lhc status & plans

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

LHC Status & Plans

V. Kain, LHC Operations

Input from: J. Wenninger, F. Zimmermann, R. Assmann, S. Myers, J.P. Koutchouk, L. Evans, A. Verwej, H. Burkhardt....

SLAC SLUO workshop 16th – 17th of July 1

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

Outline

Beam Commissioning

September 19th Incident

The cause, the problem...a cure?

2009/10 LHC run

...And beyond – LHC Upgrade

Summary

2

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

LHC Cool-down

3

First cool-down of LHC sectors

0

50

100

150

200

250

300

12-Nov-2007

10-Dec-2007

07-Jan-2008

04-Feb-2008

03-Mar-2008

31-Mar-2008

28-Apr-2008

26-May-2008

23-Jun-2008

21-Jul-2008

18-Aug-2008

15-Sep-2008

Tem

pera

ture

[K]

ARC56_MAGS_TTAVG.POSST ARC78_MAGS_TTAVG.POSST ARC81_MAGS_TTAVG.POSST ARC23_MAGS_TTAVG.POSST

ARC67_MAGS_TTAVG.POSST ARC34_MAGS_TTAVG.POSST ARC12_MAGS_TTAVG.POSST ARC45_MAGS_TTAVG.POSST

Cool-down time to 1.9 K ~ 4-6 weeks/sector[sector = 1/8 LHC]

All sectors at nominal

temperature

First beam around the LHC

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

LHC Hardware Commissioning

February to September 2008o (Re-)commissioning of the magnets & circuits (power converter, quench protection, interlocking..)

following predefined test steps.

o 1’700 circuits, 10’000 magnetso LHC was commissioned to 5.5 TeV (5 TeV target for physics in 2008).

o Magnet re-training required above ~6 TeV.

o Commissioning of other equipment (kickers, instrumentation, RF,…)

4

11’122 test steps

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

Injection Tests

August – September 2008

o Injection tests up to 4 adjacent sectors

o Almost all HW systems involved

o Essential checks for:

o Control system

o Beam Instrumentation

o Optics (magnetic model) and aperture

5

22nd – 24th of August

8th – 10th of August 5th – 7th of September

Evening of August 8th 2008:First beam in the LHC after

~25 years of design and construction.

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

September 10th

6

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

Beam Threadingo Threading by sector:

o One beam at a time AND one beam per hour

o Collimators used to intercept beam (1 bunch, 2 × 109 protons per bunch, 2 % of nominal bunch)

o Beam through sector (1/8 of ring), correct trajectory, move out collimators, carry on.

7

Beam 2 threading BPM availability ~ 99%

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

Courtesy of ATLAS

ATLAS & CMS “events”o Beam-on-collimator events, synchronized

to beam timing

8

Courtesy of CMS

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

Beam Commissioning Progresso September 10th

o 10:30: Beam 1 around the ring (in ~ 1 hour). Beam makes ~ 3 turns

o 15:00: Beam 2 around the ring. Beam makes 3-4 turn

o 22:00: Beam 2 circulates for 100s of turns

o September 11th

o Late evening beam 2 captured by RF.

o First emergency dump correctly executed.

o September 12th

o All basic instrumentation operational: BPMs, BLMs, Tune, BCTs,...

o Good beam lifetime (> 1 hour)

o Beta-beating measured

9

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

Magnetic model & beta-beatingo A sophisticated magnetic model (FIDEL) was developed to predict transfer functions and field errors

for all magnets, backed by measurements and integrated into the control system for online corrections.

10

Beta-beat tolerance : 20%

Horizontal beating ≤ 30%Vertical beating up to 90-100%

Dominant source of beating identified as trim quadrupole inversion between beam1 & beam2.

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

SEPTEMBER 19TH INCIDENT

11

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

Event sequence on 19th of September

o Last commissioning step on main dipole circuit in Sector 34: ramp to 9.3 kA (5.5 TeV)

o At 8.7 kA an electrical fault developed in the dipole bus bar in the interconnect between Q24.R34 and the neighbouring dipole

o Later correlated to a resistance of that splice in the interconnect of ~ 220 n (0.35 n nominally)

o An electrical arc developed which punctured the He enclosure

o Secondary arcs developed along the circuit

o Around 400 MJ out of the 600 MJ stored in the circuit were dissipated into the coldmass and in electrical arcs.

o Tons of He were released into the insulation vacuum

o Pressure wave along the magnets in the insulation vacuum → collateral damage

12

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

Interconnection

13

Vac. chamber

Dipole busbar

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

After the incident...

