Instantaneous luminosity determined by two independent methods for run 142193, taken by ATLAS on Dec 12, 2009. This run offered an extended stable-beam period of 4.5 hours, thus allowing ATLAS to measure the instantaneous luminosity for varying beam intensities. The blue open circles show the instantaneous luminosity as determined by the LAr and the red triangles show the instantaneous luminosity as measured by the MBTS. The instantaneous luminosity is corrected for the dead time in the data acquisition system, and therefore is an estimate of the LHC delivered luminosity at the ATLAS interaction point. For these measurements the PYHTIA Monte Carlo simulation of the pp inelastic processes have been used. The corresponding cross section used to normalize the measurements is 52.5 mb including non-diffractive, single-diffractive, and double-diffractive processes. The systematic uncertainty on the model is estimated using PHOJET. The difference between the two models translates into a variation of the luminosity of 18% for LAr and 15% for the MBTS. This uncertainty is 100% correlated between the two methods and dominates the total uncertainty on the measurements. The two curves show only the statistical error as the systematic uncertainty is time independent. For this run the estimated delivered luminosity is 3.0± 0.6μb−1: | EPS version |
Instantaneous luminosity determined by four independent methods for run 142193, taken by ATLAS on Dec 12, 2009.
This run offered an extended stable-beam period of 4.5 hours, thus allowing ATLAS to measure the instantaneous luminosity
for varying beam intensities. The plot shows the performance of the LAr, LUCID zero counting AND, and the HLT vertex counting normalized to give the same integrated luminosity as the MBTS results. The MBTS (shaded area) result provides the ATLAS luminosity. It is corrected for the dead time in the data acquisition system, and is therefore an estimate of the LHC delivered luminosity at the ATLAS interaction The corresponding cross section used to normalize the measurements is 52.5 mb includes non-diffractive, single-diffractive, and double-diffractive. The systematic uncertainty in the model is estimated using PHOJET. The difference between the two models translates into a variation of the luminosity of 15%. For this run the estimated delivered luminosity is, 3.0± 0.6μb−1: the uncertainty is dominated by the systematic on the physics model. The LUCID zero counting AND is not corrected for the dead time in the data acquisition system since the LUCID detector is not exposed to this effect. The four curves show only the statistical error as the systematic uncertainties are time independent and largely correlated among the different methods. | EPS version |
Instantaneous luminosity determined by four independent methods for run 142193, taken by ATLAS on Dec 12, 2009.
This run offered an extended stable-beam period of 4.5 hours, thus allowing
ATLAS to measure the instantaneous luminosity for varying beam intensities. The plot shows the performance of the LAr, LUCID zero counting AND, and the HLT vertex counting methods. The LUCID and the HLT are normalized to give the same integrated luminosity as the MBTS results, while the LAr is normalized using its own visible cross section. The MBTS (shaded area) result provides the ATLAS luminosity. It is corrected for the dead time in the data acquisition system, and is therefore an estimate of the LHC delivered luminosity at the ATLAS interaction The lower luminosity bin around 14:30 UTC includes a period of time where ATLAS was 100% busy and therefore it is not possible to derive a deadtime correction. The LUCID zero counting AND is not corrected for the dead time in the data acquisition system since the LUCID detector is not exposed to this effect. For this reason LUCID does not show the deep at around 14:30 UTC. The corresponding cross section used to normalize the measurements is 52.5 mb includes non-diffractive, single-diffractive, and double-diffractive. The systematic uncertainty in the model is estimated using PHOJET. The difference between the two models translates into a variation of the luminosity of 15%. For this run the estimated delivered luminosity is 3.0± 0.6μb−1: , the uncertainty is dominated by the systematic on the physics model. The four curves show only the statistical error as the systematic uncertainties are time independent and largely correlated among the different methods. | EPS version |
The plot shows the performance of the LAr, LUCID hit counting OR, LUCID zero counting
AND, and the HLT vertex counting with respect to the MBTS. The different models are normalized
to give the same integrated luminosity as the MBTS results. The four curves show only the statistical
error as as the systematic uncertainties are time independent and largely correlated among the different
methods.
| EPS version |
Comparison of the luminosity from the LAr and LUCID zero counting AND method with
respect to the MBTS during a time period affected by data acquisition dead time. The curves are not corrected
for dead time. The LAr and LUCID curves are normalized to give the same integrated luminosity
in a time period where the data acquisition was not affected by dead time. This plot shows that only
LUCID is not affected by the data acquisition dead time (UCT 14:20). In particular around 14:16 it is
visible a very short ( 14 s) time period where ATLAS was suffering 100% dead time while LUCID was
recording luminosity. This is because the LUCID detector readout is decoupled from the ATLAS data
acquisition system.
| EPS version |
Systematic uncertainties of the two methods currently used for the luminosity measurements.
