the lhc start-up: the few weeks and an outlook

LPC at CMS 27-Apr-2010 CERN Massimiliano Ferro-Luzzi 1

The LHC start-up: The LHC start-up: the few weeks and an outlookthe few weeks and an outlook

2009: – chapter 450 GeV and 1.18 TeV

2010:– chapter 1e27 (3.5TeV)

– chapter 1e28 (3.5TeV) and then...

background ? what's that ?background ? what's that ?


Chapter 450 GeV (and 1180 GeV) 2009Chapter 450 GeV (and 1180 GeV) 2009

5e9p/bch 4x4 1.5e10p/bch 4x41e10p/bch 16x16

mini transv, scans

--++-

+ -

4x4_b’ 4x4_c’4x4_a

wrong RF buckets

16x16_a’

prime indicates that there was a pilot and a +1000 RF buckets shift


Stable beams summaryStable beams summary

“stage” Total hours 4x4 5e9 p/bch 16 hrs 4x4 1.5e10 p/bch 26 hrs16x16 1e10 p/bch 1.5 hrs

43.5 hrs

Estimated numbers of pp interactions recorded by experiments Estimated numbers of pp interactions recorded by experiments

NOT STABLE BEAMS IN STABLE BEAMS (detectors partly on) (full detector on, with

preliminary bkgd subtraction)450 GeV 1.18 TeV 450 GeV

ALICE: 40k 33k ~400k ( 13k +/+ 120k 0/- dip/sol 180k -/- 81k -/0 )

ATLAS: ~340k ~34k ~540k (of which 220k not nominal fields)

CMS: ~110k ~18k ~410k (of which 60k not nominal field)LHCb: ~40k ~320k (of which ~3k with dipole off)LHCf: ~6k showers

TOTEM: with T2: 34 k at 450 GeV, 10k at 2.36 TeV , with RP: 2k halo at 450 GeV

reason why some detectors did not take data at 1.18 TeV (safety!)


Estimated 2009 integrated lumi at 450 GeVEstimated 2009 integrated lumi at 450 GeV

Approximate numbers (~30%) Absolute normalisation yet to be checked Mostly using comparison to results from MC generator (physics,

assuming “known cross section”) combined with detector simulation (acceptance)

ALICE 18 ub ATLAS 12 ub (stable) 19 ub (total) CMS 9.5 ub (quiet or stable) 16 ub (total) LHCb 6.7 ub (stable)

In addition, some 10% of that at 2.36 TeV "quiet" beams (depending on expt)


publications...publications...

ALICE, Eur.Phys.J.C65:111-125,2010 ATLAS, Phys Lett B 688, Issue 1, 21-42 CMS, JHEP 02 (2010) 041


Chapter 1e27: 3.5 TeV, all physics fillsChapter 1e27: 3.5 TeV, all physics fills

1. FillNr 1005, Tue 30.03.2010 13:22 => Tue 30.03.2010 16:29 ~3h

2. FillNr 1013, Wed 31.03.2010 21:03 => Thu 01.04.2010 05:05 ~8h

3. FillNr 1019, Sat 03.04.2010 04:23 => Sat 03.04.2010 07:23 ~3h

4. FillNr 1022, Sun 04.04.2010 17:26 => Mon 05.04.2010 13:29 ~20h

5. FillNr 1023, Tue 06.04.2010 02:44 => Tue 06.04.2010 14:59 ~12.25h

6. FillNr 1026, Wed 07.04.2010 10:28 => Wed 07.04.2010 12:52 ~2.5h

7. FillNr 1031, Sat 10.04.2010 06:13 => Sat 10.04.2010 15:47 ~9.5h

8. FillNr 1033, Mon 12.04.2010 01:24 => Mon 12.04.2010 03:23 ~2h

9. FillNr 1034, Mon 12.04.2010 08:54 => Mon 12.04.2010 17:25 ~8.5h

10. FillNr 1035, Tue 13.04.2010 05:01 => Tue 13.04.2010 09:31 ~4.5h

11. FillNr 1038, Wed 14.04.2010 05:50 => Wed 14.04.2010 10:53 ~5h

12. FillNr 1042, Thu 15.04.2010 06:22 => Thu 15.04.2010 08:54 ~2.5h

13. FillNr 1044, Fri 16.04.2010 05:50 => Fri 16.04.2010 09:12 ~3.5h

14. FillNr 1045, Sat 17.04.2010 05:55 => Sat 17.04.2010 14:58 ~9h

15. FillNr 1046, Sun 18.04.2010 06:06 => Sun 18.04.2010 06:55 ~0.8h

16. FillNr 1047, Sun 18.04.2010 11:28 => Sun 18.04.2010 14:39 ~3.1h

17. FillNr 1049, Mon 19.04.2010 03:55 => Mon 19.04.2010 05:14 ~1.3h


Chapter 1e27Chapter 1e27

2x2, 1 coll. pair, ~1.1e10 p/bch b* = 11-10-11-10 m 1022: record fill of Chapter 1e27 long lumi lifetime 20 hours stable beams ~100/ub


