expectation experiments

3rd LHC Performance Workshop / Session 7 27-January-2011 Chamonix Massimiliano Ferro-Luzzi 1

Expectation experiments...Expectation experiments...

Overview proton run– goals for 2011

– desiderata

Special runs– intermediate energy

* = 90m runs

– luminosity calibration runs

Schedule / scenari

Unless otherwise stated, the units for luminosity are in Hz/cm2


ExperimentsExperiments expectations expectations


– desiderata


* = 90m runs


Schedule / scenari


2010 vs 20112010 vs 2011

2010 was and will remain a pivot year

for the LHC2e32 Hz/cm2

Lucy in High Clouds

Yes, She can fly!


2010 vs 20112010 vs 2011

Exclusion limit @ 90% C.L.

New Physics ?

2011 could be a pivot year for physics

See Bill Murray’s talk (session 4)


2011-2012 run2011-2012 run

Focus has to be on discoveries !

Accommodate other physics requests without substantially

reducing the potential for discoveries – ALICE run at 1.38TeV/beam

– TOTEM programme

– precise lumi calib


Goals for 2011Goals for 2011

Proton runningProton running

Goal for 2011 was already set a year ago:

1 fb-1 delivered to each of IP1, IP5 and IP8 at 3.5 TeV (or >3.5TeV)

Can probably do better for IP1 and IP5 Gimme five … fb-1 ?– You can make the SM Higgs visible or … history

But it will actually be a challenge to deliver 1fb-1 to IP8– consider maximum luminosity and pile-up tolerable to LHCb

Already a big effort from LHCb side to “help” reaching the target:

Lmax : from 2e32 to 3e32 and µmax : from 0.5 to 2.5

– One fb-1 will be just reachable if we make proper choices with lumi leveling (no decay): 3e32 * 110 days * 0.35 = 1 fb-1

fraction in stable beams


Goals for 2011 second partGoals for 2011 second part

Pb running:Pb running:

ALICE’s main requirements: maximisation of luminosity opening of IR2 tertiary collimators (TCTVB) want data at two magnetic field polarities (~ 50-50%)

Additional preferences: zero real crossing angle

– crossing angle acceptable in case of substantial gain in luminosity

bunch separation of 100 ns or larger– smaller separation acceptable in case of substantial gain in luminosity

ALICE support a p-Pb exploration MD during 2011 ion run (for 2012)


Pb run: Goals for 2011Pb run: Goals for 2011

30 µb-1 delivered to each of IP1, IP2 and IP5 at 3.5 TeV

(or higher energy) sounds like a reasonable target.– quadruple statistics * = 1.5 m or smaller ? L x 2.3

– nominal scheme L x 2-5 ? N/N loss ?


General statements on beam conditionsGeneral statements on beam conditions

Energy: the higher the better => Bill Murray’s talk– But watch out the overhead or inefficiency w.r.t. the gain

Bunch spacing– Expts can accept any considered spacing, 150ns, 75 or 50ns (… 25 ns )

Choice of *:

– ATLAS/CMS: the smaller the better (as long as maximizes Lint)

– ALICE: 10m

– LHCb: 3m (I come back to that later)

Choice of N and N: (basically, pile-up)

– ATLAS/CMS built for µ up to ~20

– LHCb built for µ ~0.5, but contorting to cope with ~2.5

– ALICE will use µ < ~0.05

In general: for equal luminosity, less pile-up is better, for example if …

– Lint is bigger when N is reduced (thanks to nb or uptime?), or

– increasing N by x2 allows putting x2 more bunches (stability ?),

then running with the lower pile-up option is better!

choose such that OK for all these spacings choose such that OK for all these spacings

reduce by separation


Filling patternsFilling patterns

Trains 150ns and 50ns:

– start from: maximize collisions in IP1,5,8 => no collisions in IP2

– then, add or shift a few trains to give 10-20 bunches colliding in ALICE 75 ns:

– full collision schedule everywhere => slightly larger separation required for ALICE when exceeding ~600 bunches

TOTEM request Add 1 (or up to 4) small bunches (~1-2e10) that collide in IP1/5, as

long as does not reduce space available for the main bunch trains. – seq: 1 probe, 4b ~1us spacing, intermediate batch, bunch trains


Lumi decay and lumi levelingLumi decay and lumi leveling

Typical 2010 fill at 150ns and 368b

For LHCb 2011:recover this part by luminosity leveling

Factor ~1.4 in integrated lumi per fill.


