LHC 18 & 19 April 2015

• At 450 GeV with bumps, no increased MUFO activity. Beam screen 15R8 warming up to 80 K, ongoing for the day

• 09:00: Orbit studies with K-modulation IP1/2/8/5 at injection• 12:00: End of long fills at injection for MUFO hunting• 14:00: Beam dump aperture studies, TCDI and TDI tightening• 00:00: V-bumps 15R8 at injection• 01:30: Ramps to 6.5 TeV• 04:00: Beam at flat top, orbit changes 15R8, 08:00 dump due to cryogenics• Linac problem, no beam for a while

19/04/2015 LHC Morning meeting – MG & JU 1

Orbit Work by Jörg

19/04/2015 LHC Morning meeting – MG & JU 2

Remaining ‘bad’ BPMs

Beam Dump Aperture & co.

• All injection protection collimators (not TCLIA and TCLIB) are at +/- 10 sigma and with all the thresholds properly set up. We could inject with the interlocks unmasked.

19/04/2015 LHC Morning meeting – MG & JU 3

Wolfgang, Chiara, Francesco, Jose

Conclusions from beam dump studies

• Measured circulating apertures (circulating beam with bumps) in IP6– Should find 15 mm for the TCDS from mechanical centre, start losing at around

10 mm for both beams, the beam size was difficult to estimate (see TDI alignment where we found large beams)

• Measured extraction apertures (phase scan)– aperture slightly tighter and quite off-centre at TCDS for B2 (phase 0), otherwise

OK • Tested beam extraction for 14/15 MKD (simulation of kicker erratic), see

plot, plot descriptions to be edited for B1/B2, can distinguish in filename         - have at least +/- 2 MKDs of aperture --> OK

19/04/2015 LHC Morning meeting – MG & JU 4

Wolfgang, Chiara, Francesco, Jose

15R8 Beam Screen Temperature

19/04/2015 LHC Morning meeting – MG & JU 5

80 K we were aiming for

Beam screen entry temp.

Beam screen temp

O-night

• Applied vertical bumps at 6.5 TeV at 15R8– Significant losses….

• Also higher beam screen temperature to «unfreeze air…»• Did this cause the difference?

19/04/2015 LHC Morning meeting – MG & JU 6

Beam stayed in for 4 hours, dumped due to control problem of cryogenics

Next• Recover

– Linac 2 HV cable (this can take a while)– Cryogenics control

• One nominal bunch (about 7e10 p+) at injection– Assuming Machine Protection main outstanding items checked

and agreed – Needs RF capture set-up

• Useful for– MUFO understanding – Rerence orbit– Collimation set-up etc.

• Transverse feedback

19/04/2015 LHC Morning meeting – MG & JU 7