Pixel Operation Plots 2018

ROC Thresholds during Commissioning 2018

The following plots show the status of the pixel detector by the beginning of the run in 2018 and its evolution as of June 2018. The measured thresholds of the readout chips (ROCs) are shown for two periods; Commissioning 2018 (beginning of the year after 50fb-1 delivered LHC luminosity) and June 2018 (during TS1 additional 25fb-1 delivered LHC luminosity). An expected, slight degradation of the thresholds due to increased irradiation is observed for pixel barrel layers 2-4 and pixel forward, as the mean of these distribution is shifted towards smaller values in June compared to the beginning of the year. Pixel barrel layer 1 shows no significant degradation, as the radiation effect has already reached a plateau here. The distributions are broadened by radiation effects, more pronounced on the lower edge of the distributions.

Figure in png format	other formats	Description
	.eps .pdf	The distribution of the readout chip (ROC) threshold in number of electrons for all four layers of the pixel barrel detector normalized to the number of ROCs in the respective layer. The threshold is measured as the value where the turn-on of the ROC reaches an efficiency of 0.5. The distribution of layer 1 is different, because another type of ROC is used here. Modules in layer 2 that were damaged in 2017 and could not be replaced are shown in a separate distribution. The shown measurement was performed during the commissioning phase in 2018. The number of electrons were calculated from the measured calibration units (VCal).
	.eps .pdf	The distribution of the readout chip (ROC) threshold in number of electrons for layer 1 of the pixel barrel detector. The threshold is measured as the value where the turn-on of the ROC reaches an efficiency of 0.5. The shown measurement was performed during the commissioning phase in 2018. The number of electrons were calculated from the measured calibration units (VCal).
	.eps .pdf	The distribution of the readout chip (ROC) threshold in number of electrons for layer 2 of the pixel barrel detector. The threshold is measured as the value where the turn-on of the ROC reaches an efficiency of 0.5. Modules that were damaged in 2017 and could not be replaced are shown in yellow, while the modules showing normal behavior are shown in blue. The damaged modules show a higher threshold. The shown measurement was performed during the commissioning phase in 2018. The number of electrons were calculated from the measured calibration units (VCal).
	.eps .pdf	The distribution of the readout chip (ROC) threshold in number of electrons for layer 3 of the pixel barrel detector. The threshold is measured as the value where the turn-on of the ROC reaches an efficiency of 0.5. The shown measurement was performed during the commissioning phase in 2018. The number of electrons were calculated from the measured calibration units (VCal).
	.eps .pdf	The distribution of the readout chip (ROC) threshold in number of electrons for layer 4 of the pixel barrel detector. The threshold is measured as the value where the turn-on of the ROC reaches an efficiency of 0.5. The shown measurement was performed during the commissioning phase in 2018. The number of electrons were calculated from the measured calibration units (VCal).
	.eps .pdf	The distribution of the readout chip (ROC) threshold in number of electrons for the whole pixel forward detector normalized to the number of ROCs in the respective ring. The threshold is measured as the value where the turn-on of the ROC reaches an efficiency of 0.5. Modules in the forward pixel that were damaged in 2017 and could not be replaced are shown in a separate distribution (small effect). The shown measurement was performed during the commissioning phase in 2018. The number of electrons were calculated from the measured calibration units (VCal).
	.eps .pdf	The distribution of the readout chip (ROC) threshold in number of electrons for ring 1 of the pixel forward detector. The threshold is measured as the value where the turn-on of the ROC reaches an efficiency of 0.5. Modules that were damaged in 2017 and could not be replaced are shown in yellow, while the modules showing normal behavior are shown in blue. The damaged modules have a higher threshold. The shown measurement was performed during the commissioning phase in 2018. The number of electrons were calculated from the measured calibration units (VCal).
	.eps .pdf	The distribution of the readout chip (ROC) threshold in number of electrons for ring 2 of the pixel forward detector. The threshold is measured as the value where the turn-on of the ROC reaches an efficiency of 0.5. The shown measurement was performed during the commissioning phase in 2018. The number of electrons were calculated from the measured calibration units (VCal).

