Scenario ID 138 v3
Author Jean Slaughter with consultation from Andreas Jansson, Ralph
Pasquinelli, Paul Lebrun
Reviewers Elvin Harms.
Goal Commission Schottky detector
Level High level
Actors Fermilab Physicist (Andreas) and Engineer (Ralph) at FNAL,
Fermilab contact person at CERN (Peter), CERN Physicist
(Mike), CERN operators. Andreas and Ralph built the device.
Mike will be one of the people using it later to help understand
Trigger First beam has circulated in one ring of the LHC and tune up is in
progress. Ralph and Andreas want to see signals and time it in.
An access is scheduled in two days and they want to know if
they need to arrange for tunnel work. Mike wants to be involved
so he understands the operation.
Narrative 1. Assumptions. The Schottky detector and VME Front end
electronics in the tunnel have been debugged as much as
possible without beam using injected signals. The VME
front end electronics is not accessible without an access.
There is only a very rudimentary high level application but
it allows the operator to set most parameters and display
the FFTs. The relative delays cannot be adjusted via the
application. Scope traces, FFTs and numerous other
parameters such as voltages and temperatures are
available remotely and values can be datalogged. VME
code, raw data (before the FFT) and some parameters
can only be accessed via direct connection to the front
end. The LHC@FNAL console has been set up and is
allowed to run the application and view datalogged
parameters. However, direct access to the front end VME
is only allowed at CERN. The Schottky is not yet
commissioned, so is not yet in routine use in the CCC
2. CERN weekly planning meeting. Ralph, Andreas and
Mike have submitted a study plan for their parasitic study
to the appropriate person. It gives necessary beam
conditions. The study is approved, and will be scheduled
as appropriate during the daily planning/scheduling
3. Day 1 CERN daily meeting. The study is approved for the
evening shift, but is to be totally parasitic. The
Fermilab@LHC person (Peter) notifies Ralph and
Andreas and then goes home to sleep as he and Mike will
be on duty with a machine at CERN that can access the
front end directly.
4. 8:00 CST. Ralph and Andreas arrive in LHC@FNAL
center. Peter and Mike log into the front end in an office,
as the CCC stations are all occupied. Ralph and Andreas
set themselves up with displays that allow them to monitor
beam conditions, read the logbook, and start the Schottky
application and monitor scope traces. Using the
application they can only modify quantities which do not
affect the beam. They are in cell phone and Instant
Messenger(IM) contact with Peter and Mike. They are
also in IM contact with a CERN operator.
5. Throughout the shift there are erratic periods of beam.
Andreas monitors the beam conditions, while Ralph talks
with Peter and Mike who are actually adjusting the timing.
Ralph is watching the displays. Suddenly all signals stop.
Ralph checks all the monitoring parameters and sees that
a power supply is malfunctioning. Ralph makes an entry
in the CERN logbook about what has happened.
6. Next morning. A report is made in the daily meeting by
Peter. He passes on a formal request to be added to the
list for the next access.
7. Access shift. An access is made, and the power supply is
replaced. During the access, Ralph and Andreas monitor
while Peter and Mike run the injected signal diagnostic
from their laptop in the tunnel. Andreas notices that the
signal doesn’t look quite right. He asks Peter to double
check the voltage for the power supply. In fact, one of the
power supply voltages is low. Peter pulls up a drawing on
the laptop, while Ralph tells him where to look for the
adjustment screw. Peter readjusts the voltage, reruns the
test, and Andreas reports everything is ok.
8. Several days later, there is another opportunity for
studies, and the process is repeated.
Comments The success of this scenario depends on sufficient bandwidth for
scope pictures to be viewed and the results of the adjustments
seen in real time.
The ability to directly log into to the VME from the LNC@FNAL
center would make this much more efficient. However the
presence of someone to make an access is critical, and being
able to contact experts while on access is also needed.