Two Scenarios for the LHC Luminosity Upgrade Walter Scandale, Frank Zimmermann Special PAF meeting...
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Transcript of Two Scenarios for the LHC Luminosity Upgrade Walter Scandale, Frank Zimmermann Special PAF meeting...
Two Scenarios for the LHC Luminosity Upgrade
Walter Scandale, Frank Zimmermann
Special PAF meeting 10.04.2007
We acknowledge the support of the European Community-Research Infrastructure Activity under the FP6 "Structuring the European Research Area" programme (CARE, contract number RII3-CT-2003-506395)
outline
• beam parameters • features, IR layouts, merits and challenges
of both scenarios• luminosity evolution• bunch structures• luminosity leveling• summary & recommendations• appendix - LUMI’06 outcome, effect of off-center collisions,
shorter bunches vs crab cavities, Super-LHCb, leveling equations
Name Event DateName Event Date44
W. Scandale/F. Zimmermann, 10.04.2007
parameterparameter symbolsymbol nominalnominal ultimateultimate 12.5 ns, short
transverse emittancetransverse emittance [[m]m] 3.753.75 3.753.75 3.75
protons per bunchprotons per bunch NNbb [10 [101111]] 1.151.15 1.71.7 1.7
bunch spacingbunch spacing t [ns]t [ns] 2525 2525 12.5
beam currentbeam current I [A]I [A] 0.580.58 0.860.86 1.72
longitudinal profilelongitudinal profile GaussGauss GaussGauss Gauss
rms bunch lengthrms bunch length zz [cm] [cm] 7.557.55 7.557.55 3.78
beta* at IP1&5beta* at IP1&5 [m][m] 0.550.55 0.50.5 0.25
full crossing anglefull crossing angle c c [[rad]rad] 285285 315315 445
Piwinski parameterPiwinski parameter cczz/(2*/(2*xx*)*) 0.640.64 0.750.75 0.75
peak luminositypeak luminosity LL [10 [103434 cm cm-2-2ss-1-1]] 11 2.32.3 9.2
peak events per crossingpeak events per crossing 1919 4444 88
initial lumi lifetimeinitial lumi lifetime LL [h] [h] 2222 1414 7.2
effective luminosity effective luminosity (T(Tturnaroundturnaround=10 h)=10 h)
LLeff eff [10[103434 cm cm-2-2ss-1-1]] 0.460.46 0.910.91 2.7
TTrun,optrun,opt [h] [h] 21.221.2 17.017.0 12.0
effective luminosity effective luminosity (T(Tturnaroundturnaround=5 h)=5 h)
LLeff eff [10[103434 cm cm-2-2ss-1-1]] 0.560.56 1.151.15 3.6
TTrun,optrun,opt [h] [h] 15.015.0 12.012.0 8.5
e-c heat SEY=1.4(1.3)e-c heat SEY=1.4(1.3) P [W/m]P [W/m] 1.07 (0.44)1.07 (0.44) 1.04 (0.59)1.04 (0.59) 13.34 (7.85)
SR heat load 4.6-20 KSR heat load 4.6-20 K PPSRSR [W/m] [W/m] 0.170.17 0.250.25 0.5
image current heat image current heat PPICIC [W/m] [W/m] 0.150.15 0.330.33 1.87
gas-s. 100 h (10 h) gas-s. 100 h (10 h) bb PPgasgas [W/m] [W/m] 0.04 (0.38)0.04 (0.38) 0.06 (0.56)0.06 (0.56) 0.113 (1.13)
extent luminous regionextent luminous region l [cm] 4.54.5 4.34.3 2.1
commentcommentpartial wire
c.total heat far exceeds max. local cooling capacity of 2.4 W/m
baselineupgradeparameters2001-2005
abandonedatLUMI’06
(SR and image current heat load well known)
Name Event DateName Event Date55
W. Scandale/F. Zimmermann, 10.04.2007
parameterparameter symbolsymbol 25 ns, small * 50 ns, long
transverse emittancetransverse emittance [[m]m] 3.75 3.75
protons per bunchprotons per bunch NNbb [10 [101111]] 1.7 4.9
bunch spacingbunch spacing t [ns]t [ns] 25 50
beam currentbeam current I [A]I [A] 0.86 1.22
