V. Kain – eLTC – 5March08 1

V.Kain, H. Burkhardt, B.Goddard, W. Hofle, V.Mertens, S. Redaelli, J.Uythoven,

J.Wenninger

Injection and Associated Protection Devices

V. Kain – eLTC – 5March08 2

Scope - Contents

Scope:

– Stage A: limit 43 x 43, 156 x 156 with 9 x 1010 p+ per bunch

– Only commissioning steps which require set-up with beam

• Injection/SPS extraction interlocking not covered

– Commissioning steps are described for one beam

• other beam requires repetition of same steps

– Time estimate per step in general: 1 – 2 shifts maximum

– Not very specific yet about exact values of target parameters

Contents:

– Injection commissioning during phase A.1

– Injection commissioning during phase A.2-A.3

– Injection commissioning during phase A.4

– Injection commissioning during phase A.5

*target parameters need to be properly defined

V. Kain – eLTC – 5March08 3

Injection Region

TDIMKI +90˚

TCDD

TCLIBTCLIA

KickerMKI

LEFT OF IP2 (H plane)

RIGHT OF IP2 (H plane)

TCLIM

SeptumMSI

TCDI

V. Kain – eLTC – 5March08 4

First turn

V. Kain – eLTC – 5March08 5

Preparation Phase A.1, pilot intensity, OP/BT

Requirements: – Transfer line re-commissioned with beam

• With TED in, then TED moved out

– Orthogonal steering available for MSI and MKI

– Settings generated for TDI (out, coarse, protect)

– Shot-by-shot logging configured

– Timing tables verified (BI capture events)

– Remove extraction permit at SPS

– All TCDIs/TCLIs out

– TDI masked (completely IN)

– TCDD in point 2 IN

– MKI ON, kick disabled

• Soft-start done

– All screens in, downstream of TED and downstream of MSI

• Cameras on

BTVSS: first screen in the LHC

V. Kain – eLTC – 5March08 6

First Injections – MKI NOT pulsing Phase A.1, pilot intensity, OP/BT

Enable extraction permit

Injection (MKI disabled):

– Beam should arrive at TDI, off-center

– Steer if required

• orthogonal steering at MSI and MKI already implemented in YASP

– Check signals at screens and BPMs (BLMs no losses)

• BTVSS, BTVSI1, BTVSI2, BPTX, BPMW, BTVST (in front of TDI)

– Steer to have correct offset at TDI on screen

• ~ + 30 mm

Verify BLM readings on TDI:

– Triggered acquisition of BLM readings

• Calibrate parasitically (mGy vs. intensity lost)

– Thresholds should not trigger

Screen in front of TDI

V. Kain – eLTC – 5March08 7

First Injections – MKI pulsing Phase A.1, pilot intensity, OP/BT

Remove extraction permit – enable MKI, pulse Enable extraction permit Inject

Adjust delay such that beam is in middle of waveform

Verify vertical position on BTVST in front of TDI

– Steer MKI angle

– Beware of BETS constraints

Move TDI to PROTECT position– +/- 7 mm

– Remove BIC mask on TDI

Start threading around ring… (Move out injection screens)

V. Kain – eLTC – 5March08 8

Circulating beam – 450 GeV initial commissioning (BI, beam dump,…)

V. Kain – eLTC – 5March08 9

Injection re-steeringPhase A.2, pilot intensity, OP; Phase A.3, 3 x 1010, OP

Phase A.2: after establishing closed orbit:

– Inject & circulate

– Initial optimisation of injection oscillations: re-steer injections

Phase A.3: high precision orbit measurements:

– Inject & circulate

– Optimisation of injection oscillations: re-steer injections

• Minimise to… e < 0.5 (results in 12 % emittance growth without damping)

*target parameters need to be properly defined

V. Kain – eLTC – 5March08 10

450 GeV optics measurements

V. Kain – eLTC – 5March08 11

Injection stability - reproducibility Phase A.4, 3 x 1010, OP

Injected beam: check stability of injection point

– Transfer line and MKI effects

– Inject & dump

– 1000 shots

– Use BPMs and BTVs in injection region + BPMs and BTVs before MSI in transfer line

