Paper

{
  "raw_xml": "<entry>\n    <id>http://arxiv.org/abs/2603.18591v1</id>\n    <title>Design and implementation of a high-density sub-nanosecond timing system for a C-band photocathode electron gun test platform</title>\n    <updated>2026-03-19T07:57:49Z</updated>\n    <link href='https://arxiv.org/abs/2603.18591v1' rel='alternate' type='text/html'/>\n    <link href='https://arxiv.org/pdf/2603.18591v1' rel='related' title='pdf' type='application/pdf'/>\n    <summary>This paper presents the design and implementation of a high-density, deterministic trigger distribution system tailored for the C-band photocathode electron gun test platform at the Southern Advanced Photon Source (SAPS). Implemented within a scalable 6U VME modular architecture, the system achieves high-density integration by consolidating a master controller, clock distribution network, and 80 heterogeneous output channels into a single chassis. This design leverages a high-performance FPGA core combined with custom backplane interconnections to establish a master-slave topology, significantly reducing the system footprint compared to stacked standalone generators. To guarantee timing determinism in high-noise environments, precise placement and timing constraints are applied to the FPGA logic, while optical isolation is employed to mitigate electromagnetic interference. Furthermore, a dual-channel SFP optical signaling architecture enables seamless expansion to 160 synchronized channels. A remote control framework based on a serial server and a virtual machine Input/Output Controller (IOC) facilitates flexible configuration. Performance tests demonstrate adjustable trigger frequencies from 1 Hz to 100 Hz, with delays and pulse widths tunable from 0 to 10 ms at a resolution of 10 ns (or the RF period). The local electrical output exhibits an ultra-low RMS jitter of 6.55 ps (60 ps peak-to-peak). For remote optical distribution, the system maintains a sub-nanosecond RMS jitter of 119.5 ps, with peak-to-peak variation confined to 1 ns due to the combined effects of transceiver optoelectronic conversion (utilizing HFBR-1414T/2412T modules) and fiber transmission. The system has been successfully commissioned and is currently in reliable routine operation, verifying the architecture as a robust, highly integrated, and cost-effective solution for compact accelerator facilities.</summary>\n    <category scheme='http://arxiv.org/schemas/atom' term='physics.acc-ph'/>\n    <category scheme='http://arxiv.org/schemas/atom' term='physics.ins-det'/>\n    <published>2026-03-19T07:57:49Z</published>\n    <arxiv:primary_category term='physics.acc-ph'/>\n    <author>\n      <name>Peng Zhu</name>\n    </author>\n    <author>\n      <name>Kangjia Xue</name>\n    </author>\n    <author>\n      <name>Lin Wang</name>\n    </author>\n    <author>\n      <name>Yuliang Zhang</name>\n    </author>\n    <author>\n      <name>Yongcheng Hea</name>\n    </author>\n    <author>\n      <name>Xuan Wu</name>\n    </author>\n    <author>\n      <name>Mingtao Li</name>\n    </author>\n    <author>\n      <name>Sinong Cheng</name>\n    </author>\n    <author>\n      <name>Xiaohan Lu</name>\n    </author>\n    <author>\n      <name>Shiming Jiang</name>\n    </author>\n    <author>\n      <name>Xiao Li</name>\n    </author>\n  </entry>"
}