Design optimization of Fiber readout system Institute of High Energy Physics, CAS

Requirements on Fiber readout system Requirements on HERD prototype DR ~ 6000 Frame rate ~ 500 fps (320 fps) Requirements on HERD CALO DR ~ 3e6 (1/3 -106 MIP), two ranges 1 MIP = 10 - 100 p.e. 1e4 - 1e8 p.e. for high range Frame rate ~ 500 fps Working mode: trigger mode

Design optimization SCMOS instead of CCD Faster frame rate Global shutter; ROI readout Lower noise

Parameters comparison Diameter of front taper should be less than 150 mm; Taper ratio should be less than 3:1; FOUR sets of ISCMOS is needed for HERD CALO. SCMOS pixel size (um) 5.5 Distance between fibers (mm) 1 Number of pixels for 1 fiber (1d) 20 Taper ratio (overall) 9.09 Number of occupied pixels for one SCMOS 2304 648 3456 4608 ROI (mm) 12.672 3.564 19.008 25.344 Available number of fibers for one SCMOS 3732 5599 7465 Aspect ratio of ROI 3.56 5.33 7.11 Diameter of II (mm) 75 40 Dimension of Inscribed rectangle of II (mm) 72.20 20.31 38.51 10.83 73.72 13.82 39.31 7.37 74.27 10.44 39.61 5.57 Taper ratio (rear) 5.70 3.04 3.88 2.07 2.93 1.56 Distance between fibers on II (um) 627 334 427 228 322 172 Taper ratio (front) 1.60 2.99 2.34 4.40 3.10 5.82 Diameter of front taper 120 176 233 Number of ISCMOS system for one range 2

Image intensifier For high range ISCMOS For low range ISCMOS Magnetic focus I.I. Very high linear dynamic range (~1e5) Low gain (~200) Little diffusion (crosstalk) For low range ISCMOS MCP I.I. Reliability of I.I. in trigger mode Update of HERD prototype based on optimized design is ongoing.