The TOTEM experiment at the LHC: results and perspective

The TOTEM experiment at the LHC: results and perspective Edoardo Bossini Università degli studi di Siena and INFN-Pisa (on behalf of the TOTEM collaboration) Trieste, 24 Settembre 2013 OUTLINE: Detector overview Total, elastic and inelatic pp cross section Diffractive physics Future upgrades Edoardo Bossini, Trieste, 24 Settembre 2013 1

Totem detector TOTEM detectors Edoardo Bossini, Trieste, 24 Settembre 2013 2

Totem detector: T1 T1: 3.1 4.7 5 equally spaced planes of six trapezoidal Cathode Strip Chambers (CSC) Distance from IP5 ~ 7.5 m Edoardo Bossini, Trieste, 24 Settembre 2013 3

Totem detector: T2 T1: 5.3 6.5 20 almost semi-circular Gas Electron Multi-plier (GEM) detectors per arm Distance from IP5 ~ 13.5 m Edoardo Bossini, Trieste, 24 Settembre 2013 3

Totem detector: RP Very close to the beam, in secondary vacuum 4 stations, 2 units per station, 3 pots per unit(2 vertical, 1 horizontal) 10 planes per pot, 512 edgeless Si strips each Distance from IP5 ~ 147,220 m Edoardo Bossini, Trieste, 24 Settembre 2013 3

Totem detector CMS T1 T1 T2 T2 RP220 T2 T1 T1 T2 RP220 CMS Edoardo Bossini, Trieste, 24 Settembre 2013 4

LHC optic,, Θ, Θ, Transport matrix,, Θ, Θ, Θ Θ Θ + Θ, effective lenghts(sensitivity to scattering angle), magnifications(sensitivity to vertex position) dispersion (sensitivity to Δ ), ~ Edoardo Bossini, Trieste, 24 Settembre 2013 5

LHC optic,, Θ, Θ, Transport matrix,, Θ, Θ, Θ Θ Θ + Θ 90m@220F (,, 0) Edoardo Bossini, Trieste, 24 Settembre 2013 5

Total, elastic and inelastic pp cross sections

Total cross section measurements elastic observation only 16 1 1 d d ( = 0.14 [COMPETE]) independent independent 1 16 d d 1 Edoardo Bossini, Trieste, 24 Settembre 2013 7

Elastic Scattering: event selection in RP Raw hit distribution Elastic selection Beam halo Low-ξ p Aperture limitation The event selection requires the collinearity of the two outgoing protons, the suppression of the diffractive events and the comparison of the horizontal vertex position reconstructed from the left and right arms. Edoardo Bossini, Trieste, 24 Settembre 2013 8

Elastic Scattering: vertex reco RP beam approach Aperture limitation For elastic proton Θ Θ Edoardo Bossini, Trieste, 24 Settembre 2013 9

7 TeV extrapolation Edoardo Bossini, Trieste, 24 Settembre 2013 10

Inelastic Scattering: corrections Search for event with at least 1 «primary» track in T2 Pile up and trigger efficiency estimated with zero-bias triggered events Beam gas estimated triggering on non colliding bunches T2 recostruction eficiency with MC studies Edoardo Bossini, Trieste, 24 Settembre 2013 11

Inelastic Scattering T2 T1 T1 T2 From T1,T2 data Track in T1 (& empty T2) Edoardo Bossini, Trieste, 24 Settembre 2013 11

Inelastic Scattering Rap gap T2 T1 T1 T2 Infered from T1 data Rapidity gap in T2 for 1-arm events (hadronization fluctuation) Edoardo Bossini, Trieste, 24 Settembre 2013 11

Inelastic Scattering T2 T1 T1 T2 Central diffraction (T1,T2 empty) From MC, small correction with big uncertanties Edoardo Bossini, Trieste, 24 Settembre 2013 11

Inelastic Scattering T2 T1 T1 T2 MC based Low mass diffraction (T1,T2 empty) Edoardo Bossini, Trieste, 24 Settembre 2013 11

