High-Granularity Timing Detector (HGTD)

This page contains plots related to the High-Granularity Timing Detector project part of the ATLAS Phase-II upgrade, to be used by ATLAS speakers at conferences and similar events.

Please do not add figures on your own. Contact the responsible HGTD project leader in case of questions and/or suggestions.

Recent Plots: 2021-2022

ALTIROC2 ASIC plots

Trigger efficiency as a function of the charge for all 15 channels of one transimpedance (TZ) preamplifier column (n°9), showing the minimum charge detectable by ALTIROC2 ASIC alone irradiated up to 220 Mrad for transimpedance preamplifier channels : 1.4 fC (median at 50%) Setup : Only analog front-end from all 15 channels of one transimpedance preamplifier column n°9 (preamplifier+discriminator+TDC) turned on and all pixels in column fired simultaneoulsy

Trigger efficiency for all transimpedance (TZ) channels (105 pixels or 7 columns), showing the minimum charge detectable by the ALTIROC2 ASIC alone irradiated up to 220 Mrad for transimpedance preamplifier channels : 3.1 fC (median at 50%) Setup : All analog front-ends enabled (preamplifier+discriminator+TDC) and transimpedance preamplifier pixels fired simultaneoulsy column-by-column.

Trigger efficiency as a function of the charge for all 15 channels of one transimpedance (TZ) preamplifier column (n°9), showing the minimum charge detectable by ALTIROC2 ASIC alone irradiated up to 220 Mrad for transimpedance preamplifier channels : 1.4 fC (median at 50%) Setup : Only analog front-end from all 15 channels of one transimpedance preamplifier column n°9 (preamplifier+discriminator+TDC) turned on and all pixels in column fired simultaneoulsy

Trigger efficiency plot for all transimpedance (TZ) channels (105 pixels, 7 columns), showing the minimum charge detectable by the ALTIROC2 ASIC bump bonded onto an HPK LGAD biased at -80V : 3.8 fC (median at 50%) Setup : All transimpedance preamplifier analog front-ends enabled (preamplifier+discriminator+TDC) and transimpedance preamplifier pixels fired simultaneoulsy column-by-column.

Time of Arrival (TOA) as a function of the injected charge for all transimpedance (TZ) preamplifier channels with ALTIROC2 ASIC bump bonded onto an HPK LGAD biased at -80 V. Setup: All transimpedance preamplifier analog front-ends enabled (preamplifier+discriminator+TDC) and pixels fired simultaneoulsy column-by-column. Pixel local thresholds aligned at 3.2 fC. Outliers positions within the pixel matrix do not follow any logic (for instance: red=channel 217=middle of column, purple=channel 201=middle of column, black=channel 210=bottom). No column tendency can be observed. Dispersions result from clock tree skews after digital place and route tool.

Time Over Threshold (TOT) as a function of the injected charge for all transimpedance (TZ) preamplifier channels with ALTIROC2 ASIC bump bonded onto an HPK LGAD biased at -80 V. Setup : All transimpedance preamplifier analog front-ends enabled (preamplifier+discriminator+TDC) and pixels fired simultaneoulsy column-by-column. Pixel local thresholds aligned at 3.2 fC.

Timewalk: Time Of Arrival (TOA) versus Time Over Threshold (TOT) for various charge and for all transimpedance (TZ) preamplifier channels with ALTIROC2 ASIC bump bonded onto an HPK LGAD biased at -80 V. Setup: All transimpedance preamplifier analog front-ends enabled (preamplifier+discriminator+TDC) and pixels fired simultaneoulsy column-by-column. Pixel local thresholds aligned at 3.2 fC.Outliers positions within the pixel matrix do not follow any logic (for instance: red=channel 217=middle of column, purple=channel 201=middle of column, black=channel 210=bottom). No column tendency can be observed. Dispersions result from clock tree skews after digital place and route tool.

Jitter as function of charge with ALTIROC2 ASIC alone and ASIC+LGAD with at least all transimpedance (TZ) preamplifier channels enabled. The expectation from analog front-end simulations is also displayed as calculated with the preamplifier output noise, slope and amplitude. Discrepancies at low charge, near the threshold are still under investigation when more than one column is enabled. Pixel selected : best-of pixel minimizing jitter on average above 4 fC

Mean jitter across transimpedance (TZ) preamplifier channels as function of charge with ALTIROC2 ASIC alone with all transimpedance preamplifier channels enabled and for various global discriminator alignments at various charges. Rising jitter close to the charge used for threshold alignment is caused by the lower pulse slope on top of the pulse. This effect has been reproduced with analogue front-end monte-carlo simulations (including discriminator) as displayed on the figure.

Time Of Arrival (TOA) TDC quantification step as a function of pixel numbers at two temperatures for ALTIROC2. The variation along the column has been attributed to static voltage drops which will be corrected in the next prototype. Also the TDC resolution shown here is not compensated in temperature since Delay Lock Loop (DLL) were not used in this measurement. This measurement is performed by a direct injection at the TDC input inside the ASIC.

Time Of Arrival (TOA) TDC quantification step as a function of pixel numbers at two temperatures for ALTIROC2. The variation along the column has been attributed to static voltage drops which will be corrected in the next prototype. Also the TDC resolution shown here is not compensated in temperature since Delay Lock Loop (DLL) were not used in this measurement. This measurement is performed by a direct injection at the TDC input inside the ASIC.

Time Over Threshold (TOT) TDC quantification step as a function of pixel numbers at two temperatures for ALTIROC2. The variation along the column has been attributed to static voltage drops which will be corrected in the next prototype. Also the TDC resolution shown here is not compensated in temperature since Delay Lock Loop (DLL) were not used in this measurement. This measurement is performed by a direct injection at the TDC input inside the ASIC.

Time Over Threshold (TOT) TDC quantification step as a function of pixel numbers at two temperatures for ALTIROC2. The variation along the column has been attributed to static voltage drops which will be corrected in the next prototype. Also the TDC resolution shown here is not compensated in temperature since Delay Lock Loop (DLL) were not used in this measurement. This measurement is performed by a direct injection at the TDC input inside the ASIC.