The LHCb case, pictoriallyThe LHCb case, pictorially

Lmax

Months (push nb, N, N)

C) The best scenario:- Fixed *- With separation leveling

LHCb limited to: (any time during the fill)

1. L(t) ~ 3e32 Hz/cm2 = Lmax

2. µ(t) ~2.5 = µmax

Three possible scenari:

Must be defined for whole of 2011 based on

a guess of absolute 2011 maximum N2/N

Lmax


B) A less bad but not cheap scenario:- 3 * values- No separation allowed

Remember: LHCb was designed for 2808b, L~2e32 and µ~0.5

Remember: LHCb was designed for 2808b, L~2e32 and µ~0.5


Lmax

¼ Lmax

A) The undesiredscenario:- Fixed *- No separation allowed

Ave

rage

fill

lum

inos

ity

lost due to fill lumi decay


What separation ?What separation ?

Proposal:– Start with a chosen and fixed set of values

for { * , N , N }

why not use something like what we had end of 2010 ?

N = 2.5um, N = 1.15e11

and increase nb ~900 (75ns)

– In parallel, MDs to push N , N.

– After X weeks, decide on new { N , N } values and verify if need to change IP8 * (probably not).

IP8: See Werner’s talk

* = 3 m seems to be a good guess

(implement such that minimum impact if need to increase * later)

Typical range ALICE4 TeV, ~12 bunches,10mn=2-3.75umN=1.1-1.2e11

Typical range LHCb4 TeV, 3mn=2-3.75umN=1.1-1.2e11




– desiderata


* = 90m runs


Schedule / scenari


Intermediate energy proton run E=1.38TeV/beamIntermediate energy proton run E=1.38TeV/beam

Requestor:Requestor: ALICE 50 M events to tape

Conditions:Conditions: R = 3…10 kHz inelastic interaction rate * = 10 m IP2/8 (11 m IP1/5)

– NB: All expts want to take data Pile-up: µ < 0.05

– R = f nb µ nb = (3…10kHz)/(11kHz 0.05) = 5…18 b

= 2um: N = (0.05 4 10m 1.36nm/55mb)1/2 = 4e10 p/b Needed: ~35 h of stable beams Setup time: 3 shifts (Mike Lamont)Details: One polarity

– ALICE: any

– LHCb: one polarity gives larger net angle, to be decided

VdM scans during one of the fills (<10% lumi accuracy)

proposed:24b equalitarian scheme16 collisions at each IP=> 200kJi.e. like 4 nominal bunches at 3.5 TeV

1.38TeV

3.5 ZTeV/beam

Pb: Z=82A=208

Equivalent NN centre of mass energy


Intermediate energy proton run WHEN ?Intermediate energy proton run WHEN ?

ALICE point of viewALICE point of view Asap! Needed to extract the best from 2010 Pb data (combined analysis)

ATLAS/CMS point of viewATLAS/CMS point of view Priority should be on establishing asap LHC as 1e33 Hz/cm2 machine! Schedule special runs after having reached 1e33 and collected 1 fb-1

LPC point of viewLPC point of view Run was recommended by LHCC and endorsed by RB

To be scheduled in 2011, with minimal impact on mainstream My hope: use this run as part of the “warm-up” physics period, if this allows to

ramp up the intensity faster than presently proposed

schedule it after the 3-weeks commissioning (when ready for physics) give the EiCs/OPs something less intimidating to start with 5 days to digest the 3-week commissioning

If not a valid proposal, then put the run before/after a TS+MD block. NB: machine runs better and better lumi production more fruitful in second

part of the year…


Intermediate energy run to be scheduledIntermediate energy run to be scheduled

1.38TeV energy run1.38TeV energy runMike’s original proposal

LPC proposal300b 40/pb 1e33 1/fb

back to

with complement

DONE DEAL ?

