b * leveling and collide and squeeze mds

b* leveling and Collide and SqueezeMDs

LHC Studies Working Group Day, 2.09.2014

BE-OP-LHC

A. Gorzawski and J. Wenningerand many others

LHC Studies Working Group Day

2

Outline

1. b* leveling/ Collide and Squeeze, MDs in Run1:• MD on June 2012 + floating MD on July• MD on October 2012

2. MD scenarios for Run2:• 6.5 TeV• 450 GeV

2/09/2014


3

Outline



2/09/2014


4

Past MDs devoted to b* leveling

• 2012 June (+July)• CERN-ATS-Note-2012-071 MD• Fills: 2748 + 2828 and 2829 (20 days later, floating MD)• No of bunches: 3 and 48 (2829)

• 2012 October• CERN-ATS-Note-2013-002 MD• Fill: 3143• No of bunches: 3 nominal + probe

2/09/2014


5

MD in June (2012-071 MD)• Separate Hyper Cycle 4TeV 10Aps 0.6m BSTAR LEVEL

• RAMP 4TeV 2012 V1 BLEVEL• SQUEEZE 4TeV LONG 2012 V1 BLEVEL

• Settings were cloned and modified to provide collisions for b* values between 3m and 0.6m

• TCTs at 3m were set to Stable Beams, 0.6m, settings.

2/09/2014

At 3 m, the luminosity scan and orbit corrections were incorporated forward into the squeeze functions as constant increments to the existing settings, later procedure was repeated at each MP


6

MD in June (2012-071 MD)

2/09/2014


7

MD in October (2013-002 MD)• Same settings as during previous MD,• Only one dedicated fill: 3143• Three bunches + probe• Exercised region 9m – 3m

2/09/2014

• From 9m to skip the step with tune change.

• Goal was to ‘reconnect’ settings the with previous MD (at 3m) and check validity with a larger time interval. 1st MD

2nd MD2nd MD


8

MD in October (2013-002 MD)

2/09/2014

Luminosity evolution during the MD (2.5h)

• The Luminosity dips (upper figure) are due to feed forwarded orbit corrections

• Not negligible orbit deviations (up to 1.5s) due to long break between MDs


9

Outline



2/09/2014


102/09/2014

MD scenarios

1. In IR8 as an additional squeeze steps at 6.5 TeV2. In any IR at 6.5 TeV3. In IR1/5 at 450 GeV

+ In IR8 as a final part of the operational cycle


11

(1) At IR8 as an End of Fill test/ MD• Use an additional segment from 3m to 2m that

can be run as an extra at the end of the fill• Aperture to be checked

• It is easy to set up - only 4 optic steps.

2/09/2014

Operational part for IR8


12

(1) At IR8 as an End of Fill test/ MD• Only standard optics correction needed, IR1/5

balance is not critical (MD).• Loss maps and asynchronous dump tests could

be made in one fill.• Can only be used at the end of the very long fills

(offset leveling @3m exhausted) or as EoF tests provided the luminosity is allowed to exceed the usual target.

2/09/2014


13

(2) At any IR (1/5) at 6.5 TeV• Requires settings cloning procedure as before• 2012 MD procedure

• b* range to be defined • Full or subset of 11m – 0.65m (down to 0.4m)

Setup could directly be used for operational collide/squeeze and b* leveling

• Significant setup and validation time may be required

2/09/2014


14

(3) At IR1/5 at 450 GeV• Requires a flat machine

• to transfer aperture gain to b* reach (see fig.)

• Provides the range from 11m down to ~5m• With 1m/0.5m steps• Required PC currents seem OK (>I_min) for Q4, Q5 and

Q6

• Likely that no optics correction is required (should measure optics) as long as beta beat does not degrade

• Much easier and faster commissioning than at 6.5 TeV• Loss maps + asynchronous dump validation in 2-4h?

2/09/2014

12.5s

In blue extra aperture gained after removing

the Xing bumps


15

(3) At IR1/5 at 450 GeV Performed with 1-10 nominal(?) bunches

Could remain < SBF threshold Gives the possibility of few full procedure cycles – due to

the saved time on the ramp!• In a 8h slot up to 3-4 repetitions

• Beam - beam (?)• An Operation at the the top energy will only profit from

experience gained at the injection level • not from the settings and corrections

• The final feasibility study is still on going.

2/09/2014


16

Conclusions• Two 2012 MDs proved the possibility of using the

b* leveling• The possibility of performing MDs at 450GeV may

enable to test entire mechanics and gain significant experience.

• Only mixture of the Injection level and Top energy level MD gives the full picture of the process.

• In the view of requirements for later part of Run 2 it essential to gain an experience with the process.

2/09/2014

The end


18

At IR8 as an end of the fill test/ MD• Is a part ~5m down to 3m of the squeeze • Only fills that >7h enough can be used

Requires only 8 (instead of 20) points to commission with all corrections Will shorten the the commissioning prognostics

Needs few fills to build the loss map and perform asynchronous beam dump.

• It is not a real MD but part of the operational cycle That is postponed later in the fill.

2/09/2014

A.Gorzawski at 5th Evian Workshop

R.Tomas at LS1 LBOC meeting No 23

b * leveling and collide and squeeze mds

Documents

previous md

group day992092014lhc

critical md

md procedureb

md2092014lhc studies

group day4md

group day5

group day22outlineb