longitudinal profilelongitudinal profile Gauss Flat
rms bunch lengthrms bunch length zz [cm] [cm] 7.55 11.8
beta* at IP1&5beta* at IP1&5 [m][m] 0.08 0.25
full crossing anglefull crossing angle c c [[rad]rad] 0 381
Piwinski parameterPiwinski parameter cczz/(2*/(2*xx*)*) 0 2.0
hourglass reduction hourglass reduction 0.86 0.99
peak luminositypeak luminosity LL [10 [103434 cm cm-2-2ss-1-1]] 15.5 10.7
peak events per crossingpeak events per crossing 294 403
initial lumi lifetimeinitial lumi lifetime LL [h] [h] 2.2 4.5
effective luminosity effective luminosity (T(Tturnaroundturnaround=10 h)=10 h)
LLeff eff [10[103434 cm cm-2-2ss-1-1]] 2.4 2.5
TTrun,optrun,opt [h] [h] 6.6 9.5
effective luminosity effective luminosity (T(Tturnaroundturnaround=5 h)=5 h)
LLeff eff [10[103434 cm cm-2-2ss-1-1]] 3.6 3.5
TTrun,optrun,opt [h] [h] 4.6 6.7
e-c heat SEY=1.4(1.3)e-c heat SEY=1.4(1.3) P [W/m]P [W/m] 1.04 (0.59) 0.36 (0.1)
SR heat load 4.6-20 KSR heat load 4.6-20 K PPSRSR [W/m] [W/m] 0.25 0.36
image current heat image current heat PPICIC [W/m] [W/m] 0.33 0.78
gas-s. 100 h (10 h) gas-s. 100 h (10 h) bb PPgasgas [W/m] [W/m] 0.06 (0.56) 0.09 (0.9)
extent luminous regionextent luminous region l [cm] 3.7 5.3
commentcomment D0 + crab (+ Q0) wire comp.
two newupgradescenarios
compromisesbetweenheat loadand # pile upevents
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannW. Scandale/F. Zimmermann, 10.04.2007
for operation at beam-beam limitwith alternating planes of crossing at two IPs, luminosity equation can be written as
ghprofilebb
p
revb FFQ
r
fnL 22
*21
↓↓ 25 ns ↑↑ 50 ns↓ 50 ns
↓ 50 ns
where Qbb = total beam-beam tune shift
(hourglass effect is neglected above)
Name Event DateName Event Date77
W. Scandale/F. Zimmermann, 10.04.2007
25-ns low-25-ns low- upgrade scenario upgrade scenario• stay with ultimate LHC beam (1.7x10stay with ultimate LHC beam (1.7x101111
protons/bunch, 25 spacing)protons/bunch, 25 spacing)
• squeeze squeeze * to ~10 cm in ATLAS & CMS * to ~10 cm in ATLAS & CMS
• add early-separation dipoles in detectors add early-separation dipoles in detectors starting at ~ 3 m from IP starting at ~ 3 m from IP
• possibly also add quadrupole-doublet possibly also add quadrupole-doublet inside detector at ~13 m from IP inside detector at ~13 m from IP
• and add crab cavities (and add crab cavities (PiwinskiPiwinski~ 0), and/or ~ 0), and/or shorten bunches with massive addt’l rfshorten bunches with massive addt’l rf
→ → new hardware inside ATLAS & CMS new hardware inside ATLAS & CMS detectors, first hadron-beam crab cavities detectors, first hadron-beam crab cavities
(J.-P. Koutchouk et al)
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannW. Scandale/F. Zimmermann, 10.04.2007
CMS & ATLAS IR layout for 25-ns option
ultimate bunches & near head-on collision
stronger triplet magnetsD0 dipole
small-angle
crab cavity
Q0 quad’s
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannW. Scandale/F. Zimmermann, 10.04.2007
challenges: D0 dipole deep inside detector (~3 m from IP),Q0 doublet inside detector (~13 m from IP),crab cavity for hadron beams (emittance growth),
or shorter bunches (requires much more RF)4 parasitic collisions at 4-5 separation,“chromatic beam-beam” Q’eff~z/(4*),poor beam and luminosity lifetime ~*.