scru

b

week


TOTEMTOTEM

See M. Deile in LHC 2010 LUMI DAYS here


T1 is inT1 is in


ded

ica

ted

TOTEM wishes for 2011 (ALFA much the same)TOTEM wishes for 2011 (ALFA much the same)

Extended configuration: T1 and RP147 (12 additional pots) + ALFA (8) • Repeat RP alignment at nominal conditions note: needed after each collimator re-alignment extend the exercise for some taking data close to the beam 1 nominal bunch• Special runs with low intensity and normal optics: approach RP to ~5 to reach lowest |t| around 0.2 GeV2 pileup-free data for T2 and T1 ( ~ 10-2) diffractive phys with T1, T2, RP need more statistics for DPE mass spectrum 2 pilots (1x1010 ) + 4 bigger bunches (7x1010 ) L = 10 nb-1 / 3 h (4 TeV, = 2.5m)

(3 runs of 6 hours would give 60 nb -1 )• Constant running at 15 in normal runsimprove statistics at large |t|-values add one pilot bunch to the standard bunch scheme if possible 50 ns operation should be OK for RP & T2 T1 will mainly operate with the pilot• Prepare the * = 90 m optics measure the total cross-section and luminosity in special runs

Replace by adding one probe in above fill.Possibly, some other opportunities later.

ded

ica

ted

ded

ica

ted

para

llel

detectors commissioning not complete before end of august ?


TOTEM-desired Scenario for Runs at TOTEM-desired Scenario for Runs at * = 90 m* = 90 m

ALFA/ATLAS also interested ALICE/LHCb/CMS will profit to take data during these fills as well (10m)

– In particular: LHCb beam-gas imaging lumi calibration

=> probably more than one bunch

N

[um]RP distance(window)

bunches

p/b

L [cm-2 s-1]

µ(inelastic)

|t50| [GeV2]

stat/8 h stat uncertainty

(extrapol.)

3 8 ~1b, 7 x 1010 6.9 x 1027 0.05 0.019 0.2 nb-1 ~ 1.5 %

3 6 ~1b, 7 x 1010 6.9 x 1027 0.05 0.011 0.2 nb-1 ~ 1 %

1 8 ~1b, 6 x 1010 1.5 x 1028 0.1 0.0070 0.4 nb-1 < 1 %

1 6 ~1b, 6 x 1010 1.5 x 1028 0.1 0.0043 0.4 nb-1 < 1 %

Dominated by systematics small RP distance much more important than luminosity !Crucial: good knowledge of the optical functionsRelatively wide beams: x = 0.4 mm, y = 0.6 mm (at roman pots)Contribution from optical functions not larger than angle resolution limit from beam divergenceLy / Ly < 1.1 % or y / y < 1.1 %Lx / Lx < 0.2 % or x / x < 0.2 % (error estimates are based on 1%: sufficient)


90m optics summary90m optics summary

Requestor:Requestor: TOTEM+ALFA 4 physics fills (see previous slide)

Conditions:Conditions: N, N, nb : small, see previous slide.

* = 90 m IP1/5 (10m IP2/8) – NB: All expts want to take data

E = 4 TeV Setup time (MD): 5 shifts (Helmut Burkhardt)

– including RP beam-based alignment at 90m

Proposal:Proposal: one MD per block (as long as it is needed) first MD shift, no physics run following ones, followed immediately by a physics fill (if works) NB: count on more than one bunch for the physics fills


90m optics: when ?90m optics: when ?

MD 90m: 1 shift per block ? RP beam-based alignment, 1.5mafter collimators

physics with a partially filled machine

possibly followed by physics(depending on readiness)


Special lumi calibration fillsSpecial lumi calibration fills

2010: have (already!) reached ~5% lumi uncertainty at 3.5 TeV 2011: aim for 1-2% level => see LHC 2010 LUMI DAYS How ? => see Simon White’s talk later in this session Will benefit from:

– (a) “parasitic” studies, mainly end-of-fill, short measurements in physics conditions

vdm scans, position reproducibility studies, profit from emittance and charge spread to check systematics, co-moving TCTs, etc.

