Minutes of HERA Meeting      30.07.2002

HERA

The vacuum leak in the North was repaired and the vacuum recovered quite quickly. At this time the base pressure below 1E-8. The dynamic pressure rise is only about a factor of 10 with 20mA. Proton beam were delivered to HERA-B starting from Saturday evening. The first e+ fill was produced on Monday. 4mA of e+ were ramped and made available for ZEUS for a test run to test the shielding which has been installed during the break.

ZEUS

ep running in the beginning of the previous week seems to indicate that the collision point is about 1.5mm too high and the collimators C5a/b are about 2mm too low. The ignition of the TSP's with a proton beam stored at ZEUS seems to indicate that the vacuum pressure at around 6m SR has the highest impact on the Main chamber currents. There are no conclusive results available yet from the isolated parasitic bunch. A disappointing result from the run on Monday July29 is that the additional lead shield (2mm) in the upper half of the beam pipe at the C5a/b positions seems not to have a large impact on the chamber currents. Presentation: pdf file

Zeus requests the following tests to be made:

• move the proton orbit at the IP down by at least 2mm
• provide another e+ only run with 7x96ns bunch spacing
• provide e+ only beam at different beam energies
• continue to run with the isolated parasitic e+ bunch at position 213
• provide a long positron only fill

H1

H1 is concerned about the beam vacuum around the cold beam pipe of GG.

HERMES

There was no report from HERMES this week as no e+ beam have been delivered for HERMES. HERMES complained about lack of information concerning the rescheduling of the shutdown.

HERA B

HERA-B used well the proton beams delivered on Saturday and Sunday. They made quite some progress with vertex detectors, Rhich and trigger systems. Unfortunately, the vertex detector developed technical problems which need repair.

Schedule

• There will be an access tomorrow, July 31 from 6:00h - 18:00h
• There will be access to the tunnel which should be limited to the early shift (<15:00h). There are no plans yet to release the tunnel interlocks. Machine operation:
• Tuesday late: p steering in the ZEUS IP
• Tuesday late: e/p collision 40mA p 20mA e+
• Tuesday night: e/p collision 40mA p 20mA e+
• Wednesday late/night: Run with widely spaced e+ (7x96ns) at various beam energies (injection optics, orbits optimized respectively, energies to be determined by ZEUS)
• Thursday Morning/late: Machine shifts (e+ Lumi optics fix)
• Thursday/night Friday ep running
• Weekend: long e+-fill (depending on the progress with the H1 vacuum)

                F. Willeke