Post on 16-Dec-2015
K.Eggert/CERN
TOTEM PhysicsTOTEM Physics tot
elastic scattering
diffraction (together with CMS)
Karsten Eggert
CERN, PH Department
on behalf of the
TOTEM Collaborationhttp://totem.web.cern.ch/Totem/
Politecnico di Bari and Sezione INFN
Bari, Italy
Case Western Reserve University
Cleveland, Ohio,USA
Institut für Luft- und Kältetechnik, Dresden, Germany
CERN, Geneva, Switzerland
Università di Genova and Sezione INFN Genova, Italy
University of Helsinki and HIP, Helsinki, Finland
Academy of Sciences,Praha, Czech Republic
Penn State University
University Park, USA
Brunel University, Uxbridge, UK
XI th Int. Conf. on Elastic and Diffractive Scattering, Blois, France, May 2005
TOTEM TDR is fully approved by the LHCC and the Research Board
K.Eggert/CERN
TOTEM Physics
Total cross-section with a precision of 1%
Elastic pp scattering in the range 10 -3 < t = (p )2 < 10 GeV2
Particle and energy flow in the forward direction
Measurement of leading particles
Diffractive phenomena with high cross-sections
Different running scenarios (* = 1540, 170, 18, 0.5 m)
K.Eggert/CERN
• Current models predict for
14 TeV: 90 – 130 mb• Aim of TOTEM: ~ 1%
accuracy
Luminosity independent method:
Total p-p Cross-SectionTotal p-p Cross-Section
COMPETE Collaboration:
inelel
ttot NN
dtdN
0
2
)/(
1
16
02
2
1
16L
t
tot dt
dN
inelasticelastictot NN L
Optical Theorem
COMPETE Collaboration fits all available hadronic data and predicts at LHC:
mb 1.41.2
2.1 5.111 tot
[PRL 89 201801 (2002)]
K.Eggert/CERN
T1:3.1 << 4.7
T2: 5.3 < < 6.5
T1 T2 CASTOR (CMS)
RP1 (147 m) RP2 (180 m) RP3 (220 m)
Experimental apparatus
K.Eggert/CERN
T1 and T2 TelescopesT1 and T2 Telescopes
~3 m
T1: Cathode Strip Chambers
Compass APV hybrids400 mmCastor Calorimeter (CMS)
Vacuum ChamberT2: GEMs
2004 Test Beam in X5
<IP5
(see talk of G. Ruggiero)
K.Eggert/CERN
Roman Pot station with two units 4 m apart
Roman Pot unit
-Vertical and horizontal pots mounted as close as possible-BPM fixed to the structure gives precise position of the beam-Final prototype at the end of 2005
BPMBPM
K.Eggert/CERN
Planar technology: Testbeam 40 m dead area
Detector 1Detector 1 Detector 2Detector 2
Edgeless Silicon Detectors for the RPsEdgeless Silicon Detectors for the RPs
active edges(“planar/3D”)
planar technology CTS(Curr. Termin. Struct.)
50
m d
ead
are
a
10
m d
ead
are
a
66 m pitch
Add here photo of RP
Active edges: X-ray measurement
m
Sig
nal
[a.
u.]
5m deadarea
Strip 1 Strip 2
K.Eggert/CERN
Running ScenariosRunning Scenarios
ScenarioScenarioPhysics:Physics:
11low |t| elastic,low |t| elastic,
tot tot ,,
min. bias, min. bias, soft diffractionsoft diffraction
22large |t| large |t| elasticelastic
33diffractiondiffraction
44hard hard
diffractiondiffraction
(under study)(under study)
** [m] [m] 15401540 1818 15401540 170170
N of bunchesN of bunches 4343 28082808 156156 28082808
N of part. per bunchN of part. per bunch 0.3 x 100.3 x 101111 1.15 x 101.15 x 101111 (0.6 - 1.15) x (0.6 - 1.15) x 10101111
1.15 x 101.15 x 101111
Half crossing angleHalf crossing angle
[[rad]rad]
00 160160 00 150150
Transv. norm. emitt. Transv. norm. emitt. [[m rad]m rad]
11 3.753.75 1 - 3.751 - 3.75 3.753.75
RMS beam size at RMS beam size at IP [IP [m]m]
454454 9595 454 - 880454 - 880 270270
RMS beam diverg. RMS beam diverg.