merits:negligible long-range collisions,no geometric luminosity loss,no increase in beam current beyond ultimate
25-ns scenario assessment
Name Event DateName Event Date1010
W. Scandale/F. Zimmermann, 10.04.2007
50-ns higher 50-ns higher * upgrade * upgrade scenarioscenario• double bunch spacingdouble bunch spacing
• longer & more intense bunches with longer & more intense bunches with PiwinskiPiwinski~ 2~ 2
• keep keep *~25 cm (achieved by stronger low-*~25 cm (achieved by stronger low- quads alone)quads alone)
• do not add any elements inside detectorsdo not add any elements inside detectors
• long-range beam-beam wire compensation long-range beam-beam wire compensation
→ → novel operating regime for hadron novel operating regime for hadron colliderscolliders
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannW. Scandale/F. Zimmermann, 10.04.2007
CMS & ATLAS IR layout for 50-ns option
long bunches & nonzero crossing angle & wire compensation
wire
compensator
larger-aperture triplet magnets
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannW. Scandale/F. Zimmermann, 10.04.2007
merits:no elements in detector, no crab cavities,lower chromaticity,less demand on IR quadrupoles (NbTi possible),could be adapted to crab waist collisions (LNF/FP7)
challenges: operation with large Piwinski parameter unproven for hadron beams, high bunch charge,beam production and acceleration through SPS,“chromatic beam-beam” Q’eff~z/(4*),larger beam current,wire compensation (almost etablished)
50-ns scenario assessment
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannW. Scandale/F. Zimmermann, 10.04.2007
IR upgrade optics“compact low-gradient” NbTi, *=25 cm
<75 T/m (Riccardo De Maria, Oliver Bruning)
“modular low gradient” NbTi, *=25 cm <90 T/m (Riccardo De Maria, Oliver Bruning)
“low max low-gradient” NbTi, *=25 cm
<125 T/m (Riccardo De Maria, Oliver Bruning)
standard Nb3Sn upgrade, *=25 cm ~200 T/m, 2 versions with different magnet parameters(Tanaji Sen et al, Emmanuel Laface, Walter Scandale)
+ crab-waist sextupole insertions? (LNF/FP7)
early separation with *=8 cm, Nb3Sn includes D0; either triplet closer to IP or Q0; being prepared for PAC’07 (Jean-Pierre Koutchouk et al)
compatiblewith50-nsupgradepath
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannW. Scandale/F. Zimmermann, 10.04.2007
crab waist scheme
cyI
xpH
2
4
1 2
minimizes at s=-x/c
focal plane
realization:add sextupoles at right phase distance from IP
initiated and ledby LNF in the frame of FP7;first beam testsat DAFNE later in 2007
Hamiltonian
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannW. Scandale/F. Zimmermann, 10.04.2007
25 ns spacing
50 ns spacing
IP1& 5 luminosity evolution for 25-ns and 50-ns spacing
averageluminosity
initial luminosity peakmay not be useful for physics(set up & tuning?)
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannW. Scandale/F. Zimmermann, 10.04.2007
25 ns spacing
50 ns spacing
IP1& 5 event pile up for 25-ns and 50-ns spacing
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannW. Scandale/F. Zimmermann, 10.04.2007
old upgrade bunch structure
25 ns
12.5 ns
nominal
25 ns
ultimate
12.5-ns upgrade
abandonedat LUMI’06
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannW. Scandale/F. Zimmermann, 10.04.2007
new upgrade bunch structures
25 ns
50 ns
nominal
25 ns
ultimate& 25-ns upgrade
50-ns upgrade,no collisions @S-LHCb!
