Present:
CC: Ralph Assmann,
There were no specific comments on
the minutes of the previous meeting or
on the procedures published.
Laurette presented the MPS aspects
of the commissioning of the Beam Loss Monitoring System. An overview of the
system was given together with a list of the systems the BLMs interface to:
Before each fill an internal test
of the LBDS system is made; the user permit will be false if this tests fails.
The Individual System Tests are
summarised on slide 8. It was discussed how often the radioactive source test
should be repeated, about 3 months are needed for a full check of the machine. It
seems to make sense to only check again when work has been going on in a
specific area of the machine, except for the direct BLMs to the LBDS which
should be checked every year. The only risk is a wrong cabling, as being
disconnected is automatically detected. The SIL level tests mentioned are to be
done before every fill.
The sensitivity of the magnets to a
quench need to be validated with beam; this concerns the machine uptime and not
the machine protection (unless one assumes that if we got the quench level
really wrong, we might have a similar mistake with the damage level). Beam
tests will also show if the predicted relative values between the different
BLMs are correct.
During the cold check-out the
interface with the sequencer should be tested, like including the task that an
electronics check is made before every fill and the threshold values agree with
the data base values. There is a hardware timer, which will automatically perform
these tests when there is no beam. During the cold check-out it should be
verified that if the data base threshold settings don’t agree with the actual
settings a beam dump request is generated.
Tests with beam were briefly
described: provoke a beam dump with lowered thresholds; at least one test per
octant should be made. The effect of the masking of an interlock should also be
tested. The PM facility should be used to measure the delay between the
detection of a ‘beam loss’ and the moment that the beam is dumped. The ‘timing’
of the BLMs needs to be synchronised with the other systems. The timing for the
PM is a general issue to be checked across all systems. It was proposed to discuss
this in the LHCCWG. The tests of the interface between BLM and BIC also remain to be
defined in more detail (dependence on beam / no beam conditions).
The necessity and some details of
provoking a quench during the sector test and / or with circulating beam was
discussed. Details of the tests remain to be defined. A single turn loss test
was considered to be very important as it is a more direct measurement than for
a steady state loss. It remains to be discussed if the direct BLM to the LBDS
needs to be tested with beam (with reduced threshold?).
The procedure to disable a BLM
monitor when required needs to be defined in detail. It also needs to be
determined how many BLMs one would allow to be disabled. It also needs to be
defined which monitors will be maskable.
In the next meeting (20th
June) the commissioning procedures of the WIC and the Injection System will be
discussed.
Jan
Uythoven, 29/05/07.