The correlation coeffcient is 100%. Note, that the total systematic error is not the quadratic sum of
the individual ones in all cases since part of the detector response is correlated to the uncertainty on the
accceptance.
| EPS version |
Rate of events in LHC Fill 911 with at least one charged primary particle (pT >0.5 GeV/c, |η|<0.8)
versus UTC time (solid markers). Also shown is the raw rate of events with at least one track in this acceptance range (dashed line).
The correction factor applied to the raw rate to obtain the charged particle rate is 1.08 +/- 0.02. It corrects for any experimental
efficiencies, e.g. due to the tracking, vertexing and trigger efficiencies.
|
eps file |
Cross sections and acceptances of the requirement of have at least one charged primary particle with
|η|<0.8 and pT >0.5 GeV/c for two Pythia Monte Carlo tunes, for Pythia 8 and for
Phojet for √s=900 GeV. The statistical uncertainties on the numbers given are less than 0.1\%.
|
|
The assumed cross section model, the acceptance model, the visible cross section (σvis)
and the ratio of the visible to the total inelastic cross section
is given where σinel=σND+σSD+σDD
for √s=900 GeV.
|
|
Instantaneous Luminosity for LHC fill 911 vs UTC time comparing three methods of luminosity determination. The "Track" based method (solid circles) measures the
luminosity by counting primary charged particles with pT > 0.5 GeV/c and |η|<0.8. The "MBTS" method (open circles) counts events that have energy deposits on both
sides of the interaction point in the MBTS scintillators in the range 2.09<|η|<3.84 that are consistent in timing with a collision event. The "LAr Timing" method (open circles)
counts events that have energy deposits on both sides of the interaction point in the LAr calorimeter in the range 2.5<|η|<4.5 that are consistent in
timing with a collision event. For all methods the visible cross section is determined using Pythia MC09 for the model of inelastic collisions.
The Track based method gives an 3% larger luminosity than the MBTS method and a 7% larger luminosity than the LAr method. The MBTS (LAr) method has a systematic
uncertainty of 4% (5%) that is uncorrelated with the Track method, while the uncorrelated systematic uncertainty of the Track Counting method is 2%. |
eps file |
The instantaneous luminosity for LHC Fill 911 as a function of UTC time. The luminosity is shown assuming the
Pythia (black solid markers) vs the Phojet (blue histogram) model for the acceptances and the cross sections. |
eps file |
MBTS A-C side time difference Deltat(A-C) for events triggered by the L1_MBTS_1_1_Col for the
ATLAS run 141994. The circles
(black) correspond to events selected with L1_MBTS_1_1_Col, the shaded (yellow) area defines the events
passing the |Deltat(A-C)| < 10 ns, the triangles (blue) correspond to the Beam-Halo background of beam2, and the
squares (red) correspond to the Beam-Halo background of beam1. The Beam-Halo background has been extracted by
looking at the unpaired BCID separately for beam1 and beam2. The background normalization is fixed
to the ratio of the beam current carried by the paired bunches to the one of the unpaired bunches. | EPS version |
MBTS A-C side time difference Deltat(A-C) for events triggered by the L1_MBTS_1_1_Col for the
ATLAS run 142174. The circles
(black) correspond to events selected with L1_MBTS_1_1_Col, the shaded (yellow) area defines the events
passing the |Deltat(A-C)| < 10 ns, the triangles (blue) correspond to the Beam-Halo background of beam2, and the
squares (red) correspond to the Beam-Halo background of beam1. The Beam-Halo background has been extracted by
looking at the unpaired BCID separately for beam1 and beam2. The background normalization is fixed
to the ratio of the beam current carried by the paired bunches to the one of the unpaired bunches. | EPS version |
MBTS A-C side time difference Deltat(A-C) for events triggered by the L1_MBTS_1_1_Col for the
ATLAS run 142193. The circles
(black) correspond to events selected with L1_MBTS_1_1_Col, the shaded (yellow) area defines the events
passing the |Deltat(A-C)| < 10 ns, the triangles (blue) correspond to the Beam-Halo background of beam2, and the
