The injection forewarning event HIX.FW-CT (1s before the injection) is protected to avoid pulsing the MKIs at a wrong moment. Without this event the MKIs will not pulse.
In a normal configuration the injection forewarning is only produced by an injection request via the injection sequencer. The forewarning triggers the timing table named injection, which itself sends out other forewarnings that themselves trigger timing tables for BI etc (if loaded!). An beam will only be produced if an entire chain of interlocks and conditions (like mastership, SIS SPS & LHC, injection BIC LHC etc) are correct.
To test forewarning events (also for MKI testing) a special key must be inserted into the timing system console located above the access console. In this configuration no beam can be injected into the LHC (blocked by the presence of the key). With the key in place forewarnings can be triggered using the LHC timing application (dedicated button in the tab for sending test events). This jey is no in the OP key trakka system (no 1), the key can be taken out by J. Wenninger, M. Albert and R. Giachio ( This key was normally in B. Goddard's office. )
To pulse the LBDS system in inject and dump mode when the conditions are not normal (no regular injection request can be placed) the following conditions must be met:
- LHC cycle in the SPS,
- Injection override key in place,
- LBDS in inject and dump mode,
- Manual triggering of the Injection forewarning in the timing editor (see below and above) or through a sequence,
The LBDS trigger arrives during the SPS LHC cycle when the prepulse is generated (even if the forewarning is send out a long time before...) because the LBDS inject and dump is triggered from an RF injection prepulse.
An explanation of how the override key works is shown in this presentation.