METU-DBL: a cost effective proton irradiation facility

The Middle East Technical University Defocusing Beamline(METU-DBL) is designed to deliver protons with selectable kineticenergies between 15–30 MeV, and proton fluxbetween 10$^{6}$–10$^{10}$ protons/cm$^{2}$/s, on amaximum 21.55 to 15.40 cm target region with a beam uniformitywithin ±6%, in accordance with the ESA ESCC No. 25100specification for single event effects (SEEs) tests in the lowenergy range. The achieved high proton fluences, allow users to testspace-grade materials; electronic circuits, ASICs, FPGAs, opticallenses, structural elements, and coating layers for LEO, GEO, andinterplanetary missions.The total received dose on the Device-Under-Test (DUT) fromsecondary particles created during proton-material interactions atthe first beam collimator and the beam dump never exceed 0.1% ofthe dose from primary protons. The METU-DBL is equiped with severalmeasurement stations and services to the user teams. A secondarymeasurement station in a rotating drum that can hold multiplesamples has been constructed next to the first collimator whichprovides neutrons for transmission experiments. At the targetregion, a robotic table is located, which provides mechanical andelectrical mounting points to the samples and allows multiplesamples to be tested in a row. A modular vacuum box can also beattached on the robotic table for any test that may require a vacuumenvironment. Power rails on the robotic table provide variousoutputs for the DUT. For the data acquisition, high-speed networkingand a modular industrial PC are available at the target station. Thedesign of the METU-DBL control software enables test users tointegrate and optimize the data acquisition and controlling of theDUT.The beam properties at the target region are measured with thediamond, Timepix3, and fiber scintillator detectors mounted on therobotic table. With diamond and Timepix3 detectors, measurements aretaken from the five different points (center and the four corners)of the test area to measure the proton flux and ensure that it isuniform across the full test area. Fiber scintillators on both axes(X and Y) scan the target area to cross-check the beam profile'suniformity. Secondary doses during the irradiation are measured by aGeiger-Müller tube sensitive to electrons and gammas above0.1 MeV and by a neutron detector located at the entrance of theR&D; room. The room cools down relatively fast after any irradiation(<1 hour).Accurate linear energy deposition rates and absorbed doses on thesamples are calculated using MCNP6, FLUKA and Geant4 Monte Carlosimulations. Alanine dosimetry measurements that are calibratedagainst these simulations are also used to estimate the absorbeddose on the sample.