squares (red) correspond to the Beam-Halo background of beam1. The Beam-Halo background has been extracted by
looking at the unpaired BCID separately for beam1 and beam2. The background normalization is fixed
to the ratio of the beam current carried by the paired bunches to the one of the unpaired bunches. | EPS version |
MBTS A-C side time difference Deltat(A-C) for events triggered by the L1_MBTS_1_1_Col for the
ATLAS run 142383. The circles
(black) correspond to events selected with L1_MBTS_1_1_Col, the shaded (yellow) area defines the events
passing the |Deltat(A-C)| < 10 ns, the triangles (blue) correspond to the Beam-Halo background of beam2, and the
squares (red) correspond to the Beam-Halo background of beam1. The Beam-Halo background has been extracted by
looking at the unpaired BCID separately for beam1 and beam2. The background normalization is fixed
to the ratio of the beam current carried by the paired bunches to the one of the unpaired bunches. | EPS version |
The beam-halo time dependence is shown for events triggered by L1_MBTS_1_1 and
L1_MBTS_1_1_Col. For this plot the beam-halo is defined as all events with Deltat(A-C) > 15 ns.
Data correspond to
run 141994 which has a high beam-halo contribution. The
collision
and beam-halo events are given as a function of time.
Note that the few bins with a low number of entries correspond to short
periods of data acquisition dead time. | EPS version |
The beam-halo time dependence is shown for events triggered by L1_MBTS_1_1 and
L1_MBTS_1_1_Col. For this plot the beam-halo is defined as all events with Deltat(A-C) > 15 ns. Data correspond to
run 141994 which has a high beam-halo contamination. The ratio of collision
and beam-halo events are given as a function of time.
| EPS version |
The beam-halo time dependence is shown for events triggered by L1_MBTS_1_1 and
L1_MBTS_1_1_Col. For this plot the beam-halo is defined as all events with Deltat(A-C) > 15 ns.
Data correspond to
run 142193 which has a high beam-halo contribution. The
collision
and beam-halo events are given as a function of time.
Note that the few bins with a low number of entries correspond to short
periods of data acquisition dead time. | EPS version |
The beam-halo time dependence is shown for events trigger by L1_MBTS_1_1 and
L1_MBTS_1_1_Col. For this plot the beam-halo is defined as all events with Deltat(A-C) > 15 ns. Data correspond to
run 142193 which has a low beam-halo contamination. The ratio of collision
and beam-halo events are given as a function of time.
| EPS version |
The plot shows the BCID activity for events triggered by the MBTS in the ATLAS run 142383.
The light shaded (light blue) histogram shows the events triggered by L1_MBTS_1_1. The histograms
filled with diagonal (red) lines shows the events triggered by L1_MBTS_1_1_Col, that means only
collinging bunches. The darker shaded (green) histogram shows the difference between L1_MBTS_1_1
and L1_MBTS_1_1_Col after applying |Deltat(A-C) < 10| ns. It is interesting to notice that only in BCID=1 there
is a non negligible number of events that are selected by L1_MBTS_1_1 and not by L1_MBTS_1_1_Col.
This is due to the fact that the bunches at BCID=1 for some interval of time didn't trigger the BPTX,
and while firing L1_MBTS_1_1 failed to trigger L1_MBTS_1_1_Col. The pairs of BCIDs (1391, 1397),
(1553, 1559), and (1715, 1721) where the first BICD belongs to beam2 and the second to beam1, have
a higher rate that other unpaired bunches because they were crossing in the proximity of the ATLAS
interaction point contributing some events from displaced collision to the trigger rate.
| EPS version |
Bunch by bunch specific MBTS luminosity for the ATLAS run 142383.
| EPS version |
Bunch by bunch beam halo-background fraction for the ATLAS run 142383 for the L1_MBTS_1_1_Col trigger item. For this plot the beam-halo is defined as all events with Deltat(A-C) > 15 ns.
| EPS version |
Instantaneous luminosity for the ATLAS run 141994. The
dashed line corresponds to events selected with the L1_MBTS_1_1 trigger, the light-shaded area to events
selected by the L1_MBTS_1_1_Col and the dark area to events selected by the L1_MBTS_1_1_Col with the timing cut applied.