[[rad]rad]
0.290.29 5.285.28 0.29 - 0.570.29 - 0.57 1.71.7
Peak luminosityPeak luminosity
[cm[cm-2-2 s s-1-1]]
1.6 x 101.6 x 102828 3.6 x 103.6 x 103232 2.4 x 102.4 x 102929 ~ 0.5 10~ 0.5 103232
K.Eggert/CERN
TOTEM Optics ConditionsTOTEM Optics Conditions
High- optics for precise measurement of the scattering angle *) = / * ~ 0.3 rad
As a consequence large beam size * = * ~ 0.4 mm
Reduced number of bunches ( 43 and 156 ) to avoid interactions further downstream
Parallel-to-point focusing ( v=0) :
Trajectories of proton scattered at the same angle but at different vertex locations
LTOTEM ~ 1028 cm-2 s –1
TOTEM needs special/independent short runs at high-**1540m1540mand and lowlowScattering angles of a few rad
y = Ly y*+ vy y* L = ()1/2 sin (s)
x = Lx x *+vx x*+Dx v = ()1/2 cos (s)
Maximize L and minimize v
K.Eggert/CERN
v= ()1/2 cos (s)
L = ()1/2 sin (s)
High optics ( 1540 m ): lattice functions
DxvLx
yvLy
xxx
yy y
**
**
L (m)
v
Parallel to point focusing in both projections
K.Eggert/CERN
Elastic Scattering* = 1540 m
acceptance
K.Eggert/CERN
Elastic Scattering: ResolutionElastic Scattering: Resolutiont-resolution (2-arm measurement) -resolution (1-arm measurement)
Test collinearity of particles in the 2 arms Background reduction.
correlation in DPE
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Elastic Cross section (t=0)
Uncertainty Fit error
Beam divergence 10% -0.05%Energy offset 0.1% -0.25% 0.05% -0.1%Beam/ detector offset 100m -0.32/-0.41 % 20m -0.06/-0.08 %Crossing angle 0.2rad -0.08/-0.1%
Theoretical uncertainty (model dependent) ~ 0.5%
Beam offset (20 m)
Energy offset (0.1%)
Beam offset (100 m)
Statistical error
L dt=4 1032 cm-2
tmax = 0.1 GeV2
K.Eggert/CERN
Extrapolation uncertainty due to Coulomb interference
Change of the slope BCoulomb interference
Extrapolation to t=0 model dependent
Error < 0.5 % d/dt ~ exp( -Bt)
K.Eggert/CERN
Accuracy of tot
(inel.~80mb, el.~30mb)
(mb)(mb) Double Double armarm
Single armSingle arm After ExtrapolationAfter Extrapolation
Minimum biasMinimum bias 5858 0.30.3 0.060.06 0.060.06
Single diffractiveSingle diffractive 1414 -- 2.52.5 0.60.6
Double diffractiveDouble diffractive 77 2.82.8 0.30.3 0.10.1
Double PomeronDouble Pomeron 11 -- -- 0.020.02
Elastic ScatteringElastic Scattering 3030 -- -- 0.10.1
Trigger Losses (mb)
Acceptance
Vertex extrapolation
01.0005.00.008 22
tot
tot
simulated
extrapolated
detected
Inelastic error t=0 extrapol. error
K.Eggert/CERN
Try to reach the Coulomb region and measure interference:
• move the detectors closer to the beam than 10 + 0.5 mm• run at lower energy √s < 14 TeV
Possibilities of Possibilities of measurement measurement
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Elastic Scattering Cross-SectionElastic Scattering Cross-Section
diffractive structure
Photon - Pomeron interference
pQCD
* = 1540 m
L = 1.6 x 1028 cm-2 s-1
(1)
*=18 m
L = 3.6 x 1032 cm-2 s-1
(2)
pp 14 TeVBSW model
Multigluon (“Pomeron”) exchange e– B |t|
-t [GeV2]
t p2 2
d/ d
t [m
b / G
e V2 ]
~1 day(1) (2)
wide range of predictions
104 per bin
of 10-3 GeV2
K.Eggert/CERN
> 90 % of all diffractive protons are detected10 million min. bias events, including all diffractive processes, in a 1 day run with * = 1540 m
CMS+TOTEM: largest acceptance detector ever built at a hadron collider
Ro
ma
n P
ots
TOTEM+CMS
T1,T2 T1,T2
Ro
ma
n P
ots
Charged particles
Energyflux
CMS + TOTEM: AcceptanceCMS + TOTEM: AcceptancedNdN
chch/d/d
dE/d
dE/d
Total TOTEM/CMS acceptance (*=1540m)
RPs
=172m=172m(prelim.)(prelim.)