– (b) dedicated fills (~2), in optimal conditions (yet to be agreed upon) likely: “10/11m” optics or “1.5m”, with or without crossing angle (per IP), ~19

bunches of ~6-12e10 p, emittance 2-4 um, “private” bunches per IP

assume: no set up time (shadow of arc, benefit from co-moving TCT)

Scheduling:– If E=3.5 TeV, no urgency for any vdm scan

– If E=4 TeV, urgent to get at least some first results (type (a) above)

– In both cases, the ultimate (type (b) above) could be in second part of 2011

see also MFL session1


summary special requestssummary special requests

E=1.38TeV run

3 shifts setup

35h in stable beams

90m optics

5 shifts MD/setup

4 fills in stable beams

dedicated lumi calibration

2 fills in stable beams

some “eof” studies

this is <10% of mainstream physics time




– desiderata


* = 90m runs


Schedule / scenari


Intensity ramp upIntensity ramp up

bunches

fills Lpeak

(Hz/ub)pb-1 in 10 h fill

pb-1

50b 1 65 1.6 1.6

100b 1 130 3.3 4.9

150b 1 195 4.9 9.8

200b 1 260 6.6 16.4

250b 1 325 8.2 25

300b 3 390 9.9 55

400b 3 520 13.2 95

600b 3 780 19.8 155

800b 3 1040 26.4 230

900b many 1170 29.7 ---

seen in Evian and elsewhere: Intensity steps: 75 ns operation: 50b steps to monitor the pressure and

instabilities (50-100-150-200-250-300). Only one fill if all O.K. - 2 weeks After scrubbing run: 300 – 400 – 600 – 800 – 900 – 2.5 weeks …. Depending on observations

Input:E = 4 TeVN = 1.15e11N = 2.5um* = 1.5m /2 = 120 uradµ = 8.6

includes x0.7 for lumi decay

probably drivenby e-cloud…

max of 150ns

here is when physics starts

here is when the airship can no longer fail

Please, minimize!No physics request

for this.

remember: you gave us already 45 pb-1


How many physics days ?How many physics days ?

EVIAN CHAMONIX (see Malika)

Days

264

- 20

- 30

- 10 or less

- 20 or less

- 7 or less

- 10 or less

167 or more

PREVESSIN

Definitely, there is progress…

Or …. Wandering around CERN

Item Days

Total proton op 264

5 MDs (4 days) - 20

6 TS (4+1 days) - 30

Special requests - 10

Commissioning - 20 to -30

Intensity ramp up - 30 to -40

Scrubbing run - 10

Total High intensity

124 to 144 (135 days for integrated L)


ScenariScenari

150ns 1.1e11p2.5um~400b

1.5m/10m/3msc

rub

bin

g r

un

(th

en t

est

all

sp

aci

ng

s)

75ns 1.1e11p2.5um

up to ~900b1.5m/10m/3m

50ns 1.1e11p~2.5um

up to ~1400b1.5m/10m/3m50ns

successful

unsuccessful150ns 1.1e11p

2.5umup to ~430b

1.5m/10m/3m

75ns OK50ns not OK push up N and

push down N

50ns 1.2e11p~2um

up to 1400b1.5m/10m/3m

scrub in physics?

75ns 1.1e11p2.5um~400b

1.5m/10m/3m

how many hours ? 10 ? 20 ?

preferred by experiments


How to project integrated luminosity ?How to project integrated luminosity ?

Assume

Lstart = start luminosity for physics production = 4.5e32

we know you can do that

Lyeah = luminosity you think could be achieved fairly

quickly (even if it takes a week of scrubbing)

Lyeswecan! = the “asymptotic” luminosity, seems feasible

but there are several unknowns…

124 – 144 days high lumi physics days


Luminosities at s1/2 = 8 TeV

f nb N2 L = –––––––– S() r r = e-d2/22 d = separation

4 N*

Example:

* = 1.5 m N = 1.15 1011 Estored = 70 MJ

N = 2.5 um S() = 0.96 µ = 8.6 (inelastic, 75 mb)

nb = 936 r = 1 = 26.5 um (beam sizes)

1.21033 cm-2 s-1 ~ 30 pb-1 / 10h fill

Try with 1400 bunches, 2um, 1.2e11 …

and pick out your Lyeah and Lyeswecan! .

including overall factor 0.7 for lumi decay


Pro-jectionPro-jection

Suppose: Lstart = 4.5e32 Lyeah = ~1.2e33 Lyeswecan! = 2e33

124 days high lumi physics days

– 35% of that in stable beams, decay factor 0.7

high lumi physics days

144 high lumi physics daysLyeswecan!

