BeamSpotPublicResults

Introduction
Publications and Conference Results

Introduction

Here any results related to ATLAS beam-spot measurements are given.

Unless stated otherwise, all positions and angles are measured with respect to the ATLAS coordinate system, which has its origin in the center of the detector, with the positive x-axis, +x, pointing to the center of the ring, +y pointing upwards, and +z pointing along the outgoing beam 2 (which runs counter-clockwise around the ring).

The precise position of the origin as well as the orientation of the coordinate axes are defined as the result of a multi-level alignment procedure performed on the ATLAS Inner Detector. Due to their high sensitivity, the x and y positions of the origin are constrained such that subsequent alignments reproduce the original values within errors. The system was rotated to minimize the residual tilt angles.

Publications and Conference Results

Characterization of Interaction-Point Beam Parameters Using the pp Event-Vertex Distribution Reconstructed in the ATLAS Detector at the LHC − ATLAS-CONF-2010-027

Run 2 25ns pp Collisions, √s = 13 TeV

Beamspot Position The position of the luminous region in ATLAS during √s = 13 TeV pp collisions in second run of the LHC. The data points are the hourly average of results of a maximum likelihood fit to the spatial distribution of primary vertices collected over a two minute period. The luminosity weighted average position is provided for each year.	pdf file	pdf file	pdf file
Beamspot Size The size of the luminous region in ATLAS during √s = 13 TeV pp collisions in second run of the LHC. The data points are the hourly average of results of a maximum likelihood fit to the spatial distribution of primary vertices collected over a two minute period. The luminosity weighted average size is provided for each year.	pdf file	pdf file	pdf file
Beamspot Position The luminosity weighted distribution of the position of the luminous region in ATLAS during √s = 13 TeV pp collisions in second run of the LHC. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over a two minute period. The luminosity weighted average position is provided for each year.	pdf file	pdf file	pdf file
Beamspot Size The luminosity weighted distribution of the size of the luminous region in ATLAS during √s = 13 TeV pp collisions in second run of the LHC. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over a two minute period. The luminosity weighted average size is provided for each year.	pdf file	pdf file	pdf file

2017 25ns pp Collisions, √s = 13 TeV

Interaction Density The variation of the average interaction density at the centre of the beamspot as a function of average interactions per bunch crossing for the last two months of high luminosity pp data taking in 2017. During this period the LHC was using the 8b4e filling scheme.	pdf file
Beamspot Length The variation of the beamspot length as a function of average interactions per bunch crossing for the last two months of high luminosity pp data taking in 2017. During this period the LHC was using the 8b4e filling scheme.	pdf file

2015 25ns pp Collisions, √s = 13 TeV

x Position Position in x of the centroid of the luminous region in ATLAS over the course of the 25 ns pp running in 2015 at √s = 13 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over five minutes. Errors are statistical only.	eps file, pdf file
y Position Position in y of the centroid of the luminous region in ATLAS over the course of the 25 ns pp running in 2015 at √s = 13 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over five minutes. Errors are statistical only.	eps file, pdf file
z Position Position in z of the centroid of the luminous region in ATLAS over the course of the 25 ns pp running in 2015 at √s = 13 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over five minutes. Errors are statistical only.	eps file, pdf file
x Size The size of the luminous region in x in ATLAS over the course of the 25 ns pp running in 2015 at √s = 13 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over five minutes. Errors are statistical only.	eps file, pdf file
y Size The size of the luminous region in y in ATLAS over the course of the 25 ns pp running in 2015 at √s = 13 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over five minutes. Errors are statistical only.	eps file, pdf file
z Size The size of the luminous region in z in ATLAS over the course of the 25 ns pp running in 2015 at √s = 13 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over five minutes. Errors are statistical only.	eps file, pdf file
y Size Horizontal tilt of the luminous region of the luminous region in ATLAS over the course of the 25 ns pp running in 2015 at √s = 13 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over five minutes. Errors are statistical only.	eps file, pdf file
z Size Vertical tilt of the luminous region of the luminous region in ATLAS over the course of the 25 ns pp running in 2015 at √s = 13 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over five minutes. Errors are statistical only.	eps file, pdf file