Mean Time Of Arrival (TOA) jitter (for 15 transimpedance (TZ) preamplifier + 15 voltage preamplifier pixels) for 4 and 10 fC injected charges versus total ionizing dose for ALTIROC2 ASIC alone showing stability under radiation up to 220 Mrad. Setup : Delay Lock Loop (DLL) not used (straped) Pixels ON and injected : col7, col8 (one at a time) Dose rate : 3 Mrad/h Temperature : 22°C

Comparing pulse reconstruction of a voltage preamplifier (pixel 45) between 2 boards : ALTIROC2 ASIC alone (with and without internal detector capacitance) versus ASIC+LGAD (without internal detector capacitance). Showing same falling edge decay time and pulse amplitude between blue and green, hence confirming the internal LGAD-like capacitance corresponds indeed to 3.5 pF. Showing a slightly slowly leading edge with LGAD than with the ASIC internal emulation detector capacitance that could partially explain a larger jitter when the sensor is connect to the ASIC, still under investigation.

2021-2022 Test Beam LGAD Sensors Results

Collected charge as a function of the bias voltage for different single-pad sensors of a size of 1.3 x 1.3 mm^2: FBK-UFSD3.2-W19 (blue circles), USTC-IMEv2.1-W17 (green losanges) and IHEP-IMEv2-W7 (violet stars). Bias voltages were kept lower than the value required to operate the sensors. All 3 sensors were tested with 5 GeV electrons at DESY. Measurements were performed at temperatures from -40 to -30°C for FBK-UFSD3.2-W19, from -43 to -30°C for IHEP-IMEv2-W7Q2, and from -39°C to -24°C for USTC-IMEv2.1-W17. Sensors were irradiated with 1 MeV neutrons (at 1.5x10^15 neq/cm^2) at JSI and annealed for 80 mins @ 60°C. The fluence is known with a precision of 10%. The measurements leading to these results have been performed at the Test Beam Facility at DESY Hamburg (Germany), a member of the Helmholtz Association (HGF).

Collected charge as a function of the bias voltage for different single pad sensors of a size of 1.3 x 1.3 mm^2: FBK-UFSD3.2-W19 (green circles), USTC-IMEv2.1-W17 (violet losanges) and IHEP-IMEv2-W7 (red stars). Bias voltages were kept lower than the value required to operate the sensors. Measurements were performed at temperatures from -46 to -26°C for FBK-UFSD3.2-W19, from -43 to -29°C for USTC-IMEv2.1-W17, and at -20°C for IHEP-IMEv2-W8. FBK-UFSD3.2-W19 and USTC-IMEv2.1-W17 were tested with 5 GeV electrons at DESY while IHEP-IMEv2-W8 was tested with 120 GeV pions at SPS CERN using MALTA Telescope. Sensors were irradiated with 1 MeV neutrons (at 2.5x10^15 neq/cm^2) at JSI and annealed for 80 mins @ 60°C. The fluence is known with a precision of 10%. Measurements leading to the SPS results have been carried out using a MALTA beam telescope as part of the CERN ATLAS R&D program. The measurements leading to the DESY results have been performed at the Test Beam Facility at DESY Hamburg (Germany), a member of the Helmholtz Association (HGF).

Time resolution as a function of the bias voltage for different single-pad sensors of a size of 1.3 x 1.3 mm^2: FBK-UFSD3.2-W19 (blue circles), USTC-IMEv2.1-W17 (green losanges) and IHEP-IMEv2-W7 (violet stars). Bias voltages were kept lower than the value required to operate the sensors. Time resolution is derived from the distributions of CFD differences for all the combinations of DUTs and a reference device (SiPM) tested simultaneously and it is defined as the standard deviation of a Gaussian fit. A charge threshold of 2 fC is applied. The resolution of SiPM was ranging around 65 ps depending on the voltage applied. Uncertainties are calculated using error propagation. All 3 sensors were tested with 5 GeV electrons at DESY. Measurements were performed at temperatures from -40 to -30°C for FBK-UFSD3.2-W19, from -43 to -30°C for IHEP-IMEv2-W7Q2 and from -39°C to -24°C for USTC-IMEv2.1-W17. Sensors were irradiated with 1 MeV neutrons (at 1.5x10^15 neq/cm^2) at JSI and annealed for 80 mins @ 60°C. The fluence is known with a precision of 10%. The measurements leading to these results have been performed at the Test Beam Facility at DESY Hamburg (Germany), a member of the Helmholtz Association (HGF).

Time resolution as a function of the bias voltage for different single pad sensors of a size of 1.3 x 1.3 mm^2: FBK-UFSD3.2-W19 (green circles), USTC-IMEv2.1-W17 (violet losanges) and IHEP-IMEv2-W7 (red stars). Bias voltages were kept lower than the value required to operate the sensors. Time resolution is derived from the distributions of CFD differences for all the combinations of DUTs and a reference device (SiPM) tested simultaneously and it is defined as the standard deviation of a Gaussian fit. A charge threshold of 2 fC is applied. The resolution of SiPM was ranging around 65 ps depending on the voltage applied. Uncertainties are calculated using error propagation. Measurements were performed at temperatures from -46 to -26°C for FBK-UFSD3.2-W19, from -43 to -29°C for USTC-IMEv2.1-W17 and -20°C for IHEP-IMEv2-W8. FBK-UFSD3.2-W19 and USTC-IMEv2.1-W17 were tested with 5 GeV electrons at DESY while IHEP-IMEv2-W8 was tested with 120 GeV pions at SPS CERN using MALTA Telescope. Sensors were irradiated with 1 MeV neutrons (at 2.5x10^15 neq/cm^2) at JSI and annealed for 80 mins @ 60°C. The fluence is known with a precision of 10%. Measurements leading to the SPS results have been carried out using a MALTA beam telescope as part of the CERN ATLAS R&D program. The measurements leading to the DESY results have been performed at the Test Beam Facility at DESY Hamburg (Germany), a member of the Helmholtz Association (HGF).

Efficiency map of the sensor IHEP-IMEv2-W7Q2 (irradiated at 1.5×1015 neq/cm^2), where efficiency is defined as ratio of the reconstructed tracks with a hit in the sensor passing a 2 fC threshold on charge collection to all the reconstructed tracks penetrating the sensor area. Global efficiency of the sensor is then calculated from the ROI in the central area of the detector (inside the red 0.5×0.5 mm^2 square), while the area of the whole sensor is 1.3×1.3 mm^2. Measurements were performed using 5 GeV electrons at DESY at temperatures from -43 to -30°C. Sensor was irradiated with 1 MeV neutrons (at 1.5x10^15 neq/cm^2) at JSI and annealed for 80 mins @ 60°C. The fluence is known with a precision of 10%. The measurements leading to these results have been performed at the Test Beam Facility at DESY Hamburg (Germany), a member of the Helmholtz Association (HGF).