Beam spot parameters (luminous region)Beam spot parameters (luminous region)


Beta star values for now, 2010 (3.5 TeV), unsqueezedBeta star values for now, 2010 (3.5 TeV), unsqueezed

From BE-ABP (Glenn, Vanbavinckhove, Rogelio Garcia Tomas, Rama Calaga and Ryoichi Miyamoto et al)

Betx Beterrx Betxmdl Bety Beterry Betymdl

Beam1

IP1 11.54 0.2017 11.00 12.74 0.45 11.00

IP2 9.205 0.115 9.99 8.92 0.398 9.99

IP5 11.85 0.27 10.99 10.73 0.47 11.00

IP8 10.20 0.69 9.99 11.35 1.24 10.00

Beam2

IP1 9.89 0.27 11.01 12.70 0.15 10.98

IP2 11.54 0.145 9.99 12.04 0.07 10.00

IP5 10.74 0.21 10.96 11.15 0.40 10.98

IP8 9.45 0.15 10.07 9.19 0.05 10.01


Transverse growth, fill 1022Transverse growth, fill 1022

Lumi region PRELIMINARY

ooo vtx resolution unfoldedooo vtx resolution unfolded


beam-gas imaging (rather than background...)beam-gas imaging (rather than background...)


SqueezeSqueeze

10 m to 2 m10 m to 2 m

40 min 40 min

11 m to 2 m11 m to 2 m


CollimationCollimation

IR8IR8 IR1IR1IR2IR2 IR5IR5

Mo

me

ntu

m C

lea

nin

gM

om

en

tum

Cle

an

ing

Du

mp

Pro

tect

ion

Co

l.D

um

p P

rote

ctio

n C

ol.

2 m optics exposes IR’s as expected! Protected by tertiary collimators.

Ralph Assmann and collimation team


Hump...Hump...

Ralph Steinhagen

currently, lumi life time (>10 h!!) dominated by transverse emittance growthcurrently, lumi life time (>10 h!!) dominated by transverse emittance growth


First squeezed stable beamsFirst squeezed stable beams

All experiments: L > 1.1 × 1028 cm-2 s-1

factor ~10 achieved(confirmed by experiments)

New golden orbit: “All IP to 2 m and optimized (stable beams)”

Lost 20-30% of luminosity after first 3 hours of physics (5h30 to 8h30)!

(seems consistent with measured emittance growth)


Chapter 1e28Chapter 1e28

Fill 1058 First physics fill with

b* = 2m in all IPs 3 bunches on 3 bunches

(2 collisions per IP)

IP1 (ATLAS)IP2 (ALICE)IP5 (CMS)IP8 (LHCb)


Integrated lumi (delivered, in STABLE BEAMS)Integrated lumi (delivered, in STABLE BEAMS)

(modulo some possible luminometers down time...)


Mini scans, reproducibilityMini scans, reproducibility

Courtesy of Simon White


vdM scansvdM scans

First tests of van der Meer scans (two dimensional) Use small bunch charge ~1e10 p/bch No long-range beam-beam effects zero crossing angle (IP1 and 5)

=> minimize systematics

=> will allow a first determination of absolute luminosity

Did:

IP5 (3x3, 2 colliding pairs + one parasitic collision)

IP8 (2x2, 1 colliding pair, net internal angle due to sepctrometer bump)

IP1 (2x2, 1 colliding pair)

No time for IP2, to be done soon.


