& stato dell’esperimento Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC Prime misure di TOTEM & stato dell’esperimento Stefano Lami INFN Pisa

Principali attivita` tecniche 2010 Presa dati in IP5 : RP (220 m) + T2 Produzione RP (147 m) + Test in H8 T1 Test in H8 T1 Preparazione installazione in IP5 (+/- side) (Tools, EDR, ESR, LHCC rev.) T1 Lavori d’installazione in IP5 (7.12.2010) RP Installazione a 147m (7.12.2010) T2 Lavori di manutenzione (7.12.2010)

Presa dati 2010 L’ottima performance di DAQ & Trigger ha permesso: Installato ora Operativo nel 2010 Installate ora Operative nel 2010 3.1  h  4.7 5.3  h  6.5 L’ottima performance di DAQ & Trigger ha permesso: Periodi di presa dati con RP a ~18s dai fasci, grandi t~3.5 GeV2 Special TOTEM Runs: 21.9.2010 RP “alignment” at 3.5 TeV to define a safe running condition with the pots as close as possible to the circulating beams Short data taking (one pilot bunch) with RP to 7s 30.10.2010 Special run with 1 bunch (1e10 p/b) + 4 bunches x 7e10 p/b 5 hours data taking for TOTEM data with T2 at reduced pile-up on mini-bunch crossing (~ 10-2) RP at int. L 20 sigma 184 nb-1   18 sigma 3.5 pb-1 7 sigma 9.5 nb-1 (1 y(x) = 0.42 (0.19) mm @ β* = 3.5m)

Prime misure di Scattering Elastico: il sistema delle Roman Pot scattering angle q Horizontal Pot Vertical Pot BPM

Tracce ricostruite (RP220 raw distribution) Hit map (side 4,5) - Coincidenze Left - Right |t|~p2q*2 x = Dp/p * = at IP Lx~0 , vx,y small at 220m for x 0 Reconstructed tracks in “left (45) AND right (56)” Elastic scattering in the vertical plane visible from raw data

Collinearity in qx Low x, i.e. |x| < 0.4 mm and 2s cut in Dqy* Compatible with the beam divergence (17 rad, for nominal  = 3.75 m rad)

Collinearity in qy Low x, i.e. |x| < 0.4 mm and 2s cut in Dqx* Compatible with the beam divergence

Preliminary t distribution ~ 84K elastic scattering candidate events in ~ 9 nb -1 s = 7 TeV * = 3.5 m RPs @ 7 (V) and 16 (H) “Raw” distribution: - No smearing corrections - No acceptance corrections - No background subtraction Syst. error sources under study: alignment, beam position and divergence, background, optical functions, efficiency, … 0.7 GeV2

Elastic Scattering - from ISR to Tevatron ~ 1.7 GeV2 ~ 0.7 GeV2 ~1.5 GeV2 Diffractive minimum: analogous to Fraunhofer diffraction: |t|~p2 q2 exponential slope B at low |t| increases minimum moves to lower |t| with increasing s  interaction region grows (as also seen from stot) depth of minimum changes  shape of proton profile changes depth of minimum differs between pp, pˉp  different mix of processes

Telescopio T2 GEM telescopes for tracks and vertex reconstruction 5.3<|h|<6.5 Df=2p T2 trigger in “special run” min-bias only on minibunch

Alcuni eventi ricostruiti da T2 6 tks 4tks 5 tks 4 tks 9 tks 8 tks 46 tks 39 tks

Min. bias events and elastics in T2

Single diffraction low x

T2 - Preliminary Work ongoing on unfolding corrections Data from 30/10/2010 TOTEM special run - trigger: min bias on mini-bunch only (~400K inelastic events) Raw distribution including secondaries pointing to IP and no efficiency correction Work ongoing on unfolding corrections

Towards the Unfolding Corrections Preliminary study with PYTHIA + full GEANT detector simulation Work in progress on: - Understanding secondary contribution and smearing effects - Proper tuning of detector performance simulation - Optimization of track algorithm and selection cuts for improved rejection of secondary charged tracks - Estimate of systematic uncertainties IP5 HF Beam Pipe cone at  ~ 5.54 (>100 radiation lengths)

Lavori durante lo Shutdown General installation schedule T1 – Installation of both arms Installation started on 7.12.2010 Minus side fully installed by 10.01.2011, Plus side by 14.01.2011 First tests OK, Commissioning with first data T2 – Service Work packages were integrated in T1 installation schedule Priority given to T1 installation RP (147m) at 4/5 and 5/6 RP installation started on 7.12.2010, installed by end 2010 Calibration: main activity in 2011

