Public Inner Detector BCM Plots for Collision Data

Average number of events per bunch crossing satisfying the AND algorithm condition, color-coded for individual colliding bunches. Data for BCM horizontal modules is shown over ATLAS run 166924 for all 295 colliding bunches. For an event to satisfy the AND condition, it must contain a coincidence of hits in the two horizontal A and C side BCM modules, within the second half (12.5 ns) of the bunch interval.

Average number of events per bunch crossing satisfying the OR algorithm condition, color-coded for individual colliding bunches. Data for BCM horizontal modules is shown over ATLAS run 166924 for all 295 colliding bunches. For an event to satisfy the OR condition, it must contain at least one hit in four horizontal BCM modules within the second half (12.5 ns) of the bunch interval.

Average number of events per bunch crossing satisfying the AND algorithm condition versus time. For an event to satisfy the AND condition, it must contain a coincidence of hits in the A and C side BCM modules (vertical or horizontal) within the second half of the bunch interval. Event counts are averaged over all colliding bunches and scaled to one LHC turn. Data for both RODs (two independent measurements) was extracted from run 166924.

Average number of events per bunch crossing satisfying the OR algorithm condition versus time. For an event to satisfy the OR condition, it must contain a hit anywhere in BCM detector within second half of the bunch interval. Event counts are averaged over all colliding bunches and scaled to one LHC turn. Data for both RODs (two independent measurements) was extracted from run 166924.

Average number of events per bunch crossing satisfying the exclusive OR-A (XOR-A) algorithm condition versus time. For an event to satisfy the XOR-A condition, it must contain a hit on A side, and no hits on C side vertical or horizontal modules of the BCM detector within the second half of the bunch interval. Event counts are averaged over all colliding bunches and scaled to one LHC turn. Data for both RODs (two independent measurements) were extracted from run 166924.

Average number of events per bunch crossing satisfying the exclusive OR-C (XOR-C) algorithm condition versus time. For an event to satisfy the XOR-C condition, it must contain a hit on C side, and no hits on A side in the vertical or horizontal modules of the BCM detector within the second half of the bunch interval. Event counts are averaged over all colliding bunches and scaled to one LHC turn. Data for both RODs (two independent measurements) were extracted from run 166924.

Average number of events per bunch crossing satisfying different algorithm conditions versus time. Event counts are averaged over all colliding bunches. Data are shown for comparison of different algorithm occupancies. For clarity, only the data from horizontal modules are plotted for the run 166924.

Average number of events per LHC turn satisfying the OR algorithm condition. Horizontal axis denotes the sequential number of possible bunch slots, and extends over all 3564 slots covering the entire LHC beam. Bunch train structure of the beam is clearly visible, as well as the relative strength between signals induced by colliding and unpaired bunches (bunch numbers 1500-1600). The latter is comparable to the amplitude of the afterglow following each colliding bunch. For clarity, only data for horizontal modules are plotted for ATLAS run 166924 (16.10.2010).

Average number of events per LHC turn satisfying the AND algorithm condition. Horizontal axis denotes the sequential number of possible bunch slots, and extends over all 3564 slots covering the entire LHC beam. Bunch train structure of the beam is clearly visible, as well as the relative strength between signals induced by colliding and by unpaired bunches (bunch numbers from 1500-1600). The AND algorithm imposes a stricter selection, which suppresses the afterglow signal visible in OR algorithms. For clarity, only data for horizontal modules are plotted for ATLAS run 166924 (16.10.2010).

Average number of events per LHC turn satisfying the AND algorithm condition. Horizontal axis denotes the sequential number of possible bunch slots, highlighting only a part of the entire LHC beam. Individual bunches are well distinguishable within the bunch train even for the unpaired bunches. For selective algorithms such as AND, the random background is five orders of magnitude lower than the signal. For clarity, only data for horizontal modules are plotted for ATLAS run 166924 (16.10.2010).

BCM data collected during the van der Meer scan on 1.10.2010. The vertical axis quantifies the number of events satisfying the OR algorithm condition normalized to single LHC turn. Only the six colliding bunches are summed into the values shown. Data for both RODs (two independent measurements) is shown as a function of beam separation.

BCM data collected during the Van der Meer scan on 1.10.2010. The vertical axis quantifies the number of events satisfying OR algorithm condition normalized to single LHC turn. All, except colliding bunches, are summed into the values shown. Data for both RODs (two independent measurements) is shown as a function of beam separation. The signal is two orders below the contribution of colliding bunches, but still exhibiting scan-typical beam separation dependence due to afterglow effects.

BCM data collected during the Van der Meer scan on 1.10.2010. The vertical axis quantifies the number of events satisfying the AND algorithm condition normalized to single LHC turn. Only the colliding bunches are summed into the values shown. Data for both RODs (two independent measurements) is shown as a function of beam separation.

BCM data collected during the Van der Meer scan on 1.10.2010. The vertical axis quantifies the number of events satisfying the AND algorithm condition normalized to single LHC turn. All, except colliding bunches, are summed into the values shown. Data for both RODs (two independent measurements) is shown as a function of beam separation.

Distribution of events against difference of arrival times of hits on A and C side of BCM detector for run 152779. From difference of arrival times to both sides it is possible to distinguish collision and background coming from LHC beam 1 and beam 2.

Signal seen at the LHC dump by ATLAS BCM on 26.3.2010 at 13:41 (Geneva local time). LHC was doing collimator studies at 3.5TeV. Plot shows development of signal in low threshold channels in about 90ms prior and 10ms after the post mortem event.

Signal seen at the LHC dump by ATLAS BCM on 26.3.2010 at 13:41 (Geneva local time). LHC was doing collimator studies at 3.5TeV. Plot shows development of signal in high threshold channels in about 90ms prior and 10ms after the post mortem event.

Signal seen at the LHC dump by ATLAS BCM. LHC was doing collimator studies at 3.5TeV. Coincidence seen on one ROD. From the relative timing of the channels it is obvious that it was due to beam 2 going from C side to A side of ATLAS. Plot shown is an example of automatically generated gif picture after PM analysis.

BCM Time-Of-Flight (TOF) collision and beam background events as function of the Bunch Crossing Identifier (BCID) showing the LHC fill structure for run 142193. Beam background and collision events are visible for bunch crossings with the IDs 1,101 and 2774. Bunch crossings 424 & 2209 have only beam background events from Beam 1 and bunch crossings 1315 & 1880 only beam background events from Beam 2, respectively. These bunch crossings are presumably creating collisions in ALICE and LHCb.

Time evolution of beam background and collision events for run 142193 measured as a BCM Time-Of-Flight (TOF) distribution between the two detector stations located at z = ±1.84m. The time is binned in units of Event Counter Reset (ECR), which are 5s signals. The ECR itself is reset approximately every 21 minutes. Since the run was almost 6 hours long, the plot shows a superposition of ~18 ECR sweeps. A higher beam background period for Beam1 is visible between ECR values 210 and 230.

BCM Time-Of-Flight (TOF) distribution for run 142193 between the two BCM detector stations located at z = ±1.84m. Δt values of 12.5 ns represent beam background events from LHC Beam 1 whereas Δt values of -12.5 ns represent LHC Beam 2 background events, respectively. Collision events have Δt values of 0 ns. A Gaussian fit of the collision peak in the tC - tA TOF distribution yields a width of 972 ps; this is consistent with a single side time resolution of 687 ps.