50 ns
50-ns upgradewith 25-ns collisionsin LHCb
25 ns
new alternative!
new baseline!
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannF. Zimmermann, W. Scandale, 10.04.2007
luminosity leveling in IP1&5experiments prefer more constant luminosity, less pile up at the start of run, higher luminosity at end
how could we achieve this?
25-ns low- scheme: dynamic squeeze
50-ns higher- scheme:dynamic squeeze, and/ordynamic reduction in bunch length
(less invasive)
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannF. Zimmermann, W. Scandale, 10.04.2007
dynamic squeeze for 25-ns option
N150
N75
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannF. Zimmermann, W. Scandale, 10.04.2007
dynamic squeeze for 50-ns option
N150
we might also reduce the charge/bunchand go for shorter bunches
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannF. Zimmermann, W. Scandale, 10.04.2007
dynamic bunch length change for 50-ns option
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannF. Zimmermann, W. Scandale, 10.04.2007
25 ns, low *,
with leveling
50 ns, long bunches,
with levelingevents/crossing 300 300run time N/A 2.5 h
av. luminosity N/A 2.6x1034s-1cm-2
events/crossing 150 150run time 2.5 h 14.8 h
av. luminosity 2.6x1034s-1cm-2 2.9x1034s-1cm-2
events/crossing 75 75
run time 9.9 h 26.4 h
av. luminosity 2.6x1034s-1cm-2 1.7x1034s-1cm-2
assuming 5 h turn-around time
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannF. Zimmermann, W. Scandale, 10.04.2007
25 ns spacing
50 ns spacing
IP1& 5 luminosity evolution for 25-ns and 50-ns spacingwith leveling
averageluminosity
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannF. Zimmermann, W. Scandale, 10.04.2007
25 ns spacing
50 ns spacing
IP1& 5 event pile up for 25-ns and 50-ns spacingwith leveling
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannF. Zimmermann, W. Scandale, 10.04.2007
150 evts/Xing
example tune shifts with luminosity leveling
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannF. Zimmermann, W. Scandale, 10.04.2007
average luminosity & run time vs. final for 25-ns option with dynamic * squeeze
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannF. Zimmermann, W. Scandale, 10.04.2007
average luminosity & run time vs. final for 50-ns option with dynamic * squeeze
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannF. Zimmermann, W. Scandale, 10.04.2007
average luminosity & run time vs. final z
for 50-ns option with dynamic z change
Name Event DateName Event Date3030
W. Scandale/F. Zimmermann, 10.04.2007
summary summary • two scenarios of L~10two scenarios of L~103535 cm cm-2-2ss-1-1 for which heat load for which heat load
and #events/crossing are acceptableand #events/crossing are acceptable• 25-ns option25-ns option: pushes : pushes *; requires slim magnets *; requires slim magnets
inside detector, crab cavities, & Nbinside detector, crab cavities, & Nb33Sn Sn quadrupolesquadrupoles and/or Q0 doublet; attractive if total and/or Q0 doublet; attractive if total beam current is limited; transformed to a 50-ns beam current is limited; transformed to a 50-ns spacing by keeping only ½ the number of bunches spacing by keeping only ½ the number of bunches
