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LHCb-Facts

Papers

Integrated luminosity

pp-collisions
Year 2010 2011 2012 2015 2016 2017 SUM
$ \rm L_{int}/{fb^{-1}} $ 0.038 1.107 2.082 0.328 1.665 1.609 6.829
$ \rm E_p / TeV $ 3.5 3.5 4 6.5 6.5 6.5 -
pA-collisions
Year 2013 SUM
L_int/pb-1 35?
Ecm/GeV 8000 -
LHCb efficiency breakdown in pp collisions in 2010-2012
93.05%

  • (Instantaneous) luminosity : $ \rm L = (2 \ldots 4) \cdot 10^{32}/cm^{2}/s = (0.2 \ldots 0.4)\,nb^{-1}/s $

Reference: LHCb Operations Plots Webpage

Cross-Sections

Process $ pp \to b\bar{b} X $ $ pp \to B^{\pm} X $ $ pp \to B^{0}/ \bar{B}^0 X $ $ pp \to B^{0}_s/ \bar{B}_s^0 X $
E(pp) $ 7\, {\rm TeV} $ $ 7\, {\rm TeV} $ $ 7\, {\rm TeV} $ $ 7\, {\rm TeV} $
σ $ (75.3\pm14.1) {\rm \mu b} $ $ (38.9\pm2.8) \mu b $ $ (38.1\pm6.0) \mu b $ $ (10.5\pm1.3) \mu b $
Source Paper Paper

  • $ 1 \mu b = 10^9 / 10^{-15} / b^{-1} = 10^9\ {\rm Events} / fb^{-1} $

LHCb event characteristics

ν (nu) : The average number of pp interactions per bunch crossing

  • Only used in MC

  • $ \nu = \frac{L \times \sigma_{tot}}{N_{\rm bunches} \times f_{\rm Crossing}} = \rm \frac{0.4\,nb^{-1}}{1262\,s} \times 91.1\,mb^{-1} \times \frac{1}{11\,245\,Hz} = 2.57 $

μ (mu): The average number of visible pp interactions per bunch crossing

  • The only thing we can measure at LHCb

  • We measure $ P(n=0|\mu)=exp(-\mu) $, assuming L0 selects ALL visible interactions, i.e. $ n\neq0 $

  • $ \mu = 0.699 \cdot \nu = 1.79 $ (at 7 TeV, a bit less at 8 TeV)

Pile-up: the average number of pp interactions in visible events

  • The relevant quantity for the Hlt processing time

  • Pile-up $ = \mu/(1-P(0|\mu)) = \mu / 1-exp(-\mu) = 2.15 \ @\ \mu = 1.79 $

  • The average pile-up is not what we see in the Hlt if we have a biasing L0

Reference: LHCb event characteristics

Magnetic field and track definition

tracksmagnet.png

Detector VELO TT T1-3 Ca. 72 tracks in bbar events
Long Track X (X) X 26 (36%)
Upstream Track X X - 11 (15%)
Down Track - X X 4 (6%)
VELO Track X - - 26 (36%)
T Track - - X 5 (7%)

  • Successfully reconstructed : a track must have at least 70% of its associated hits originating from a single MonteCarlo particle

  • Ghost tracks : reconstructed tracks that are not matched to a true MonteCarlo particle

  • Cloned tracks : several reconstructed tracks that origin from the same particle

  • Track Types:
    -- 0 = Unknown
    -- 1 = Velo track
    -- 2 = 2D Velo track
    -- 3 = Long (or forward) track
    -- 4 = Upstream track
    -- 5 = Downstream track
    -- 6 = seed track
    -- 7 = muon track
    -- 8 = calorimeter cosmic track
    -- 9 = TT track

Reference: The LHCb detector at the LHC, p178-179

Performance

Reference: Standard set of performance numbers

Beam Conditions

Run2015.png

Trigger

LHCb Trigger 2012 LHCb Trigger 2015
img85a8700b4beda9c6f3f9a3c5cbb11fd5.png imgf02dd55b3e38c469099f3d99c5fe850f.png

Reference: Trigger Schemes

LHCb Storage Overview

LHCb data storage overview.png

Reference: Talk of Silvia Amerio on 10.09.2013 at LHCb week in Krakow, slide 24

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Topic revision: r22 - 2017-11-14 - GeorgeCoombs
 
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