Speaker
Description
The High Energy Photon Source (HEPS) in Beijing will be one of the world's brightest synchrotron radiation X-ray sources, with brightness >10²², photon energies up to ~300 keV, and an eventual capacity of 90 beamlines (14 in Phase I). Such extreme source parameters place stringent demands on detector performance, and detectors have become a key factor limiting how fully the source can be exploited. This contribution presents the detector development program at IHEP, spanning photon-counting, spectroscopy, position-monitoring and timing instruments.
The flagship effort is the HEPS-BPIX 6M (BPIX-40) photon-counting pixel detector, the fourth generation of the BPIX family and the first to reach beamline-grade scale. Using a 140 µm × 140 µm pixel on a 450-µm silicon sensor and 2×6-chip modules of 256 × 576 pixels, forty modules yield 5.9 Mpixels per system. The chip provides two thresholds and 2-bit tunable gain, >1 Mcps/pixel, 14-bit counting depth and a 100 Hz continuous frame rate (up to 1 kHz). The full system—ASIC, sensor, bump-bonded packaging, readout electronics, mechanics, DAQ and software—is designed as an integrated solution. After commissioning it has served as the main detector of the biological macromolecular crystallography beamline, supporting user experiments at 1.5 Å resolution, and a 6M/2M/1M series is being prepared as standard equipment for Phase-I and Phase-II beamlines.
Complementary detectors address the other beamline needs. A single-crystal diamond X-ray beam position monitor (XBPM; 50 µm thick, four-quadrant, ~30 units installed) provides real-time sub-micron spot-position monitoring at up to 4 MHz sampling. A silicon drift detector (SDD) achieves 144 eV FWHM at 5.9 keV with semiconductor cooling and vacuum packaging, and is being extended to 16–64 pixel array spectroscopy detectors for XRF/XAFS. An APD-based time-resolved detector delivers sub-nanosecond timing and up to 8 Mcps for nuclear resonance scattering. A photon-counting silicon strip detector (100 µm strip, 187 e⁻ ENC, 3.4 keV threshold, 2.3 MHz/strip) offers a high-rate alternative to commercial strip systems, while LGAD sensors supply 90% of the ATLAS HGTD production and are being adapted for X-ray timing. Future directions—high-frame-rate ultrafast and large-dynamic-range integrating pixel detectors, array SDD spectrometers—are briefly outlined, together with the supporting PAPS R&D platform.