The red curve corresponds to an exponential fit to the luminosity lifetime, the fit parameters are given in the box.
The bins with lower instantaneous luminosity ( UTC Time
2 : 45) correspond
to short periods of time where the data acquisition system was suffering dead time.
| EPS version |
Instantaneous luminosity for the ATLAS run 142174. The
dashed line corresponds to events selected with the L1_MBTS_1_1 trigger, the light-shaded area to events
selected by the L1_MBTS_1_1_Col and the dark area to events selected by the L1_MBTS_1_1_Col with the timing cut applied.
The red curve corresponds to an exponential fit to the luminosity lifetime, the fit parameters are given in the box.
The drop of luminosity visible in the plot is due to the loss of L1_MBTS_1_1_Col events caused
by instability of the L1 BPTX signals
The bins with lower instantaneous luminosity ( UTC Time
20 : 10) correspond
to short periods of time where the data acquisition system was suffering dead time.
| EPS version |
Instantaneous luminosity for the ATLAS run 141994. The
dashed line corresponds to events selected with the L1_MBTS_1_1 trigger, the light-shaded area to events
selected by the L1_MBTS_1_1_Col and the dark area to events selected by the L1_MBTS_1_1_Col with the timing cut applied.
The red curve corresponds to an exponential fit to the luminosity lifetime, the fit parameters are given in the box.
The bins with lower instantaneous luminosity ( UTC Time
14 : 20) correspond
to short periods of time where the data acquisition system was suffering dead time.
| EPS version |
Instantaneous luminosity for the ATLAS run 141994. The
dashed line corresponds to events selected with the L1_MBTS_1_1 trigger, the light-shaded area to events
selected by the L1_MBTS_1_1_Col and the dark area to events selected by the L1_MBTS_1_1_Col with the timing cut applied.
The red curve corresponds to an exponential fit to the luminosity lifetime, the fit parameters are given in the box.
The bins with lower instantaneous luminosity ( UTC Time
00 : 50) correspond
to short periods of time where the data acquisition system was suffering dead time.
| EPS version |
Specific luminosity as function of the local (Geneva) time for three selected LHC fills. The specific luminosities for fills 911 and 919 (both taken at 900 GeV centre-of-mass energy) are comparable and stable versus time. The specific luminosity for fill 923 is higher, as expected due to the beams being more focussed at the higher energy. During fill 923 the specific luminosity suddenly descreased at 3:00, and then returned to the previous level at 3:45. This is correlated with the beams being separated horizontally as is seen in the lower figure. The errors shown are purely statistical. The luminosity was measured using the forward Liquid-Argon calorimeters. The acceptance of the selection was taken from pythia as described above. The specific luminosity is given by the instantaneous luminosity divided by the number of protons per bunch in each of the beams and the number of colliding bunches. The number of protons per beam is taken from TIMBER. eps files are also available for the spec. luminosity for fill 911, fill 919, fill 923 and for the IP separation plot |
|
Luminosity weighted relative fraction of detector uptime and good quality data delivery of the various ATLAS subsystems during LHC fills with stable beams. Not included in the numbers is the 7% average DAQ inefficiency during runs with stable beams. Also excluded are 4.5% of the integrated luminosity taken in a special detector configuration. The first row gives the average numbers for all stable beam periods, and the second row shows the numbers for Dec 12, when, during 6 runs, almost half of the integrated luminosity has been collected. The 'All' column requires all detectors to be running and deliver good data quality.