14

Dipole bus bar Dipole bus bar

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

Collateral damage – pressure waveo He-pressure wave travels along magnet inside insulation vacuum up to vacuum

barriers (every 2 cells)

o Self actuating relief valves could not handle pressure

o Designed for 2 kg He/s: incident ~ 20 kg He/s

o Large forces exerted on vacuum barriers

o Designed for 1.5 bar: incident ~ 8 bar

o Several quadrupoles displaced by ~ 50 cm

o Connection to cryo-line damaged

o Beam vacuum atmospheric pressure

15

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

Collateral damage - beam vacuumo Beam vacuum affected over entire length of arc: 2.7 km

16

Beam Screen (BS) : The red color is characteristic of a clean copper

surface

BS with some contamination by super-isolation (MLI multi layer

insulation)

BS with soot contamination. The grey color varies depending on the thickness of the soot, from grey to

dark.

Clean surface Covered with MLI flakes~ 60 % of all chambers

Covered with soot.~ 20 % of all chambers

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

LHC Repair

17

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

THE CAUSE, THE PROBLEM...A CURE?

18

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

Incident cause: poor quality joint

o Cryogenic measurements indicate local resistance of superconducting cable joint of ~ 220 nOhm in cell where incident occured.

o Simulation of fatal ramp: “thermal runaway at 8700 A”o 1 V detection threshold of “OLD” quench protection system (QPS) not adequate

o → 0.3 mV is required to protect busbars → new QPS system 19

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

Busbar quench: current through Cu stabilizer

20

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

Bad connection in Cu stabilizer

→ New QPS does not protect

21

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

o Has to be measured at warm.

Bad Cu stabilizer: bus bar quench

22

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

Measurement at cold: 1.9 Ko Goal for next run: beam energy 4 TeV – 5 TeV

o Splices above inadequate resistance have to be fixed

23

0

2000

4000

6000

8000

10000

12000

10 100 1000

I_ru

n [

A]

R_joint [nOhm]

RRR=240, weak thermal contact (Incident)

RRR=120, no thermal contact (worst case)

0.3 mV

1 mV

0.5 mV

58

5 TeV

Arjan Verweij, TE-MPE, 9 June 2009

25

4 TeV

Cold 1.9K

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

Measurement at300 K (80 K)o Copper stabilizers... “simulations are only as good as their input conditions...”

24

4000

5000

6000

7000

8000

9000

10000

11000

12000

0 20 40 60 80 100 120

Max

. saf

e cu

rren

t [A

]

R_additional [microOhm]

RB, tau=100 s

RB, tau=68 s

RB, tau=50 s

RQ, tau=30 s

RQ, tau=15 s

Adiabatic conditions, without QPS delay, RRR (bus and cable)=160,cable without bonding at one bus extremity, self field included,no contact between bus stabiliser and joint stabiliser.

Arjan Verweij, TE-MPE, 30 June 2009

7052

4 TeV

5 TeV

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

Measurement status & strategyo SC joint measurements: calorimetry (down 40 nOhm), high precision voltage (down

to 1 nOhm) measurements,...

o 3 sectors still to be tested (S34, S23, S45): so far:

o two “bad” internal joints found (50 nOhm, 100 nOhm)

o Cu stabilizers:

o 3 sectors still to be tested (S 23, S 78, S 81): so far:

o MB: 10 joints repaired > 35 Ohm

o MQ: 10 joints repaired > 80 Ohm

o Strategy:

o Measure remaining sectors

o Determine which splices need to be repaired as a function of safe current

o Discuss safe operating energy vs. start-date with beam25

NEW QPS TO PROTECT!

DANGEROUS

IN CASE OF

QUENCH

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

LHC RUN 2009/10 - PLANS

26

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

Current Planning

27

High cur. powering

Low cur. powering

Cool-Down

o Machine fully hardware-tested end of October.

o First beam end of October.

o ...followed by a long LHC run until November 2010 with a short break around Christmas/New Year.

o Target energy 4 – 5 TeV

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

Luminosity Goalso Present 4-stage collimation system limits intensity to ~ 10 % of nominal.

o Operational goals 2009/10

o End of 2010: short Pb ion run foreseen

28

No. bunches/beam

Protons/bunch

% of nominalintensity

* (m)Peak L

(cm-2 s-1)

43 51010 0.7 2 6.9x1030

156 51010 2.4 1 5.0x1031

156 11011 4.8 1 2.0x1032

720 (50 ns) 51010 11.1 2 1.2x1032

No crossing angle

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

...AND BEYOND – LHC UPGRADEsLHC – Luminosity upgrade

29

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

Upgrade for Nominal - Collimationo Issue: loss of off-momentum particles in the dispersion suppressor right downstream

of collimation zones.

