In this paper a detailed simulation of irradiated pixel sensors was used to investigate the effects of radiation damage on charge sharing and position determination. The simulation implements a model of radiation damage by including two defect levels with opposite charge states and trapping of charge carriers. We show that charge sharing functions extracted from the simulation can be parameterized as a function of the inter-pixel position and used to improve the position determination. For sensors irradiated to Phi=5.9x10^14 n/cm^2 a position resolution below 15 um can be achieved after calibration.
The tracking system of the CMS experiment, currently under construction at the Large Hadron Collider (LHC) at CERN (Geneva, Switzerland), will include a silicon pixel detector providing three spacial measurements in its final configuration for tracks produced in high energy pp collisions. In this paper we present the results of test beam measurements performed at CERN on irradiated silicon pixel sensors. Lorentz angle and charge collection efficiency were measured for two sensor designs and at various bias voltages.
The CMS experiment at the LHC includes a hybrid silicon pixel detector for the reconstruction of charged tracks and of the interaction vertices. The detector is made of three barrel layers and two disks at each end of the barrel. Detector modules consist of thin, segmented silicon sensors with highly integrated readout chips connected by the bump bonding technique. In this paper we report on the progress of the detector construction and testing. In addition, first results from the commissioning systems at CERN and PSI are presented.
The CMS experiment at the LHC includes a hybrid silicon pixel detector for the reconstruction of charged tracks and of the interaction vertices. The barrel region consists of n-in-n sensors with 100X150 um^2 cell size processed on diffusion oxygenated float zone silicon. A biasing grid is implemented and pixel isolation is achieved with the moderated p-spray technique. An extensive test program was carried out on the H2 beam line of the CERN SPS. In this paper we describe the sensor layout, the beam test setup and the results obtained with both irradiated and non-irradiated prototype devices. Measurements of charge collection, hit detection efficiency, Lorentz angle and spatial resolution are presented.
The Compact Muon Solenoid experiment at the Large Hadron Collider at CERN includes a silicon pixel detector as its innermost component. Its main task is the precise reconstruction of charged particles close to the primary interaction vertex. This paper gives an overview of the mechanical requirements and design choices for the barrel pixel detector. The distribution of material in the detector as well as its description in the Monte Carlo simulation are discussed in detail.
The CMS experiment will include a pixel detector for pattern recognition and vertexing. It will consist of three barrel layers and two endcaps on each side, providing three space-points up to a pseudoraditity of 2.1. Taking into account the expected limitations of its performance in the LHC environment an 8-9 layer pixel detector for an upgraded LHC is discussed.