Handshake IssuesHandshake Issues

Sigi WenigCERN/PH-ATLAS

4-September-2009

Handshake 4-Sep-09 Sigi Wenig 2

Detector Actions – Adjust, Beam Dump HandshakesDetector Actions – Adjust, Beam Dump Handshakes

• Adjust Handshake – during “Prepare”– Assure that SCT/Pixel/Muon are brought to stand-by “Ready”

Assume that Beam Mode stays on “Stable_Beams” until LHC sends “Ready” (following new sequence), because Pixel goes to stand-by during “Prepare” in a different way than when “Stable_Beams” flag disappears

Observation: Shifters are confused to see Beam Mode changes while experiment is on “Prepare”

Proposal: Do not change beam mode until LHC sends “Ready”

• Beam Dump Handshake – during “Prepare”– Assure that SCT/Pixel/Muon are brought to stand-by “Ready”

Assume that Beam Mode stays on “Stable_Beams” until LHC sends “Ready” (following new sequence), idem

• Injection Handshake – during “Prepare”– Assure that BCM/BLM are operational– Assure that SCT/Pixel/Muon are on stand-by– Assure that Roman Pots are out– Turn manually a key in ACR to give final Injection_Permit “Ready”

Assume that Beam Mode stays on “Prepare_for_Injection” until LHC sends “Ready” (following new sequence; incompatibility of (1) and (3) in Minutes)

• Injection_Permit removed automatically if– BCM/BLM not operational– Pixel/SCT/Muon on running voltage– RP in– Stable beam flag “TRUE”– Post Mortem Event received

• Injection_Permit can be removed manually via emergency button in ACR if “abnormal “ beam conditions are observed after injection cycle

– Experience will tell how useful and whether possible to make automatic

Injection – Handshake – Permit – InhibitInjection – Handshake – Permit – Inhibit

Handshake 4-Sep-09 Sigi Wenig 3

Handshake – DCS PanelHandshake – DCS Panel

Handshake 4-Sep-09 Sigi Wenig 4

Switch to LHC Timing/ClockSwitch to LHC Timing/Clock

• Reminder– Experiments requested stable availability of LHC clock at any moment– RF experts declared that this is not possible (during RF synchronization)– It was agreed that stable availability of LHC clock is guaranteed as soon as beam

is in LHC

• Proposal/Understanding– Stable availability of LHC clock is guaranteed with Beam Mode change from

“Prepare_for_Injection” to “Injection_Pilot”

• Comment– Stable availability of LHC clock only when Beam Mode “Stable_Beams” is too late

Handshake 4-Sep-09 Sigi Wenig 5

Open Issues and AOBOpen Issues and AOB

• Where is “Prepare_for_Injection” in Beam Mode diagram– Injection Handshake can also lead to “Inject_and_Dump” and

“Circulate_and_Dump” !?

• Clarify when LHC message “OK” appears during Handshakes, in particular Injection

• “Problem” message– How to handle controlled beam dump request of experiment in case of a

problem which does not justify an emergency beam dump request

• During handshake dry run on 13-Au-09 Safe Machine Parameters have not been available on DIP

Handshake 4-Sep-09 Sigi Wenig 6