– Shot-by-shot, restarting after a couple of days (temperatures, MKI soft-start, …)

Circulating beam at injection

– Orbit at injection point/TDI

– Beam sizes at injection point/TDI

– Looking at nominal cycle only…

– Parasitically every time we fill

V. Kain – eLTC – 5March08 12

Aperture in injection region (1) Phase A.4, pilot intensity – 3 x 1010, OP/BT

Aperture bottlenecks in the LHC injection regions:

– MSI, Q5, MKI, D2

– → Q5 tilted

• + 1 mm on IP side

• - 2 mm on IP side

Q5 tight under nominal conditions – n1 = 6.2

MKI and D2 tight for

– Non-kicked injected beam

– Kicked circulating beam → beam in the injection kicker rise time gap (~ 0.9 s)

Injected non-kicked beam

IP2 (n1) IP8 (n1)

MSI ~ 5.5 ( 2 mm trajectory tol.)

~ 5.5 ( 2 mm trajectory tol.)

Q5 8.7 6.2

MKI 6.8/5.4 6.3/6.1

D2 4.9/4.2 6.7/5.1 J. Uythoven

J. Uythoven: InjWG 07-05

V. Kain – eLTC – 5March08 13

Aperture in injection region (2) Phase A.4, 3 x 1010, OP/BT

Aperture measurement: MSI and Q5

– Use injected beam → inject & dump, TDI out

• BLMs triggered acquisition mode

• FBCTs in point 4/point 6

– Transfer line knobs in sigma to measure aperture

– Limited by aperture of MSI

– Calibrate BLMs at MSI (on TCDIM and MSIs)

Aperture measurement: MKI and D2

– Use circulating beam → circulate & dump, TDI needs to be in PROTECT

– Kick circulating beam + scan bump at D2 or MKI

• BLMs triggered acquisition mode

– (Take out bumps at the end)

V. Kain – eLTC – 5March08 14

Scan MKI waveform Phase A.4, 3 x 1010, BT/OP

Scan MKI waveform:

– Inject & dump

– Use screen at TDI (90º downstream)

– Scan kicker delay

Example: LHC extraction commissioning – SPS LSS6 – 2006kick delay was changed, position measured with screen.

V. Kain – eLTC – 5March08 15

Injection Matching (1) Phase A.4, 3 x 1010

Mismatch possibilities – leads to emittance growth and tail repopulation

Emittance growth:

– Betatron, dispersion mismatch – measurement of twiss parameters at injection point

– Energy, steering mismatch – verify with BPMs around the ring → see Jorg’s talk

– Geometry

Tail repopulation: verify with scraped beam from SPS and scrapers in the LHC → stage B

Results from simulations: Dominant effect: betatron and dispersion mismatch

Emittance growth predicitio

n about 3 %

Tail repopulatio

n after s

craping in SPS

V. Kain – eLTC – 5March08 16

Injection Matching (2)Phase A.4, 3 x 1010, OP/ABP

Oscillation of image on matching screen indicates mismatch

– Matching screen in point 3 (will not be there for 2008)

LHC optics needs to be measured

To measure twiss parameters at injection point (dispersion, betas and alfas)

– Matching screen turn-by-turn

– Screens in injection region

Eventually (= stage B) need to control better than:

– Betatron mismatch: < 1.15

– Dispersion: maximum mismatch of 10 cm, 0.001 rad

Screen matching application:used for TI 2: • 2 D fit for beam sizes• optics calculated at any point in the line• same application can be used for LHC

*target parameters need to be properly defined

V. Kain – eLTC – 5March08 17

Increasing intensity4 bunches max injected for 43 x 4316 bunches max injected for 156 x 156

V. Kain – eLTC – 5March08 18

Operational States?

