Prototype Design, Fabrication, and Testing of a 5-m Large Mirror Support Structure for the TALE Experiment

To extend the detector measurement range to above 1016 eV so as to encompass for ultra-highenergy cosmic rays (UHECRs), Korean collaborators have contributed to the design, development, and structural evaluation of the telescope array (TA) experimental fluorescence detector (FD). With a 5-m diameter, this is the world’s largest interferometer. This new design requires stability; i.e., it must be constructed on a sturdy, reinforced foundation so as to provide reliability, suitability, and serviceability. Thus, fundamental analyses considering all environment-related factors have been conducted to test and evaluate the components of our large detection system. These analyses include a static stress analysis with 80-kg loads for 1 day, a static fluid stress analysis under a moderately heavy wind at 16−27 m/s, a thermal stress analysis at high temperatures of 47−58 C, and an optical reflectivity test. There by, we determined a static pressure of 380 MPa (static fluid pressure: 0.1 MPa) and a thermal pressure of 10 MPa. The optical spot size was 30−40 mm with a very high peak (estimated value: 34.5 mm). Note that a brief description of the design and the production results for the Telescope Array Low-Energy Extension (TALE)-FD Mirror Support Structure prototype were presented at the December 13, 2013, TA collaborative meeting in Japan (ICRR).