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[1] Integrated dose [mGy] as a function of time for the irradiation period of the CMS DT spare chamber ‘MB2’ at GIF++. The layers 1 and 4 from superlayer 1 were irradiated with HV on (3550 V). The rest of the chamber was irradiated with HV in standby (1900 V) and used as reference. The vertical grey lines correspond to the 2017 and 2018 winter breaks when the chamber is kept off and the vertical orange lines mark the two irradiation and data-taking periods (eras). During summer 2018, 8 wires were extracted for later inspection and replaced with new non-aged wires. The axis on the right shows the equivalent expected luminosity for MB1 chambers in the external wheels for the HL-LHC. |
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[2] Hit efficiency for cosmic muons as a function of integrated luminosity for the aged layers (SL1L1 and SL1L4) at 3550 V. Each of the points in this plot corresponds to the data-taking during HV scans (with the source off) that were collected about every week. The DT auto trigger was used for cosmic muon tracks identifying a track in both projections on SL2 and SL3 of the DT chamber, avoiding any bias on the layers irradiated with HV on. The integrated luminosity used in these studies corresponds to the integrated luminosity expected for the MB1 chambers in the external wheels of the CMS detector (YB+/-2) during the HL-LHC. No atmospheric condition corrections have been applied. |
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[3] Hit efficiency for cosmic muons as a function of HV for the aged layers (SL1L1 and SL1L4) when the source is off and the front-end threshold 30 mV. The DT auto trigger was used for cosmic muon tracks, identifying a track in both projections on SL2 and SL3 of the DT chamber, avoiding any bias on the layers irradiated with HV on. There are three series of datasets each corresponding to a different integrated luminosity: beginning, middle and end of the irradiation period of MB2. The integrated luminosity used in these studies corresponds to the integrated luminosity expected for the MB1 chambers in the external wheels of the CMS detector (YB+/-2) during the HL-LHC. |
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[4] Hit efficiency for cosmic muons as a function of HV for the aged layers (SL1L1 and SL1L4) when the source is off. It shows the comparison of the hit efficiency for the front-end threshold values of 20 mV and 30 mV at the end of the irradiation period. The DT auto trigger was used for cosmic muon tracks, identifying a track in both projections on SL2 and SL3 of the DT chamber, avoiding any bias on the layers irradiated with HV on. The integrated luminosity, 5737 fb-1, corresponds to the integrated luminosity expected for the MB1 chambers in the external wheels of the CMS detector (YB+/-2) during the HL-LHC. |
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[5] Hit efficiency for cosmic muons as a function of instantaneous dose for the aged layers (SL1L1 and SL1L4) at 3550 V and for SL1L3 (reference) at 3600 V at a front-end threshold of 20 mV. The DT auto trigger was used for cosmic muon tracks, identifying a track in both projections on SL2 and SL3 of the DT chamber, avoiding any bias on the layers irradiated with HV on. There are three series of datasets each corresponding to a different integrated luminosity. The integrated luminosity used in these studies corresponds to the integrated luminosity expected for the MB1 chambers in the external wheels of the CMS detector (YB+/-2) during the HL-LHC. |
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[6] Hit efficiency for test beam muons as a function of instantaneous dose for the aged layers (SL1L1 and SL1L4) at 3550 V and for SL1L3 (non-aged) at 3600 V at a front-end threshold of 20 mV. The external trigger scintillators were used for muon tracks, identifying a track in both projections on SL2 and SL3 of the DT chamber in coincidence with the scintillators, avoiding any bias on the layers irradiated with HV on. The test beam was performed after an irradiation integrated dose equivalent to an HL-LHC integrated luminosity of 3600 fb-1. |
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[7] Hit efficiency for test beam muons as a function of instantaneous dose for the aged layers (SL1L1 and SL1L4) at 3550 V at a front-end threshold of 20 mV. The external trigger scintillators were used for muon tracks, identifying a track in both projections on SL2 and SL3 of the DT chamber in coincidence with the scintillators, avoiding any bias on the layers irradiated with HV on. The test beam was performed after an irradiation integrated dose equivalent to an HL-LHC integrated luminosity of 3600 fb-1. An exponential is used to fit the hit efficiency of SL1L1 and SL1L4 layers resulting in: * ![]() * ![]() |
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[8] Normalized Current for aged (SL1L1 and SL1L4) and non-aged (SL1L3) layers at 3550 V. The Normalized Current is defined as the ratio between the instantaneous current and the instantaneous dose. Values are scaled with respect to the initial value measured in SL1L3. Currents are corrected for the measured pressure in the bunker. Each of the points in this plot corresponds to the mean current of reading along a day. Gaps are caused by the loss of monitoring. The integrated luminosity used in these studies corresponds to the integrated luminosity expected for the MB1 chambers in the external wheels of the CMS detector (YB+/-2) during the HL-LHC. |
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[9] Hit efficiency for cosmic muons as a function of integrated luminosity for the aged layer SL1L1 taken with the source on at a background rate slightly higher than the expected background rate at the HL-LHC (corresponding to a instantaneous luminosity of 5.8x1034 cm-2s-1) at 3550 V and at a front-end threshold of 20 mV. The data are fitted using an exponential model, ![]() |
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[10] Expected hit efficiencies at the end of the HL-LHC for all the DT chambers of the CMS muon system, MB4 chambers (upper) and for MB1, MB2 and MB3 (lower). These efficiencies have been estimated considering a safety factor of 2 for the expected HL-LHC background rate (10x1034 cm-2s-1) and a safety factor of 2 for the expected integrated luminosity (6000 fb-1) to obtain the expected hit efficiency for the MB1 chambers in wheels ±2 and extrapolating to the rest of the CMS muon system using the expected integrated charge at the end of HL-LHC. |
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[11] Muon reconstruction efficiency at CMS as a function of absolute η for non aged DT chambers and aged DT chambers with the efficiencies shown in Fig. 10. The efficiencies have been calculated using simulated sample of dimuon events. |