Lyeah

Lstart

going to Lyeah asap can make quite a difference at the end

5 fb-15 fb-1SM Higgs is discovered

or SM Higgs is history


Contra-jectionContra-jection

Suppose: Lstart = 4.5e32 Lyeah = ~7e32 Lyeswecan! = 1e33

124 days high lumi physics days

– 35% of that in stable beams, decay factor 0.7

high lumi physics days

144 high lumi physics days


LET’S BE AMBITIOUSLET’S BE AMBITIOUS

fast, secure and far-reaching


backupbackup


Protons: Main requests by the four large experimentsProtons: Main requests by the four large experiments

… beyond the obvious max integrated lumi ATLAS/CMS:

– ATLAS: one low µ fill, µ < 0.01 , 1 µb-1

– both: non-colliding bunch (far behind others) ALICE:

– pp run: 5e29 < L < 5e30, µ < 0.05 (at nb ~650, L limit overtakes µ limit)

– polarity flips (~ at TS)

– intermediate energy run, 50M events on tape LHCb

– polarity flips. The more often the conditions changes, the more frequent the reversals needed

– Lmax = ~3e32 , µmax = ~ 2.5 (at nb ~800, L limit overtakes µ limit)

– Use lumi leveling to maximize integrated lumi Big gain! All:

– possibly, accurate lumi calibration measurements

not needed if small bunch present


2011: aim at dL/L ~ 1-2% ??? will need some studies2011: aim at dL/L ~ 1-2% ??? will need some studies

A few “eof” studies (as much as possible in nominal stable beams)– All-IP //scans and systematic effects due to IR steering “cross-talk”

– Position reproducibility effects (hysteresis ?)

– Co-moving TCTs

– Minimizing (and measuring) charge outside the nominal RF buckets

– B-by-b emittance ctrl (to equalize emittances between beams and bunches)

– VdM scan reproducibility tests (to be agreed upon machine & experiments) scans more useful if can go to +/- 3 sigma separation

the faster, the better (<1 hour)

probe and nominal bunch in same fill: compare small vs large N2 in IP1&5

requires BCTs to work in physics conditions (short spacing)

exact conditions & procedure to be defined

Complementarity: VdM and beam-gas imaging methods (LHCb)– mostly different systematics, but correlated BCT systematics

Complementarity: Direct (Vdm/BGI) vs Indirect methods (elastic/total)– widely different systematics, comparable accuracy reach


How far can we go in separation ? (lumi stability)How far can we go in separation ? (lumi stability)

Assume expt requests a relative stability of luminosity of

|dL/L| < s

At separation x, the lumi leveling factor is

F = e-(x/2)2 = e-(/2)2 where = x/

F-1 dF/d = - / 2

Imposing |dF/F| < s gives (dx/) (x/) < 2 s

Small : get hit twice


Condition for changing energy: Tchge/(Tchge+T4tev) < 0.2 => Tchge < T4tev / 4

sfv

L3.5tev

0.8*L3.5tev

time to change E

3.5 to 4 TeVsame peak lumi

E=3.5TeVE=4TeV

Tchge T4tev

Linzepocket set to 0


Elastic scattering, total cross sectionElastic scattering, total cross section

Measurement of tot via the Optical Theorem with increasing precision.Several runs to study the systematics.Gives also absolute luminosity “indirectly” => complentary to vdm scans


Projections Higgs Projections Higgs See Bill Murray’s talk See Bill Murray’s talk


But Higgs is not everything But Higgs is not everything See Bill Murray’s talk See Bill Murray’s talk

Beauty also counts LHCb expectations for

Bs µ µ (FCNC)

Exclusion limit @ 90% C.L.

And the Bs equivalent of the “Bd CKM angle” (from B factories)

Strongly suppressed in Standard Model!!

Possible enhancement by New Physics!!

New Physics ?

expectation experiments

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