When the stable beam flag is raised, the inner detector and muon systems undergo a so-called "warm start", which includes a ramp of the high-voltage and, for the pixel system, the preamplifiers are turned on. This procedure takes typically several minutes, which, in case of short stable beam periods, sums up to a significant fraction. This dominates the quoted inefficiencies. Longer runs and automation of the warm start will help to reduce the inefficiency. |
PDF version of table |
I | Attachment | History | Action | Size | Date | Who | Comment |
---|---|---|---|---|---|---|---|
png | IPpositions_B1B2_16Dec09.png | r1 | manage | 15.4 K | 2010-02-16 - 10:41 | BeateHeinemann | |
eps | Run_Off_lumi_141994.eps | r1 | manage | 60.3 K | 2010-04-08 - 18:41 | AndreaMessina | MBTS luminosity run 141994 eps |
png | Run_Off_lumi_141994.png | r1 | manage | 19.4 K | 2010-04-08 - 18:41 | AndreaMessina | MBTS luminosity run 141994 |
eps | Run_Off_lumi_142174.eps | r1 | manage | 27.5 K | 2010-04-08 - 18:42 | AndreaMessina | MBTS luminosity run 142174 eps |
png | Run_Off_lumi_142174.png | r1 | manage | 15.8 K | 2010-04-08 - 18:42 | AndreaMessina | MBTS luminosity run 142174 |
eps | Run_Off_lumi_142193.eps | r1 | manage | 54.9 K | 2010-04-08 - 18:42 | AndreaMessina | MBTS luminosity run 142193 eps |
png | Run_Off_lumi_142193.png | r1 | manage | 17.7 K | 2010-04-08 - 18:43 | AndreaMessina | MBTS luminosity run 142193 |
eps | Run_Off_lumi_142383.eps | r1 | manage | 28.8 K | 2010-04-08 - 18:43 | AndreaMessina | MBTS luminosity run 143283 eps |
png | Run_Off_lumi_142383.png | r1 | manage | 17.4 K | 2010-04-08 - 18:43 | AndreaMessina | MBTS luminosity run 143283 |
eps | bcid_142383.eps | r1 | manage | 16.4 K | 2010-04-08 - 18:23 | AndreaMessina | MBTS bc specific luminosity run 142383 eps |
png | bcid_142383.png | r1 | manage | 23.9 K | 2010-04-08 - 18:23 | AndreaMessina | MBTS bc specific luminosity run 142383 |
eps | bkgdBCID_141994.eps | r1 | manage | 27.8 K | 2010-04-08 - 16:50 | AndreaMessina | Mbts bkgd run 141994 eps |
png | bkgdBCID_141994.png | r1 | manage | 16.0 K | 2010-04-08 - 16:39 | AndreaMessina | mbts bkgd run 141994 |
eps | bkgdBCID_142174.eps | r1 | manage | 27.6 K | 2010-04-08 - 16:52 | AndreaMessina | Mbts bkgd run 142174 eps |
png | bkgdBCID_142174.png | r1 | manage | 14.8 K | 2010-04-08 - 16:51 | AndreaMessina | Mbts bkgd run 142174 |
eps | bkgdBCID_142193.eps | r1 | manage | 30.2 K | 2010-04-08 - 16:53 | AndreaMessina | Mbts bkgd run 142193 eps |
png | bkgdBCID_142193.png | r1 | manage | 16.3 K | 2010-04-08 - 16:54 | AndreaMessina | Mbts bkgd run 142193 |
eps | bkgdBCID_142383.eps | r1 | manage | 30.1 K | 2010-04-08 - 16:56 | AndreaMessina | Mbts bkgd run 142383 eps |
png | bkgdBCID_142383.png | r1 | manage | 16.5 K | 2010-04-08 - 16:59 | AndreaMessina | Mbts bkgd run 142383 |
eps | run141993_beamHalo_frac.eps | r1 | manage | 6.8 K | 2010-04-08 - 18:33 | AndreaMessina | MBTS bc beam halo fraction run 142383 eps |
png | run141993_beamHalo_frac.png | r1 | manage | 15.8 K | 2010-04-08 - 18:32 | AndreaMessina | MBTS bc beam halo fraction run 142383 |
eps | run141993_spec_lumi.eps | r1 | manage | 5.4 K | 2010-04-08 - 18:32 | AndreaMessina | MBTS bc specific luminosity run 142383 eps |
