Safe mode transmission The issue as discussed in the meeting with the machine held on October 10 Proposal from people present at the meeting Call for comments First reactions To be done LEADE, 27/11/06 D. Macina TS/LEA

Movable devices and Machine Modes Devices: Roman pots and LHCb Velo If devices are at the end switch (OUT position): for all LHC modes UserPermit=TRUE If devices move away from end switch AND MODE≠StableBeams AND MODE≠UnstableBeams then UserPermit=FALSE (results in a beam dump) If LHC enters into MODE=StableBeams: devices can move away from end switch and UserPermit=TRUE If LHC enters into MODE=UnstableBeams: devices can still be away from end switch and UserPermit=TRUE Devices should move OUT Devices should not be moved IN during such mode (slides from R. Schmidt)

The mode is transmitted via the GMT system Machine Modes The mode is transmitted via the GMT system The interface to the experiments is via a level (TTL or equivalent), coax or other cable The interlock systems of the experiments requires the modes StableBeams and UnstableBeams Options: There is only one flag that is TRUE if MODE=StableBeams or MODE=UnstableBeams, else FALSE There are two flags: Flag 1 = TRUE if MODE=StableBeams, else FALSE Flag 2 = TRUE if MODE=UnstableBeams, else FALSE (slides from R. Schmidt)

Layout for Safe Machine Parameters distribution via the timing (idea from 7/8/2006) Beam Energy Tracker Energy 1 Beam Energy Tracker CTG Master Timing Generator Energy 2 Events, UTC, & Telegrams ( including Safe Machine Parameters) Timing Network Operator / LSA SBF1, SBF2 Energy Mode SqF Mode Squeeze Currents CSG Safe Machine Parameter Generator Injection kickers BLM Aperture Kickers Experiments Collimators User_Permit EI_th Imin_th E_physics E_injection deltaE, Emax SqueezeMap Critical Settings LHC BIS CTRV CTRV CTRV CTRV CTRV CTRV BCT I_beam1/2 BCT SPS Extraction BIS (TI8 / TI2) CTRV BPF1/2 (1 kHz) (slides from R. Schmidt)

Meeting 10 october 2006 on Stable and Unstable Beam Flags (machine proposal) Participants: B.Puccio, D.Macina, D.Swoboda, J.Serrano, R.Schmidt, J.Wenninger Proposals: see slides We propose the distributions of two flags: Flag 1 = TRUE if MODE=StableBeams, else FALSE Flag 2 = TRUE if MODE=UnstableBeams, else FALSE There might be a very short time (order of nanoseconds) during the transition from StableBeams to UnstableBeams that both flags are FALSE During this time, the User Permit should remain TRUE Delivery of the flags to the electronics of the experiments will use cables connected to a GMT receiver in a VME crate Using TTL, for limited distance Using a unit that transforms TTL into RS422, for longer distances Javier pointed out the development of the GMT system is in his section, and the installation and operation in Marc Vanden Eyndens section. (slides from R. Schmidt)

Actions following the meeting Machine proposal sent to all experiments on 13/10/2006 Only one comment from LHCb (R. Jacobsson) so far: no glitch in between the Stable Beam and the Unstable Beam mode, not even picoseconds. A lot of work has gone into making this system immune to all sorts of effects (EMI, etc) and make it simple. Therefore, the logic which adds up the status flags with the user permit will not and should not have to include some mechanisms which exclude glitches. LHCb proposal: Safe Stable Beam flag is kept as is, that is only during the Stable Beams. Its absence will be used to signal the movable detectors to move out, automatically or on confirmation from operator. A second flag "Movable Devices Allowed" (please, feel free to propose a different name) is added which is present during Stable Beams AND Unstable Beams without interrupt. It is this signal which would be ANDed together with the user permit to make up the beam permit sent to the CIBU. signal is not produced in the GMT receiver but that it is produced in the Master Timing Generator together with the SB flags and that it is transmitted as a telegram to the Timing Receivers

Next actions Identify in all experiments the people in charge of the interface to the BIC / GMT systems to be able to discuss technical details ALICE (?) ATLAS (Siegried Wenig, Nicolas Massol) CMS (R. Hall-Wilton?) LHCb (R. Jacobsson) LHCf (?) TOTEM (W. Snoyes) Call for a meeting in order to take a decision on the technical implementation of the safe “stable & unstable” flag transmission