Total cross section @ 7 TeV EPL 95 (2011) 41001 EPL 96 (2011) 21002 EPL 101 (2013) 21002 EPL 101 (2013) 21003 EPL 101 (2013) 21004 elastic observation only 16 1 1 d d ( = 0.14 [COMPETE]) June 2011 : 98.3 2.8 Oct 2011 : 98.6 2.2 independent independent 1 16 d d 1 99.1 4.3 98.0 2.5 Edoardo Bossini, Trieste, 24 Settembre 2013 12

Total cross section @ 7 TeV EPL 95 (2011) 41001 EPL 96 (2011) 21002 EPL 101 (2013) 21002 EPL 101 (2013) 21003 EPL 101 (2013) 21004 elastic observation only 16 1 1 d d ( = 0.14 [COMPETE]) June 2011 : 98.3 2.8 Oct 2011 : 98.6 2.2 independent independent 1 16 d d 1 99.1 4.3 d d 16 1 measurements 98.0 2.5 ρ 0.14 0.09 Edoardo Bossini, Trieste, 24 Settembre 2013 12

7 TeV: results comparison Edoardo Bossini, Trieste, 24 Settembre 2013 13

8 TeV results Phys.Rev.Lett. 11,012001 16 1 1 d d Luminosity independent 0.14±0.007 [COMPETE] = (101.7±2.9) mb From, measurements 0.362 0.011 0.266 0.006 27.1 1.4 74.7 1.7 Edoardo Bossini, Trieste, 24 Settembre 2013 14

Cross sections summary Edoardo Bossini, Trieste, 24 Settembre 2013 15

Very low measurement Measurement of require the study of the Coulomb Nuclear interference region down to ~6 10 of 1 needed! ħ ħ = relative Coulomb-nuclear phase G(t) = nucleon el.-mag. form factor /, 0 Edoardo Bossini, Trieste, 24 Settembre 2013 16

Coulomb interference Analysis aim: 1. Measure d d at the smallest possible proton t (where the Coulomb interaction can be probed). 2. Fit the data with many theoretical models: evaluate the agreement, extract physics parameters (, ), further improve the measurement. Edoardo Bossini, Trieste, 24 Settembre 2013 17

: preliminary result 0.107 0.027 0.010.. Edoardo Bossini, Trieste, 24 Settembre 2013 18

Charged-particle pseudorapidity density EPL 98 (2012) 31002 Analysis with only T2 telescope 5.3 6.5, 40 Data Vs MC prediction Since about 80% of the T2 reconstructed tracks are secondaries, it has been crucial to find a procedure for primary charged particle identification with strong discriminating power. Analysis has been performed on each quarter independently 7 Edoardo Bossini, Trieste, 24 Settembre 2013 19

Eta distribuiton with CMS New analisys ongoing for 8, with CMS! Both CMS and TOTEM analysis obtained triggering with T2, on the same events. Same CMS-TOTEM event slection (at least a track reconstructed in T2) Edoardo Bossini, Trieste, 24 Settembre 2013 20

Diffractive physics

Event topology RP RP T2 T1 CMS Edoardo Bossini, Trieste, 24 Settembre 2013 22

CERN-PH-EP-2013-170 Double Diffractive This measurement uses data collected in October 2011 at 7. The data were collected with the T2 minimum bias trigger. No leading proton only inelastic detector used Aim: Measurement of soft double diffractive cross section with particle visible to TOTEM T2 (4.7 6.5). Edoardo Bossini, Trieste, 24 Settembre 2013 23

Double Diffractive: analysis Event selection: trigger with T2, at least one track in both T2 hemispheres, no track in T1 («0T1+2T2» topology). ND (Non Diffractive) background estimated scaling the MC prediction using a data sample dominated by ND (tracks on T1 and T2 on both sides) SD (Single Diffractive) background from data using a data sample dominated by SD (tracks only in one side of T2) and requiring proton in the RP Four additional exclusive data samples defined for testing the background model. Edoardo Bossini, Trieste, 24 Settembre 2013 24