• 50-ns option:50-ns option: has fewer longer bunches of higher has fewer longer bunches of higher charge ; can be realized with NbTi technologycharge ; can be realized with NbTi technology if if needed ; compatible with LHCb ; open issues are needed ; compatible with LHCb ; open issues are SPS & beam-beam effects at large Piwinski SPS & beam-beam effects at large Piwinski angleangle; luminosity leveling may be done via bunch ; luminosity leveling may be done via bunch lengthlength and via and via **
bb
Name Event DateName Event Date3131
W. Scandale/F. Zimmermann, 10.04.2007
recommendationsrecommendations• luminosity levelingluminosity leveling should be seriously should be seriously
considered: considered: → → higher quality events, moderatehigher quality events, moderatedecrease in average luminositydecrease in average luminosity
• it seems it seems long-bunch 50-ns option entails less risklong-bunch 50-ns option entails less risk and less uncertainties; however not w/o problemsand less uncertainties; however not w/o problems
• leaving the leaving the 25-ns option as back up25-ns option as back up until we have until we have gained some experience with the real LHC may gained some experience with the real LHC may be wisebe wise
• needed for both scenarios are needed for both scenarios are concrete optics concrete optics solutionssolutions, , beam-beam tracking studiesbeam-beam tracking studies, and , and beam-beam machine experimentsbeam-beam machine experiments
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannF. Zimmermann, W. Scandale, 10.04.2007
appendix
Name Event DateName Event Date3333
W. Scandale/F. Zimmermann, 10.04.2007
1) quadrupole 1st preferred over dipole 1st
2) pushed NbTi or Nb3Sn still pursued, or hybrid solution - new
3) slim magnets inside detector (“D0 and Q0”) – new
4) wire compensation ~established; electron lens – new
5) crab cavities: large angle rejected; small-angle – new
6) 12.5-ns scenario strongly deprecated
7) e-cloud/pile-up compromise: 25-ns w *~8 cm, or 50-ns spacing, *=0.25 m, long bunches – new
Reminder of LUMI’06 OutcomeReminder of LUMI’06 OutcomeIR upgrade and beam parametersIR upgrade and beam parameters
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannW. Scandale/F. Zimmermann, 10.04.2007
4 parasitic collisions at 4-5 offset in 25-ns low- case
concerns:
• poor beam lifetime • enhanced detector background
discouraging experience at RHIC, SPS, HERA and Tevatron
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannF. Zimmermann, W. Scandale, 10.04.2007
RHIC experiments in 2005 and 2006
single off-center collision
one collision with 5-6 offset strongly reduces RHIC beam lifetime; worse at smaller offsets
(W. Fischer et al.)
24 GeV
100 GeV
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannF. Zimmermann, W. Scandale, 10.04.2007
proton background with 1 head-on and 1 off-center collision vs beam-beam separation (K. Cornelis, LHC99);significantly affected by single LR collision at 3(W.Herrsee also PhD thesis M.Meddahi, CERN SL/91-30, Fig. 22
SPS collider ~1980s
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannF. Zimmermann, W. Scandale, 10.04.2007
HERA ~1992proton beam lifetime drops from 50 h to 1-5 h for single off-center collision with beam-beam separation between 0.3 and 2 (F. Willeke & R. Brinkmann, PAC 93; T. Limberg, LHC’99)
Tevatron 2006removal of the four closest long-range collisions at about 6.2separation has increased integrated Tevatron luminosity per run by up to 30%(V. Shiltsev, private communication)
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannF. Zimmermann, W. Scandale, 10.04.2007
shorter bunches for 25 ns?
