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Status and future measurements on Micron detectors Outline: Irradiation and measurement in dry atmosphere Measurements in vacuum.

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Presentation on theme: "Status and future measurements on Micron detectors Outline: Irradiation and measurement in dry atmosphere Measurements in vacuum."— Presentation transcript:

1 Status and future measurements on Micron detectors Outline: Irradiation and measurement in dry atmosphere Measurements in vacuum

2 Irradiation and measurement in dry atmosphere Motivation: test of the oxide charge as possibly shorting the read- out strips after heavy irradiation. Oxide charge build-up favoured by irradiation under bias. Test ability to stand high voltage in dry air. Is there a saturation oxide charge concentration? Our p-spray: ± 0.3 B cm -2 Possible scenario: strips could be shorted if oxide charge > p- spray. But: evidences from other works (MPI) that after irradiation strips are insulated also with p-spray doses < p-spray. Tentative explanation is that insulation is given by interface states.

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5 Monitoring the irradiation Irradiation was performed in the ATLAS cool box, in nitrogen atmosphere.

6 Detector was vertical in the beam. The irradiated area is ~ 2x2 cm 2, maximum fluence > p cm -2. Typical Irrad 7 fluence horizontal profile (to be rescaled to max ~ cm -2 ).

7 Reverse bias current during irradiation Bias changed from 100V to 200V.

8 Measurements foreseen with the irradiated device: CCE(V) measurement of the irradiated area (to determine, if possible, the irradiation profile). Measurement of strip insulation (charge spread over multiple strips) with laser light injection next to a strip as a function of the fluence. Possible estimation of the maximum survival limit (fluence on the detector varies from 0 to > cm -2 )

9 Measurements in vacuum A LHCb VELO phi measuring detector, PR02 version has been put in vacuum (~10 -2 mb) and left under 250V for 6 days (its still running at present). The reverse current (initially 0.8 µA) didnt vary significantly over this period (small variations due to temperature variation where in the order of ± 2%.


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