Efficiency, for a collected charge threshold of 2 fC, as a function of the bias voltage for different single pad sensors of a size of 1.3 x 1.3 mm^2: FBK-UFSD3.2-W19 (blue circles), USTC-IMEv2.1-W17 (green losanges) and IHEP-IMEv2-W7 (violet stars). Bias voltages were kept lower than the value required to operate the sensors. All 3 sensors were tested with 5 GeV electrons at DESY. Measurements were performed at temperatures from -40 to -30°C for FBK-UFSD3.2-W19, from -43 to -30°C for IHEP-IMEv2-W7Q2 and from -39°C to -24°C for USTC-IMEv2.1-W17. Sensors were irradiated with 1 MeV neutrons (at 1.5x10^15 neq/cm^2) at JSI and annealed for 80 mins @ 60°C. The fluence is known with a precision of 10%. The measurements leading to these results have been performed at the Test Beam Facility at DESY Hamburg (Germany), a member of the Helmholtz Association (HGF).

Efficiency, for a collected charge threshold of 2 fC, as a function of the bias voltage for different single-pad sensors of a size of 1.3 x 1.3 mm^2: FBK-UFSD3.2-W19 (green circles), USTC-IMEv2.1-W17 (violet losanges) and IHEP-IMEv2-W7 (red stars). Bias voltages were kept lower than the value required to operate the sensors. Measurements were performed at temperatures from -46 to -26°C for FBK-UFSD3.2-W19, from -43 to -29°C for USTC-IMEv2.1-W17 and -20°C for IHEP-IMEv2-W8. FBK-UFSD3.2-W19 and USTC-IMEv2.1-W17 were tested with 5 GeV electrons at DESY while IHEP-IMEv2-W8 was tested with 120 GeV pions at SPS CERN using MALTA Telescope. Sensors were irradiated with 1 MeV neutrons (at 2.5x10^15 neq/cm^2) at JSI and annealed for 80 mins @ 60°C. The fluence is known with a precision of 10%. Measurements leading to the SPS results have been carried out using a MALTA beam telescope as part of the CERN ATLAS R&D program. The measurements leading to the DESY results have been performed at the Test Beam Facility at DESY Hamburg (Germany), a member of the Helmholtz Association (HGF).

Collected charge for an unirradiated single-pad sensor of a size of 1.3 x 1.3 mm^2: IHEP-IMEv2-W7Q2. Measurements were performed at room temperature. 5 GeV electrons at three incidence angles were used at DESY. The measurements leading to these results have been performed at the Test Beam Facility at DESY Hamburg (Germany), a member of the Helmholtz Association (HGF).

Collected charge for an unirradiated single-pad sensor of a size of 1.3 x 1.3 mm^2: FBK-UFSD3.2-W19. Measurements were performed at room temperature. 5 GeV electrons at three incidence angles were used at DESY. The measurements leading to these results have been performed at the Test Beam Facility at DESY Hamburg (Germany), a member of the Helmholtz Association (HGF).

LGAD Sensors

Collected charge (left) and time resolution (right) of USTC-IME-v2.1 at fluences of 0, 8E14, 2.5E15 n_eq/cm^2. This β-scope test is performed at USTC. The target collected charge is 4 fC and time resolution of 50 ps.

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Comparison of measured inter-pad gap and nominal inter-pad gap. The nominal inter-pad gap is define as the distance between the edges of the gain layers of neighbouring pads. For un-irradiated USTC-IME-v2.1 sensors, the measured IP is larger than nominal one. For sensors with nominal IP3 (30 um) and IP5 (50 um), the measured IP is about 100 um. For sensors with nominal IP7 (70 um), the measured IP is about 130 um.

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Inter-pad gap vs bias voltage. The Y-axis is measured inter-pad gap from TCT test. The X-axis is sensor’s bias voltage during laser TCT test.

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(Left) The response of the infrared laser as a function of the beam position measured with Particulars® scanning TCT. The wavelength of the laser is 1064 nm, and the beam spot size is about 10 um. (Right) The response as function of the x for fixed y = 0.4375 mm, fitted with error functions. The inter-pad gap size is defined as the distance between the two positions where the response is 50% of the plateau, determined from the fitted functions.

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An example of current voltage characteristics for all pads of a full size (15x15 pads) HGTD sensor coming from the latest IHEP-IME run. The sensor fulfils all the required specifications of the current and breakdown voltage spread (left and middle plots). They have been produced in 8” wafer (right plot).

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Typical Single Event Burnout mark is shown in the right plot (2019 DESY test-beam with 5 GeV e). The reconstructed track in the SEB event pointed to the location of the burn mark (middle and right plot). All the reconstructed tracks distribution across the detector before SEB is shown in the left plot.

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Single Event Burnout voltage dependence on sensor thickness. The minimum VSEB at which SEB was observed after several 106 particles/pad for each thickness in 2021 HGTD End-Of-Lifetime Test beams is shown (manufacturer-run (type, test-beam)). About 80 sensors (single-pad, 2x2, 5x5 arrays) were tested. Note that 55 mm thick device survived at indicated voltage. The line fit to the points results in critical average electric field of 12.1 V/mm where SEB occurs. The safe zone of 11 V/mm where no SEB was ever observed is indicated in yellow.

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Collected charge (left) and time resolution (right) of LGADs from various vendors (vendor-run-wafer) being considered for HGTD at a fluence of 2.5x1015 neq/cm2. The target collected charge is 4 fC and time resolution of 50 ps for the HGTD. Carbon enriched sensors (IHEP-IMEv2-W7Q2, FBK-UFSC-2.3-W19, USTC-IME-V2.0-W16) show stable performance at much lower bias voltages than non-carbon enriched sensors. USTC-IME-V2.0-W16 performance before irradiation is however not adequate.

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Gain layer depletion voltage dependence on equivalent fluence of reactor neutrons for different investigated prototype sensors (producer-run-wafer). The dashed lines are the acceptor removal model (exponential) fits to the data.

