Micron detector testing in Liverpool G. Casse – O. Lodge Laboratory, University of Liverpool

Micron detector testing in Liverpool 5/21/02 LHCb week G. Casse – O. Lodge lab. University of Liverpool Outline: Irradiation of n-in-n and p-in-n 200 µm thick Phi-type detectors Test of distortion of the charge sharing ( function) in non- homogeneously irradiated n-in-n detectors Comparison with simulations Comparison of charge collection efficiency vs voltage curves obtained with beta particles ( 106 Ru source) and 1060 nm laser Signal to noise with SCT128-VG Comparison of CCE with n and p read out strips (n-in-n vs p-in-n diode geometry)

Micron detector testing in Liverpool 5/21/02 LHCb week G. Casse – O. Lodge lab. University of Liverpool A n-in-n and a p-in-n phi detectors have been irradiated in the 24GeV/c CERN-PS beam area (Irrad1 zone). They were positioned to get a non-homogenous irradiation profile

Micron detector testing in Liverpool 5/21/02 LHCb week G. Casse – O. Lodge lab. University of Liverpool The n-in-n phi-detector has been scanned using the fine spot 1060 nm laser in order to study the N eff profile and the function across the irradiated area. The manual x-y stage has a scale with 2µm step which allows the intermediate positioning with 1 µm precision. The light spot has a FWHM of about 7µm. The detector has been scanned near the outer region where the strip pitch is about 100µm. The metallisation on the backside of the detector has holes to avoid reflections of the laser light. The intermediate read-out strip screens the laser beam in the mid-strip area.

Micron detector testing in Liverpool 5/21/02 LHCb week G. Casse – O. Lodge lab. University of Liverpool The effective doping concentration as measured by the CCE curves in correspondence of laser illumination of different strips. The high gradient region is about from strip #550 to #600.

Micron detector testing in Liverpool 5/21/02 LHCb week G. Casse – O. Lodge lab. University of Liverpool Measurement of the function in differently irradiated area of the detector: low gradient area (irradiation about at type inversion fluence)

Micron detector testing in Liverpool 5/21/02 LHCb week G. Casse – O. Lodge lab. University of Liverpool Measurement of the function in differently irradiated area of the detector: high gradient area

Micron detector testing in Liverpool 5/21/02 LHCb week G. Casse – O. Lodge lab. University of Liverpool Measurement of the function in differently irradiated area of the detector: most irradiated area

Micron detector testing in Liverpool 5/21/02 LHCb week G. Casse – O. Lodge lab. University of Liverpool ISE simulation of the electric field (300 V applied bias) in the high gradient area of an irradiated (> cm -2 ) p-in-n silicon detector and signal of two neighbour strips generated by a MIP crossing mid way of the two strips

Micron detector testing in Liverpool 5/21/02 LHCb week G. Casse – O. Lodge lab. University of Liverpool ISE simulation of the electric field (120 V applied bias) in the high gradient area of an irradiated (> cm -2 ) n-in-n silicon detector and signal of two neighbour strips generated by a MIP crossing mid way of the two strips. The difference in signal height corresponds to the one obtained by moving the impact point of the MIP off centre by half a micron.

Micron detector testing in Liverpool 5/21/02 LHCb week G. Casse – O. Lodge lab. University of Liverpool Comparison between CCE obtained with 1060 nm laser and 106 Ru source

Micron detector testing in Liverpool 5/21/02 LHCb week G. Casse – O. Lodge lab. University of Liverpool Preliminary comparison of CCE between n-in-n and p-in- n detectors: highly irradiated region. The signal was induced by 1060 nm laser. The detectors were irradiated together. Thickness of both types: 200 µm.

Micron detector testing in Liverpool 5/21/02 LHCb week G. Casse – O. Lodge lab. University of Liverpool Noise performances: The measured S/N for b particle ( 106 Ru) signal signal with SCT128VG for this detector is ~16 in the low irradiation region and ~13.5 in the higher irradiated region. The noise level is independent on the applied bias between 50 to 400 volts, as expected with irradiated silicon detectors. There is no evidence of microdischarge at any voltage. This results is preliminary: only 1/8 of the detector has been tested up to now.

Micron detector testing in Liverpool 5/21/02 LHCb week G. Casse – O. Lodge lab. University of Liverpool Results with populated (12 chips) IDE hybrid and irradiated 200µm p-in-n detector

Micron detector testing in Liverpool 5/21/02 LHCb week G. Casse – O. Lodge lab. University of Liverpool Status of VELO hybrid support card (T. Smith)

Micron detector testing in Liverpool 5/21/02 LHCb week G. Casse – O. Lodge lab. University of Liverpool Conclusions: Distortion of the resolution due to non-homogeneous irradiation does not need correction CCE with n-strip read-out superior at low voltages after irradiation No evidence of microdischages up to 500 V in n-in-n (p-spray) detectors