Xth Blois Workshop on Elastic and Diffractive Scattering The TOTEM Experiment V. Avati CERN, EP Division on behalf of the TOTEM Collaboration http://totem.web.cern.ch/Totem/

Collaboration Institut für Luft- und Kältetechnik, Dresden, Germany CERN, Geneva, Switzerland Università di Genova and Sezione INFN, Genova, Italy Institut des Sciences Nucléaires, IN2P3,/CNRS, Grenoble, France University of Helsinki and HIP, Helsinki, Finland Warsaw University of Technology,Plock, Poland Academy of Sciences, Praha, Republic Czech Brunel University, Uxbridge, UK

The measurement of stot Historical : CERN Tradition (PS-ISR-SPS) Dispersion relation fit (logs)g , g=2.20.3 Current models predictions: 100-130mb Aim of TOTEM: ~1% accuracy Absolute calibration of Luminosity

-6.5<h<6.5 ~150m ~220m (Optical Theorem)

Forward Inelastic Detector Fully inclusive trigger : loss < 2% NSD double arm inelastic trigger - SD single arm inelastic trigger + proton Reconstruction of the collision vertex to disentangle beam-beam events from background Good pattern recognition to identify the tracks (see talk F. Ferro)

T1 Inelastic telescope Measures from η~3.1 to 4.7 on each side Track chambers CSC Cathode strip read-out for vertex reconstruction 5 planes on each telescope Space resolution better than 0.5mm Trigger by RPC Two double gap chambers Pad read-out with projective geometry Time resolution ~1ns T1 telescope

(In agreement with CMS) RAILS ARE ASSEMBLED ON A TRUSS STRUCTURE, TO WITHSTAND THE FLEXURAL LOAD THE TRUSS IS COMPLETELY RESTRAINED ON THE OUTERMOST SPACER RING PUSH/PULL RODS AT THE END TIE THE 2 TRUSSES AND LIMITS THE TORSION BASIC SOLUTION: STEEL MADE, ONE TRUSS WEIGHS ROUGHLY 120 Kg PUSH ROD: COULD BE MADE OF ALUMINIUM OR FIBERGLASS (BETTER PARTICLE TRANSPARENCY) AND/OR ARC-SHAPED PUSH/PULL RODS TRUSS (In agreement with CMS)

T2 inelastic telescope 5.32 <h<6.71 13570 400 New T2 design (compatible with CASTOR) with Si detectors Distance from IP: 13570 mm T2 inner radius:33mm Vacuum chamber inner radius: 25 mm

Lightweight Structure Space for services  470 mm Bellow Thermal Insulation Weight estimation: ~30 Kg 400 mm

General remarks on the “special” optics for the measurement of the forward proton(s) y = Ly qy*+ vy y* L = (bb*)1/2 sin m(s) x = Lx qx *+vx x*+x Dx v= (b/b*)1/2 cos m(s) LOW t measurement At the IP : small beam divergence  large b* sq=(e / b*)1/2  large beam size sx=(e b* )1/2 At the detector stations: parallel to point focussing planes (v=0)  unique position-angle relation lowest emittance (10-6 m. rad ) largest Leff  sizeable distance to the beam center (~1mm) Luminosity : 1028 cm-2 sec-1,36 bunches (with the official baseline b*=1100 m) An alternative optics (b*=1550m) is under study: interesting feature and better performances - parallel to point focussing planes in x and y simultaneously at ~220 m - better “one arm resolution”

Elastic Scattering b* = 1100 m b* = 1550 m

Acceptance log(-t) (GeV2) b=1550 b=18

Large acceptance : elastic rate and extrapolation t=0 acceptance dependence on detector position b=1100m t=0.004 GeV2 A=44% t=0.01 GeV2 A=67% b=1550m t=0.004 GeV2 A=64% t=0.01 GeV2 A=78%

f and t – resolution versus the azimuthal angle f coplanarity

Elastic Cross section: stat. and syst. errors L=1028 cm-2 s-1 run time = 4 . 104 sec 10mm detector position uncertainty

Large t scattering Ldt = 1033 1037 cm-2 1 eff.day (105sec) at high b and 18 m -t(GeV2) 15/GeV2 27.103/GeV2 Ldt = 1033 1037 cm-2 ds/dt (pp) (mb/GeV2) (M. Islam)

To measure the total cross section with ~ 1% precision total inelastic rate within 2 % extrapolation to t=0 within 0.3-0.4 % importance of systematic: detector position, trigger efficiency, machine precision (cross angle variation, beam position precision..)