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Plots prior to 2021

2018-2019 Test Beam LGAD Sensors Results

Collected charge as a function of the bias voltage for different CNM sensors doped with Boron (squares), Boron plus Carbon (circles) and Gallium (stars). Single-pads (S) were tested before (black markers) and after irradiation (coloured markers). The fluence, known with a precision of 10%, is indicated in units of 10^14 neq/cm2 (1, 6 and 30) as well as the type of irradiation with neutrons (n) or protons (p). Measurements were performed at temperatures from -35°C to -24°C for irradiated sensors and at 20°C for unirradiated sensors.

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Collected charge as a function of the bias voltage for different HPK sensors type 3.1 and 3.2. Single-pads (S) and 2×2 arrays of pads (A), were tested before (full black markers) and after irradiation (coloured markers). Channel 0 (Ch0) and channel 1 (Ch1) refer to two tested pads of an array which show the same performance. The fluence, known with a precision of 10%, is indicated in units of 10^14 neq/cm2 (8, 10 and 15) as well as the type of irradiation with neutrons (n) or protons (p). Measurements were performed at temperatures from -47°C to -29°C for irradiated sensors and from -39°C to -32°C for unirradiated sensors.

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Time resolution as a function of the bias voltage for different CNM sensors doped with Boron (squares), Boron plus Carbon (circles) and Gallium (stars). Single-pads (S) were tested before (black markers) and after irradiation (coloured markers). The fluence, known with a precision of 10%, is indicated in units of 10^14 neq/cm2 (1, 6 and 30) as well as the type of irradiation with neutrons (n) or protons (p). Measurements were performed at temperatures from -35°C to -24°C for irradiated sensors and at 20°C for unirradiated sensors.

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Time resolution as a function of the bias voltage for different HPK sensors type 3.1 and 3.2. Single-pads (S) and 2×2 arrays of pads (A), were tested after irradiation (coloured markers). Channel 1 (Ch1) refers to the tested pad of an array. The fluence, known with a precision of 10%, is indicated in units of 10^14 neq/cm2 (8, 10 and 15) as well as the type of irradiation with neutrons (n) or protons (p). Measurements were performed at temperatures from -47°C to -29°C for irradiated sensors and from -39°C to -32°C for unirradiated sensors.

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Time resolution as a function of the collected charge for different CNM sensors doped with Boron (squares), Boron plus Carbon (circles) and Gallium (stars) and HPK sensors type 3.1 and 3.2. Single-pads (S) and 2×2 arrays of pads (A), were tested after irradiation (coloured markers). Channel 1 (Ch1) refers to the tested pad of an array. The fluence, known with a precision of 10%, is indicated in units of 10^14 neq/cm2 (1, 6, 8, 10, 15 and 30) as well as the type of irradiation with neutrons (n) or protons (p). Measurements were performed at temperatures from -47°C to -24°C.

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Collected charge as a function of the the bias voltage for different single pad sensors built by CNM from wafer W4, doped with Boron. Measurements were performed at -32°C for sensors irradiated with neutrons (at 1x10^14 neq/cm2 and 6x10^14 neq/cm2) or with protons (empty markers) at 1x10^14 neq/cm2 and at 20 °C for the unirradiated one. The fluences are provided with a precision of 10%.

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Time resolution as a function of the bias voltage for different single pad sensors built by HPK. Sensors were irradiated with neutrons with different fluences. The time resolution is computed from hits in the pad center region. Measurements were performed at temperatures from -41°C to -30°C for sensors irradiated with neutrons (at 8x10^14 neq/cm2 and 1.5x10^15 neq/cm2). The fluences are provided with a precision of 10%

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Efficiency as a function of bias voltage for different single pad sensors built by CNM from wafer W6, doped with Gallium. Sensors were irradiated with neutrons (solid markers) or protons (empty markers) with different fluences. The efficiency is computed for a charge threshold of 2 fC and from hits in the pad center region (in 0.5x0.5mm^2 area). Measurements were performed at -30°C for sensors irradiated with neutrons (at 1x10^14 neq/cm2 and 3x10^15 neq/cm2) and with protons at 1x10^14 neq/cm2. The non irradiated sensor was tested at -32°C. The fluences are provided with a precision of 10%.

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Efficiency as a function of the threshold on the collected charge for different single pad sensors built by CNM from wafer W6, doped with Gallium. Sensors were irradiated with neutrons (solid markers) or protons (empty markers) with different fluences. The efficiency is computed from hits in the pad center region (in 0.5x0.5mm^2 area). Measurements were performed at -30°C for sensors irradiated with neutrons (at 1x10^14 neq/cm2 and 3x10^15 neq/cm2) and with protons at 1x10^14 neq/cm2. The non irradiated sensor was tested at -32°C. The fluences are provided with a precision of 10%.

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2D maps of efficiency for a single pad sensor built by CNM from wafer W5, doped with Boron with Carbon-spray, and irradiated with protons at a fluence of 1\times10^{14}~n_{eq}/cm^{2} operated at 210 V and for a collected charge of 9.7 fC. The measurement was performed at -32°C. The fluence is known with a precision 10%. The efficiency is computed for a charge threshold of 2 fC. The averaged efficiency in the 0.5x0.5mm^2 center area is 99.8%.

2020 TDR Figures

Link to all TDR figures

TDR ALTIROC performance plots

Average Time Of Arrival measurement with the TDC as a function of the programmable delay using the external trigger.	pdf
Channel LSB divided by the averaged LSB as function of the channel number for one ASIC	pdf
Efficiency measured as a function of the injected charge for an ASIC alone with Cd = 4 pF (purple) and with an ASIC bump bonded to a sensor (blue) measured with the calibration setup	pdf
Jitter measured as a function of the injected charge for an ASIC alone with Cd = 4 pF (purple) and with an ASIC bump bonded to a sensor (blue) measured with the calibration setup with a Dirac signal as an input. The open circle shows the jitter for an LGAD input signal estimated from the calibration data and the simulation	pdf
Time-over-threshold measured as a function of the injected charge for an ASIC bump bonded to a sensor	pdf
Preamplifer amplitude measured with the discriminator probe for three different charges as a function of the irradiation during high dose period. The dashed vertical line represents the maximal TID for HGTD. The step observed at 0.5 MGy is due to large temperature variations at the beginning of the measurements, which were subsequently controlled	pdf
Relative jitter measured with the discriminator probe for a charge of 10.3 fC as a function of the irradiation during high dose period.The dashed vertical line represents the maximal TID for HGTD.	pdf
Distribution of the TOA as a function of the TOT. The dots correspond to the mean value of the TOA distribution for a given TOT bin extracted from a Gaussian. The red line is a fit of the average TOA as a function of the TOT	pdf
Distributions of the time difference between LGAD+ALTIROC and the Quartz+SiPM system before (red) and after (black) time walk correction together with Gaussian fits. The numbers are the fitted Gaussian widths where the time resolution of the Quartz+SiPM system has been substracted quadratically.	pdf