30

Coming either 2010/11 or 2013/14

• cryo-collimators

• low impedance collimators → HiRadMat

• in-built BPMs

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

LHC Luminosity Upgrade

31

o Luminosity upgrade → sLHC

F4

fnN*

n

rb

2

b

L

Limitations:Nb, n injector chain nb electron cloud effectF beam separation schemes insertion

sLHC: Phase I

sLHC: Phase II

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

Phase II: 2018

Plans...

32

Phase I: 2014

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

Phase I and Phase II

o Phase I - 2014

o New NbTi larger apterure triplets, new quadrupole absorbers (TAS), new separation dipoles → * = 25 cm

o Linac4 → ultimate intensity 1.7 × 1011 p+ per bunch

o Luminosity: 3 × 1034 cm-2s-1

o Phase II - 2018:

o Two new injectors: SPL and PS2 → 2x ultimate beam brightness (Nb/)

o New triplets? Nb3Sn? More robust, larger aperture → * = 15 cm

o New separation schemes? Other compensatory measures?

o Luminosity: 1035 cm-2s-1

33

Still open questions

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

Phase II: new separation scheme required

34

for nominal crossing angle(“9.5 σ”), only modest luminosity gain from reduced β*, if notcomplemented by other measures

Crossing angle reduces beam-beam tune shift but also luminosity.

21

1F

y,x

zc

2

Geometric factor

Piwinski angle

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

Beam separation schemes/ Compensatory measures: possibilities

o Low emittance: 1- 2m

o Draw back: limited by beam-beam tune shift and IBS

o Work against lumi-decrease from geometric overlap reduction: different possibilities

o Long-range beam-beam compensation

o Early separation: dipole magnets in experiment

o Plus possible crab cavities

o Full crab crossing with dedicated crab cavities

o “Large Piwinski angle” – at beam-beam limit: larger Piwinski angle (and/or larger emittance) increases luminosity: 50 ns, 4.9 × 1011 p+ per bunch

35

SPS wire

Beam-beam compensation

Crab crossing

1.7

-2.3

× 1

01

1 p

er

bu

nch

,2

5 n

s

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

Contact Names - Upgradeo http://project-slhc.web.cern.ch/project-slhc/contacts/

o sLHC project leader: L. Evans

o Linac4: M. Vretenar, A. Lombardi

o SPL: R. Garoby, A. Lombardi

o PS2: M. Benedikt, Y. Papaphilippou

o SPS upgrade: E. Shaposhnikova

o IR upgrade (phase I): R. Ostojic, S. Fartoukh: http://slhc-irp1.web.cern.ch/SLHC-IRP1/

o EuCARD Coordinator: J.-P. Koutchouk https://eucard.web.cern.ch/EuCARD/about/

o Crab cavities: J. Tuckmantel, F. Zimmermann

o Collimators: R. Assmann

o High field magnets: L. Rossi

o ....

o Other things:

o Machine protection, operational issues, software,...: J. Wenninger, R. Schmidt, V. Kain

36

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

Summaryo With beam the LHC is a wonderful machine.

o All key systems were operational

o Remarkable performance of the beam instrumentation

o The incident of the 19th of September was most probably due to the poor quality of a bus-bar joint.

o → Quench protection system upgrade

o → Improvement of the pressure relief system

o → Measurement campaign for all splices and stabilizers: systematic problem

o Repair and further measurements are well under way

o We will start-up in autumn this year. The goal is to run until autumn 2010.

o Upgrade: luminosity upgrade in several stages. Different work packages have been defined.

o Collimators need upgrade to go to nominal intensity

o The first upgrade phase is planned for 2014

37

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

RESERVE SLIDES

38

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

Bad surprise...voids in jointso Voids are present in most of the joints. Solder (SnAg) flows out when soldering in

situ.

39

V. K

ain,

SLA

C, 1

6th -

17th o

f Jul

y 20

09

LHC

Splice and Stabilizer Measurements (Status June 5)

40

Sector Status

on

June 5

2009

Splices

Calorimetric Ohmic

Stabilizers

Biddle R16

Stabilizers

Biddle

1.9K 7kA Warm 80K

Dipoles Quads Dipoles Quads Dipoles Quads

12 warm Done Done Done Done No need No need

23 2K

34 warm Done Done No need No need

45 80K Analysis Problems



78 40K Done Done

81 40K Done Done

lhc status & plans

Documents