ROC Thresholds during TS1 (June) 2018

Figure in png format	other formats	Description
	.eps .pdf	The distribution of the readout chip (ROC) threshold in number of electrons for all four layers of the pixel barrel detector normalized to the number of ROCs in the respective layer. The threshold is measured as the value where the turn-on of the ROC reaches an efficiency of 0.5. The distribution of layer 1 is different, because another type of ROC is used here. Modules in layer 2 that were damaged in 2017 and could not be replaced are shown in a separate distribution. The shown measurement was performed in June 2018. The number of electrons were calculated from the measured calibration units (VCal). A minimal degradation of the threshold with respect to the measurement during commissioning is observed. This effect is due to the increased irradiation of the ROCs. The effect cannot be seen in layer 1, as the effect has already reached a plateau here for most ROCs.
	.eps .pdf	The distribution of the readout chip (ROC) threshold in number of electrons for layer 1 of the pixel barrel detector. The threshold is measured as the value where the turn-on of the ROC reaches an efficiency of 0.5. The shown measurement was performed in June 2018. The number of electrons were calculated from the measured calibration units (VCal). No degradation effect due to irradiation with respect to the measurement during commissioning is observed here, as for most ROCs a plateau of this effect is already reached.
	.eps .pdf	The distribution of the readout chip (ROC) threshold in number of electrons for layer 2 of the pixel barrel detector. The threshold is measured as the value where the turn-on of the ROC reaches an efficiency of 0.5. Modules that were damaged in 2017 and could not be replaced are shown in yellow, while the modules showing normal behavior are shown in blue. The damaged modules have a higher threshold. The shown measurement was performed in June 2018. The number of electrons were calculated from the measured calibration units (VCal). A minimal degradation of the threshold with respect to the measurement during commissioning is observed. This effect is due to the increased irradiation of the ROCs.
	.eps .pdf	The distribution of the readout chip (ROC) threshold in number of electrons for layer 3 of the pixel barrel detector. The threshold is measured as the value where the turn-on of the ROC reaches an efficiency of 0.5. The shown measurement was performed in June 2018. The number of electrons were calculated from the measured calibration units (VCal). A minimal degradation of the threshold with respect to the measurement during commissioning is observed. This effect is due to the increased irradiation of the ROCs.
	.eps .pdf	The distribution of the readout chip (ROC) threshold in number of electrons for layer 4 of the pixel barrel detector. The threshold is measured as the value where the turn-on of the ROC reaches an efficiency of 0.5. The shown measurement was performed in June 2018. The number of electrons were calculated from the measured calibration units (VCal). A minimal degradation of the threshold with respect to the measurement during commissioning is observed. This effect is due to the increased irradiation of the ROCs.
	.eps .pdf	The distribution of the readout chip (ROC) threshold in number of electrons for the whole pixel forward detector normalized to the number of ROCs in the respective ring. The threshold is measured as the value where the turn-on of the ROC reaches an efficiency of 0.5. Modules in the forward pixel that were damaged in 2017 and could not be replaced are shown in a separate distribution (small effect). The shown measurement was performed in June 2018. The number of electrons were calculated from the measured calibration units (VCal). A minimal degradation of the threshold with respect to the measurement during commissioning is observed. This effect is due to the increased irradiation of the ROCs.
	.eps .pdf	The distribution of the readout chip (ROC) threshold in number of electrons for ring 1 of the pixel forward detector. The threshold is measured as the value where the turn-on of the ROC reaches an efficiency of 0.5. Modules that were damaged in 2017 and could not be replaced are shown in yellow (small effect), while the modules showing normal behavior are shown in blue. The damaged modules have a higher threshold. The shown measurement was performed in June 2018. The number of electrons were calculated from the measured calibration units (VCal). A minimal degradation of the threshold with respect to the measurement during commissioning is observed. This effect is due to the increased irradiation of the ROCs.
	.eps .pdf	The distribution of the readout chip (ROC) threshold in number of electrons for ring 2 of the pixel forward detector. The threshold is measured as the value where the turn-on of the ROC reaches an efficiency of 0.5. The shown measurement was performed in June 2018. The number of electrons were calculated from the measured calibration units (VCal). A minimal degradation of the threshold with respect to the measurement during commissioning is observed. This effect is due to the increased irradiation of the ROCs.

DCDC Characterization

In October 2017 DCDC converters in the CMS Pixel started failing. At the end of 2017 data taking 5% of the DCDCs did not provide power to the modules. In the YETS the Pixel was extracted and the DCDC converters were examined. During the YETS examination 30% of the DCDC where found to have a higher current than expected. The preliminary findings were reported at the ACES conference After this report additional findings suggest a failure mechanism that is only present in a radiated DCDC ASIC. In the disabled state one of the radiated transistors has a leakage current, which is amplified by the circuit and not drained. This stress can then either break the DCDC ASIC or make it a high current DCDC. In the enabled state the current is drained.

This material shows the results of the investigations during the YETS. First the characterization of the DCDC is shown and then the distribution of the DCDCs in the detector. The Pixel DCDC are used to provide the low voltage to the analog and the digital part of the modules, therefore the DCDCs have different output voltages 2.4-2.5V for the analog and 3.0 - 3.3V for the digital voltage.