Double Diffractive: results for events where for both diffractive masses 3.4 8 Edoardo Bossini, Trieste, 24 Settembre 2013 25

Single Diffractive Edoardo Bossini, Trieste, 24 Settembre 2013 26

Single Diffractive: analysis SD event selected requiring only 1 proton in the RP in events triggered by T2 Diffractive mass can be obtained from the rapidity gap estimation base on charged particle track in T1 and T2 (Δ ). Better resolution for low-medium mass. SD events classified into 4 categories,based on the rapidity gap: Requiring a proton allow strong background rejection Inelastic+beam gas beckground estimated from data, esing mirrored events (diffractive mass and proton on same side) Edoardo Bossini, Trieste, 24 Settembre 2013 27

Single Diffractive: preliminary results Low Mass Medium Mass Correction included: Trigger efficiency Recostruction efficiency Proton acceptance Background substraction Extrapolation to t=0 High Mass Missing: resolution and beam divergence effect Uncertainty (estimated): ~15% ; ~20% Very preliminary: 6.5 1.3 3.4 1100 Very High masses measurement ongoing Edoardo Bossini, Trieste, 24 Settembre 2013 28

Central diffraction (Totem/CMS) Cuts: Vertex 1 Rp near edge removed (background suppression) Rp top-bot/bot-top topology 1.5%, better resolution FSC empty (suppress back.) CMS RP CMS RP MM(pp) = 244 GeV; M(CMS) = 219 GeV Jets 65,45,27 GeV Σ (CMS) = 3.4 GeV

Consolidation and upgrade

Current Setup 2 vertical RP (strip) ~1.5 ~10 5 147 Near 147 Far (200m) 220 Near 220 Far 2 vertical RP (strip) 2 vertical RP (strip) 2 vertical RP (strip) 6 (230m) 1 horiz. RP (strip) 1 horiz. RP (strip) 1 horiz. RP (strip) 1 horiz. RP (strip) ~147 Outgoing beam ~220 CD physics (small cross section) High luminosity needed but How to deal with pile up? Edoardo Bossini, Trieste, 24 Settembre 2013 31

New LHC optics Edoardo Bossini, Trieste, 24 Settembre 2013 32

RP multitrack capability Current limitation: not able to reconstruct events with 2 tracks in same pot Patch 1: move 147 stations to 210 meters and tilt Far RP by ~8 True tracks reco track+ghost Tilt(degree) Patch 2 (long term): replace existing strip detectors with pixel detectors Edoardo Bossini, Trieste, 24 Settembre 2013 33

Timing detector Vertex reconstruction by measuring the time of flight differences of the proton Improve physics capability at moderate pile-up (high-,vertical pots) Reduce trigger rates unisng proton left-right correlation without killing CD signal Signal background simuation has been performed usind real data ( ~9, 8, low, @6 ) to: estimate pile-up scenario in timing dector for 30 optimizing timing sensor cell find effective trigger strategy Edoardo Bossini, Trieste, 24 Settembre 2013 34

Detector segmentation Timing pixel have big impact in detector efficiency Inefficiency due to multiplicity cut reduced by factor ~ 2 w.r.t. fixed square cell size!! Edoardo Bossini, Trieste, 24 Settembre 2013 35

Trigger strategy Trigger strategy: Apply multiplicity cut Edoardo Bossini, Trieste, 24 Settembre 2013 36

Trigger strategy Trigger strategy: Apply multiplicity cut Compute for all combination Edoardo Bossini, Trieste, 24 Settembre 2013 36

Trigger strategy Trigger strategy: Apply multiplicity cut Compute for all combination Select vertex displaced (highest prob. to be isolated) Longitudinal distribution of vertices separated by at least 1 cm from the others Edoardo Bossini, Trieste, 24 Settembre 2013 36

Trigger strategy Trigger strategy: Apply multiplicity cut Compute for all combination Select vertex displaced (highest prob. to be isolated) Send list to CMS HLT to compare with CMS isolated vertex list Few KHz with purity 30%! Longitudinal distribution of vertices separated by at least 1 cm from the others Edoardo Bossini, Trieste, 24 Settembre 2013 36

