris Diaphragm Beam Halo Detector

Over the past few years many beam halo and profile detection techniques have been invented to minimize the beam interception rate and accuracy of measurements. However, many of them require complex systems and are not modular. The systems are hard to be re-configured or customized for a different facility, or even a different section of the beamline. Most halo detectors cannot work with a large dynamic range of beam charges, beam energy and/or beam sizes. Therefore, these systems can hardly be modularized. Moreover, most systems are too expensive to be considered in instrumentation upgrades. There is a strong need for a halo/profile monitor that is modular and generally applicable, which can be installed at various electron facilities, such as medical linacs and circular rings, with minor modifications. Euclid Techlabs, LLC has been designing and testing a cost-effective iris diaphragm halo/profile detector, which can be easily configured to work with various primary beam energies and sites. Besides working as a measurement device, it can also work as a controllable beam scraper/collimator. This novel iris diaphragm detector utilizes the current signal produced by the beam charge deposition on the moveable conductive iris blades, or ionization of biased blades, to accurately measure the beam distribution from the outlier to the beam core. It is an “add-on” design that is contained in a 6-way cross and can be conveniently transferred to other locations if needed. We have accomplished more than the Phase I proposal deliverables: We have already made and tested two versions of the iris diaphragm beam detector. The experimental results of version-alpha prototype demonstrated the proof-of-principle and showed a beautiful linear response of the measured signal on the total beam current. The version-beta design has the controllable iris diaphragm structure, with 4 iris blades, demonstrated the diaphragm mobility and was tested on Dec. 4th to show independent signals from the blades. We also made a Geant4 environment to do Monte Carlo simulations of the beam-matter interaction of different beam energy and materials. We did thermal and stress simulations in COMSOL with the version-beta model and designed the integrated circuit with operational amplifier to elongate the signal for DAQ. We will continue improving the robustness of the structure and optimize the design. We have agreed with the Argonne Wakefield Accelerator of ANL, and Duke University to test the detectors at their medium- energy beamlines. We will model the full system in Geant4 and do more detailed thermal and stress analyses. We will investigate thin-film insulation and enhanced radiation cooling, along with active cooling methods. We will then test the product at other electron facilities, such as UMER at University of Maryland, APS at ANL, etc. We will further investigate the option of customizing the detector as a controllable beam scraper with active feedback, as we have seen needs for such a device at many sites.