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Systematic Error Related to the Transport Model Systematic Error Introduced by the Material Budget Uncertainties Using Geant3 interface (GHEISHA) to transport (anti-)protons through the central detectors Variation of the detector materials and the gas mixtures from 90% up to 110% of the nominal material budget Systematic error is estimated by taking the difference between the lowest and highest values of the obtained particle yields after reconstruction. Corresponding results on the systematic error for the particle ratio and asymmetry yield 2.3% max for 20% material uncertainty (P>0.525 GeV/c). For the more reasonable material budget uncertainty of 5% (10%) the systematic error for P>0.525 GeV/c is 0.4% (0.6%). Systematic Error due to Beam Gas Events Scattering of beam particles with the residual gas inside the beam pipe (mainly C, H, and O nuclei) is a problem at LHC due to the high beam intensity. Long drift time of the TPC (88 s) makes it sensitive even for far out-of-time events. Simple beam-gas events are efficiently rejected, but coincidences of beam-gas events with beam-beam reactions are problematic. An estimated beam-gas interaction rate of 12 kHz/m and an experimental area of roughly ±20 m results in an integrated rate of 500 kHz which compares to 200 kHz for pp collisions, only. Many additional background protons (less anti-protons) will be produced. Simulation: p-O fixed target collisions at 7 TeV on top of PYTHIA 14 TeV pp collisions. Beam-gas event rate varied from 12 kHz/m (worst case scenario) to 1 kHz/m. Baryon Number Transport Mechanisms at LHC with the ALICE Experiment Baryon-Antibaryon Measurements in Nucleus- Nucleus Collisions Aim: Understand transport of baryon number (BN) from beam-rapidity to mid-rapidity Gain knowledge about baryon energy loss and nuclear stopping Different models predict different net-baryon densities at mid-rapidity –Quark-Gluon String Model  small (~2%) net-baryon density at mid-rapidity. Contradicted by HERA  and RHIC [3,4,5] measurements. two new approaches based on string junctions –Baryon number is carried by valence quarks , joined by strings connected at a string junction (SJ) baryon transport to mid-rapidity allowed, but exponentially suppressed –Baryon number is carried by gluonic field  baryon number transport allowed over large rapidity gaps: asymmetry (A, see definition below) at mid-rapidity for protons ~ 5% Challenges: ALICEs central detectors acceptance allows to measure asymmetries only in a region where the predicted differences are small. Study of systematic errors of great importance! Definitions: –Ratio: relative differences –Asymmetry: absolute differences –Systematic Error: half the difference between the extreme values of R or A P. Christakoglou and M. Oldenburg Effect of Variations of Event and Track Cuts Event and track cuts reduce the overall event sample and the number of found (anti-)protons. Even carefully chosen cuts reduce not only the background but also remove part of the signal. The final result is affected by those cuts. Even though the overall error due to these cut variations stays below 1%, this is the largest contributor on the systematic error. These studies have to be repeated once real data are available. CutLower value Upper value Step size Nominal value Vertex z-position±5 cm±15 cm2 cm±10 cm Max. distance of closest approach to the primary vertex (DCA) Minimum number of TPC track clusters BN/3 A y=0ybyb -y b BN A y=0ybyb -y b A y= Three types of cuts were varied, in order to see how much the final result is changing: –Event quality cuts. –(Primary) track quality cuts –Particle identification quality cuts. Applying ALICEs standard event and track quality cuts leaves us with only 0.1% of (anti- )protons originating from beam-gas interactions. ITS refit cut is most important, but even without it we still exclude 98% of the background (anti-)protons. The resulting systematic error on both the ratio and the asymmetry is well below 1%. Using published anti-proton+nuclei cross sections  to estimate interaction cross sections in the ITS (Inner Tracking System) and the ALICE TPC. Comparing different transport codes –Geant3 with Gheisha interface –Geant3 with Fluka interface –Fluka stand alone by using a flat input momentum and pseudo-rapidity distribution Calculate reconstruction efficiency: Systematic error obtained by evaluating the differences between the efficiencies Large differences between the survival probability for Geant3/Gheisha and Fluka triggered a detailed search in literature to understand the compliance between experimental data (input)  and the results obtained. Results: Fluka gives the better description of the macroscopic cross-section. Even though the above estimated error (comparing Geant3 with Fluka) was on the order of 2-4%, based on Fluka alone we estimate the error of the cross section to be about 200 mb, which translates to 0.8% absolute in asymmetry. 2 layers of Silicon 4 layers 6 layers 6 layers of Silicon + TPC gas P [GeV/c] protonsanti-protons protonsanti-protons Summary and Outlook Systematic Effects: Error on asymmetry 0.8%.Transport Model: Comparing the cross-sections with experimental data we conclude Fluka is the better transport code. Error on asymmetry 0.8%. 0.6% absolute errorMaterial Budget: For 10% material uncertainty we obtain 0.6% absolute error on the asymmetry. error below 1%Beam Gas Events: Normal track and event selection cuts result in an error below 1% for the asymmetry. error of the asymmetry around 1%Variation of Event and Track Cuts: Largest contribution to the overall error of the asymmetry around 1%. Has to be re-evaluated with real data. Future: Studies will be extended to other Baryons, e.g. Lambdas.   Bendiscioli and Kharzeev, Riv. Nuovo Cim.17N6 (1994) 1.2  G. Cohen-Tannoudji, A. E. Hssouni, J. Kalinowski, R. Peschanski, Phys. Rev. D19 (1979) 3397; A. B. Kaidalov, Phys. Lett. B52 (1982) 459; A. Capella, J. Tran Thanh Van, Phys. Lett. B114 (1982) 450.  C. Adloff et al. [H1 Collaboration], published in the proceedings of ICHEP98, Vancouver, Canada July  I. G. Bearden et al. [BRAHMS Collaboration], Phys. Rev. Lett. 87 (2001) ; I. G. Bearden et al. [BRAHMS Collaboration], Phys. Rev. Lett. 90 (2003) ; I. G. Bearden et al. [BRAHMS Collaboration], Phys. Lett. B607 (2005)  C. Adler et al. [STAR Collaboration], Phys. Rev. Lett. 86 (2001)  B.B. Back et al. [PHOBOS Collaboration], Phys. Rev. C71 (2005)  G. C. Rossi, G. Veneziano, Nucl. Phys. B123 (1977) 507; G. C. Rossi, G. Veneziano, Phys. Rep. 63 (1980) 149.  B. Z. Kopeliovich, Sov. J. Nucl. Phys. 45 (1987) 1078; B. Z. Kopeliovich, B. G. Zakharov, Phys. Lett. B211 (1988) 221; B. Z. Kopeliovich, B. G. Zakharov, Sov. J. Nucl. Phys. 48 (1988) 136; B. Z. Kopeliovich, B. Povh, Z. Phys. C75 (1997) 693; B. Z. Kopeliovich, B. G. Zakharov, Z. Phys. C43 (1989) 241; B. Z. Kopeliovich, B. Povh, Phys. Lett. B446 (1999) 321. MDO Production ©2008 – –
ILC Snowmass workshop, August 2005 p. 0 Physics potential of vertex detector as function of beam pipe radius Sonja Hillert, Chris Damerell (on behalf of.
