1. Hand-shake Signals Between LHC Machine and Experiments
Mike Lamont
Thanks to Daniela Macina for her input

2. Communication GMT BST DIP
events, telegrams, time of day, safe machine parameters
BST
DIP
publish/subscribe
a very loose coupling
10/03/2008
Handshakes

3. Modes
Accelerator
Beam
Operational
10/03/2008
Handshakes

4. Beam Modes
10/03/2008
Handshakes

5. Injection & Transfer
No Beam
10/03/2008
Handshakes

6. Proposal – publish values in DIP
LHC_READY_FOR_INJECTION
none, prepare, imminent, injection
ATLAS_READY_FOR_INJECTION
no injection, prepare, ready for beam
Flags monitored by Software Interlock System
injection inhibit if all experiments not equal ready
10/03/2008
Handshakes

7. Proposal LHC publishes “Injection Imminent”
Need to know that expt has got the message
Experiment publishes “preparing” with 10 seconds, say.
If it doesn’t it gets a phone call
LHC continues preparation when ready checks and/or waits for all expts “ready” - phone call possible
When all expts ready, switch mode and ramp to injection level
10/03/2008
Handshakes

8. DIP
10/03/2008
Handshakes

9. Imminent injection
the experiments are ultimately protected by the “injection inhibit signal”.
an “imminent injection” warning signal would give time to the experiment to put the detector in stand-by mode therefore allowing injection into the machine “in time”.
The optimal delay between the warning signal and injection would be minutes
The switch from SETUP to INJECT PROBE will be made less than a minute before the machine would like to inject (eventually). Thus the “injection imminent” flag would be set in one of the SETUP sub-phases (this can be tuned).
10/03/2008
Handshakes

10. Physics
10/03/2008
Handshakes

11. Stable beam to Adjust LHC_TO_ADJUST ATLAS_READY_FOR_ADJUST
None, prepare, ready, OK
ATLAS_READY_FOR_ADJUST
None, prepare, ready
Going to have to go on trust here, rely on sequencer, hard to imagine imposing an inhibit
10/03/2008
Handshakes

12. Scheduled Beam Dump LHC_READY_FOR_BEAMDUMP ATLAS_READY_FOR_BEAMDUMP
none, prepare, imminent, OK
ATLAS_READY_FOR_BEAMDUMP
none, prepare, ready
Going to have to go on trust here, rely on sequencer, cannot impose an inhibit
10/03/2008
Handshakes

13. Suggest we suck it and see – dry runs incoming
DIP - comments
Pub/Sub not ideal
never know who’s subscribing and whether or not intended recipient has got the message
with these asynchronous messages, subscriber doesn’t know if the publisher is alive and kicking
no persistency
no message logging
What we have is an attempt to do a loose command/response
possible two-way heartbeats during the relevant modes
Suggest we suck it and see – dry runs incoming
10/03/2008
Handshakes

14. Dry Runs
10/03/2008
Handshakes

15. Physics/Experiments Dry Run
Luminosity
Acquisition and display, BRA application
Optimization, trims, bumps etc.
Scans
Experiment Instrumentation & signals
BCMs, Lumi etc.
Experiment communication
DIP – to & from
Vetos, Handshakes
Interlocks
Beam abort, injection inhibit
Magnets
Alice/LHC dipoles and compensation
10/03/2008
Handshakes