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The pair creation energy, ω and the Fano factor of silicon were measured using a CCD sensor and X-rays from an 55 F e source. The measurements were performed at a sensor temperature of 185K. The pair creation energy was measured for X-rays in the 1.7–6.5 keV range. The measured pair creation energy is ω = ( 3 . 650 ± 0 . 009 ) eV at the M n K α line energy. The Fano factor at this energy is F = 0 . 128 ± 0 . 001 . The agreement with theory and previous measurements is satisfactory. The system gain was obtained from flat field exposures using the Poisson distribution properties. These results and the details of our measurement procedure are presented below. [ABSTRACT FROM AUTHOR]

Abstract: Modern mosaic cameras have grown both in size and in number of sensors. The required volume of sensor testing and characterization has grown accordingly. For camera projects as large as the LSST, test automation becomes a necessity. A CCD testing and characterization laboratory was built and is in operation for the LSST project. Characterization of LSST study contract sensors has been performed. The characterization process and its automation are discussed, and results are presented. Our system automatically acquires images, populates a database with metadata information, and runs express analysis. This approach is illustrated on 55Fe data analysis. 55Fe data are used to measure gain, charge transfer efficiency and charge diffusion. Examples of express analysis results are presented and discussed. [Copyright &y& Elsevier]

Abstract: In thick fully depleted CCDs charge carrier transport from the back window to the gates is accompanied by charge diffusion. Lateral diffusion smooths out density variations of the incoming photon flux by redistributing charges spatially. This creates short range positive correlations in recorded amplitudes. Pixel-to-pixel amplitude variations can also be caused by pixel size and quantum efficiency variations. Pixel size variations result in short range negative correlations. Our study shows that the characteristic diffusion width can be extracted from flat field data. The study was performed on fully depleted, thick CCDs produced in a technology study for the Large Synoptic Survey Telescope (LSST). Data were taken in the laboratory at bias voltages between −5 and −40V. To increase statistical accuracy, images taken in identical conditions were co-added after base line subtraction and master files were produced. A flat field image simulator was developed for statistical comparison of simulated and measured images. Results on diffusion, pixel response variations, data features, analysis and modeling techniques are presented and discussed. [Copyright &y& Elsevier]

The charge sharing between neighboring pixels in pixelated sensors can be used to measure particle or x-ray coordinates with accuracy better than the pixel pitch. The accurate model of the charge distribution shape is essential to achieve ultimate coordinate accuracy. The charge sharing is caused by charge carriers diffusion on the path from the generation point to pixels. This paper is focused on the diffusion of the initially compact charge cloud in the field free region. The diffusion equation solutions are obtained using separation of variable and Fourier synthesis method for different initial conditions and resulting charge distributions are integrated over pixel areas. The look up table containing pre-calculated values for pixel charge fractions is proposed to speed up numerical calculations. [ABSTRACT FROM AUTHOR]

The pocket pumping technique is used to detect small electron trap sites. These traps, if present, degrade CCD charge transfer efficiency. To reveal traps in the active area, a CCD is illuminated with a flat field and, before image is read out, accumulated charges are moved back and forth number of times in parallel direction. As charges are moved over a trap, an electron is removed from the original pocket and re-emitted in the following pocket. As process repeats one pocket gets depleted and the neighboring pocket gets excess of charges. As a result a “dipole” signal appears on the otherwise flat background level. The amplitude of the dipole signal depends on the trap pumping efficiency. This paper is focused on trap identification technique and particularly on new methods developed for this purpose. The sensor with bad segments was deliberately chosen for algorithms development and to demonstrate sensitivity and power of new methods in uncovering sensor defects. [ABSTRACT FROM AUTHOR]

X-ray frames offer a lot of information about CCD. 55 Fe sources are traditionally being used for CCD gain and charge transfer efficiency (CTE) measurements. In addition X-rays can be used for the system linearity test. We demonstrate how spectral lines of 55 Fe and 241 Am rad. sources are used for system linearity measurements. The pixel size of modern scientific CCDs is getting smaller. The charge diffusion causes the charge spread among neighboring pixels especially in thick fully depleted sensors. This enables measurement of the charge diffusion using 55 Fe X-rays. On the other hand, the usual CTE characterization method based on single pixel X-ray events becomes statistically deficient. A new way of measuring CTE using shape and amplitude analysis of X-ray clusters is presented and discussed. This method requires high statistical samples. Advances in test automation and express analysis technique allow for acquiring such statistical samples in a short period of time. The lateral diffusion measured using e2v CCD250 is presented and implications for X-ray cluster size and expected cluster shape are discussed. The CTE analysis using total X-ray cluster amplitude is presented. This analysis can reveal CTE problems for certain conditions. The statistical analysis of average X-ray cluster shape is presented. The details of our measurement procedure are presented. [ABSTRACT FROM AUTHOR]

