LSS6/TT60 beam commissioning on 24th August 2006

On behalf of E.Carlier, E.Gaxiola, M.Gourber-Pace, E.Hatziangeli, L.Jensen, R.Jones, V.Kain, A.Koschik, M.Lamont, J.Uythoven,

J.Wenninger and many more…

http://proj-lti.web.cern.ch/proj-lti/LTIcoordination/relatedmeetings/Extraction6/Extraction-test.htm

Overview• New fast extraction channel in LSS6 commissioned with beam

– LHC beam 1 through TT60 towards TI2: ~100 m of TT60 onto TED beam dump.

• Successful and efficient test– Beam extracted to TED on first attempt– Equipment all worked, eventually, almost perfectly.– Controls & SW all worked, almost perfectly.– Almost all planned measurements completed in ~16 hours.– ~3500 pilot extractions with 5 109 p+, 12 extractions with 12 bunches, 5 1011 p+.– No major issues discovered. First shot on BTV.610317 (TED), 12:35:03

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Test program & overview

1. PREPARATION………………………………..

2. CYCLE & EQUIPMENT SETTING UP………

3. LHC BEAM SETTING UP IN SPS…………..

4. PILOT EXTRACTION………………………...

5. APERTURE CHECKS………………………..

6. TPSG ALIGNMENT CHECKS……………….

7. STEERING AND OPTICS CHECKS………..

8. 3 of 4 KICKER TANK TEST………………….

9. KICKER WAVEFORM MEASUREMENT…..

10. REPRODUCIBILITY………………………….

11. MULTI-BUNCH EXTRACTION………………

12. RECOVERY……………………………………

OK

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Partial (during 5 and 6)

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Skipped

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OK

How the time was used

• Total ~1.751013 p+ on TED (cf 51013 maximum announced)• About 3500 extractions made using fast LHC cycle

Preparation ~4.5 h Pilot extraction ~9 h

PilotIntermediate ~1 h

Intermediate extraction ~0.2 h

Recovery ~1.5 h

Extraction and aperture measurements

V.Kain

Verified positions of all extraction elements with circulating or extracted beam

• Detailed data reduction still in progress but no major surprises• Same measurements will be made for LHC extraction septa MSD and TCDS

Calibrated beam loss measurements and profile for circulating and extracted beams

• Different signatures along the extraction channel to LSS4, as expected from TPSG designs• Needed to set BLM interlock thresholds• Allows subsequent quantification of absolute loss levels

Measured aperture along TT60 with varying corrector/septum strengths

• Handicapped by lack of BPCKs and fact that BCT is halfway between extraction and TED• Used positions on screens to estimate maximum possible excursions• Results so far analysed fit well with expected aperture from model (madx plus physical layout)

Beam loss per proton

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Optics checks

V.Kain/A.Koschik

Using data taken for aperture and extraction calibration measurements

Only BTV data available at that time (BPCK firmware problem was being solved)

Automatic data analysis difficult• Positions not returned consistently by BTV device• SDDS used to get positions from 2-D profiles

Already see some interesting results: reasonably good agreement with MAD model

Will extend to all corrector/kicker/septum excitations and measured responses

• Preparing input files from raw data for thorough analysis – rather painstaking

Comparison: Screen positions (inversed sign) vs. MAD predictions

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MSE angle [rad]

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BTV_610018

MAD_610018

BTV_610252

MAD_610252

BTV_610317

MAD_610317

MKE results – saturation/calibration

J.Uythoven/E.Gaxiola

No evidence of non-linearity seen over the range tested

Would allow use of 3 MKE for extraction – merits being discussed

Varied MKE strength from nominal (26 kV) to 33% higher (35 kV).

Checked for saturation effects at higher current /field (up to 0.13 T).

y = -0.8165x + 26.065

y = 0.3921x - 14.356

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MKE delay [us]

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MKE results - waveform

Find ±1% ripple • ±0.5% specification – needs improving

Flat-top about 18 s• Too long – needs shortening• Bunches kicked outwards on rising edge and make full SPS turn before extraction

See effect of non-linear QFA618 field• Should measure this explicitly

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Varied MKE delay wrt beam position to measure kicker waveform

• as planned for MKD/MKB systems during commissioning of LHC dump system

J.Uythoven/E.Gaxiola

Bunches being kicked on the rising edge, making 1 turn and being extracted

Beam Instrumentation specifics

L.Jensen

Useful for AB/BI in verifying new electronics in place for LHC beam extraction

Found with beam: •Some cabling/SW inversions in LSS60 BPCEs were found with the beam• Firmware problem with BPCKs in TT60

Difficulties in accurate measurement of low intensity with TT60 BCT (kicker noise)

Certain problems remain to be solved:• Most difficult probably signal to noise ratio for the very low intensity pilot beam• Problem with BPMI firmware been investigated and fix believed available.• possible BTV vs BPCK scaling errors being investigated

BTVs had x10 smaller RMS (31 m) in position measurement than BPCKs!

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BTV: RMS 31 m

BPCK: RMS 299

Measured position [mm]

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Controls & SW specifics

M.Gourber-Pace

Major progress made since earlier tests

All CO applications ran smoothly •LSA AP (EquipState, Cycle Manager ) •OASIS Viewer•Fixed Displays•DB Logging•SDDS Logging•ALARMS

Some adjustments performed on the fly to Fixed Displays and DB logging

Main outstanding issues concern logging• Systematic wrong data time stamping at source

for SPS Ring BLM + MUGEF• Septa logged asynchronously (NO timing in FE)• Sporadic holes in data • OASIS scope and channel settings

Missing alarms from mugefs

Fixed display showing all 7 LSS6/TT60 BTVs

Radiation protection

Heinz Vincke/N.Conan

Continuous monitoring of dose rate at accessible gates showed background levels during test – max. predicted was 1 Sv/h (pessimistic)

Radiation survey showed activation levels as expected – 450 Sv/h at TED

Waiting for results from dosimeters

Positive aspects

• High beam availability from SPS

• Fast 8.4 s LHC cycle and pilot bunch from SPS rapid data taking

• Controls & SW very stable and mature– Reaping the LSA harvest

• “Fast” switch to 12 bunches at midnight (~1 hour)

• Very few problems with equipment systems– Most problems shaken out in dry runs in preceding weeks

• Comprehensive and stable logging

• Excellent support from OP, BI and CO

Problems/issues encountered

• No time to condition MKE kickers to full voltage prior to the test– Sparks occurred in magnets - caused several vacuum interlocks

• SPS BPCEs with polarity/plane inversions – Could have been seen before the test, with another beam

• TT60 BPCKs needed several hours’ from experts to work correctly– Not available for aperture/response measurements

• Not possible to change polarity of MDLV for aperture tests– Still some LSA issues with polarity change and ‘zero’ current functions

• Synchronisation of logged data imperfect– TIMESTAMP data different within cycle from different equipment (BPCK, BTV, mugef)– Data 2 cycles late for BLMS!– Makes data analysis much more difficult: has to be properly addressed for 2007!!!

Outlook for 2006/2007

• Some measurements still to make in interleaved LSS4/6 test– Shorten MKE pulse and use only 3 kickers (tbc), and measure new waveform– Measure of non-linear field in QFA618– Full optics/response measurement with BPCKs– Repeat subset of aperture measurements, with BPCKs available

• Commissioning still to make in 2007– Interlock system available and to be tested– High intensity tests - full LHC beam extracted– Interleaved low and high intensity extraction with LSS4 and LHC injection

sequencing– Get ready for TI2 commissioning later in the year