•Short Review HERA Run 2002 / 2003•Luminosity•Polarization •Backgrounds•Shutdown Activities•Plans for Restart

H1

ZEUS

HERMES

HERA-B HERA

PETRA

778 m

6336 m long

DE

SY Polarized Electrons

Protons

H1

ZEUS

HERMES

HERA-B HERA

PETRA

778 m

6336 m long

DE

SY Polarized Electrons

Protons

Report on HERA64th Meeting of the DESY PRC

May 7, 2003 F. Willeke, DESY

Short Review of HERA Run 2002/2003

January-March 2002 Repairs, Collimator modifications, machine studies

March 2002 Start up, machine studies,

bakeout

April 2002: Set-up of luminiosity, synchrotron radiation studies

June-Sept. 2002 Luminosity Run with low intensity (5d/w), machine studies, background studies (2d/w)

Sept./Oct. 2002 High Luminosity Studies, polarization Studies

Nov. 2002-Febr. 2003 Luminosity Runs wih moderate intensity

February 2003 Machine Studies,high luminosity studies,polarization Tune-up

Operations

Problems6%

Machine Studies

3%

Proton Inj +ramp

9%Posirton Inj

+ramp9%

Lumi Prep9%

Cycling6%

Other17%

Lumirun41%

Luminosity Efficiency

in February 2003: 43%

Luminosity operations in February 2003

D. Pitzl’s Plott of CJC2 Chamber currents contributions from ep gas events relative to values obtained in September 2002

Global trend follows the vacuum pressure, there is stagnation

since December 2002

Accelerator Handling, Understanding, Modeling, Improvements

Beam based alignment

Orbit feedback

Improved magnet cycling

Online optics correction

Improved background tuning algorithm

On-line IR beam envelopes inside magnet aperture

Working on proto emittance control

Improved beam stability

Improved beam handling

More save operations

Higher beam quality

Larger luminosity

Beam Based Alignment

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,

Oct. 7, Nov 4, Dec 2

Maximum Peak LuminosityMaximum Peak Luminosity

yx

pbebb

fe

IInL

0

22 yx

pbebb

fe

IInL

0

22Ieb = 0.300mA (design)

0.600mA (2 x design)

Ipb= 0.600 mA (Y2000 max)

2max

22000 ImAII pp 1500 mA2

4000 mA2

yx

bpeb

fe

IIIL

02

max

2 yx

bpeb

fe

IIIL

02

max

2

A likely scenarioA likely scenario

2maxIII pe 2maxIII pe

I2max/mA2 Iep/mA2 Ipb/mA nb L/cm -2sec -1

2000 0.3 0.6 100 3.75535E+311500 0.3 0.6 90 3.37982E+314000 0.3 0.6 140 5.2575E+312000 0.6 0.6 70 5.2575E+311500 0.6 0.6 60 4.50643E+314000 0.6 0.6 90 6.75964E+31

I2max/mA2 Iep/mA2 Ipb/mA nb L/cm -2sec -1

2000 0.3 0.6 100 3.75535E+311500 0.3 0.6 90 3.37982E+314000 0.3 0.6 140 5.2575E+312000 0.6 0.6 70 5.2575E+311500 0.6 0.6 60 4.50643E+314000 0.6 0.6 90 6.75964E+31

Peak Luminosity Prospects 2003 Peak Luminosity Prospects 2003

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