Minutes of the meeting held with the experiments about DIP
Handshake 10.08.2009
Presents: Richard Jacobsson (LHCb), Hiroaki Menjo (LHCf), Antonello di Mauro (ALICE), Sigi Wenig
(ATLAS), Nicola Bacchetta (CMS), Daniela Macina (EN), Kris Kostro (BE), Delphine Jacquet (BE), Reyes
Alemany (BE)
Reyes prepared a presentation explaining the current Handshake protocol over DIP and presented
proposals to deal with the following issues:
1. How to handle the COMPLETE INJECTION phase?
2. How to handle the PROBLEM message?
3. How to communicate that the LHC synchronization phase is done and experiments can
switch to the LHC timing?
Handshake protocol over DIP
It is applied during the accelerator phases: INJECT, ADJUST and DUMP.
It consists on the following sequence of messages to be exchanged:
1.
2.
3.
4.
5.
6.
7.
8.
LHC TO EXP MSG=WARNING
EXP TO LHC MSG=PREPARE
LHC TO EXP MSG=IMMINENT
LHC TO EXP MSG=READY
EXP TO LHC MSG=READY
LHC TO EXP MSG=OK
LHC TO EXP MSG=STANDBY
EXP TO LHC MSG=VETO
The meaning of the messages is the following:
Machine
Experiment
Comment
STANDBY
VETO
Default when nothing is happening
WARNING
PREPARE
10 minutes warning, experiment starts preparing
IMMINENT
READY
2 minutes warning
READY
-
Machine ready for injection, adjust or dump
-
Experiments ready for action
OK
Successful completion of action
1. How to handle the COMPLETE INJECTION phase?
Proposal: after receiving the READY from all the experiments, LHC starts the injection process:
injection probe beam, injection setup beam, injection probe beam and injection physics beam. Then,
once the whole injection process is finished, LHC sends the message OK and STANDBY. The
experiments can follow up the injection looking at the BEAM MODE published via DIP. Therefore the
sequence of events is as follows:
1.
2.
3.
4.
5.
6.
7.
8.
9.
LHC TO EXP MSG=READY
EXP TO LHC MSG=READY
INJECTION PROBE BEAM
INJECTION SETUP BEAM
INJECTION PROBE BEAM
INJECTION PHYSICS BEAM
LHC TO EXP MSG=OK
LHC TO EXP MSG=STANDBY
EXP TO LHC MSG=VETO
Proposal accepted by the experiments.
2. How to handle the PROBLEM message?
Here we mean by PROBLEM anything except an action that requires a beam dump or is interlocked.
Proposal: In these cases LHC expects the message PROBLEM as an alternative to PREPARE or READY,
and only in those two cases.
Outside these three phases INJECTION, ADJUST and DUMP, the machine doesn’t use Handshake
protocol and therefore the Machine doesn’t listen to the message PROBLEM. Other mechanism
needed.
Proposal accepted by the experiments.
3. How to communicate that the LHC synchronization phase is done and
experiments can switch to the LHC timing?
Proposal: the following sequence of events is proposed to deal with this request:
 Change beam mode to INJECTION PROBE BEAM
 Check that the RF power is on
 Prepare the RF Beam Control for filling (here all the LHC RF synchronization is done)
 Send the IMMINENT Handshake DIP message to experiments
 Etc…. (the sequence goes on with other tasks)
The beam mode change to INJECTION PROBE BEAM signals the start of the synchronization, the DIP
message IMMINENT signals that the synchronization has been done successfully.
Proposal accepted by the experiments.
Miscellaneous
-
Accelerator mode is not used by the experiments, except for information.
The STANDBY message gets an automatic reply (VETO) by the experiments.
Only when an experiment sends the READY, we get the injection permit from the
experiment.
The details about the dry run on Thursday 13.082009 can be found in
https://espace.cern.ch/mddb/Activity%20Tracking%20Tool/Activity%20Tracking%20Welcome.as
px?View={593B6E53-F6F9-4485-8646-E7E683D0F681}&SelectedID=44
-
We agreed on writing an EDMS document compiling all this information.
Reyes will ask Jorg to include in the agenda of the next Machine Protection Meeting a
discussion about the use of the STABLE BEAM and UNSTABLE BEAM modes to order to
clarify few unknowns.
Minutes by Reyes Alemany BE/OP/LHC/