2019 Sensors plots from TDR and for HSTD proceedings

V op as a function of fluence after irradiation for different LGAD types for neutron irradiation. The red horizontal line represents the maximum allowed voltage of 750 V as discussed in Section 5.5.7. Solid markers indicate n irradiation (n), open markers p irradiation at CYRIC (pCy).	pdf
Vop as a function of fluence after irradiation for different LGAD types for proton irradiation. The red horizontal line represents the maximum allowed voltage of 750 V as discussed in Section 5.5.7. Solid markers indicate n irradiation (n), open markers p irradiation at CYRIC (pCy).	pdf
Collected charge as a function of bias voltage for different fluences for HPK-3.2 (a) and at maximum fluence for all vendors (two representative sensors with different performance for HPK-3.2 are shown) (b). The horizontal lines indicate the HGTD lower charge limit of 4 fC at all fluences. Solid markers indicate n irradiation (n), open markers p irradiation at CYRIC (pCy). Measurements were performed at −30 ◦ C except for the pre-rad measurement that was done at 20 ◦ C.	(a) pdf (b) pdf
pdfI-V curves of different types of HPK single pad prototype sensors. The measurements are taken with a single needle and the guard rings are grounded.	pdf
Figures to show the uniformity of the HPK-3.1-50 sensors. Distribution of LGAD leakage current at 200 V of 648 measured single pad sensors. Measured with an automatic probe station and guard ring floating.	pdf
Figures to show the uniformity of the HPK-3.1-50 sensors. Distribution of breakdown voltages of 648 measured single pad sensors. Measured with an automatic probe station and guard ring floating	pdf
Distribution of VBD on an HPK-3.2-50 5 × 5 pads array. The measurement is taken by a dedicate probe card with guard ring and neighbor pads grounded.	pdf
C-V (a) and 1/C 2 -V (b) curves of different types of HPK prototype sensor. The measurement is taken by single needle on the single pads with guard ring grounded.	pdf pdf
Collected charge (a) and time resolution (b) of different types of HPK prototype sensor before irradiation as a function of bias voltage. The requirements of the HGTD project are indicated by the horizontal red lines.	pdf pdf
The inverse of capacitance square as a function of the biased voltage of NDL LGAD sensors.	pdf
The doping profile of NDL LGAD sensors estimated from CV measurements.	pdf
(a) Time resolution as a function of bias voltage for NDL #9 and BV170 before irradiation. (b) Time resolution as a function of bias voltage for NDL #10, NDL #9, BV170 after 1.02 ⇥ 1015neq/cm2 irradiation at -30 oC.	pdf pdf
(a) Collected charge as a function of bias voltage for NDL #9 and BV170 before irradiation. (b) Collected charge as a function of bias voltage for NDL #10, NDL #9, BV170 after 1.02 ⇥ 1015neq/cm2 irradiation at -30 oC.	pdf pdf
Collected charge as a function of bias voltage for different fluences for HPK1.1 (active thickness 35 µm) and HPK-3.2 (active thickness 50 µm). The horizontal line indicates the HGTD lower charge limit of 4 fC at all fluences. The HPK-1.1 did not satisfy the charge requirement for highest fluence. Measurements were performed at -30◦C except for the pre-rad measurement that was done at 20◦C.	pdf
Collected charge as a function of bias voltage for different fluences for HPK3.2. The horizontal line indicates the HGTD lower charge limit of 4 fC at all fluences. Solid markers indicate n irradiation (n), open markers p irradiation at CYRIC (pCy). Measurements were performed at -30◦C except for the pre-rad measurement that was done at 20◦C.	pdf
Time resolution as a function of bias voltage for different fluences for HPK-3.2 sensors measured on custom-made HGTD-specific readout boards. Solid markers indicate n irradiation (n), open markers p irradiation at CYRIC (pCy). The red line represents the maximum allowed time resolution (70 ps) in the lifetime of HGTD. Measurements were performed at -30◦C except for the pre-rad measurement that was done at 20◦C.	pdf

Dec 2019 Radiation levels in HGTD Link to original figures without rings replacement

Expected Si 1MeV neq radiation levels in HGTD, using Fluka simulations, as a function of the radius considering a replacement of the inner ring every 1000 fb^-1 and the middle ring replaced at 2000 fb^-1. For the radiation levels, the particle type is included and the contribution from charged hadrons is included in ’Others’. These curves included a factor of 1.5 to account for simulation uncertainty. Figures are based off original figures.

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Expected Done [MGy] radiation levels in HGTD, using Fluka simulations, as a function of the radius considering a replacement of the inner ring every 1000 fb^-1 and the middle ring replaced at 2000 fb^-1. For the radiation levels, the particle type is included and the contribution from charged hadrons is included in ’Others’. These curves included a factor of 1.5 to account for simulation uncertainty. An additional factor of 1.5 is applied to the TID to account for low dose rate effects on the electronics, leading to a SF = 2.25. Figures are based off original figures. pdf

2019 Sensor Performance from testbeam

LGAD (Low Gain Avalanche Diode) sensors have been exposed to 5 GeV electrons at DESY TB22 beam line in March and May 2019.

• Sensor characteristics: LGAD arrays and single pad sensors of 1 x 1 mm2 with a 45 μm thickness produced by CNM (runs 10478 & 10924), HPK, FBK and NDL vendors.
• The setup was equipped with a 3x3x10 mm3 quartz read out by a SiPM to have a reference.

