LHC status

Saturday 15th May

One bunch 1 e11 per beam 09:57: start ramp Lifetime drops at start of ramp from > 25h to ~7h. Losses

seen at momentum collimators ==> initial losses of uncaptured beam as expected.

Strong emittance growth during the ramp, from the start onwards: 450 GeV 3.5 TeV B1, H: 3.2 ==> 8.8 micron B1, V: 2.6 ==> 5.4 micron B2, H: 3.9 ==> 10.3 micron B2, V: 3.4 ==> 8.2 micron

16-05-10

LHC status

Nominal bunch up ramp

Losses started at around 1.8 TeV. First losses seen on beam 1. Lifetime drops steeply from ~40 h to 0.04 h. All losses at collimators in IR7 (betatron losses).

Losses start to quiet down around 2.6 TeV. No losses of b1 above 3.3 TeV. Losses for b2 continuing all the way to 3.5 TeV, but at lower levels.

Lost ~40% of beam during the ramp. Both beam 1 and beam 2 show similar overall intensity loss, even though loss peaks are not correlated in time.

Minimum beam lifetime during ramp: ~0.03 hours Beam loss finally reappeared at 3.5 TeV for beam 2 (see

below), after end of flat top adjustments. Lost another 30% of beam before being dumped by BPM software interlock.

16-05-10

LHC status

Nominal bunch up ramp

Orbit well corrected at 3.5 TeV – a lot of history – will try and establish this as baseline for high energy

RF - PhilippeFor the beam: Losses do not seem caused by the RF. At 3.5 TeV, fast scope and Bunch-Peak meas show ?quiet? situation and disagree with BQM. On the fast scope B2, probably saturation at the beginning of ramp, generating false satellite bunches For the BQM: At 3.5TeV, measurement is very noisy. Probably caused by the measurement itself as it is not confirmed by Bunch-Pk or fast scope.

16-05-10

LHC status

Out of bucket flash at start of ramp

16-05-10

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~35 Hz

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Qh instabilities saturate the BBQ (> ~ 1 mm amplitudes)

LHC status

Bunch length

16-05-10

LHC status

Lifetime up the ramp

16-05-10

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LHC status

Re-fill for physics

6 bunches of around 2 e10 per beam Orbit feedback behaved well

16-05-10

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LHC status

Fill 1104

16-05-10

Bit slow getting establishing collisions

RT orbit trims make it difficult to correct back to reference orbit without getting radical – had to get beam into collision by hand and then scan

LHC status

Fill 1104

16-05-10

All rather boring thereafter

LHC status

Today

14:00 ish - end of fill 30 mins single beam – CMS BG

Two test ramps low intensity

measure chromaticity clean up orbit

high intensity new orbit octupoles

Overnight - physics

16-05-10