T. Mäenpää

Silicon beam telescope for CMS detector tests

Abstract A beam telescope providing precision track measurements as reference for other detectors has been upgraded in the CERN H2 test beam. The apparatus was completely rebuilt from the detector wafers and front-end electronics to the data acquisition system. The new detector setup consists of eight 5.6×5.6 cm 2 sized DC coupled silicon microstrip detectors. Typical position resolution values of about 7.5 μm were measured. Details of the setup are described and results from the recent beam tests are reported.

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.

Performance and calibration studies of silicon strip detectors in a test beam

Abstract Performance of single-sided DC-coupled silicon strip detectors is studied in the CERN H2 test beam. A great emphasis is put on the calibration of the detector response as well as on the geometric alignment of the detector planes. Performance results are presented for different angles of incidence for the particles.

Track-Induced Clustering in Position Sensitive Detector Characterization

The formation of clusters in the data analysis of position-sensitive detectors is traditionally based on signal-to-noise ratio thresholds. For detectors with a very low signal-to-noise ratio, e.g., as a result of radiation damage, the total collected charge obtained from the clusters is biased to the greater signal values resulting from the thresholds. In this paper an unbiased method to measure the charge collection of a silicon strip detector in a test beam environment is presented. The method is based on constructing the clusters on test detectors around the impact point of the reference track.

Irradiation effects in electronic components of the RPC trigger for the CMS experiment

The results of proton radiation test of electronic devices for RPC trigger electronic system of CMS detector are presented. For Xilinx Spartan-IIE FPGA the cross section for Single Event Upsets (SEUs) in configuration bits was measured. The dynamic SEUs in flip-flops was also investigated, but not observed. For the FLASH memories no single upsets were detected, but after a huge dose permanent damages of devices were observed. For SDRAM memories, the SEU cross section was measured. A brief description of radiation inducted effects in FPGAs, SRAM and FLASH memories is also presented.

Recent Progress in CERN RD39: Radiation Hard Cryogenic Silicon Detectors for Applications in LHC Experiments and Their Future Upgrades

CERN RD39 Collaboration develops radiation-hard cryogenic silicon detectors. Recently, we have demonstrated improved radiation hardness in novel Current Injected Detectors (CID). For detector characterization, we have applied cryogenic Transient Current Technique (C-TCT). In beam tests, heavily irradiated CID detector showed capability for particle detection. Our results show that the CID detectors are operational at the temperature -50°C after 1016 1 MeV neutron equivalent fluence.

Track-induced clustering in position sensitive detector characterization

The formation of clusters in the data analysis of position-sensitive detectors is traditionally based on signal-to-noise ratio thresholds. For detectors with a very low signal-to-noise ratio, e.g. as a result of radiation damage, the total collected charge obtained from the clusters is biased to the greater signal values resulting from the thresholds. In this paper an unbiased method to measure the charge collection in a test beam environment is presented. The method is based on constructing the clusters on test detectors around the impact point of the reference track.

Strip Detectors Processed on High-Resistivity 6-inch Diameter Magnetic Czochralski Silicon (MCz-Si) Substrates

Tracking detectors for future high-luminosity particle physics experiments have to be simultaneously radiation hard and cost efficient. This paper describes processing and characterization of p+ /n-/n+ (n-type silicon bulk) detectors made of high-resistivity Magnetic Czochralski silicon (MCz-Si) substrates with 6-inch wafer diameter. The processing was carried out on a line used for large-scale production of sensors using standard fabrication methods, such as implanting polysilicon resistors to bias individual sensor strips. Special care was taken to avoid the creation of Thermal Donors (TD) during processing. The sensors have a full depletion voltage of 120-150 V which are uniform over the investigated sensors. All of the leakage current densities were below 55 nA/cm2 at 200 V bias voltage. A strip sensor with 768 channels was attached to readout electronics and tested in particle beam with a data acquisition (DAQ) similar to the system used by the CMS experiment at the CERN LHC. The test beam results show a signal-to-noise ratio greater than 40 for the test beam sensor. The results demonstrate that MCz-Si detectors can reliably be manufactured in the industrial scale semiconductor process.

Forward-backward asymmetry of Drell-Yan lepton pairs in pp collisions at root s=8 TeV

A measurement of the forward–backward asymmetry