In this phase injection protection starts to play a role

The systems will be commissioned for a certain envelope – Optics

– Emittance

– Crossing-/separation angle, experimental magnet polarity

– Maximum injected intensity

– …

What/who makes sure that the systems are not used outside these “operational states” without re-commissioning or adjusting?

V. Kain – eLTC – 5March08 19

Multi-bunch injectionPhase A.5, 4 x 3 x 1010 or 16 x 3 x 1010, OP/BT

Multi-bunch injection: – Adjust delay for MKI kick

For 16 x 3 x 1010: – Only after setting up the TDI

– For 4 x 3 x 1010: TDI roughly set up

• Optics knowledge from phase A.4

• Centered

Example: LSS4/LSS6 extraction

V. Kain – eLTC – 5March08 20

Setting-up of TDIPhase A.5, 3 x 1010 – 4 x 3 x 1010, BT/collimation team/OP

The required setting of the moveable passive protection devices depends on the LHC aperture. Assume 7.5 .

TDI:– ~ 4m long, ~ 10 m upstream of D1, additional mask in front of

D1 (TCDD)

– Protects machine against MKI failures

– Required setting: 6.8 TDI – setting-up

– At this stage independent of cleaning collimators

– Setting-up like cleaning collimators: covered by Ralph’s talk• Centering, alignment, beam size measurement

– Test of synchronized (automated) setting-up with the beam cleaning collimators

– Verify fill-to-fill reproducibility, orbit feedback

Verify aperture for second beam Verify protection against MKI failure (3 x 1010):

– Trim the MKI angle (beware of BETS limits and critical settings)

– Maximum escaping amplitudes must be < 7.5 and primary loss should only occur at the TDI

TCLIs → Stage B– Unless phase advance between TDI and MKI compromised

V. Kain – eLTC – 5March08 21

Setting-up of Transferline Collimators (TCDI)Phase A.5, 3 x 1010, BT/collimation team/OP

Requirement:

– Transferline optics measured

Setting-up: each TCDI individually (the others need to be out)• Inject & dump

• Centering, alignment, beam size cross-check, set to 4.5

• Use BLMs (local, non-local), BCTs TL/point 4/point 6

– Calibrate BLMs on TCDIs and masks parasitically

• Thresholds set to: maximum allowed loss: 1 x 1011

• Verify response on nearby superconducting magnets

Check phase space coverage: maximum amplitudes escaping system: < 6 • Inject & dump, move out TDI

• Use aperture scan knobs from transfer lines

– Oscillations down the line, generated by combinations of corrector magnets

*target parameters needs to be properly defined

4.5 setting with maximumtolerance

V. Kain – eLTC – 5March08 22

Setting-up transverse damperPhase A.5, 3 x 1010 – 4 x 3 x 1010, RF/OP

Details in Wolfgang’s talk

Commission transverse damper to damp injection oscillations:– Inject & circulate

– Could be done in phase A.4: single bunch: mis-steer injection

• Measure emittance in line and in ring after injection (with and without damping)

– Multi-bunch: injection kicker waveform effect

• Verify with emittance measurement

Commission transverse damper to clean MKI rise time gap → stage B / depending on re-population mechanism and aperture in D2

– Might need to clean abort gap at the same time

V. Kain – eLTC – 5March08 23

Injection protection needs to be revisited for…

New LHC optics version

Emittance changes

Injection re-steering

– Aperture verifications in the injection region

– Transfer line collimator centering needs to be verified

– Injection protection needs to be set up again

Poor reproducibility after re-cycling

– Re-set up injection protection system

Rematching of transfer lines

– Transfer line collimators need to be set up again

Crossing-, separation angle changes, polarity changes of experimental magnets

– Injection re-steering

V. Kain – eLTC – 5March08 24

Conclusions

A commissioning plan has been developed to prepare the LHC injections for up to 156 x 156 with 9 x 1010 particles per bunch

Injection quality and injection protection has been taken into consideration

Details of target parameters still need definition

A “procedure/formalism/check list…” must be put in place to guarantee that the systems are not operated outside the parameters they have been commissioned for.