Collected charge as a function of the bias voltage for a 1 x 1 mm2 CNM Gallium-doped LGAD irradiated to 3e15 neq/cm2. The collected charge is obtained from a Landau-Gauss convoluted function and defined as the Most Provable Value of the fit.	png, pdf
Time resolution as a function of the collected charge for a 1 x 1 mm2 CNM Gallium-doped LGAD irradiated to 3e15 neq/cm2. The time of the reference sensor is extracted at 20% of the signal amplitude and for the Gallium irradiated sensor is extracted at 50% of the signal amplitude. The contribution to the time resolution from the reference sensor is already subtracted.	png, pdf
Time difference distribution between the time at a CFD=50% for the CNM Gallium sensor and the time at a CFD=20% for the reference sensor.	png, pdf
Signal efficiency in a 1 x 1 mm2 CNM Gallium-doped LGAD irradiated to 3e15 neq/cm2, as a function of the reconstructed position X and Y of particles (in mm). The efficiency is defined as the ratio between the number of tracks with a collected charge larger than 2 fC and the total number of reconstructed tracks that are extrapolated to the sensitive area of the sensor, where only single track events are considered. A cut of 2 fC equivalent to 15mV is applied because it is the minimum charge required by the ALTIROC discriminator. The efficiency in the bulk is 99.1%.	png, pdf
Time resolution of a a 1 x 1 mm2 CNM Gallium-doped LGAD irradiated to 3e15 neq/cm2, as a function of the reconstructed position X and Y of particles (in mm) for the full sensor. Each bin size is 100 x 100 μm2 to ensure sufficient statistics. A cut of 2 fC equivalent to 15mV is applied because it is the minimum charge required by the ALTIROC discriminator. Time resolution degrades at the edges which also suffers from low statistics. In the central area the performance is quite homogeneous with an average time resolution of about 55 ps. The central area matches the gain layer size of 0.7 x 0.7 mm2.	png, pdf
Time resolution of a 1 x 1 mm2 CNM Gallium-doped LGAD irradiated to 3e15 neq/cm2, as a function of the reconstructed position X and Y of particles (in mm) for the gain layer area. Each bin size is 100 x 100 μm2 to ensure sufficient statistics. A cut of 2 fC equivalent to 15mV is applied because it is the minimum charge required by the ALTIROC discriminator. In the central area the performance is quite homogeneous with an average time resolution of about 55 ps. The central area matches the gain layer size of 0.7 x 0.7 mm2.	png, pdf

2018/2019 Sim/Perf figures (TDR draft April 2019)

Module overlap scheme: Schematic drawing showing the overlap between the modules on the front and back of one cooling disk of the HGTD. The sensors overlap 20% at r > 320 mm, and 80% for r < 320 mm.	pdf, png
Material distributions: Material distributions for the HGTD as a function of pseudorapidity , expressed in (a) radiation lengths and (b) nuclear interaction lengths . The material is broken down into various components of the HGTD. The moderator is situated completely behind the active detector but included here as it is located within the hermetic vessel of the HGTD.	pdf, png
Material distributions: Material distributions for the HGTD as a function of pseudorapidity , expressed in (a) radiation lengths and (b) nuclear interaction lengths . The material is broken down into various components of the HGTD. The moderator is situated completely behind the active detector but included here as it is located within the hermetic vessel of the HGTD.	pdf, png
Main HGTD design parameters	pdf, png
Event display: Visualization of a simulated QCD dijet event showing HGTD hits and trajectories of charged particles. An angular slice has been removed, and volumes representing some ITk services and all services and supports of the HGTD are also removed to expose the individual modules.	pdf, png
Module placement: The layout of individual HGTD modules is shown for the first cooling disk for (a) one quadrant without any rotation, and for (b) the full disk with the 15 degree rotation. The modules are laid out in the same way for the second cooling disk (not shown) which is rotated in the opposite direction to avoid non-instrumented gaps from overlapping for both disks.	pdf, png
Module placement: The layout of individual HGTD modules is shown for the first cooling disk for (a) one quadrant without any rotation, and for (b) the full disk with the 15 degree rotation. The modules are laid out in the same way for the second cooling disk (not shown) which is rotated in the opposite direction to avoid non-instrumented gaps from overlapping for both disks.	pdf, png
Timing resolution: The expected HGTD timing resolution (a) per hit and (b) per track as function of radius and $\eta$ after different amounts of delivered integrated luminosity at the HL-LHC. The different curves show how the sensor timing resolution deteriorates due to radiation exposure. The scenarios shown here include a planned replacement of the modules at $R < 320$~mm after half of the HL-LHC program. The intrinsic timing resolution of the sensors and the contribution from the readout electronics are both considered and are added in quadrature.	pdf, png
Timing resolution: The expected HGTD timing resolution (a) per hit and (b) per track as function of radius and $\eta$ after different amounts of delivered integrated luminosity at the HL-LHC. The different curves show how the sensor timing resolution deteriorates due to radiation exposure. The scenarios shown here include a planned replacement of the modules at $R < 320$~mm after half of the HL-LHC program. The intrinsic timing resolution of the sensors and the contribution from the readout electronics are both considered and are added in quadrature.	pdf, png
Occupancy: Hit occupancy as a function of the radius for a pixel size of 1.3 x 1.3 mm2 at a pileup of 200.	pdf, png
Number of hits per track: The average number of hits as a function of the position in x-y plane. The overlap between the active areas of the modules on the front and back of the cooling plates is 80% at r < 320 mm and 20% at larger radii..	png

2018/2019 HGTD T0 calibration performance (TDR draft April 2019)

HGTD hit time distribution, before (red) and after (blue) the reference time, t0 , calibration procedure. The calibration constant is calculated every 1 ms from the mean of the smeared hit times of a grid of 15 by 15 sensors corresponding to one ASIC. The nominal hit time distribution is obtained from a Geant 4 simulation of the ATLAS Detector which includes the time resolution of the sensor and the time dispersion of the LHC collision. Non-Gaussian tails arise from late particles, backscatter, and other effects. Additional hit time smearing is applied to model the effects of clock jitter and time dispersion arising in the ASIC, flex cable, lpGBT, and FELIX. The expected systematic LHC RF variation time is added as an additional effect. Finally, a sinusoidally varying 100 ps offset of 20 ms period is added to model sources of time jitter that might arise from heat cycles or other effects.	pdf
Hit time resolution, tsmear - treco after the t0 calibration procedure as a function of the variation period, and for several different choices of calibration window time, shown for R=150 mm. treco is the hit time taken from simulation and includes inherent hit time resolution effects from the sensor and electronics and the collision time spread. The tsmear term adds additional sources of time jitter from the ASIC, FELIX, flex cable, lpGBT, and ATLAS collision time drift, with an additional sinusoidally varying 100 ps offset of variable period. If no calibration is applied the time jitter is approximately 70ps and is shown as the dashed line. For a variation period of greater than 10 ms, and with the right choice of calibration window size, the calibration procedure will always improve the t0 precision.	pdf
Hit time resolution, tsmear - treco after the t0 calibration procedure as a function of the variation period, and for several different choices of calibration window time, shown for R=350 mm. treco is the hit time taken from simulation and includes inherent hit time resolution effects from the sensor and electronics and the collision time spread. The tsmear term adds additional sources of time jitter from the ASIC, FELIX, flex cable, lpGBT, and ATLAS collision time drift, with an additional sinusoidally varying 100 ps offset of variable period. If no calibration is applied the time jitter is approximately 70ps and is shown as the dashed line. For a variation period of greater than 10 ms, and with the right choice of calibration window size, the calibration procedure will always improve the t0 precision.	pdf