K.Eggert/CERN
CMS/TOTEM PhysicsCMS/TOTEM Physics
CMS / TOTEM detector ideal for study of diffractive and forward physicsCMS / TOTEM detector ideal for study of diffractive and forward physics
Soft and hard diffraction in Single and Double Pomeron Exchangeproduction of jets, W, J/, heavy flavours, hard photons
Excellent proton measurement: gap survival
Double Pomeron exchange as a gluon factory
Production of low mass systems (SUSY, ,D-Y,jet-jet, …)
Glue balls, …
Higgs production ???
Structure functions (parton saturation) with and without detected protons
Forward physics: DCC, particle and energy flow
physics
K.Eggert/CERN
TOTEM+CMS Physics: Diffractive EventsTOTEM+CMS Physics: Diffractive Events
X
XDoublePomeronExchange
-Triggered by leading proton and seen in CMS-Central production of states X: X = c, b, Higgs, dijets, SUSY particles, ...
Measure > 90% of leading protons with RPs and diffractive system ‘X’ with T1, T2 and CMS.
K.Eggert/CERN
Running ScenariosRunning Scenarios
ScenarioScenarioPhysics:Physics:
11low |t| elastic,low |t| elastic,
tot tot ,,
min. bias, min. bias, soft diffractionsoft diffraction
22large |t| large |t| elasticelastic
33diffractiondiffraction
44hard hard
diffractiondiffraction
(under study)(under study)
** [m] [m] 15401540 1818 15401540 170170
N of bunchesN of bunches 4343 28082808 156156 28082808
N of part. per bunchN of part. per bunch 0.3 x 100.3 x 101111 1.15 x 101.15 x 101111 (0.6 - 1.15) x (0.6 - 1.15) x 10101111
1.15 x 101.15 x 101111
Half crossing angleHalf crossing angle
[[rad]rad]
00 160160 00 150150
Transv. norm. emitt. Transv. norm. emitt. [[m rad]m rad]
11 3.753.75 1 - 3.751 - 3.75 3.753.75
RMS beam size at RMS beam size at IP [IP [m]m]
454454 9595 454 - 880454 - 880 270270
RMS beam diverg. RMS beam diverg.
[[rad]rad]
0.290.29 5.285.28 0.29 - 0.570.29 - 0.57 1.71.7
Peak luminosityPeak luminosity
[cm[cm-2-2 s s-1-1]]
1.6 x 101.6 x 102828 3.6 x 103.6 x 103232 2.4 x 102.4 x 102929 ~ 0.5 10~ 0.5 103232
K.Eggert/CERN
TOTEM
log()
log(-t)
Diffractive protons are observed in a large -t range> 90% are detected
-t > 2.5 10 -3 GeV2
10-8 < < 0.1
resolution ~ few ‰
Diffractive protons at *=1540 m
K.Eggert/CERN
Diffractive proton detection at 0.5 m> 2.5 %
mm
log
log -t
420
(mm)
(mm)(mm)
(mm)
log -t
log
K.Eggert/CERN
New optics m
• Ly large (~270 m)
tmin =2 x 10-2 GeV2
• Lx ~ 0 independent
• Vertex measured by CMS
determination with a precision of few 10 -4
To optimize diffractive proton detection at L=1032 in the “warm” region at 220m
Lyy Lxx+vxx+D
=0-2
10m (CMS)
30mm
~ 65% of all diffractive protons are seen
10 beam
K.Eggert/CERN
Diffractive protons at =172 m
Log() vs Log(-t)
TOTEM
Pre
limin
ary
Log() vs Log(-t)
TOTEM
Prelim
inar
y
420
K.Eggert/CERN
Conclusion on new optics (*=172 m) - preliminary
• Luminosity of 0.5 x 1032 cm-2 s-1
• About 65% of diffractive protons are seen in the RP at 220 m
• resolution of 4 10 -4
• resolution of few rad
Future: • more detailed studies on resolution
• further optimization towards higher luminosities
K.Eggert/CERN
Example ProcessesExample Processes
2
22 '
p
pp
P
p1
p2p2’
X d/dproton:p2’
diffractive system Xrapidity gap =–ln
min 0ln(2pL/pT)max
Measure leading proton ( and rapidity gap ( test gap survival).
