ESS Timing System Plans
and Requirements
Timo Korhonen
Chief Engineer, Integrated Control System Division
www.europeanspallationsource.se
May 19, 2014
The European Spallation Source
• An accelerator-based neutron source to be built
in Lund, southern Sweden
– Material and life sciences research
• A collaboration of 17 European nations
Neutron scattering of
hydrogen in a metal
organic framework
– Construction budget about 1860 million Euro
• Targeted to be the world’s most powerful
neutron source
– 5 MW beam power, 2.5 GeV proton energy, 14 Hz
repetition rate, 2.86 ms pulse@50 mA beam current
– 22 neutron beam lines in construction budget
• First neutrons in 2019, full configuration in 2025
X-Ray
Image
Neutron
radiograph
Where Will ESS Be Built?
• ESS is located in southern
Sweden adjacent to MAXIV (A 4th generation light source)
• To provide a world-class
material research center
for Europe
What will ESS look like?
Target
Instruments
Linac
What is Different About ESS?
• The average proton beam
power will be 5 MW
– Average neutron flux is
proportional to average beam
power
– 5 MW is five times greater than
SNS beam power
• The total proton energy per
pulse will be 360 kJ
– Beam brightness (neutrons per
pulse) is proportional to total
proton energy per pulse
– 360 kJ is over 20 times greater
than SNS total proton energy
per pulse
What does 5 MegaWatts mean?
• At 5 MegaWatts,
– one beam pulse
• has the same energy as
a 16 lb (7.2kg) shot
traveling at
– 1100 km/hour
– Mach 0.93
• Has the same energy as
a 1000 kg car traveling
at 96 km/hour
• Happens 14 x per
second
– You boil 1000 kg of ice
in 83 seconds
• A ton of tea!!!
ESS Control System
• ESS Integrated Control System Division (ICS) is in charge
of building the control system(s) for the accelerator, the
neutron target, and providing controls for the beamline
components
• EPICS as the control system software
• Project scope includes also
– protection systems (Machine, Personnel)
– Global timing system for site-wide synchronization
• Some parts of the controls will be provided by ESS
partner laboratories as in-kind contributions
– e.g., proton source and LEBT controls by Saclay (France)
– More to come
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Timing system requirements
• Accelerator parameters for timing
– Front end frequency is 352 MHz (CERN Standard)
– High energy section is at 704 MHz
– Master oscillator at 88 MHz
• (even if we could divide from 352 MHz)
– Repetition rate 14 Hz
• Dictated by neutron choppers
• No need to do AC sync (I was told)
– Repetition rate must be programmable
• No RF pulsing when no beam (power consumption)
• But “some” devices need still 14 Hz triggers (?? Needs clarification.)
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Timing system requirements
• Typical requirements for a pulsed accelerator
– Triggering of devices
– Synchronous acquisition and data handling
• Long pulses mean a lot of data per pulse!
– Distributing beam parameters
• Machine mode: where will the beam go (target, tuning dump)
• Beam mode: pulse intensity, length
– Repetition rate control
• Possibly even single pulses – if possible
– Timestamping of data
– Some top-level requirements are still under discussion…
• ESS challenge:
– Interfacing with the machine protection system
– Ensuring that machine and beam modes are propagated
correctly to all receivers
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Timing system requirements
• The typical requirements are “easy”
– 14 Hz vs 100 Hz (or higher) repetition rate
– Long pulses create some issues in data handling
• For control system in general, not too much for timing
• More work in software side
– Ramping up the beam power; intensity and pulse length
– Beam mode handling
– Beam synchronous data handling
• Interfacing to MPS is critical
– Or, find a way to make MPS totally independent
• I cannot yet imagine how that could be done in a reasonable way
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Issues to be considered
• Synchronizing with “slow” devices with no EVR
– PLCs, etc.
– We need to be able to correlate data
– NTP server in EVG IOC? Is it sufficient?
• Handling user’s devices
– Oscilloscopes, etc. (known issue)
• Access to API & hardware interfaces?
– Purpose-built devices: detectors, etc.
• No standard interfaces
• There is still time to think about this, though.
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Summary
• ESS timing requirements are not too different from other
pulsed accelerators
• Machine protection is a big issue, though
– One single mis-steered pulse will break the machine
• Platform (form factor) is pending final decision
– Lots of push for microTCA, though
– How to integrate other devices?
• Project timespan is an issue
– We are building now something that will be in full use after 10
years, and have an expected lifetime of 40 years
– Roadmap for upgrades and technology refresh
• Collaboration is very much appreciated!
– Sharing of knowledge, applications, ideas…
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