Correlations and Fluctuations WorkshopFirenze, July 9 th 2006 Event-by-Event physics in ALICE Chiara Zampolli ALICE-TOF Centro E. Fermi (Roma), INFN (Bologna)
Vertex Detector Contribution to ILC Physics Analyses, 16 th November 2005Sonja Hillert (Oxford)p. 0 Vertex Detector Contribution to ILC Physics Analyses.
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New Particle Searches at the LHC SUSY - Inclusive search - Backgrounds - SUSY parameters Resonances in the Drell-Yan mass distribution Heavy long-lived.
Putting it all together - Particle Detectors Writeup for 3 rd section:
LISHEP 18 March 2013 N. Cartiglia, INFN Turin. 1 Total pp cross section measurements at 2, 7, 8 and 57 TeV A)One (out of several) theoretical framework.
The SLHC prospects at ATLAS and CMS 1)Introduction 2)Physics motivation 3)LHC machine upgrade 4)Experiment upgrades 5)New inner trackers for SLHC 6)Conclusions.
High-p T probes of heavy-ion collisions at RHIC and LHC Marco van Leeuwen, LBNL.
ILC Software and Physics Workshop, Cambridge, 4 th April 2006Overview of the LCFI Vertex PackageSonja Hillert (Oxford)p. 0 Overview of the LCFI Vertex.
Highlights from STAR at RHIC Evan Finch Yale University.
The Physic of LHC - Italo-Hellenic School – Lecce – May 2004 Alessandro Ballestrero 1 Electroweak Physics at the LHC PHASE Monte Carlo Boson Boson Scattering.
1 Pier Francesco Manfredi Lawrence Berkeley National Laboratory - Berkeley, California (USA) Dipartimento di Fisica dellUniversità di.
1 Luminosity measurement in the ATLAS experiment at the LHC 26 November 2008 Per Grafstrom CERN.
ILC VTX workshop at Ringberg, 29 th May 2006Sonja Hillert (Oxford)p. 0 The Vertex Detector in the LDC Concept Sonja Hillert (Oxford) on behalf of the LCFI.
LCUK Meeting, 26 th September 2006Sonja Hillert (Oxford)p. 0 LCFI Simulation and Physics Studies LCUK Meeting, Durham, 26 th September 2006 Sonja Hillert.
B. HeinemannSearches for New Physics at the Tevatron 1 B. Heinemann University of Liverpool From Tevatron to the LHC Cosenors House,
Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep Quarkonium plus photon at LHC: diffractive production* Maria Beatriz Gay Ducati.
Sampling and monitoring the environment Marian Scott March 2009.
IDEA for a measurement of the Pion Structure Function using BONUS rTPC, SBS, BigBite, LAC in Hall A.
Sampling and monitoring the environment Marian Scott Sept 2006.
Hall A Collaboration Meeting, December 13-14, 2007 E03-104: Probing the Limits of the Standard Model of Nuclear Physics with the 4 He(e,ep) 3 H Reaction.
Heavy Ion Physics and the Large Hadron electron Collider Paul Newman Birmingham University … for the LHeC Study Group Strangeness in Quark Matter Birmingham,
1 Wake Fields and Beam Dynamics Kai Meng Hock. 2 Overview A study of how particles affect other particles in accelerators: –The importance of wake fields.
1 Guénolé BOURDAUD -jet physics with the EMCal calorimeter of the ALICE experiment at LHC La physique des -jets avec le calorimètre EMCal de lexpérience.
NUCLAT, April 21-22, 2008, 1 Kees de Jager Jefferson Lab NUCLAT April , 2008 Nucleon Electro-Weak Form Factors General Introduction Electromagnetic.
Spectroscopic Factors and A TL from Quasielastic (e,e'p) Reaction in 208 Pb, 12 C and 16 O at JLab J.L. Herraiz 1, J.M. Udías 1 J.C. Cornejo 2, A. Camsonne.
1 Statistical sampling principles for the environment Marian Scott August 2013.
How to measure the charm content of the proton? Two challenging proposals for heavy quark physics at EIC 2. Test of the pQCD applicability to charm photoproduction:
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