•Short Review HERA Run 2002 / 2003 •Luminosity •Polarization •Backgrounds •Shutdown Activities •Plans for Restart 6336 m long DESY H1 ZEUS HERMES H ER A-B HERA PETRA 778 m 6336 m long DESY Polarized Electrons Protons Report on HERA 64th Meeting of the DESY PRC May 7, 2003 F. Willeke, DESY
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Short Review HERA Run 2002 / 2003 Luminosity Polarization Backgrounds Shutdown Activities Plans for Restart Report on HERA 64th Meeting of the DESY PRC.
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•Short Review HERA Run 2002 / 2003•Luminosity•Polarization •Backgrounds•Shutdown Activities•Plans for Restart
Improvement of accelerator lattice: on-line correction of beam envelope and phase beating
Online display of beam envelopes inside relative to limiting magnet apertures
Proton Logitudinal Stability
Coupled Bunches 2p-Mode pattern
Coupled Bunches 2p-Mode pattern
Average Phase and BunchlengthAverage Phase and Bunchlength
Phase Ocsillation Monitor
Phase Ocsillation Monitor
Coupled Bunches 4p-Mode pattern
Coupled Bunches 4p-Mode pattern
Finding: HERA p bunches lenghened by longitudinal bunch instability
Cure: Bunch-to-bunch synchrotron frequency spread by RF amplitude modulation with frev
High LuminosityHigh Luminosity
H1 February 03 Extrapolated Luminosity vs Bunch Currents
0.00E+00
1.00E+31
2.00E+31
3.00E+31
4.00E+31
5.00E+31
6.00E+31
7.00E+31
8.00E+31
0 0.05 0.1 0.15 0.2 0.25
Ieb / mA x Ipb / mA
L / c
m-2sec-1
Feb2003
Y2002 Goal
Design
Y2002 Studies
Series5
Feb 03 Studies
Absolute H1 Luminosity
0.00E+00
1.00E+31
2.00E+31
3.00E+31
4.00E+31
5.00E+31
6.00E+31
7.00E+31
8.00E+31
0 5000 10000
Ipb / mA x Ie / mA
Lu
min
osi
ty/c
m-2
sec
-1
Feb03 Run
Oct02 Studies
Design
Y2002 Goal
Feb03 Studies
Specific Luminosity vs Proton Intensity
0.00E+00
5.00E+29
1.00E+30
1.50E+30
2.00E+30
2.50E+30
3.00E+30
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8Ipb / mA
Ls
p/cm
-2sec-1
mA
-2
Feb-03
Y2002 Goal
design
Y2002Studies
Feb03Studies
120 Bunches120 Bunches
IIpp < 70 mA < 70 mA
IIe e < 35 mA< 35 mA
LLpeakpeak<2.7 x 10<2.7 x 103131 cm cm-2-2ss-1-1
120 Bunches120 Bunches
IIpp < 70 mA < 70 mA
IIe e < 35 mA< 35 mA
LLpeakpeak<2.7 x 10<2.7 x 103131 cm cm-2-2ss-1-1
Polarization4 challenges
• HERA is operated now with three pairs of spin rotators.
• The solenoid fields are not locally compensated and the beam design trajectories are not perfectly parallel to the solenoid axis.
• The luminosity upgrade enhances the electromagnetic fields in collisions with the proton beam.
• The natural vertical positron emittance for a well compensated and spin tuned orbit does not match the proton vertical beam size. In order to avoid poor lifetime and transverse tails of the protons, the vertical positron emittance must be enlarged without affecting the polarization.
4 Steps
•Test Polarisation in 72o optics in old >IR in 2000
•Repeat this test successfully in Oct 2002 with flat rotaotrs in South and North
•Turn all all three Rotators simultaneously and tune up polarization
•Collide polarized beam in North and South IR with protons
4 Measures
•Enhanced spin matching
•Enhanced harmonic bump scheme
•Improved closed orbit control
•Close to perfect optics
Shut Down Activities
Survey straight sections in North and South rotators East, North, South, arc NE
Vacuum e-beam pipe in GA-Magnet SL/NL 30m gets a NEG
pump SR absorbers for RF-Finger in straigths coating of Absorber 4 SR, NR 11m with Cu-Mo movable collimator collimator ati 66m SL/NLModification of RF screens at Pumping ports Absorbers 1
&2 NR, SR 3.5m, 6mNew RF screens at rotator beam pipesbeam pipes which replace HERA-B beam pipes new shutters at Insulation vacuum s GG/Ginstall VPS with cold bypasp-Vacuumleck SR 28m
Cold Magnets p Reconnect busses at VPS Stecker erneuen
Diagnosticsnew e BPM system (electronics)partial replacement of p bpm electronic replace all fans for tunnel electronicsInstallation of OTR Monitors WL18m Wire measurment system repair work on electrical safety in tunnel electronics
PSInstallation of bipolare choppers for VO VG South & Norrepair some ground faultsmaintenance of dump switchesCoolingReduction of cooling water temperature GI/GJ NR, SRImprovement of QR coolingImprove water cooling of cavitiesInjectionImprovement of fast e-injection kickersSuperconducting CavitiesExchange RF Windows Repair of HV Isolation coupler shaft, p-HFNew power tubes 208MHzTuning of FeedbacksystemsTroubleshooting Stoerlinien 52MHze-HFPlunger exchange at several RF StationsKlystrons tuningInterlockNew door contacts, new cablingWater rinterlock WR
NEG in –GA e-Chamber
7mm
NEG Pump
Increase conductance of he pumping port
Remove every second cross piece of the rf shield
Molybdenum coating of Absorber 4 100m Mo, 10m Cu
4 Absorber inserts available now
But this is the critical path
Schedule Summer/Fall 2003
Start up with beams (3 days delay) July 14Turn-on both Rings July 17-31Vacuum Conditioning operation August 1 -August 3112 GeV, frequent warm up GG/GOPolarization Studies September 1-14High energy conditioningSet-up Luminosity Operation Sept 14-30Luminosity Operation for all experiments October 1-Dec 15Accelerator Studies Dec 15-22Maintenance days August 5, Sept 2,
Can’t get to maximum Can’t get to maximum Luminosity with 180 bunches Luminosity with 180 bunches Can’t get to maximum Can’t get to maximum Luminosity with 180 bunches Luminosity with 180 bunches
Conclusions• Backgrounds in Experiment widely, though not
completely understood• Operations poor due to ever changing
conditions, accumulated luminosity far behind expectations
• Time was well used o polish up the accelerator, many improvements
• High luminosity demonstrated• High polarazation with collisions demonstrated• Improvement programme under way• Plans for restart being finalized