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First Results at the LHC seen through the eyes of ALICE

First Results at the LHC seen through the eyes of ALICE. Научный руководитель – . Курепин А.Б Координатор - Каравичева Т.Л. Коллектив участников : ЛМЯВ : Губер Ф.Ф. ,Карпечев Е.Н., Коневских А., Маевская А.И., Решетин А.И., Тифлов В.В.

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First Results at the LHC seen through the eyes of ALICE

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  1. First Results at the LHCseen through the eyes of ALICE Научный руководитель – . Курепин А.Б Координатор - Каравичева Т.Л. Коллектив участников : ЛМЯВ : Губер Ф.Ф. ,Карпечев Е.Н., Коневских А., Маевская А.И., Решетин А.И., Тифлов В.В. КОРЭ: Аношко А.С., Веселовский А.В., Каравичев О.В., Курепин А.Н., Марин В.И.,Тихонов А.А.

  2. T0 and V0 V0C V0A IP RB26 RB24 T0-A T0-C T0-C

  3. T0 detector Precise start signal for TOF • (time resolution of about 50 ps) Trigger functions (on-line): • Rough vertex position position resolution (along the beam direction)  1 cm; • Rough multiplicity • vertex-independent interaction time “wake-up” signal to TRD The past-future protection Luminosity using T0

  4. some anxious minutes waiting for collisions.. ~ 16:35

  5. The first ‘event’ pops up in the ACR . ~ 16:41 Fig. 1. The first pp collision candidate shown by the event display in the ALICE counting room (3D view, r-_ and r-z projections), the dimensions are shown in cm. The dots correspond to hits in the silicon vertex detectors (SPD, SDD and SSD), the lines correspond to tracks reconstructed using loose quality cuts. The ellipse drawn in the middle of the detector surrounds the reconstructed event vertex

  6. Trigger rate ~30 Hz T0vx ~5.9 Hz ( ~19 %) Simulation rate ~18,8 % Interaction in vertex between T0_A and T0_C (green). Integrated (60s) interaction rate (magenta). hit rates per second for each PMT Total number of hits for each PMT

  7. RUN 104321 RAW+ slewing corr RAW CFDC1-CFDC2 Time resolution (2.39/1.41) *24.4=42 ps

  8. »p This is the first (and easiest) of many numbers we need to (re)measure to get confidence in our detectors, tune the simulations, study background, .... Phase 2 is still a long way to go.. last time measured at the ISR for pp Physics exploitation of ALICE has started for good ! Phase 1: rediscovering the standard model (QCD in the case of ALICE) submitted to EPJC 28 Nov 2009 The average number of charged particles created perpendicular to the beam in pp collisions at 900 GeV is: dN/dh = 3.10 ± 0.13 (stat) ± 0.22 (syst)

  9. all plots: preliminary calibration & alignment ! TOF Protons Kaons Pions TOF PID spectra to study particle production velocity v/c Particle identification On 6th December, ‘stable beams’ were declared & we could switch on all ALICE detectors for the first time.. Total events collected: > 1 M ‘Good pp interactions’: 500 k - 100 k : B = 0 (alignment) - 10 k : B reversed (systematics) - 30 k : √s = 2.36 TeV ALICE special: Particle Identification (very important for heavy ion physics later in 2010)

  10. Beam spot at 2.36 TeV SPD Vertex resolution versus # tracks preliminary alignment ! Tracking works beautifully

  11. LHC Ös = 900 GeV Finally… Work in progress.. dN/dh at 2.36 TeV statistical error negligible final systematic error under evaluation (still 7% for the time being) LHC Ös = 2.36 TeV

  12. ALICE is a very happy (and busy) girl right now

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