• reduced longitudinal emittance 2.5 eVs → 1.78 eVs (loss of Landau damping if z
5frf3Vrf < const Nb Im(Z||/n);
also stronger IBS) • 43 MV rf voltage at 1.2 GHz
(nominal LHC: 16 MV at 400 MHz)• not sufficient to avoid large luminosity loss
(for which crab cavities are needed anyhow)
bunch shortening rf voltage:
c
rfrf
ccrab Rfe
cE
Rfe
cEV
12
0
12
0
42
2/tan
crab cavity rf voltage:
unfavorable scaling as 4th power of crossing angle and inverse 4th power of IP beam size; can be decreased byreducing the longitudinal emittance; inversely proportionalto rf frequency
proportional to crossing angle & independent of IP beam size;scales with 1/R12; also inversely proportional to rf frequency
4*4
4
0
32||,
40
32||,
16 7.02
1
2 x
c
rf
rms
zrf
rmsrf fE
Cc
fE
CcV
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannF. Zimmermann, W. Scandale, 10.04.2007
LHCb recipe for 50-ns scenario
• add satellites at 25 ns spacing• these can be produced by highly asymmetric bunch
splitting in the PS (possibly large fluctuation)• in LHCb satellites collide with main bunches • satellite intensity should be lower than 3x1010 p/bunch
to add <5% to beam-beam tune shift and to avoide-cloud problems; 3x1010 ~ 1/16th of main-bunch charge
• function of ~3 m would result in desired luminosity equivalent to 2x1033 cm-2s-1; easily possible with present IR magnets & layout
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannF. Zimmermann, W. Scandale, 10.04.2007
• here head-on collisions unavoidably contribute to beam-beam tune shift of the bunches colliding in ATLAS & CMS
• two potential ways out:– collisions with transverse offset; concerns: offset
stability, interference with collimation, poor beam lifetime, detector background
– collide at LHCb only in later part of each store, when the beam-beam tune shift from IP1 & 5 has decreased (H. Dijkstra)
LHCb schemes for 25-ns scenario
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannF. Zimmermann, W. Scandale, 10.04.2007
L = L0 exp (-d2/(42))
LHCb collisions with transverse offset d
luminosity:
Q LHCb = 2 QIP1or5 / (d/2tune shift:
suppose tune shift from LHCb should be less than 10% of that from CMS or ATLAS → d>4.5 then luminosity L ~ 0.006 L0
if we wish LLHCb~0.01 LIP1or5 (~1-2x1033 cm-2s-1)
we need * ~0.08 m → IR triplet upgrade!
offset collisions w/o IR upgrade LLHCb ~ 4x1031 cm-2s-1
(for Gaussian distribution)
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannF. Zimmermann, W. Scandale, 10.04.2007
LHCb luminosity for 25 ns with offset & 50 ns
25 ns spacing,4.5 offset,*~0.08 m
50 ns spacing,satellites
LHCb 50-ns luminosity decays 2x more slowlythan 25-ns luminosity or that at ATLAS and CMS
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannF. Zimmermann, W. Scandale, 10.04.2007
25 ns spacing
50 ns spacing
tune shift during store for 25-ns & 50-ns spacing
changeQ ~-0.0033
LHCb 25-ns collisions from middle of each store?! *~3 m (5 h turnaround time is assumed)
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannF. Zimmermann, W. Scandale, 10.04.2007
LHCb luminosity for 25-ns late collisions & 50 ns
25 ns spacing,* ~ 3 m,no transverseoffset
50 ns spacing,*~3 m,satellites
(5 h turnaround time is assumed)
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannF. Zimmermann, W. Scandale, 10.04.2007
S-LHCb collision parametersparameter symbol 25 ns, offset 25 ns, late collision 50 ns, satellites
collision spacing Tcoll 25 ns 25 ns 25 ns
protons per bunch Nb [1011] 1.7 1.7 4.9 & 0.3
longitudinal profile Gaussian Gaussian flat
rms bunch length z [cm] 7.55 7.55 11.8
beta* at LHCb [m] 0.08 3 3
rms beam size x,y* [m] 6 40 40
rms divergence x’,y’* [rad] 80 13 13
full crossing angle c [urad] 550 180 180
Piwinski parameter cz/(2*x*) 3.3 0.18 0.28
peak luminosity L [1033 cm-2s-1] 1.13 2.1 2.4
effective luminosity (5 h turnaround time) Leff [1033 cm-2s-1] 0.25 0.35 0.67
initial lumi lifetime L [h] 1.8 2.8 9
length of lum. region l [cm] 1.6 5.3 8.0
rms length of luminous region:
2
,*
2
222
21
yx
c
zl
PAF/POFPA Meeting 20 November 2006LHC Upgrade Beam Parameters, Frank ZimmermannF. Zimmermann, W. Scandale, 10.04.2007
constLL 0constn
LXingevents
b
inel 0/
IPtot
brun nL
nNt
max
aroundturnb
IPtotave
TnN
nLL
L
max
0
0
1
tn
nLNN
b
IPtot00
beam intensitydecays linearly
length of run average luminosity
leveling equations