RP installation at 147m during shutdown TOTEM has installed the last 12 detectors in the LHC tunnel (“147 m”) completing in this way the detectors installation 12 detector packages have been produced, completely assembled by Nov 2010; final checks with particles were completed in H8 All services for the RPs at 147m were already installed. Installation in the tunnel completed by end 2010. Under test TIF H8

T1 installation Update on mechanical components (EDR with CMS held on June 2010) Update on electrical components (ESR with CMS held on September 2010) 30 Nov 2010: Final Installation Review with CMS Installation at IP5 (7.12.2010 – 21.01.2011) All issues have been monitored by TOTEM and CMS and followed up in close collaboration Detailed installation planning, required the presence of the T1 /CMS team during Christmas break Schedule finalized with manpower from CERN & INFN

Summary of main Review issues TRUSS installation tool (Cantilever): new tool built, stress calculations, certificate (DGS-SEE) Transfer of T1: from cage truss, successful for all 4 telescopes Survey: measurement of deformation during & after transfer, shimming Mock up simulating CMS-YE: measurement of clearance during/after transfer Leak test of cooling system Sensors (B, position) mounted Alignment system of CMS traversing T1: checked all cables for possible interference Electrical consolidation: shielding, grounding, low voltage connectors Mock up simulates CMS-YE T1 supported by cage Transfer rails IP side Al Truss

Installazione T1 lato ‘–’ 21/12/2010 Installazione del traliccio di supporto 22/12/2010 Posizionamento in piattaforma del rivelatore nelle gabbie di installazione 22 - 30/12/2010 Connessione temporanea ai servizi e test in piattaforma

Installazione T1 lato ‘–’ 7/1/2011 Prova di inserimento dei due semibracci 10/1/2011 Inserimento del rivelatore, connessione finale servizi lato rivelatore 13/1/2011 Innalzamento piattaforma

Installazione T1 lato ‘+’ 20-30/12/2010 Installazione servizi (gas, raffreddamento, fibre ottiche) su YE3+ 10/1/2011 Installazione traliccio di supporto 11/1/2011 Posizionamento in piattaforma del rivelatore nelle gabbie di installazione 11 - 12/1/2011 Connessione temporanea ai servizi e test in piattaforma

Installazione T1 lato ‘+’ 13/1/2011 Prova di inserimento dei due semibracci (1 giorno di anticipo) 14/1/2011 Inserimento del rivelatore, connessione finale servizi lato rivelatore (1 giorno di anticipo) 20/1/2011 Innalzamento piattaforma

Test completo 21/1/2011 Connessione finale servizi e test completo sull’intero rivelatore (accensione e lettura di tutte le camere in run di rumore)

Test sul rivelatore Ad ogni passo dell’installazione di ciascun braccio (T1 in piattaforma, T1 inserito, T1 inserito e piattaforma sollevata) sono stati ripetuti i test sul rivelatore: tenuta alta tensione; corretta lettura dei sensori; presenza di tutti i canali di lettura e scan di soglia per il livello di noise La corretta mappatura dei canali di DCS e DSS è stata verificata A rivelatore inserito, un test congiunto con le CSC di CMS è stato effettuato da entrambi i lati: nessun contributo di rumore aggiuntivo riscontrato dai due rivelatori quando l’altro è acceso. Soglie per rumore < 5% (tutti i VFAT) misure in H8 (Nov 2010) misure dopo l’installazione soglia (canali ADC)

Detector Control System Durante i test, il controllo dello stato e delle operazioni del rivelatore è stato effettuato interamente utilizzando i pannelli del DCS di TOTEM

Posizione del rivelatore Le misure effettuate durante i test di inserzione hanno permesso di verificare il corretto posizionamento delle camere rispetto al tubo a vuoto di LHC e all’end-cap di CMS La posizione delle camere è costantemente mantenuta sotto controllo dai sensori di posizione

TOTEM Running Strategy for 2011 Understand the new optics and improve statistics at large t-values Repeat RP alignment at nominal conditions: approach the RP detectors to the sharp beam edges produced by the LHC collimators For regular running at closer approaches to the beams (~15s) Low proton density bunches (~1 1010 p/b) Special runs with such bunches: Approach RP to ~ 5s to reach a minimum t of ~ 0.2 GeV2 Addition of one small bunch during normal low b runs (if possible) Take data with T1, T2 at reduced pile-up (< 10 -2 ) Prepare the b* = 90 m optics Measure the total cross-section and luminosity at 7 TeV (small difference if running at 8 TeV) Targets: With b*=90m optics and RP close to the beams measure stot and sel Correlations between the forward proton and topologies in T1 and T2 with a rich programme on Single Diffraction and Double Pomeron exchange