Trigger strategy Trigger strategy: Apply multiplicity cut Compute for all combination Select vertex displaced (highest prob. to be isolated) Send list to CMS HLT to compare with CMS isolated vertex list Longitudinal distribution of vertices separated by at least 1 cm from the others Few KHz with purity 30%! Ongoing studies on: Clock distribution Detector impedance DAQ & Trigger Edoardo Bossini, Trieste, 24 Settembre 2013 36

Final setup 5 (200m) ~210 Outgoing beam ~10 210 Near 220 Far 2 vertical RP (strip) 1 horiz. RP (strip/pixel) 2 vertical RP (strip) 1 horiz. RP (tilt/pixel) 2 vertical RP (strip) 1 horiz. RP (strip) ~220 ~5 220 Near 220 Far Timing 2 horiz. RP (timing) 2 vertical RP (strip/timing) 1 horiz. RP (strip) TCL 6 6 (230m) Highly flexible/scalable system! Different combinations of tracking+timing can be used to make different physics Edoardo Bossini, Trieste, 24 Settembre 2013 37

Many phisics analysis have been performed.. Total, elastic and inelastic pp cross section at 7 and 8 Foward charged particle pseudorapity distribution at 7 Double diffractive cross section (3.4 8 ) indirect measurements at 7 many others are ongoing Conclusion Hadronic/coulomb interference, measure of at 8 Soft diffractive cross section for 3.4 1100 Foward charged particle pseudorapity distribution at 8 (TOTEM/CMS joint analysis) Other analysis with CMS (softcd and CD with dijets, SD and dijets, pa, ) and many others will begin after the consolidation/upgrade program (and the LHC restart )!! Thanks for your attention Edoardo Bossini, Trieste, 24 Settembre 2013 38

Totem detector: coverage CMS RP T2 T2 T1 T1 T1 T1 T2 T2 RP CMS Edoardo Bossini, Trieste, 24 Settembre 2013 4

DataSet Data at 7, 90 Data at 8, 90 Edoardo Bossini, Trieste, 24 Settembre 2013 52

Elastic cut 1-2 track collinearity 3-4 low cut. If 0 reconstuction equation are invalid 5-6 low cut. If 0 correlation between position and track angle is lost 7 horizontal vertex comparison between opposite arms. Very strong cut Edoardo Bossini, Trieste, 24 Settembre 2013 53

8 TeV extrapolation uncertainties Very good undertanding of beam optic needed!! Edoardo Bossini, Trieste, 24 Settembre 2013 54

Elastic scattering uncertainties (7TeV) Edoardo Bossini, Trieste, 24 Settembre 2013 55

Elastic scattering: model comparison Edoardo Bossini, Trieste, 24 Settembre 2013 56

7 TeV results summary Edoardo Bossini, Trieste, 24 Settembre 2013 57

ZImpact Edoardo Bossini, Trieste, 24 Settembre 2013 58

High eta pseudorapidity correction Edoardo Bossini, Trieste, 24 Settembre 2013 59

Pseudorapidity formula Edoardo Bossini, Trieste, 24 Settembre 2013 60

Pseudorapidity uncertainties (7TeV) Edoardo Bossini, Trieste, 24 Settembre 2013 61

T1/T2 acceptance for diffratctive masses Edoardo Bossini, Trieste, 24 Settembre 2013 62

Models for Hadron/Coulomb region Edoardo Bossini, Trieste, 24 Settembre 2013 63

DPE Cross section Edoardo Bossini, Trieste, 24 Settembre 2013 64

Proton CD and mass acceptance Edoardo Bossini, Trieste, 24 Settembre 2013 34

Segmentation for vertical RP Edoardo Bossini, Trieste, 24 Settembre 2013 66

Cilindrical pots Edoardo Bossini, Trieste, 24 Settembre 2013 67

Cilindrical pots Edoardo Bossini, Trieste, 24 Settembre 2013 68