2018/2019 Sensor Performance from lab (TDR draft April 2019 )

LGAD sensors of different vendors, geometries and types have been studied by HGTD institutes, including:

• HPK-3.1-50: Hamamatsu, 50 um thick, 1.3 mm x 1.3 mm pad size (HGTD geometry), standard doping
• HPK-3.2-50: Hamamatsu, 50 um thick, 1.3 mm x 1.3 mm pad size (HGTD geometry), deep doping
• FBK-UFSD3-C-60: FBK, 60 um thick, 1.3 mm x 1.3 mm pad size (HGTD geometry), with Carbon addition
• HPK-Proto-30: Hamamatsu 30 um prototype, 0.8 mm2 pad size (small pads)
• CNM AIDA: CNM 50 um, 1.3 mm x 1.3 mm pad size (HGTD geometry)

Microscope photo of an HPK-3.1-50 15x15 array (partial view).	jpg
I-V measurement of 25 pads from an unirradiated HPK-3.1-50 5x5 array without UBM measured with a 5x5 probe card at room temperature (all pads and GR grounded).	pdf
Breakdown voltage 2D map of 15x15 array: 2D map of breakdown voltage of an HPK-3.1-50 15x15 array (~2x2 cm2 large sensor) measured with an automatic probe station (i.e. scanning of each pad one after another).	pdf
Time resolution vs. gain for two irradiated HPK LGADs of 50 and 30 um thicknesses with time walk correction applied.	pdf
Collected charge as a function of bias voltage for different fluences for HPK-3.1-50 sensors. Solid markers indicate n irradiation (n), open markers 70 MeV p irradiation at CYRIC (pCy). Measurements were performed at -30 C.	pdf
Collected charge as a function of bias voltage for different fluences for HPK-3.2-50 sensors after n irradiation (n). Measurements were performed at -30 C.	pdf
Collected charge as a function of bias voltage for different fluences for FBK-UFSD3-C-60 sensors after n irradiation (n). Measurements were performed at -30 C.	pdf
Collected charge as a function of bias voltage for different fluences for HPK-Proto-30 sensors after n irradiation (n). Measurements were performed at -20 C and -27 C.	pdf
Time resolution as a function of bias voltage for different fluences for HPK-3.1-50 sensors. Solid markers indicate n irradiation (n), open markers 70 MeV p irradiation at CYRIC (pCy). Measurements were performed at -30 C.	pdf
Time resolution as a function of bias voltage for different fluences for HPK-3.2-50 sensors after n irradiation (n). Measurements were performed at -30 C.	pdf
Time resolution as a function of bias voltage for different fluences for FBK-UFSD3-C-60 sensors after n irradiation (n). Measurements were performed at -30 C.	pdf
Time resolution as a function of bias voltage for different fluences for HPK-Proto-30 sensors after n irradiation (n). Measurements were performed at -20 C and -27 C.	pdf
Inter-Pad distances for several HPK-3.1-50 sensors measured with a laser TCT system	pdf
Hit efficiency as a function of collected charge. The curve includes the data of 16 individual sensors before and after irradiation, which all show a universal behaviour. The threshold to accept events with a hit was chosen at a measured noise occupancy of 0.1% and 0.01%, respectively. A hit efficiency above 99% is obtained for a charge larger than 2 fC.	pdf
*The charge at Vmax and 95% of Vmax as a function of fluence for the different sensor types.*	pdf
Leakage current for single pads at -30 C as a function of bias voltage for HPK-3.1-50 irradiated with 1 MeV neutrons (solid lines) and 70 MeV protons (dashed lines). The dashed-dotted horizontal line represents the ALTIROC maximum acceptable current of 5 uA.	pdf
Collected charge vs bias voltage for sensors irradiated to 3E15 Neq cm-2 and 6E15 Neq cm-2, respectively. In the plots are measured data of the existing prototypes and the simulated prospect of the proposed sensors combining deep implantation of the Boron gain layer with carbon implantation.	pdf
Collected charge vs bias voltage for sensors irradiated to 3E15 Neq cm-2 and 6E15 Neq cm-2, respectively. In the plots are measured data of the existing prototypes and the simulated prospect of the proposed sensors combining deep implantation of the Boron gain layer with carbon implantation.	pdf

2018/2019 ALTIROC0/1 and (ALTIROC0+Sensors) performance (TDR draft April 2019)

Time of arrival in a channel of an unirradiated 2x2 LGAD array bump-bonded on an ALTIROC0 ASIC as a function of the amplitude of the preamplifier probe. The profile of the 2D distribution (black points) and a polynomial fit (red line) are superimposed. The fit is used to correct for the time walk effect.

- pdf

Time resolution of a channel of an unirradiated 2x2 LGAD array bump-bonded on an ALTIROC0 ASIC as a function of the discriminator threshold (in DAC units) before and after time walk correction. A SiPM with a resolution of 40 ps is used as a time reference - it's contribution has been substracted. The amplitude of the preamplifier probe is used to correct for the time walk, resulting in a 30% improvement in the time resolution.

- pdf

*Jitter measured as a function of the injected charge for a Cd = 3.5 pF..	pdf

2017 sensors performance from Test Beam

LGAD (Low Gain Avalanche Diode) sensors have been exposed to 120 GeV charged pions at CERN SPS H6 beam line in September 2017.

