MKI UFO MD

LHC Injection and Beam Dump MeetingNovember 8th 2011 1

MKI UFO MD

LIBD MeedingTobias Baer for the UFO MD TeamNovember, 8th 2011

M. Barnes, B. Goddard, C. Bracco, E. Carlier, S. Jackson, V. Kain, M. Misiowiec, A. Nordt, G. Papotti, J. Uythoven, J. Wenninger, C. Zamantzas.


MD Plan

Plan: Study four main aspects:• Study UFOs at MKQ.• Study delay of UFO occurence w.r.t. MKI kick (UFO dynamics).• Study influence of e-cloud solenoids.• Study UFO asymmetry between kickers (pulsing individual kickers).

What was done:• 01:45 – start verification procedure with pilots, both beams. 3.5h• 05:20 – injecting 1236b, problem with PS cavity. 2.75h• 08:05 – 1236b circulating, start data taking. 2h• 08:43 – start pulsing MKI.05R8.• 08:55 – start pulsing MKI.05L2.• 09:13 – start pulsing all MKQs inbetween MKI pulses.• 09:44 – switch off e-cloud solenoids around MKI.05R8.• 09:56 – beams dumped (injection cleaning problem), MD recovery. 0.5h


UFOs at MKIs

Losses and MKI pulsesat MKI.5L2.• 3 UFOs in 2 hours.

Losses and MKI pulsesat MKI.5R8.• Many UFOs, especially after

MKI pulse.• Sometimes vacuum spike

after MKI pulse.

MKI pulses

MKI pulses

Vacuum at MKI.D Switch off

e-cloud solenoids

2 UFOs after MKI pulseuncorrelated

UFO

Inje

ctio

n


No UFOs at MKQ

No UFOs around MKQs.

Pulsing of MKQs


UFO at 09:54:28

Study buffer provides for the first time .

11.2s2.56ms resolution

Losses of unbuched

beam at TDI

UFOs

beam


UFO at 09:40:52

Assuming free fall: UFO dynamics cannot be explained by gravitational force.

Many similar events recorded.

UFO

18ms

MKI Pulse


Beam Dump

Due to communication problem with server, injection cleaning was switched off prior to last MKI pulse.Losses were a factor 2.5 higher.

Last pulse: No injection cleaning.

Injection cleaning

No injection cleaning

x 2.5


Conclusion

• Took data for 120 pulses of MKIs and MKQs in effectively 2 hours.• Preliminary results:

• No UFOs at MKQ found• Often candidate UFOs after MKI found, especially in Pt.8. Sometimes even

several events.• Delay of first event to MKI pulse between 12.8ms and 128ms, expectation

from gravitational force: 62ms.

• Beams dumped before individual MKI kicks could be performed.• Detailed analysis will follow

• UFO rates.• Correlation with e-cloud solenoids and vacuum activity.• UFO distribution between individual MKIs.• etc.


Thank you for your attention!

Tobias BaerCERN BE/[email protected]: +41 22 76 75379

Further information:• T. Baer et al., “UFOs in the LHC”, IPAC’11, TUPC137, September 2011.

• C. Bracco et al., “UFOs at MKIs”, 9th LSWG meeting, August 2011.

• T. Baer et al., “MKI UFOs at Injection”, CERN-ATS-Note-2011-065 MD, August 2011.


Backup slides


Initial schedule

Investigation on the sources of the UFOs seen at the injection kickers MKI. The UFO rates will be measured for specified beam condition, by pulsing the MKI on a gap in the partly filled machine.

Difference with previous MD– This time test MKIs both IP2 and IP8, last time only IP8.

• The big UFO storms happened at IP2– First MD was a proof of principle showing that:

• We can pulse the individual kicker magnets• That we get interesting data by pulsing without injecting beam

– As a dedicated MD, get more them and better statistics– This time we have extended BLM buffers, which allow us to measure the time

difference between pulsing and the UFO– Also pulse the MKQ in a beam free gap to check the behaviour of continuously coated

ceramic chamber• MKQ @ 450 GeV: kick 1.3 for 2800 V (max),

with a total pulse length of 7 s


Initial MD Plan

Check procedure of pulsing a single kicker with 12 pilots in the machine for B1 & B2 (1.0 hours)

Check kicking the MKQ, 4 kickers together with 12 pilots in the machine for B1 & B2 (0.5 hour)

Fill the machine (0.5 hour)Fill the machine with 1236 bunches and pulse the injection

kickers for both IP2 and IP8– All 4 MKIs (1.5 hour, pulse about every 2 min)– MKI-A only, B1 & B2 (1.5 hours, pulse about every 2 min)– MKI-D only, B1 & B2 (1.5 hours, pulse about every 2 min)

Pulse the MKQ in the beam free gap (1.5 hours, pulse every 2 min)


UFO Studies

Aim: Investigation of production mechanism of UFOs at MKIs by pulsing the MKIs on the partly filled machine.

Preceding parallel MKI UFO MD (MD#2) showed that UFO production can be stimulated by MKI pulsing.

In parallel to TDI studies: UFO studies (postponed from MD#3.)

Three main aspects:• Study UFO asymmetry between kickers (UFO location)• Study delay of UFO occurence w.r.t. MKI kick (UFO dynamics)• Study UFOs at MKQ (Metalized vacuum chamber as possible

mitigation)


Condensed version

Tentative Program

Beam 1 (UFO studies) Beam 2 (TDI studies)

Machine protection validation of procedure with pilot bunches for both beams. (45min)Inject 1236 nominal bunches. Inject single nominal bunch.

Move TEDs in, disable SPS MKE timing on LHC cycle, switch to BLM study buffer.

Test 1: Pulse all four MKI kickers, every minute for 1.5h.

Test 1: Measure tune for different TDI positions.

No pulsing of MKIs.Inject 1380 nominal bunches.During injection: TI8 TED out, use IQC buffer, SPS LSS4 MKE timing on LHC cycle enabled.

Test 2: Pulse only MKI D, every minute for 1h. Test 2: Measure tune for different TDI positions.

Test 3: Pulse only MKI A, every minute for 1h.

Test 4: Pulse the MKQ magnets at full strength, H & V simultaneously, every minute for 1h.

Dump beams, recovery and revalidation. (30min)

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MKI UFO MD

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