IP5 vdM scanIP5 vdM scan


charm, D’s, J/Psicharm, D’s, J/Psi

Weak bosons (W, Z)Weak bosons (W, Z)

Lumi evolutionLumi evolution

30.3 - 19.410m 2x2 1.1e10 p/bch

30.3 - 19.410m 2x2 1.1e10 p/bch

23.4 - ...2m 3x3 1.1e10 p/bch

23.4 - ...2m 3x3 1.1e10 p/bch

November 7November 7

4 coll pairs5e9 p/bch4 coll pairs5e9 p/bch


Apr 23Apr 23


LHCf

test crossing angle IP1test crossing angle IP1


the next 4 weeks or sothe next 4 weeks or so

Commissioning 450 GeV N=5-10e10p/bch

commissioning

put collimators in ramp

introduce post-squeeze separation collapse

finish dump protection for intensity increase at 3.5 TeV

revisit collimation at 450 GeV (1e11p/bch)

Stable beams 450 GeV at 5e10p/bch 4x4 or 1e11p/bch

2x2, 1 or 2 fills (~1e6 inelastics/IP) 3.5 TeV at 2e10p/bch 2x2, 2m

3.5 TeV at 4.5e10p/bch 2x2, 2m

3.5 TeV at 4.5e10p/bch 4x4, 2m

3.5 TeV at 8e10p/bch 4x4, 2m


Lumi evolutionLumi evolution

why 1/fb ??


LHC, a parton colliderLHC, a parton collider

LHC

e+

e-

+

-

Z

+

-

Zq

q

e+e- collider

Parton Distribution Functions

clockwise proton anticlockwise proton

many “partons”(quarks, gluons, and antis...)


the “Master Plot”the “Master Plot”

Simplified:

For a given center-of-mass energy (s), the larger the mass of the produced system, the steeper the curve

Absolute cross section scales and details of s-behaviour, depend on types of partons involved (gluons, quarks, antiquarks) and on couplings (strong, weak, etc.)

NB: physics bkg typically increase less fast with s than physics signal

W (MW=80 GeV)

Z (MZ=91 GeV)

[nb]


Pedagogical example: Z’ Pedagogical example: Z’ Calculated from eq. (3.16) in arxiv:hep-ph/9805494v1 from Calculated from eq. (3.16) in arxiv:hep-ph/9805494v1 from

A.LeikeA.Leike

/ TeV / TeV


GRAPH DATE: 12 JAN 2009GRAPH DATE: 12 JAN 2009

State of the Art: TevatronState of the Art: Tevatron

Projected integrated lumiProjected integrated lumi

how much by end 2010 ?

per

expe

rim

ent

reco

rde

d

2010 2011

time (years)

10 fb-1

8 fb-1

6 fb-1

Higgs searchHiggs search

per Exptend 2008end 2008

per Exptend 2009end 2009

2004 2005 2006 2007 2008 2009


Ecm

dependence from

ATLAS G4 simulation of eνμν channelassuming gg→H dominantInt. lumi scale uncertainty is ~50%

Tevatron expect 1.9σ sensitivity at m=160 with 8fb-1(one expt)

Higgs 95% CL at LHC, HHiggs 95% CL at LHC, H weak bosons, indicative weak bosons, indicative

Massive loss of sensitivity below 6 TeV

Energy s1/2 14 10 6 TeV

Lumi needed 0.1 0.2 0.6 fb-1

Combined HWW + HZZ: lumi for 95% CL Compare sensitivity to Tevatron with 8 fb-1

( only HWW ll )

To challenge Tevatron at s1/2 = 7 TeV, we need ~500 pb-1 g.d.To challenge Tevatron at s1/2 = 7 TeV, we need ~500 pb-1 g.d.


Z' resonanceZ' resonance

Z': Heavy partner of the Z (SSM)Z': Heavy partner of the Z (SSM) Very clean experimental signal: Z'→ℓℓ

Tevatron 95% CL limit at mZ' =1 TeV

ATLAS fast simulation

Needed luminosity for 95%CL exclusion

at mZ’ = 1 TeV :

s1/2 : 14 10 6 TeV

Lumi: 13 30 110 pb-1

95% CL limit with ~100 pb-1 g.d.for mZ' 1TeV, with s1/2 = 7 TeV

5 discovery possible with ~300 pb-1g.d. 95% CL limit with ~100 pb-1 g.d.

for mZ' 1TeV, with s1/2 = 7 TeV 5 discovery possible with ~300 pb-1g.d.

5 discovery


LHCb (1)LHCb (1)

B cross section does not vary as drastically as for high mass objects (b-bbar is “light“ , ~10 GeV). Thus, the request to go to highest possible energy is milder.

Need ~0.5 fb-1 at s1/2 7 TeV to surpass Tevatron in Bs physics

LHCb 90% C.L. exclusion limits at 8 TeV

BR

(Bs0

μ+μ

- ) (

x10-9

)

b

s

??

b

s

W


Thank you for your attentionThank you for your attention

the lhc start-up: the few weeks and an outlook

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