png | run141993_spec_lumi.png | r1 | manage | 10.2 K | 2010-04-08 - 18:31 | AndreaMessina | MBTS bc specific luminosity run 142383 |
eps | run141994_beamHaloVsTime.eps | r1 | manage | 15.6 K | 2010-04-08 - 17:03 | AndreaMessina | MBTS signal and halo run 141994 eps |
png | run141994_beamHaloVsTime.png | r1 | manage | 19.5 K | 2010-04-08 - 17:02 | AndreaMessina | MBTS signal and halo run 141994 |
png | run141994_beamHaloVsTime_ratio.png | r1 | manage | 20.1 K | 2010-04-08 - 17:04 | AndreaMessina | MBTS signal and halo ratio run 141994 |
eps | run142193_absolute_luminosity.eps | r2 r1 | manage | 26.6 K | 2010-04-26 - 10:41 | AndreaMessina | un142193_absolute_luminosity - eps |
png | run142193_absolute_luminosity.png | r3 r2 r1 | manage | 20.7 K | 2010-04-26 - 10:39 | AndreaMessina | un142193_absolute_luminosity - png |
eps | run142193_beamHaloVsTime.eps | r1 | manage | 14.5 K | 2010-04-08 - 17:15 | AndreaMessina | MBTS signal and halo run 142193 eps |
png | run142193_beamHaloVsTime.png | r1 | manage | 19.1 K | 2010-04-08 - 17:15 | AndreaMessina | MBTS signal and halo run 142193 |
png | run142193_beamHaloVsTime_ratio.png | r1 | manage | 20.0 K | 2010-04-08 - 17:17 | AndreaMessina | MBTS signal and halo ratio run 142193 |
eps | run142193_relative_luminosity.eps | r1 | manage | 50.1 K | 2010-04-26 - 10:38 | AndreaMessina | run142193_relative_luminosity.eps |
png | run142193_relative_luminosity.png | r2 r1 | manage | 25.8 K | 2010-04-26 - 10:38 | AndreaMessina | run142193_relative_luminosity.png |
eps | run142193_relative_luminosity_larAbsolute.eps | r2 r1 | manage | 21.9 K | 2010-04-26 - 10:36 | AndreaMessina | run142193_relative_luminosity_larAbsolute.eps |
png | run142193_relative_luminosity_larAbsolute.png | r2 r1 | manage | 21.2 K | 2010-04-26 - 10:37 | AndreaMessina | run142193_relative_luminosity_larAbsolute.png |
eps | run142193_relative_luminosity_noDeadtime.eps | r1 | manage | 17.9 K | 2010-04-23 - 14:36 | AndreaMessina | run142193_relative_luminosity_noDeadtime.eps |
png | run142193_relative_luminosity_noDeadtime.png | r2 r1 | manage | 17.4 K | 2010-04-23 - 14:36 | AndreaMessina | run142193_relative_luminosity_noDeadtime.png |
eps | run142193_relative_luminosity_ratio.eps | r1 | manage | 19.9 K | 2010-04-23 - 14:37 | AndreaMessina | run142193_relative_luminosity_ratio.eps |
png | run142193_relative_luminosity_ratio.png | r2 r1 | manage | 20.5 K | 2010-04-23 - 14:37 | AndreaMessina | run142193_relative_luminosity_ratio.png |
eps | run142193_relative_luminosity_rebin_larAbsolute.eps | r1 | manage | 21.9 K | 2010-04-23 - 14:38 | AndreaMessina | run142193_relative_luminosity_rebin_larAbsolute.eps |
png | run142193_relative_luminosity_rebin_larAbsolute.png | r1 | manage | 20.9 K | 2010-04-23 - 14:38 | AndreaMessina | run142193_relative_luminosity_rebin_larAbsolute.png |
png | specl_run142193.png | r1 | manage | 23.6 K | 2010-02-16 - 10:40 | BeateHeinemann | |
png | specl_run142383.png | r1 | manage | 20.0 K | 2010-02-16 - 10:40 | BeateHeinemann | |
png | specl_run142402.png | r1 | manage | 28.9 K | 2010-02-16 - 10:40 | BeateHeinemann | |
png | systematic_table.png | r1 | manage | 16.4 K | 2010-04-23 - 16:40 | AndreaMessina | |
eps | systematic_table1.eps | r1 | manage | 16.8 K | 2010-04-23 - 16:40 | AndreaMessina |