Backup

Telescopi per Inelastico: Apparato Sperimentale ~14 m CMS T1: 3.1 < |h| < 4.7 CSC Trackers T2: 5.3 < |h| < 6.5 GEM Trackers 10.5 m T1 T2 HF Telescopi per Inelastico: Roman Pots: RP2 RP1 147 220

T1 Telescope with Cathode Strip Chambers (CSCs) CMS muon end-caps 5 planes with measurement of 3 coordinates per plane 3 deg rotation and overlap between adjacent planes Primary vertex reconstruction allows background rejection Trigger with anode wires 3m 3.1 < |η| < 4.7

CSC efficiencies with muons (triple coincidences) T1 Telescope Both arms assembled and successfully tested with pion and muon beams in the test line H8 rec. hits (transverse plane) Efficiency CSC efficiencies with muons (triple coincidences) Pions on Cu target to get many-trk events Longitudinal vertex reconstruction Cu target Beam monitor frame sz ~ 80-90 cm Vtx-X (z<1m) sx ~ 3-4 cm Vtx-Y (z<1m) sy ~ 3-4 cm

Hit profile in T2

T2 Global Alignment and Vertex Reconstruction Before Align. rms=1.4cm rms=1.7cm rms=3.1m After Align. rms=0.8cm rms=1.0cm rms=2.3m

RP Alignment w.r.t. the Beam: Beam-Based Method Test done at 450 GeV and at 3.5 TeV using BLM (beam loss monitor) signal during special collimator/RP setup runs Collimator cuts a sharp beam edge symmetrically to the centre RP approaches this edge until it scrapes … … producing spike in BLM downstream The second RP approaches When both top and bottom pots “feel” the edge: they are at the same number of sigmas from the beam centre as the collimator and the beam centre is exactly in the middle between top and bottom pot Procedure repeated in different configurations, allowing safe insertion down to 18 (V) in standard runs and down to 7s (V) in special runs. (1 x (y) = 0.19 (0.42) mm @ β* = 3.5 m) 35

Prime misure di Scattering Elastico exponential region 7 TeV Range della presa dati del 2010 b* = 3.5m b* = 1540m b* = 90m squared 4-momentum transfer t  - p2 q2

Hit map (side 5,6) for left - right coincidences

Single diffraction large x

Double Pomeron Exchange

Stato dell’ Elettronica For INSTALLATION & COMMISSIONING T1 Reviewed grounding and shielding by the TOTEM/CMS task force. CABLING RP 147: quite a bit of work done ELECTRICAL TRIGGER: on hold for the moment, would like to install sufficient amount to test correctly. SPARE PARTS: 5 new HOST boards received for TOTEM, 14 still in production in Israel. Purchased from CMS 60 transmitters (GOH), (already had damage in a few Roman Pot due to special reset condition, and needed to carry out replacement) Hybrids for Gas VFATs needed.

Total p-p cross-section Current models predict for 14 TeV: 90 – 130 mb Status of the art Aim of TOTEM: ~ 1% accuracy Optical Theorem Luminosity independent method el Misura concettualmente semplice ma…: ottica speciale (* alto) + sistematica

Totem menu ~ 60 mb 18 - 35 mb 10 - 16 mb 4 - 14 mb 0.2 - 1.5 mb Double Pomeron Exchange Double Diffraction Single Diffraction Elastic Scattering ~ 60 mb 18 - 35 mb 10 - 16 mb 4 - 14 mb 0.2 - 1.5 mb << 1 mb

TOTEM Physics goals TOTEM TOTEM & CMS TOTpp with a precision ~ 1%, simultaneously measuring: Nel down to -t ~10-3 GeV2 Ninel with losses < 3% Elastic pp scattering in the range 10-3 < |t| ~ (p)2 < 10 GeV2 Soft diffraction (SD and DPE) Particle flow in the forward region (cosmic ray MC validation/tuning) TOTEM & CMS Soft and hard diffraction in SD and DPE (production of jets, bosons, h.f.) Central exclusive particle production Low-x physics Particle and energy flow in the forward region

Acceptance for Inelastic Events Efficiency increases 4 5 3 2 1 PHOJET s = 7 TeV T2 Large uncertainties in inelastic cross sections: non-diffractive minimum bias (MB) 40  60 mb single diffraction (SD) 10  15 mb double diffraction (DD) 4  11 mb Accepted event fraction: T1 h Low multiplicities in diffraction