Minutes of HERA Meeting
17.09.2002
HERA
B.Holzer summarized the HERA operation of last week, see transparency
- The goal of the machine studies on Monday was to prepare for high beam
currents. The proton timing and phase-loop was optimized to reduce
longitudinal oscillations. Positron orbit response matrix measurements
were done.
- Tuesday HERA provided a long positron fill (starting at 30mA) for
background studies.
- A positron energy scan was done on Wednesday.
- During luminosity running, Thursday to Friday, the positron beam current
was increased from 14 to 20mA; 60 proton bunches, 85 positron bunches.
During a long run, Ie starting at 18mA, the proton beam emittance
increased from 16 to 30 pi mm mrad. The initial specific luminosity
measured by H1 was 1.7 10**30 cm-2 s-1 mA-2.
- Yesterday morning, the vertical positron beam emittance was measured
(2.5 rad nm), about a factor of two too low. It was increased to 4.7 to 5.1 rad nm
using long vertical bumps in the arcs in order to match the beam sizes
at the IPs and to avoid blow up of the proton beam.
- There were a few technical problem last week including a ground fault of
a sextupole magnet (SK82 east), which will be repaired today.
- Sudden chances was beam positions and tune were observed. Power supplies
are being monitored. Some hardware problems were found and repaired
(poor power connections).
H1
- Background conditions were good. Chamber HV was turned on immediately
after stable conditions were declared. On Friday the background was
slightly higher, the HERA B interaction rate was high. The background
improved when the p collimators were moved in. Conditions on
Saturday and Sunday were very good. HV trips were less frequent.
- A fast dump dump of the solenoid happened Friday to Saturday night.
- The FPS is ready to be inserted. The proton beam orbit is now at the
correct position.
- Today, the interlock will be set around noon.
ZEUS
- The background conditions, in parcular CTD currents, were somewhat
unstable during the long positron fill.
HERMES
- Successful data taking. 31470 polarized and 14630 unpolarized events were
taken last week.
- The temperature of the HERA cooling water was still too high on Wednesday.
- The HERA electron clock is unstable.
HERA B
- Had 40 hours of target operation.
- Thursday, the tune controller was still on, exiting the first bunch. All
interactions were from the first bunch.
- On Saturday the bunch distribution was not uneven, due to PETRA kicker problems.
The interaction rate had to be increased to equalize the bunch distribution.
- Took minimum bias events, collecting J/Psis.
- Beam based alignment of the west straight section has to be done.
Schedule
- Today: activate NEG pumps north and south. Night shift restart with proton beam.
- Tomorrow: background studies. Activate individual Ti pumps south and north
- Prepare ep run without collisions (offset bunch trains).
- Luminosity run with similar bunch currents.
- Thursday to Monday morning: luminosity operation. Beams should be dumped
when positron current is at 6mA.
- ZEUS is the coordinating experiments.
Uwe Schneekloth