Single Diffraction:
2=– ln 1=– ln
p1
p2 p2’
p1’
PMX
2 = s
P
X
diffractive system Xproton:p2’
proton:p1’
rapidity gaprapidity gap
min max
Double Pomeron Exchange:
Measure leading protons ( 1, 2) and compare with MX, 1, 2
MX2 = s
K.Eggert/CERN
Exclusive Central DiffractionThe Pomeron has the internal quantum numbers of vacuum.
PP: C = +, I=0,...
P: JP = 0+, 2+, 4+,...
PP: JPC = 0++
Gap GapJet+Jet
p1
p2p2’
p1’
P
P
diffractive systemproton:p2’proton:p1’
rapidity gaprapidity gap
min max
min max
Signature:2 Leading Protons &2 Rapidity Gaps
Exclusive physics Gluon factory Threshold scan for New Physics
Large mass objects O(1TeV)
c: 10 6-7 events before decay
b: 10 3-4 events before decay
- a precursor to DPE Higgs, SUSY
K.Eggert/CERN
Exclusive Production by DPE: ExamplesExclusive Production by DPE: Examples
Advantage: Selection rules: JP = 0+, 2+, 4+; C = +1 reduced background, determination of quantum numbers.Good resolution in TOTEM: determine parity: P = (-1)J+1 d/d~ 1 +– cos 2
ParticleParticle exclexcl Decay channelDecay channel BRBRRate at Rate at
22xx10102929 cm cm-2-2 s s-1-1
Rate at Rate at
10103131 cm cm-2-2 s s-1-1
(no acceptance / analysis cuts)(no acceptance / analysis cuts)
c0c0
(3.4 GeV)(3.4 GeV)3 3 b b [KMRS][KMRS]
J/J/ ++––
+ + – – KK+ + KK––
6 x 106 x 10-4-4
0.0180.018
1.5 / h1.5 / h
46 / h46 / h
62 / h62 / h
1900 / h1900 / h
b0b0
(9.9 GeV)(9.9 GeV)4 nb 4 nb [KMRS][KMRS] ++–– < 10< 10-3-3 0.07 / d0.07 / d 3 / d3 / d
HH
(120 GeV)(120 GeV)
0.1 0.1 100 fb 100 fb
assume 3 fbassume 3 fbbbbb 0.680.68 0.02 / y0.02 / y 1 / y1 / y
Higgs needs L ~ 1033 cm-2 s-1, i.e. a running scenario for = 0.5 m:• try to modify optics locally,• try to move detectors closer to the beam,• install additional Roman Pots in cold LHC region at a later stage.
