H. Moilanen

Beam Test Measurements With Planar and 3D Silicon Strip Detectors Irradiated to sLHC Fluences

The planned luminosity upgrade of the CERN LHC to the super LHC (sLHC) requires investigation of new radiation hard tracking detectors. Compared to the LHC, tracking detectors must withstand a 5-10 times higher radiation fluence. Promising radiation hard options are planar silicon detectors with n-side readout and silicon detectors in 3D technology, where columnar electrodes are etched into the silicon substrate. This article presents beam test measurements per formed with planar and 3D n-in-p silicon strip detectors. The detectors were irradiated to different fluences, where the maximum fluence was 3 × 1015 1 MeV neutron equivalent particles per square centimeter (neq/cm2) for the planar detectors and 2 × 1015 neq/cm2 for the 3D detectors. In addition to signal measurements, charge sharing and resolution of both detector technologies are compared. An increased signal from the irradiated 3D detectors at high bias voltages compared to the signal from the unirradiated detector indicates that charge multiplication effects occur in the 3D detectors. At a bias voltage of 260 V, the 3D detector irradiated to 2 × 1015 neq/cm2 yields a signal almost twice as high as the signal of the unirradiated detector. Only 30% of the signal of an unirradiated detector could be measured with the planar detector irradiated to 3 × 1015 neq/cm2 at a bias voltage of 600 V, which was the highest bias voltage applied to this sensor.

Beam Test Measurements With 3D-DDTC Silicon Strip Detectors on n-Type Substrate

For the planned luminosity upgrade of the CERN LHC to the sLHC new radiation hard technologies for the tracking detectors are investigated. Corresponding to the luminosity increase, the radiation dose will be approximately a factor of ten higher than for the detectors currently installed in the LHC experiments. One option for radiation tolerant detectors are 3D silicon detectors with columnar electrodes penetrating into the silicon bulk. This article reports results of beam test measurements performed with 3D-DDTC (Double-Sided, Double Type Column) silicon strip detectors, where the columns do not pass through the detector completely. The devices were produced by IMB-CNM (Barcelona, Spain) and by FBK-irst (Trento, Italy). Important properties like space-resolved charge collection and efficiency are investigated.

Measurements of 3D Silicon Strip Sensors by two Manufacturers

The increase of the radiation dose at the luminosity upgrade of the LHC (sLHC) necessitates the development of novel tracking detectors. Among these, 3D silicon detectors constitute a promising option. By etching columnar electrodes of both doping types into the sensor, the distance for depletion and charge collection is decoupled from the sensor thickness and can be considerably smaller than in standard planar sensors. Two of the main effects of radiation damage in silicon detectors (increasing depletion voltage and trapping) can be significantly reduced. Silicon strip detectors in 3D-DDTC (double-sided, double type column) design produced by FBKIRST (Trento, Italy) and CNM-IMB (Barcelona, Spain) have been measured in a test beam at the CERN SPS. Important properties like spatially resolved charge collection and detection efficiency were investigated.