Minutes of HERA Meeting
18.06.2002
HERA
- The goal of last week was to set up luminosity with 9 colliding bunches,
repeat this about 20 times to optimize the procedures and to get into
some routine operation. Collisions were achieved 7 times. After some
optimization collisions are now found relatively fast. There are two
intermediate files now, which are reproducible. There is no increased
background during the file transfer.
- The proton and positron beam lifetimes were poor during collisions.
The proton lifetime was improved on Sunday. The reduced positron lifetime
is not yet understood.
- There was some down-time due to a UPS failure. Trips of the ZEUS solenoid
caused some delay.
- Friday to Saturday two fills of stable positron beam at injection energy
(1.5mA and 7mA) were delivered to the experiments. It took a while to
go to luminosity optics (at 12GeV).
- Machine studies have been performed yesterday and today. The influence
of the stray field of the final proton quadrupole magnets on the positron
beam was studied. The effect is larger than expected after the field
measurements on the magnet test stand. Positron beam tail studies will
be done this afternoon.
- Some proton beam position monitors were repaired during the last access.
As a result some large orbit deviations were reduced.
- The automatic orbit correction program was tested. It is not yet available
for routine operation.
- The vacuum is slowly improving (there were no high current positron fills
last week). One pump in the north IR (NL6) still indicates a relatively
high pressure.
ZEUS
- The chamber currents were significantly lower at 12 GeV. The data are
still being studied.
H1
- The CJC currents at 12 GeV were similar to currents at good fills at
full energy. Studying the drift-time distribution is difficult since
the drift cells integrate over more than 7 bunch spacings (the bunches
had 6 empty bunches).
HERMES
HERA B
Schedule
- Finish beam scraper studies this afternoon.
- One long positron beam only tonight; 6 empty bunches, last gap 11 empty
bunches.
- Repeat luminosity run (10 bunches) with same conditions (files) as on
Sunday.
- Continue making collisions with increasing intensity, 30 bunches about
15mA protons and positron beams. Short fills when currents are small.
Longer fills when higher beam currents. Procedure: collisions,
close ZEUS calorimeter and collimators, HERA B and HERMES turn on,
optimize for H1 and ZEUS.
- H1 is the coordinating experiments.
Uwe Schneekloth