Classification based on I-V curve measurement

Figure in png format	other formats	Description
	.eps .pdf	Two tests are performed to classify the DCDC converters as either working normally, having high-current or being broken. The first test is the disable test, where the DCDC converter is disabled and the input voltage is scanned from 0 V to 5.5 V (upper plot). The second test is the enable test, where the DCDC is enabled and a load of 1.5A is connected. The input voltage is then scanned from 0 V to 10 V. There is a difference in the behavior between a high-current DCDC and a normal working DCDC in the disabled test, while the converters show the same behavior in the enable test. A DCDC converter is considered as having high-current, when the input current at 5.5V is larger than 4mA. The behavior of a broken DCDC converter is not shown. A DCDC converter is considered broken, when the input current at 10V in the enabled test is less than 400mA.
	.eps .pdf	The input current of the DCDC converters that were extracted from the detector after the 2017 run. The current was measured at an input voltage of 5.5V while the DCDC is disabled. DCDCs with an input current less than 4mA are considered as working normally. DCDCs with an input current greater than 4mA are considered as high-current.
	.eps .pdf	The input current of the DCDC converters that were extracted from the detector after the 2017 run. The current was measured at an input voltage of 10V while the DCDC is enabled. A clear separation between the broken DCDC converters (input current less than 400 mA), the working analog converters (input current between 400 and 540 mA) and the working digital converters (input current greater 540 mA) is observed. While a DCDC converter is enabled no difference between the normal behavior and the high-current behavior is visible in this distribution.

Maps with DCDC classifications after run 2017

Pixel Barrel

Figure in png format	other formats	Description
	.pdf	Summary of the characterization of the 2017 DCDC converters for the barrel pixel detector. The number of normal behaving, high-current and broken DCDC converters is given for each half-cylinder separately and for the total barrel pixel detector. The defects of DCDCs are randomly distributed.
	.eps .pdf	Overview of the DCDC converter classification after the 2017 run for the half-cylinder in minus direction wrt. the beam on the inner side (BmI) of the barrel pixel detector. The coordinates correspond to the position of the DCDC converter in the detector during the run. Analog DCDC converter are marked with an “a”, digital DCDC converter are marked with a “d”. The defects of DCDCs are randomly distributed.
	.eps .pdf	Overview of the DCDC converter classification after the 2017 run for the half-cylinder in minus direction wrt. the beam on the outer side (BmO) of the barrel pixel detector. The coordinates correspond to the position of the DCDC converter in the detector during the run. Analog DCDC converter are marked with an “a”, digital DCDC converter are marked with a “d”. The defects of DCDCs are randomly distributed.
	.eps .pdf	Overview of the DCDC converter classification after the 2017 run for the half-cylinder in plus direction wrt. the beam on the inner side (BpI) of the barrel pixel detector. The coordinates correspond to the position of the DCDC converter in the detector during the run. Analog DCDC converter are marked with an “a”, digital DCDC converter are marked with a “d”. The defects of DCDCs are randomly distributed.
	.eps .pdf	Overview of the DCDC converter classification after the 2017 run for the half-cylinder in plus direction wrt. the beam on the outer side (BpO) of the barrel pixel detector. The coordinates correspond to the position of the DCDC converter in the supply tube in the detector. Analog DCDC converter are marked with an “a”, digital DCDC converter are marked with a “d”. The defects of DCDCs are randomly distributed.

Pixel Forward

Figure in png format	other formats	Description
	.pdf	Summary of the characterization of the 2017 DCDC converters for the forward pixel detector. The number of normal behaving, high-current and broken DCDC converters is given for each half-cylinder separately and for the total forward pixel detector. The defects of DCDCs are randomly distributed.
	.eps .pdf	Overview of the DCDC converter classification after the 2017 run for the half-cylinder in minus direction wrt. the beam on the inner side (BmI) of the forward pixel detector. The converters are grouped into readout groups (ROG) and the coordinates correspond to the position in the detector. Analog DCDC converter are marked with an “a”, digital DCDC converter are marked with a “d”. The defects of DCDCs are randomly distributed.
	.eps .pdf	Overview of the DCDC converter classification after the 2017 run for the half-cylinder in minus direction wrt. the beam on the outer side (BmO) of the forward pixel detector. The coordinates correspond to the position of the DCDC converter in the detector during the run. Analog DCDC converter are marked with an “a”, digital DCDC converter are marked with a “d”. The defects of DCDCs are randomly distributed.
	.eps .pdf	Overview of the DCDC converter classification after the 2017 run for the half-cylinder in plus direction wrt. the beam on the inner side (BpI) of the forward pixel detector. The coordinates correspond to the position of the DCDC converter in the detector during the run. Analog DCDC converter are marked with an “a”, digital DCDC converter are marked with a “d”. The defects of DCDCs are randomly distributed.
	.eps .pdf	Overview of the DCDC converter classification after the 2017 run for the half-cylinder in plus direction wrt. the beam on the outer side (BpO) of the forward pixel detector. The coordinates correspond to the position of the DCDC converter in the detector during the run. Analog DCDC converter are marked with an “a”, digital DCDC converter are marked with a “d”. The defects of DCDCs are randomly distributed.

-- BenediktVormwald - 2018-08-17