CMS-PAS-LUM-16-001 | ||
CMS luminosity calibration for the pp reference run at $\sqrt{s}= $ 5.02 TeV | ||
CMS Collaboration | ||
December 2016 | ||
Abstract: The measurement of the integrated luminosity delivered to the CMS Experiment during the very first LHC proton-proton run at 5.02 TeV center-of-mass energy is presented. The Pixel Cluster Counting method is used and the absolute luminosity scale calibration is derived from an analysis of Van der Meer Scans performed in November 2015. The overall uncertainty on the luminosity measurement is 2.3%. The time stability of such calibrations is also studied and taken into account for the final systematic uncertainty. | ||
Links: CDS record (PDF) ; inSPIRE record ; CADI line (restricted) ; |
Figures | |
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Figure 1:
Instantaneous luminosity as a function of bunch crossing, showing the impact of type 1 and type 2 corrections. |
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Figure 1-a:
Instantaneous luminosity as a function of bunch crossing, showing the impact of type 1 and type 2 corrections. |
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Figure 1-b:
Instantaneous luminosity as a function of bunch crossing, showing the impact of type 1 and type 2 corrections. |
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Figure 2:
The relative contributions in percentage of the different pixel layers for the entire November 2015 data-taking period. Note that the innermost pixel layer is excluded from the PCC rate measurements. Only periods where the CMS detector was fully operational were considered. |
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Figure 3:
Horizontal and vertical beam displacements, measured with the DOROS BPMs, during the VdM scan campaign on November 2015 . The displacement is set to zero at the beginning of the Fill. Scans that were excluded from the PCC measurement are marked with purple. |
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Figure 4:
Fitted scan curves recorded by PCC during $Y_3$ (left) and $X_3$ (right). |
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Figure 4-a:
Fitted scan curves recorded by PCC during $Y_3$ (left) and $X_3$ (right). |
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Figure 4-b:
Fitted scan curves recorded by PCC during $Y_3$ (left) and $X_3$ (right). |
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Figure 5:
Fitted scan curves of the Vertex Counting rates during $Y_3$ (left) and $X_3$ (right). |
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Figure 5-a:
Fitted scan curves of the Vertex Counting rates during $Y_3$ (left) and $X_3$ (right). |
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Figure 5-b:
Fitted scan curves of the Vertex Counting rates during $Y_3$ (left) and $X_3$ (right). |
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Figure 6:
The fitted $\Sigma _{x/y}$ (a,b) as a function of BCID (a) and Scan sequence (b). |
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Figure 6-a:
The fitted $\Sigma _{x/y}$ (a,b) as a function of BCID (a) and Scan sequence (b). |
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Figure 6-b:
The fitted $\Sigma _{x/y}$ (a,b) as a function of BCID (a) and Scan sequence (b). |
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Figure 7:
a) The weighted average of PCC visible cross sections per BCID. b) The resulting cross sections with statistical error for all BCID measured over all scans. c) The weighted average of PCC visible cross sections per scan. |
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Figure 7-a:
a) The weighted average of PCC visible cross sections per BCID. b) The resulting cross sections with statistical error for all BCID measured over all scans. c) The weighted average of PCC visible cross sections per scan. |
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Figure 7-b:
a) The weighted average of PCC visible cross sections per BCID. b) The resulting cross sections with statistical error for all BCID measured over all scans. c) The weighted average of PCC visible cross sections per scan. |
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Figure 7-c:
a) The weighted average of PCC visible cross sections per BCID. b) The resulting cross sections with statistical error for all BCID measured over all scans. c) The weighted average of PCC visible cross sections per scan. |
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Figure 8:
Examples of the measured beam spot positions as a function of the beam centroid offsets are shown for a horizontal (left) and a vertical (right) LSC scans. The points are fitted with a straight line to derive the LSC calibration constant. |
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Figure 8-a:
Examples of the measured beam spot positions as a function of the beam centroid offsets are shown for a horizontal (left) and a vertical (right) LSC scans. The points are fitted with a straight line to derive the LSC calibration constant. |
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Figure 8-b:
Examples of the measured beam spot positions as a function of the beam centroid offsets are shown for a horizontal (left) and a vertical (right) LSC scans. The points are fitted with a straight line to derive the LSC calibration constant. |
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Figure 9:
Difference of the two vertical and horizontal beam orbits from before and after each scan as measured by the DOROS BPM in ${ \mu \text {m}}$ is shown. |
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Figure 10:
An example of beam-beam deflection estimated as a function of the nominal beams displacement. |
Tables | |
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Table 1:
Summary of the LHC beam parameters for fill 4634 . |
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Table 2:
Results of the length-scale calibration for the two horizontal and vertical LSC scans . |
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Table 3:
Comparison of the effective areas from the simulated VdM scans with bunch proton densities extracted having applied Eq. {eq:dgmodel1} to the Beam Images (Eq. {eq:deriveFitModel2}) against the beam overlap integrals incorporating genuine non-factorizabilities. Statistical uncertainties are minor. |
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Table 4:
Summary of the systematic uncertainties entering the CMS luminosity measurement for $\sqrt {s}=$ 5.02 TeV proton-proton collisions. When applicable, the percentage correction is shown. |
Summary |
In summary, the total uncertainty on the CMS luminosity measurement in November 2015 is 2.3% for CMS data recorded with proton-proton collisions at $\sqrt{s}=$ 5.02 TeV. |
References | ||||
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Compact Muon Solenoid LHC, CERN |