p. 1K. Eggert – Early TOTEM Running with the  * =90m Optics Karsten Eggert on behalf of the TOTEM Collaboration Politecnico di Bari and Sezione INFN Bari, Italy Case Western Reserve University Cleveland, Ohio,USA CERN Geneva, Switzerland Università di Genova and Sezione INFN Genova, Italy University of Helsinki and HIP Helsinki, Finland INFN Sezione di Pisa and Università di Siena Pisa/Siena, Italy Academy of Sciences Praha, Czech Republic Estonian Academy of Sciences Tallinn, Estonia Penn State University University Park, USA Brunel University Uxbridge, UK 87 th LHCC Meeting

p. 2K. Eggert – Current models predictions: mb Aim of TOTEM: ~1% accuracy Total p-p Cross-Section LHC: COMPETE Collaboration fits all available hadronic data and predicts: [PRL (2002)]

p. 3K. Eggert – TOTEM Detector Configuration ~14 m T1:  3.1 <  < 4.7 T2: 5.3 <  < m T1 T2 HF CMS RP1(RP2)RP3 220 m 147 m

K. Eggert – Parameters    = 1540 m (baseline optics)    = 90 m (early optics) Crossing angle0.0 N of bunches N of part./bunch 3 ∙ ∙ Emittance  n [  m ∙ rad] RMS beam size at IP [  m] RMS beam divergence [  rad]  beam width at RP220 [mm] Peak luminosity [cm -2 s -1 ]1.6 · ·10 29 Injectionspecialstandard MD commissioningmore difficultless difficult Comparison of High  * Optics  * = 90 m fits into the 2008 run scenario; small integrated luminosity loss in 2008 ideal for training the RP operation due to wide beams; helps beam diagnostics luminosity beam position vertex distribution

p. 5K. Eggert – Parameter Evolution and Rates ParametersBeam levelsRates in 1 and 5Rates in 2 (and 8) kbkb N  * 1,5 (m) I beam proton E beam (MJ) Luminosity (cm -2 s -1 ) Events/ crossing Luminosity (cm -2 s -1 ) Events/ crossing << << << All values for nominal emittance, 7TeV and 10m  * in points 2 and 8 R. Bailey

p. 6K. Eggert – Optical Functions L = (   ) 1/2 sin  (s) v= (   ) 1/2 cos  (s)  Idea: L y large L x =0 v y = 0  y (220) =  x (220) =  (m) (x *, y * ): vertex position (  x *,  y * ): emission angle hit distribution (elastic)

p. 7K. Eggert – t-Acceptance at RP220 for Elastic Scattering   =1540   =90   =2   =1540   =90 log 10 (-t) (GeV 2 ) log 10 (-ty) (GeV 2 ) 10  beam = 0.8 mm 6.25 mm mm detector displacement t = t x + t y tyty  (t y ) / t y ~ 0.02 GeV / t y 1/2 t ~ - (p  ) 2

p. 8K. Eggert – Elastic Scattering  * = 90 m  * = 11 m  * = 2 m 14 TeV exponential region squared 4-momentum transfer

p. 9K. Eggert – Elastic Scattering at low |t| Exponential Slope B(t)  * = 1540 m: |t| min = GeV 2  * = 90 m: |t| min = 0.04 GeV 2 d  /dt = exp [-B(t)·t] fit interval B(t) = B 0 + B 1 t + B 2 t 2

p. 10K. Eggert – Extrapolation to the Optical Point (t = 0) ∫ L dt = 2 nb -1 (few hours running time) (extrapol. - model) / model in d  /dt | t=0 Extrapolation uncertainty Common bias due to beam divergence : -2% Spread of most of the models: ±1% Systematic error due to uncertainty of optical functions: ± 3%

p. 11K. Eggert – Combined Uncertainty in  tot Extrapolation of elastic cross-section to t = 0: ± 4 % Total elastic rate (correlated with extrapolation): ± 2 % Total inelastic rate: ± 1 % (error dominated by Single Diffractive trigger losses) ==> Total uncertainty including correlations in the error propagation: ± 4 %

p. 12K. Eggert – Measurement of Beam Parameters 10   t < 10 s Luminosity measurement (together with  tot ): ±6% Beam profile measurement in x-projection at RP220 (elastic scattering) ==> beam position measurement at RP220 with precision ~ 1  m every minute to be compared with the machine’s BPMs. ==> horizontal vertex position determination: ==> vertex distribution (shape and width) ==> assuming round beams: luminosity from beam parameters

p. 13K. Eggert – Diffractive events  t)-acceptance  =  p/p) Mass Distribution for Double Pomeron events   = 90 m 65% of all diffractive proton are detected, independent of their momentum loss  ==> wide range of diffractive studies (Single Diffraction and Double Pomeron Exchange) combined with Rapidity Gap studies in T1/T2   =90   =1540   =2

p. 14K. Eggert – Summary The proposed optics will allow the measurement of: Total cross section within ± 4% Luminosity within ± 6% Horizontal beam position and profile at RP220 within few  m every minute Horizontal vertex distribution at IP5 ==> luminosity determination based on machine parameters Diffraction due to the  independent proton acceptance (~ 65%) The proposed optics can be commissioned at an early LHC stage (see talk by Helmut Burkhardt) After gaining experience with this optics, more precise measurements with the baseline optics (1540 m)

p. 15K. Eggert –

p. 16K. Eggert – Overall commissioning strategy for protons (est d. 2005) Hardware commissioning Machine checkout Beam commissioning 43 bunch operation 75ns ops 25ns ops I Install Phase II and MKB 25ns ops II Stage I IIIII No beamBeam IV I.Pilot physics run First collisions 43 bunches, no crossing angle, no squeeze, moderate intensities Push performance Performance limit cm -2 s -1 (event pileup) II.75ns operation Establish multi-bunch operation, moderate intensities Relaxed machine parameters (squeeze and crossing angle) Push squeeze and crossing angle Performance limit cm -2 s -1 (event pileup) III.25ns operation I Nominal crossing angle Push squeeze Increase intensity to 50% nominal Performance limit cm -2 s -1 IV.25ns operation II Push towards nominal performance

p. 17K. Eggert –

p. 18K. Eggert – Measurement of the Total Rate N el + N inel  [mb] T1/T2 double arm trigger loss [mb] T1/T2 single arm trigger loss [mb] Systematic error after extrapolation [mb] Minimum bias Single diffractive14 –30.6 Double diffractive Double Pomeron Elastic Scattering30––0.2 (2) Acceptance single diffraction simulated extrapolated detected Loss at low diffractive masses M Extrapolation of diffractive cross-section to large 1/M 2 using d  /dM 2 ~ 1/M 2. Total: 0.8 mb  0.8  * = 1540 m 2 – 5 mb  2 – 5  * = 90 m using  * = 1540, 90  * = 1540 (90) m Trigger Losses using  * = 1540, 90 m