Minutes of HERA Meeting
06.08.2002
HERA
F.Willeke summarized the HERA operation of last week, see transparencies
- Last week HERA operation suffered from several technical problems, mainly
failures of power supplies. Machine studies after the Wednesday access
were not successful.
- A magnet short (magnet on bridge at N IR) was caused by a cable, which
was not installed properly. Everybody was reminded that the magnet
connections are not electrically insulated. Special care should be
taken during access activities.
- Stable positron beam at various beam energies was provided Wednesday to
Thursday night in order to study the synchrotron radiation background.
Background conditions were not always stable. The run was successfully
repeated on Saturday. Background conditions were carefully optimized
at each energy.
- There was a stable proton beam run on Friday with the HERA B magnet turned
off.
- Two stable "high" current positron fills starting at 20 and 24mA were
done on Sunday and Monday.
- The distortion of the positron betatron phase was studied on Monday.
The beta beat was reduced from 60 to 20%. The correction is not yet
implemented. It should increase the specific luminosity by about 10%
ZEUS
- Summary of the positron beam runs last weekend: pdf file
- This morning there is problem with the luminosity monitor. It is working again.
H1
Various plots of the positron only runs were shown:
- Jet chamber current as function of time. gif file
- Jet chamber currents as function of beam current. ps file
CJC1 current showed small quadratic component, consistent which beam gas interactions.
- Event display, beam gas interaction ps file
- Event display, random trigger ps file
- CJC2 chamber current at different beam energies gif file
(Backgrounds were initially high at 21GeV and required significant tuning)
- HERA bunch pattern. gif file
The isolated bunch was used for studying timing of random hits
- FADC timing distribution, comparison of random and tracker triggers: ps file
- CJC2 current as function of positron and proton current. ps file
For positron beam only the estimated maximum beam current is 50mA. For colliding beams, the estimated maximum currents are given by Ie*Ip = 600mA**2
- Estimate of CJC chamber currents: ps file
HERMES
- The HERA electron beam clock signal was unstable. On Sunday it changed by 24ns.
- Requested a 1/2h access this week.
HERA B
- Requested a 10 minutes access.
Schedule
- Today, HERA will setup collisions again.
- The schedule and priorities will be discussed in a special HERA meeting tomorrow afternoon.
- ZEUS is the coordinating experiments.
Uwe Schneekloth