2015 pp Collisions, √s = 900 GeV

x Position Position of the reconstructed beamspot as a function of time for LHC fill 3683. The outer layers of the pixel detector were turned on at 21:33, the second layer of the pixel detector was turned on at 21:50, and the innermost tracking layer (IBL) was turned on at 22:20.	eps file, pdf file
y Position Position of the reconstructed beamspot as a function of time for LHC fill 3683. The outer layers of the pixel detector were turned on at 21:33, the second layer of the pixel detector was turned on at 21:50, and the innermost tracking layer (IBL) was turned on at 22:20.	eps file, pdf file
z Position Position of the reconstructed beamspot as a function of time for LHC fill 3683. The outer layers of the pixel detector were turned on at 21:33, the second layer of the pixel detector was turned on at 21:50, and the innermost tracking layer (IBL) was turned on at 22:20.	eps file, pdf file
x Size Transverse width of the reconstructed beamspot as a function of time for LHC fill 3683. The outer layers of the pixel detector were turned on at 21:33, the second layer of the pixel detector was turned on at 21:50, and the innermost tracking layer (IBL) was turned on at 22:20.Size of the reconstructed beamspot as a function of time for LHC fill 3683. The outer layers of the pixel detector were turned on at 21:33, the second layer of the pixel detector was turned on at 21:50, and the innermost tracking layer (IBL) was turned on at 22:20. The change in the transverse width when the IBL turns on is not expected to be due to real changes in the LHC beams.	eps file, pdf file
y Size Transverse width of the reconstructed beamspot as a function of time for LHC fill 3683. The outer layers of the pixel detector were turned on at 21:33, the second layer of the pixel detector was turned on at 21:50, and the innermost tracking layer (IBL) was turned on at 22:20.Size of the reconstructed beamspot as a function of time for LHC fill 3683. The outer layers of the pixel detector were turned on at 21:33, the second layer of the pixel detector was turned on at 21:50, and the innermost tracking layer (IBL) was turned on at 22:20. The change in the transverse width when the IBL turns on is not expected to be due to real changes in the LHC beams.	eps file, pdf file
z Size Longitudinal width of the reconstructed beamspot as a function of time for LHC fill 3683. The outer layers of the pixel detector were turned on at 21:33, the second layer of the pixel detector was turned on at 21:50, and the innermost tracking layer (IBL) was turned on at 22:20.Size of the reconstructed beamspot as a function of time for LHC fill 3683. The outer layers of the pixel detector were turned on at 21:33, the second layer of the pixel detector was turned on at 21:50, and the innermost tracking layer (IBL) was turned on at 22:20.	eps file, pdf file

2012 pp Collisions

x Position in 2012 Position in x of the centroid of the luminous region in ATLAS over the course of pp running in 2012 at √s = 8 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. Errors are statistical only.	eps file
y Position in 2012 Position in y of the centroid of the luminous region in ATLAS over the course of pp running in 2012 at √s = 8 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. Errors are statistical only. The large movement at the beginning of May was associated with movement of the inner detector.	eps file
z Position in 2012 Position in z of the centroid of the luminous region in ATLAS over the course of pp running in 2012 at √s = 8 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. Errors are statistical only.	eps file
x Size in 2012 Size in x of the luminous region in ATLAS over the course of pp running in 2012 at √s = 8 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. The size is corrected for the transverse vertex resolution. Errors are statistical only. The variation in each fill is due to transverse-emittance growth of the beams.	eps file
y Size in 2012 Size in y of the luminous region in ATLAS over the course of pp running in 2012 at √s = 8 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. The size is corrected for the transverse vertex resolution. Errors are statistical only. The variation in each fill is due to transverse-emittance growth of the beams.	eps file
z Size in 2012 Size in z of the luminous region in ATLAS over the course of pp running in 2012 at √s = 8 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. Errors are statistical only. The variation in each fill reflects bunch lengthening in the beams.	eps file
x-z Tilt in 2012 Horizontal tilt of the luminous region in ATLAS over the course of pp running in 2012 at √s = 8 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. Errors are statistical only. The tilt is defined with respect to the ATLAS coordinate system.	eps file
y-z Tilt in 2012 Vertical tilt of the luminous region in ATLAS over the course of pp running in 2012 at √s = 8 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. Errors are statistical only. The tilt is defined with respect to the ATLAS coordinate system.	eps file

