J. Lindgren

The DELPHI Microvertex detector

The DELPHI Microvertex detector, which has been in operation since the start of the 1990 LEP run, consists of three layers of silicon microstrip detectors at average radii of 6.3, 9.0 and 11.0 cm. The 73728 readout strips, oriented along the beam, have a total active area of 0.42 m2. The strip pitch is 25 μm and every other strip is read out by low power charge amplifiers, giving a signal to noise ratio of 15:1 for minimum ionizing particles. On-line zero suppression results in an average data size of 4 kbyte for Z0 events. After a mechanical survey and an alignment with tracks, the impact parameter uncertainty as determined from hadronic Z0 decays is well described by (69pt)2 + 242 μm, with pt in GeV/c. For the 45 GeV/c tracks from Z0 → μ− decays we find an uncertainty of 21 μm for the impact parameter, which corresponds to a precision of 8 μm per point. The stability during the run is monitored using light spots and capacitive probes. An analysis of tracks through sector overlaps provides an additional check of the stability. The same analysis also results in a value of 6 μm for the intrinsic precision of the detector.

Measurement of spatial resolution of a double-sided AC-coupled microstrip detector

Abstract Capacitively coupled Si strip detectors with readout on both the p-side and the n-side have been developed. A novel scheme to separate strips ohmically on the n-side by means of field depletion via a suitable potential applied to the readout strips has been successfully demonstrated. Results on the spatial resolution of these detectors for both sides measured in a high energy beam are presented. The spatial resolution of the n-side has been measured at different incident angles of the beam tracks with respect to a vertical plane through the n + strips at 0°, 20° and 40°.

Ion-implanted capacitively coupled silicon strip detectors with integrated polysilicon bias resistors processed on a 100 mm wafer

Abstract Double-sided silicon strip detectors with integrated coupling capacitors and polysilicon resistors have been processed on a 100 mm wafer. A detector with an active area of 19 × 19 mm 2 was connected to LSI readout electronics and tested. The strip pitch of the detector is 25 μm on the p-side and 50 μm on the n-side. The readout pitch is 50 μm on both sides. The number of readout strips is 774 and the total number of strips is 1161. On the p-side a signal-to-noise of 35 has been measured using a 90 Sr β-source. The n-side has been studied using a laser.

Ion-implanted silicon detectors processed on a 100 mm wafer

Abstract A planar process for manufacturing large silicon detectors on a 100 mm wafer has been developed. Several oxidation and annealing temperatures were studied in order to optimize detector performance. A strip detector with an active area of 32 × 58 mm2 together with various single detector diodes were processed and tested. The 1280 strip detector with 25 μm strip and readout pitch was connected to multiplexing LSI electronics and tested with tracks from a 90Sr beta source. The most probable signal pulse height was found to be 14 times the σnoise of any individual channel.

Beam test results of an ion-implanted capacitively coupled silicon strip detector processed on a 100 mm silicon wafer

Abstract A capacitively coupled silicon strip detector with 50 μm readout pitch has been tested in a pion beam at CERN. The spatial resolution of the detector equipped with LSI readout chips was 4.9 μm and the most probable signal-to-single-channel noise ratio was 31.

Beam test results of an ion-implanted silicon strip detector on a 100 mm wafer

Abstract Results are presented from a beam test in the CERN SPS North Area of a silicon strip detector. The detector is directly coupled and has an active area of 32 × 58 mm and a strip pitch of 25 μm. It is processed on a 100 mm wafer. Spatial resolution of the detector equipped with LSI readout chips was measured to be 3.9 μm and the most probable signal to single channel noise ratio was 20.

Double-sided capacitively coupled silicon strip detectors on a 100mm water

Abstract Silicon strip detectors with double-sided readout have been designed and processed on 100 mm silicon wafers. Detectors with integrated coupling capacitors and polysilicon bias resistors were tested by static electrical measurements, laser illumination and with tracks from a 90 Sr source. Strip separation on the detector n-side has been achieved by the use of capacitively coupled readout electrodes as field-plates. Interstrip resistance of > 10 Mω has been measured in all detector designs. Measurements with 90 Sr tracks show S/N = 21 on the detector p-side and S/N = 18 on the n-side.

Cluster-finding algorithm suitable for a silicon strip detector readout chip

Abstract A cluster finding algorithm for a VLSI silicon strip detector readout chip has been developed and tested with real data. The algorithm includes a simpl

The DELPHI microvertex detector

The main characteristics of the DELPHI Microvertex Detector are presented. The performance in terms of impact parameter resolution, association efficiency, and ambiguity is evaluated after two years of data taking at LEP.