General Machine Timing System at GSI and FAIR

The FAIR facility involves a long chain of accelerators which need to be tightly synchronized. This is achieved by the General Machine Timing (GMT) system, a distributed event generation system based on the notion of time. Time synchronization is achieved by using White Rabbit (WR), a fully deterministic Ethernet-based field bus for clock transfer and synchronization. The key components of the GMT are a so-called Data Master (DM) that schedules actions by broadcasting messages, a WR network and Timing Receiver (TR) nodes executing machine relevant actions on time.

The primary tasks of the timing system are the following.

• Time-Synchronization of ~2000 - 3000 nodes with sub-ns accuracy over fiber lengths of up to 2 km.
• Distribution of TAI counters with ns accuracy.
• Generation of timing events for synchronization of equipment.

About...

The aim of this timing web is to provide an overview on the timing system and its relationship to other systems. Moreover, it is the central point for documentation. Please note, that the timing system is still under development.

Topics

• Introduction
  • Accelerator Control System, Clocks and Time, Network Basics
• Getting Started
  • Essentials, Timing Receiver: ECA, Timing Receiver: Usage
• Documentation
  • Documents, HOW-TOs, Current Release, Releases, Getting an IP for Timing Receivers
• Acronyms

Announcements

Please checkout this mattermost channel.

Scheduled downtime of the GMT production system as agreed with operations are marked with bold letters. Non-bold letters are activities by others are only listed for information.

• DD-DD MM YYYY: maintenance window INN
• 09 Apr 2025: short maintenance window (White Rabbit Switches)

Figure: Schedule for the next weeks based on shutdown planning. For an overview, click here or here.

News

• 06 Feb 2025
  • beam in experiment storage ring ESR
• 05 Feb 2025
  • begin user beam time 2025
• 03 Feb 2025
  • begin beam-setup to experiments
• 31 Jan 2025
  • beam in main synchrotron SIS18
  • begin operator training
• 21 Jan 2025
  • shutdown ends
  • begin commissioning of all accelerators (and decelerators )
• 17 Dec 2024
  • our colleagues from HEL added outlets for three 'missing' MIL buses at UNILAC; we can now monitor MIL events on all seven MIL buses at UNILAC
• 16 Dec 2024
  • we have moved from https://www-acc.gsi.de/wiki to https://wiki.gsi.de
• 06 Dec 2024
  • minor maintenance
• Older News

GSI Timing Team

-- DietrichBeck - 31 January 2025