• Sensor characteristics: two arrays of four LGAD sensors of 1.1 x 1.1 mm2 with a 45 μm thickness produced by CNM (run 10478)
• The setup was equipped with a 3x3x10 mm3 quartz read out by a SiPM to have a reference. Time resolution of reference is about 10 ps
• More information can be found in the 2016 testbeam paper: https://arxiv.org/abs/1804.00622

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Signal efficiency in an unirradiated array of four LGAD sensors of 1.1 x 1.1 mm2 each, as a function of the X and Y coordinates (in mm). The voltage threshold to select the signal is 3 times larger than the noise (~5mV). The efficiency in the bulk is larger than 99.8%.	eps - pdf
Signal efficiency in an irradiated array of four LGAD sensors of 1.1 x 1.1 mm2 each, as a function of the X and Y coordinates (in mm). The voltage threshold to select the signal is 3 times larger than the noise (~5mV). The bottom right pad is not displayed due to a broken channel in the readout board. ). The efficiency in the bulk is larger than 99.8%.	eps - pdf
Signal amplitude in the bulk of LGAD pads of size 1.1 x 1.1 mm2 in an array sensor. The dashed line shows the default threshold corresponding to 3 times the noise.	eps - pdf
Signal efficiency in the bulk of LGAD pads of size 1.1 x 1.1 mm2 in an array sensor as a function of the voltage threshold. The dashed line shows the default threshold corresponding to 3 times the noise.	eps - pdf
Signal efficiency in the interpad region for an unirradiated array of four LGAD sensors of 1.1 x 1.1 mm2 each, as a function of X (in mm) for 3 different voltage thresholds.	eps - pdf
Signal efficiency in the interpad region for an irradiated array of four LGAD sensors of 1.1 x 1.1 mm2 each, as a function of X (in mm) for 3 different voltage thresholds.	eps - pdf
Time resolution in an un-irradiated array of four LGAD sensors of 1.1 x 1.1 mm2 each, as a function of the X and Y coordinates (in mm). The bottom left pad is not displayed because this channel was not plugged to the same oscilloscope as the quartz+SiPM used as a reference to estimate the time resolution (in this case, more sophisticated analysis technique would be required). The time resolution is larger in the guard rings around the pads where there is no multiplication of the charge. The fluctuations are dominated by statistical fluctuations since very small bins are used in order to show the structure around the pad.	eps - pdf
Time resolution in an irradiated array of four LGAD sensors of 1.1 x 1.1 mm2 each, as a function of the X and Y coordinates (in mm). The bottom right pad is not displayed due to a broken channel in the readout board. The time resolution is larger in the guard rings around the pads where there is no multiplication of the charge.	eps - pdf

2016 Sensors performance from Test Beam

LGAD (Low Gain Avalanche Diode) sensors have been exposed to 120 GeV charged pions at CERN SPS H6B beam line in August 2016 Sensor characteristics: * Two single pad LGAD produced by CNM through RD50 * 1.2 x 1.2 mm² size (C=3.3 pF) * 45 μm thickness Readout : * Board designed and assembled at University of California Santa Cruz: first stage trans impedance preamplifier on printed circuit (R_f =470 Ohm) followed by a second stage broadband amplifier (gain 20 dB) * The data were read‐out by a oscilloscope with 40 GSample/s and a 2 GHz bandwidth. The setup was equipped with a 3x3x10 mm³ quartz read out by a SiPM to have a reference. Time resolution of reference is about 15‐17 ps

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Typical Pulse Shape: Typical pulse shape recorded with a LGAD sensor with 200 V bias voltage with 120 GeV pions. The charge is computed integrating the signal over the yellow area, taking into account the gain of the electronics readout (~95).	_ _ eps - pdf
Charge Distribution: Charge distribution for a LGAD biased with 150 V. A Landau convoluted by a Gaussian fit is superimposed.	_ _ eps - pdf
Charge as a Function of Bias Voltage: Most probable value of the charge as a function of the bias voltage for two LGAD sensors.	_ _ eps - pdf
Gain as a Function of Bias Voltage: Gain as a function of the bias voltage for two LGAD sensors. The gain is computed as the charge divided by 0.46 fC, which is the mean signal deposited by dE/dx in 45 μm of silicon when no amplification mechanism is present.	_ _ eps - pdf
Signal to Noise Ratio: Signal to noise ratio as a function of the bias voltage for two LGAD sensors. Signal is measured as the amplitude at the signal peak. The noise is computed as the rms of the baseline and does not take into account the increase of the Landau width due to the multiplication process in the LGAD.	_ _ eps - pdf
Time Resolution: Time resolution as a function of the bias voltage for two LGAD sensors. The time of each sensor is extracted at 20 % of the signal amplitude with a linear interpolation between the measurements. The time resolution is extracted from data in which the considered sensor was not used for triggering, by computing the rms of all time differences between the considered sensor, the reference quartz/!SiPM and the trigger sensor. The resulting equation system (under the assumption of uncorrelated resolutions) is solved o obtain the time resolution. of each device.	_ _ eps - pdf
Time Resolution: Time resolution as a function of the gain for two LGAD sensors. The time of each sensor is extracted at 20 % of the signal amplitude with a linear interpolation between the measurements. The time resolution is extracted from data in which the considered sensor was not used for triggering, by computing the rms of all time differences between the considered sensor, the reference quartz/!SiPM and the trigger sensor. The resulting equation system (under the assumption of uncorrelated resolutions) is solved o obtain the time resolution. of each device.	_ _ eps - pdf
Signal Rise Time: Signal rise time (computed between 20% and 80 % of the signal amplitude) as a function of the bias voltage for two LGAD Sensors of each device.	_ _ eps - pdf

• 0fC_vs_bias_.pdf: Figure 5.7: V op as a function of fluence after irradiation for different LGAD types for neutron (a) and proton (b) irradiation. The red horizontal line represents the maximum allowed voltage of 750 V as discussed in Section 5.5.7. Solid markers indicate n irradiation (n), open markers p irradiation at CYRIC (pCy).

• 0fC_vs_bias_.pdf: Figure 5.7: V op as a function of fluence after irradiation for different LGAD types for neutron (a) and proton (b) irradiation. The red horizontal line represents the maximum allowed voltage of 750 V as discussed in Section 5.5.7. Solid markers indicate n irradiation (n), open markers p irradiation at CYRIC (pCy).

• HGTD-Sensors-Jan2022-Figure4.pdf: Example of SEB event in the 2019 DESY test beam.

• HGTD-Sensors-Approval_plots_for_USTC-IME-v2.1_Figure1.pdf: Inter-pad measurements for USTC-IMEV2.1 W19 sensor (IR laser)