K.Eggert/CERN
y = – ln
ymax = 6.5
Trigger via Roman Pots > 2.5 x 10-2
Trigger via rapidity gap < 2.5 x 10-2
* = 1540 m: ~ 0.5% L 2.4 x 1029 cm-2 s-1
* = 172 m: ~ 0.2 - 0.4 L ~ 0.5 1032 cm-2 s-1
* = 0.5 m: ~ 0.2-0.6 ‰ L ~ 1033 cm-2 s-1
Detection Prospects for Double Pomeron EventsDetection Prospects for Double Pomeron Events
dN/dy
– ln – ln
y
pp
CMS
CMS + TOTEM
p1
p2 p2’
p1’
PM2 = s
P
* = 0.5 m
K.Eggert/CERN
ExHume
Phojet
log -t
log -t
log
log
input
and t distributions for 120 GeV Higgs
Proton acceptance 68%
Proton acceptance 63%
Detected protons at 220 m
K.Eggert/CERN
ExHume
Phojet
Mass Acceptance in DPE (preliminary)
=172 m
=0.5 m
220 m
420 m
420 + 220 m
ExHume
Phojet
Totem
Prelim
inar
y
K.Eggert/CERN
420m PHOJET
Asym. 420+215 m
420m EXHUME
Mass resolution at 420 m and 420+220m
Note:beam position accuracy 10 m
K.Eggert/CERN
p1
p2 p2’
p1’
PMX
2 = s
P
X
DPE cross-sections
=1540 m ∫L dt = 40 nb-1
3days
=172 m ∫L dt = 10 pb-1
3days
c0 3b x BR(10-3) ~ 3 nbb0 4nb x BR(10-3) ~ 4 pb
• pp pXp ~ 0.1 - 1 mb• pp p j1 j2 p ptjet >10 GeV inclusive ~ 1 b exclusive ~ 7 nb
jet-jet background to the Higgs:• pp p j1 j2 p
M(j1 j2) = 120 GeV exclusive ~ 18 pb / M= 10 GeV (Eur. Phys. J.C25,391)
K.Eggert/CERN
K.Eggert/CERN
ConclusionsConclusions
Measure Measure total cross-section total cross-section tot tot with a precision of with a precision of 1 % 1 % LL = ~10 = ~1028 28 cmcm-2-2 s s-1-1 with with * * = 1540 m= 1540 m
Measure Measure elastic scatteringelastic scattering in the range in the range 10 10 -3-3 < t < 8 GeV < t < 8 GeV 22
With the same dataWith the same data study of study of soft diffraction and forward physicssoft diffraction and forward physics::~ 10~ 1077 single diffractivesingle diffractive events events~ 10~ 1066 double Pomerondouble Pomeron events events
With With * * = 1540 m optics at = 1540 m optics at LL = 2 = 2 10 1029 29 cmcm-2-2 s s-1-1 : :semi-hard diffraction (psemi-hard diffraction (pTT > 10 GeV) > 10 GeV)
With With * * = 170 m optics (under study) at = 170 m optics (under study) at LL ~ 0.5 10 ~ 0.5 1032 32 cmcm-2-2 s s-1-1::hard diffraction and DPEhard diffraction and DPE
Study of rare events (Higgs, Supersymmetry,…) with Study of rare events (Higgs, Supersymmetry,…) with * = 0.5 m* = 0.5 musing eventually detectors in the cold region (420m)using eventually detectors in the cold region (420m)
TOTEM and CMS will write a common physics LOI in 2005
K.Eggert/CERN
K.Eggert/CERN
DiffractionDiffraction
Exchange of colour singlets (“Pomerons”) rapidity gaps Most cases: leading proton(s) with momentum loss p / p
P() = e-, = dn/d
p
p
g, qg, q
Exchange of colour triplets or octets:Gaps filled by colour exchange in hadronisation
Exponential suppression of rapidity gaps:
p
p
p
p
P
P
Unlike minimum bias events:
Example:
K.Eggert/CERN
02
2
1
16L
t
tot dt
dN
inelasticelastictot NN L inelel
ttot NN
dtdN
0
2
)/(
1
16
Optical Theorem
T1:3.1 << 4.7
T2: 5.3 < < 6.5
K.Eggert/CERN
Determination of the emission angle via the measurement at RP-147 m
x (147 m)
precision ~ few rad
K.Eggert/CERN
Measurement of Measurement of tottot
Measurement of the total cross section with the luminosity Measurement of the total cross section with the luminosity independent method using theindependent method using the Optical TheoremOptical Theorem..
02
2
1
16L
t
tot dt
dN
inelasticelastictot NN L inelel
ttot NN
dtdN
0
2
)/(
1
16
Measurement of the elastic and inelastic rate with a precision better than 1%.
K.Eggert/CERN
Particle elongation (x) for Lx=0 and different -values
Lx = 0
x(m)x(m)
s(m) s(m)
Example at =0.007 and different emission angles
Lx=0
Lx
K.Eggert/CERN
X22
0-x
216 (m
)
(x220+x216)/2 (mm)
2
2
=172 m: resolution ~ 4 10-4 (preliminary)
TOTEM
Prelim
inar
y
= 10-3 2 10-3
K.Eggert/CERN
Detector Layout y(m
m)
y(m
m)
y(m
m)
x(mm) x(mm) x(mm)
Leading diffractive protons seen at different detector locations (* = 0.5m)
215m 300m 420m
Dispersion D = 0.08 m D=0.7m D=1.5m