2012 pp Collisions - Single Fill

x Position Position in x of the centroid of the luminous region in ATLAS during LHC fill 3351. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. Errors are statistical only.	eps file
y Position Position in y of the centroid of the luminous region in ATLAS during LHC fill 3351. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. Errors are statistical only. The movement at the beginning of the run is observed consistently in 2012.	eps file
z Position Position in z of the centroid of the luminous region in ATLAS during LHC fill 3351. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. Errors are statistical only.	eps file
x Size Size in x of the luminous region in ATLAS during LHC fill 3351. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. The size is corrected for the transverse vertex resolution. Errors are statistical only. The increase in size during the fill is expected from the transverse-emittance growth of the beams.	eps file
y Size Size in y of the luminous region in ATLAS during LHC fill 3351. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. The size is corrected for the transverse vertex resolution. Errors are statistical only. The increase in size during the fill is expected from the transverse-emittance growth of the beams.	eps file
z Size Size in z of the luminous region in ATLAS during LHC fill 3351. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. The size is corrected for the transverse vertex resolution. Errors are statistical only. The increase in size during the fill reflects bunch lengthening in the beams.	eps file
x-y Tilt Horizontal tilt of the luminous region in ATLAS during LHC fill 3351. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. Errors are statistical only. The tilt is defined with respect to the ATLAS coordinate system.	eps file
y-z Tilt Vertical tilt of the luminous region in ATLAS during LHC fill 3351. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. Errors are statistical only. The tilt is defined with respect to the ATLAS coordinate system.	eps file
Vertex x distribution Vertex x distribution during LHC fill 3351, between 12:29-12:39 CET, together with a projection of the 3D Gaussian beam spot fit. In each event, only the vertex with the highest ∑_track p_T² is included. Vertices are required to have at least 5 tracks.	eps file
Vertex y distribution Vertex y distribution during LHC fill 3351, between 12:29-12:39 CET, together with a projection of the 3D Gaussian beam spot fit. In each event, only the vertex with the highest ∑_track p_T² is included. Vertices are required to have at least 5 tracks.	eps file
Vertex z distribution Vertex z distribution during LHC fill 3351, between 12:29-12:39 CET, together with a projection of the 3D Gaussian beam spot fit. In each event, only the vertex with the highest ∑_track p_T² is included. Vertices are required to have at least 5 tracks.	eps file
Vertex x-y distribution Vertex x-y distribution during LHC fill 3351. In each event, only the vertex with the highest ∑_track p_T² is included. Vertices are required to have at least 5 tracks.	eps file
Vertex x-z distribution Vertex x-z distribution during LHC fill 3351. In each event, only the vertex with the highest ∑_track p_T² is included. Vertices are required to have at least 5 tracks.	eps file
Vertex y-z distribution Vertex y-z distribution during LHC fill 3351. In each event, only the vertex with the highest ∑_track p_T² is included. Vertices are required to have at least 5 tracks.	eps file

2011 pp Collisions

x Position in 2011 Position in x of the centroid of the luminous region in ATLAS over the course of pp running in 2011 at √s = 7 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. Errors are statistical only.	eps file
y Position in 2011 Position in y of the centroid of the luminous region in ATLAS over the course of pp running in 2011 at √s = 7 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. Errors are statistical only.	eps file
z Position in 2011 Position in z of the centroid of the luminous region in ATLAS over the course of pp running in 2011 at √s = 7 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. Errors are statistical only.	eps file
x Width in 2011 Size in x of the luminous region in ATLAS over the course of pp running in 2011 at √s = 7 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. The size is corrected for the transverse vertex resolution. Errors are statistical only. The decrease in beamspot size in September was due to changes in the beam optics reducing the β*.	eps file
x Width in 2011 in one fill Size in x of the luminous region in ATLAS over the course of one fill in 2011 at √s = 7 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. The size is corrected for the transverse vertex resolution. Errors are statistical only. The growth of the beamspot during a fill is expected from the transverse-emittance growth of the beams.	eps file
y Width in 2011 Size in y of the luminous region in ATLAS over the course of pp running in 2011 at √s = 7 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. The size is corrected for the transverse vertex resolution. Errors are statistical only. The decrease in beamspot size in September was due to changes in the beam optics reducing the β*.	eps file
y Width in 2011 in one fill Size in y of the luminous region in ATLAS over the course of one fill in 2011 at √s = 7 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. The size is corrected for the transverse vertex resolution. Errors are statistical only. The growth of the beamspot during a fill is expected from the transverse-emittance growth of the beams.	eps file
z Width in 2011 Size in z of the luminous region in ATLAS over the course of pp running in 2011 at √s = 7 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. Errors are statistical only.	eps file
z Width in 2011 in one fill Size in z of the luminous region in ATLAS over the course of one fill in 2011 at √s = 7 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. Errors are statistical only. The growth of the beamspot during a fill is expected from the longitudinal-emittance growth of the beams.	eps file
x-z Tilt in 2011 Horizontal tilt of the luminous region in ATLAS over the course of pp running in 2011 at √s = 7 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. Errors are statistical only. The tilt is defined with respect to the ATLAS coordinate system.	eps file
y-z Tilt in 2011 Vertical tilt of the luminous region in ATLAS over the course of pp running in 2011 at √s = 7 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. Errors are statistical only. The tilt is defined with respect to the ATLAS coordinate system.	eps file