Forward Physics First time at a collider a large acceptance detector TOTEM+CMS+ CASTOR First time at a collider a large acceptance detector 1 day run at large beta: 10 million minimum bias events, including single and double diffraction 90% of all diffractive protons are detected Forward physics important for the understanding of Cosmic Ray events

Diffraction at high b 90% of all diffractive protons x<10-3 x=0.06 x=0.01 -t=10-2 -t=10-1 log(-t) (GeV2) 90% of all diffractive protons are seen in the Roman Pots

Total TOTEM/CMS acceptance (b*=1550m) microstation at 19 m ? RPs

Total TOTEM/CMS acceptance (b*=18m) RPs

Detector requirements High and stable efficiency near the edge facing the beam, edge sharpness < 10 mm Try to do better than present technology guard rings ~0.5 mm Detector size is ~3x 4 cm2 Spatial resolution ~20 micron Moderate radiation tolerance (~1014 n /cm2 equiv) ~3cm CMS Hybrid

Cold Silicon RD39/NA60 have investigated/used silicon at cryogenic temperatures (~ 100-130 K) Studies hint at possibility of operating silicon microstrip without guard rings at LN temp. K.Borer et al., “Charge collection efficiency of irradiated silicon detector operated at cryogenic temperatures” NIM A 440 (2000) 5. L.Casagrande et al.,"A new ultra radiation hard cryogenic silicon tracker for heavy ions beams“ NIM A (2002) 325-329. S.Grohman et al., “Detector development for TOTEM Roman Pots”, IX Blois Workshop on El. and Diff. Scatt., Pruhonice, Czech Republic, (2001), 363. In 2002 we have performed a first measurement on cold edgeless silicon detector Z. Li et al, "Electrical and TCT characterization of edgeless Si detector diced with different methods", IEEE NSS Proc., San Diego, Nov. 2001

Reconstruction of the cut edge Hits in the telescope (all good tracks) Hits in the cut detector Efficiency Edge at: 0+20micron

Development with planar technology cut edge n+ ring (20 mm) at 30mm from p+ set at the same pot as backplane hope: n+ ring stops the C current B under control with temperature test of various configuration in summer p+ n+ A B C p+ n+ A B D

PLANAR-3D DETECTORS i Edge sensitivity ~20 mm TRADITIONAL PLANAR DETECTOR + DEEP ETCHED EDGE FILLED WITH POLYSILICON p + Al E-field n + Al i n + Al signal a.u. position [mm] Edge sensitivity ~20 mm Leakage current =6nA at 200V Brunel, Hawaii, Stanford

3D DETECTORS AND ACTIVE EDGES Brunel, Hawaii, Stanford EDGE SENSITIVITY <10 mm COLLECTION PATHS ~50 mm SPATIAL RESOLUTION 10-15 mm DEPLETION VOLTAGES < 10 V DEPLETION VOLTAGES ~105 V at 1015n/cm2 SPEED AT RT 3.5 ns AREA COVERAGE 3X3 cm2 SIGNAL AMPLITUDE 24 000 e before Irradiation SIGNAL AMPLITUDE 15 000 e- at 1015n/cm2 15 mm InfraRed beam spot FWHM = 772 mm Edge Al strip width = 16 mm INSENSITIVE EDGE (INCLUDING 16 mm Al STRIP): (813 - 772) / 2 = 21 mm CERN Courier, Vol 43, Number 1, Jan 2003

first prototype ready at the end of 2003 Design of the Roman Pot Design of the Pot Design of the Roman Pot Station Integration in the Tunnel Main items: Secondary Vacuum : outgassing and RF shielding Mechanical Design of a thin window Integration of detectors inside the pot: mounting, cooling Design of flange to routing the detector’s services outside the pot High mechanical precision ( < 20 mm) and reproducibility first prototype ready at the end of 2003 (see M. Oriunno talk)

Roman Pot Device (Second Version) Compensation bellow Pot Lever Arm Capacitive sensor Roman Pot Device (Second Version)

QRL (LHC Cryogenic Line) 4m

A novel detector for measuring the leading protons - the Microstation - is designed to comply with the LHC requirements. (M.Ryynänen, R.Orava. /Helsinki group) a compact and light detector system integrated with the beam vacuum chamber geometry and materials compatible with the machine requirements mm accuracy in sensor movements robust and reliable to operate Si strip or pixel detector technology Development in cooperation with the LHC machine groups (see M.Ryynänen talk)

Microstation Inch worm motor Emergency actuator 6cm Detector Inner tube for rf fitting 6cm Space for cables and cooling link Detector Space for encoder Note: A secondary vacuum is an option. M.Ryynänen, R.Orava. /Helsinki group

Radiation fluence in the RP silicon detectors (N. Mokhov,I Radiation fluence in the RP silicon detectors (N.Mokhov,I. Rakhno,Fermilab-Conf-03/086) Maximum fluence (1014 cm-2) for charged hadrons (E>100 KeV , L= 1033 cm-2 s-1, t=107s): RP4 (215 m)  Vertical: 0.58, Horizontal: 6.7 Dose (104 Gy/yr) RP4 (215 m)  Vertical: 0.37 (max: 1.9), Horizontal:1.2 (max:55) Main source of background: pp collisions Tails from collimators and beam-gas scattering ~ 0.1-1% Radiation level manageable

Running scenario Total Cross Section and Elastic Scattering Runs with single beams (calibration + background) Several 1 day runs with b*=1550m (CMS Magnet On/Off) Several 1 day runs with b*=18m for large-t elastics Diffraction Runs with CMS (active or passive trigger) with b*=1550m for L =1028cm-2 s-1 Runs with CMS (active or passive trigger) with b*=0.5m for L < 1033cm-2 s-1

consolidation of the collaboration! Plans: test of Si detectors (2003-2004) Roman Pot prototype end 2003 trigger studies (2003-2004) TDR end 2003 consolidation of the collaboration! CMS/TOTEM collaboration for high luminosity diffractive measurements (see A. De Roeck talk)