2010 pp Collisions

Two dimensional distribution in the x-z plane of primary vertices with at least 10 tracks per vertex for run 152166 at √s = 7 TeV. One can recognize a small tilt of the luminous region of 471μrad ± 15μrad. With the small beam spot expected at √s = 7 TeV, the width of the transverse distribution of primary vertices is dominated by the vertexing resolution of about 75μm for the selection used for this figure. First results from beam spot fits indicate a luminous size σ(x) of about 45μm with an error that is completely dominated by systematics.	eps file
Two dimensional distribution in the y-z plane of primary vertices with at least 10 tracks per vertex for run 152166 at √s = 7 TeV. With the small beam spot expected at √s = 7 TeV, the width of the transverse distribution of primary vertices is dominated by the vertexing resolution of about 75μm for the selection used for this figure. First results from beam spot fits indicate a luminous size σ(y) of about 70μm with an error that is completely dominated by systematics.	eps file
Two dimensional distribution in the transverse plane of primary vertices with at least 10 tracks per vertex for run 152166 at √s = 7 TeV. With the small beam spot expected at √s = 7 TeV, the width of the transverse distribution of primary vertices is dominated by the vertexing resolution of about 75μm for the selection used for this figure. First results from beam spot fits indicate a luminous size of about 45μm in x and 70μm in y with errors that are completely dominated by systematics.	eps version of the figure
Luminous centroid position in x over the course of run 152166 (LHC Fill 1005) at √s = 7 TeV. The data points shown are the results from fits to samples of 10 minutes of data. Errors are statistical only.	eps version of the figure
Luminous centroid position in y over the course of run 152166 (LHC Fill 1005) at √s = 7 TeV. The data points shown are the results from fits to samples of 10 minutes of data. Errors are statistical only.	eps version of the figure
Luminous centroid position in z over the course of run 152166 (LHC Fill 1005) at √s = 7 TeV. The data points shown are the results from fits to samples of 10 minutes of data. Errors are statistical only.	eps version of the figure
Luminous size in z over the course of run 152166 (LHC Fill 1005) at √s = 7 TeV. The data points shown are the results from fits to samples of 10 minutes of data. Errors are statistical only.	eps version of the figure

Obsolete Plots

The plots shown here have been superseded by results presented above. These plots are kept here as a historical record.

x Position in 2012 Position in x of the centroid of the luminous region in ATLAS over the course of pp running in 2012 at √s = 8 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. Errors are statistical only.	eps file
y Position in 2012 Position in y of the centroid of the luminous region in ATLAS over the course of pp running in 2012 at √s = 8 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. Errors are statistical only. The large movement at the beginning of May was associated with movement of the inner detector.	eps file
z Position in 2012 Position in z of the centroid of the luminous region in ATLAS over the course of pp running in 2012 at √s = 8 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. Errors are statistical only.	eps file
x Width in 2012 Size in x of the luminous region in ATLAS over the course of pp running in 2012 at √s = 8 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. The size is corrected for the transverse vertex resolution. Errors are statistical only.	eps file
y Width in 2012 Size in y of the luminous region in ATLAS over the course of pp running in 2012 at √s = 8 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. The size is corrected for the transverse vertex resolution. Errors are statistical only.	eps file
z Width in 2012 Size in z of the luminous region in ATLAS over the course of pp running in 2012 at √s = 8 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. Errors are statistical only.	eps file
x-z Tilt in 2012 Horizontal tilt of the luminous region in ATLAS over the course of pp running in 2012 at √s = 8 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. Errors are statistical only. The tilt is defined with respect to the ATLAS coordinate system.	eps file
y-z Tilt in 2012 Vertical tilt of the luminous region in ATLAS over the course of pp running in 2012 at √s = 8 TeV. The data points are the result of a maximum likelihood fit to the spatial distribution of primary vertices collected over ten minutes. Errors are statistical only. The tilt is defined with respect to the ATLAS coordinate system.	eps file

Major updates:
-- JamieBoyd - 31-Jul-2012

Responsible: JamieBoyd
Subject: public

Topic revision: r10 - 2020-11-19 - JackLindon

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