Abstract: Variations of the doping concentration inside a silicon device result in electric field distortions. These distortions, “parasitic” fields, have been observed in Silicon Drift Detectors [D. Nouais, et al., Nucl. Instr. and Meth. A 501 (2003) 119; E. Crescio, et al., Nucl. Instr. and Meth. A 539 (2005) 250]. Electric fields inside a silicon device can be calculated for a given doping profile. In this study, the ATLAS device simulator. [ http://www.silvaco.com/ and http://www.silvaco.com/products/device_simulation/atlas.html ] was used to calculate the electric field inside an inhomogeneously doped device. Simulations were performed for 1D periodic doping profiles. Results show strong dependence of the parasitic field strength on the ‘smoothness’ of the doping profile. [Copyright &y& Elsevier]

Large area, 7.25 cm×8.76 cm silicon drift detectors have been developed and are in production for the ALICE experiment at LHC. An active area of the detector of more than 50 cm2 imposes high demands on the quality of processing and raw material. Automated testing procedures have been developed to test detectors before mounting them on the ladders. Probe stations for ALICE SDD testing were designed and built at INFN, Trieste and Ohio State University (OSU). Testing procedures, detector selection criteria and some details of the OSU probe station design are discussed. [Copyright &y& Elsevier]

Electron Multiplying Charge Coupled Devices, EMCCD are used as x-ray detectors. The NSLS-II Soft Inelastic x-ray Scattering (SIX) beam line has two EMCCDs for x-ray detection in the spectrometer arm. The spectrometer with high resolving power disperses x-rays vertically. The x-ray vertical position on the sensor plane is related to its energy. This allows for very accurate x-ray energy measurements through x-ray coordinates. X-rays interact with silicon and create a number of electron–hole pairs proportional to the x-ray energy. Electrons drift and diffuse toward pixel gates and are collected there. The diffused electrons form a charge cloud distributed over several neighboring pixels. This charge sharing enables coordinate measurements with accuracy better than the pixel pitch. The charge distribution shape has to be taken into account to achieve ultimate accuracy in coordinate measurements. In this paper, we present a method of the charge distribution shape analysis and demonstrate its applications. The drift and diffusion of electrons from the point of generation to pixel gates results in the bell-shaped electron cloud usually approximated by Gaussian shape. The number of electrons collected under a pixel is proportional to the shape function integral. These electron packets get transferred to the sense node of the output amplifier. The transfer process could introduce distortions to the original charge distribution. For example, during transfers, electrons in the packet could be exposed to traps if they are present in the sensor. The trapping and later the release processes distort the apparent shape of the charge distribution. Therefore, deviations of the charge distribution shape from the originally symmetrical form can indicate the presence of trap centers in the sensor and can be used for sensor diagnostics. [ABSTRACT FROM AUTHOR]

Abstract: The ALICE experiment, one of the four LHC experiments, is dedicated to study Heavy Ion collisions at the center-of-mass energy of the 5.5TeV per nucleon pair. The ALICE detector is designed as a general purpose detector capable of measuring most phenomena related to the Quark Gluon Plasma (QGP) state of matter. A set of high granularity detectors is used for tracking and includes an Inner Tracking System, a large-volume Time-Projection Chamber and a Transition–Radiation Detector. The Inner Tracking System is designed for high precision reconstruction of the primary and secondary vertices and tracking and identification of low momentum particles. Motivations and requirements for the ITS tracking system are presented and specifics of the design and performance are discussed. [Copyright &y& Elsevier]

Abstract: Tight requirements on the Large Synoptic Survey Telescope point spread function (PSF) demand sensor contribution to PSF be both small and well characterized. The sensor PSF is determined by the lateral charge diffusion on the drift path from the CCD window to the gates. Different techniques for charge diffusion characterization have been developed, each with its own systematics and measurement difficulties. A new way to measure charge diffusion using an X-ray source is presented. We demonstrate the effectiveness and limitations of our technique. [Copyright &y& Elsevier]

Abstract: The method of computation of currents induced on electrodes by charges moving in vacuum was introduced in Refs. . This method was extended for the case of a semiconductor with assumption that only fixed charges are presented. In presented paper, Ramo''s method is applied for charges moving in a media without limitation of the presence of fixed charges only. [Copyright &y& Elsevier]

The sPHENIX Time Projection Chamber Outer Tracker (TPOT) is a Micromegas based detector. It is a part of the sPHENIX experiment that aims to facilitate the calibration of the Time Projection Chamber, in particular the correction of the time-averaged and beam-induced distortions of the electron drift. This paper describes the detector mission, setup, construction, installation, commissioning and performance during the first year of sPHENIX data taking. [ABSTRACT FROM AUTHOR]

CdZnTe (CZT) detectors have been used in the past and are being actively considered for future gamma-ray space telescopes. One of the challenges of operating CZT detectors in low Earth orbit is radiation damage caused by energetic protons. Previous studies concluded that fluences of 108 -109 p/cm 2 are sufficient to cause shifting of peak positions and degradations of energy resolution. Degradation of detectors after proton irradiation has been extensively investigated to determine their radiation resistance limits and performance recovering procedures for their applications in space and nuclear nonproliferation. Here we present the study of radiation effects induced by 100 MeV protons in 3-cm long CdZnTe detectors that we recently proposed for the gamma-ray telescope GECCO. The goal of this study is to evaluate the feasibility of using such long CZT detectors in future space missions. [ABSTRACT FROM AUTHOR]

The Solenoidal Tracker At RHIC-Silicon Vertex Tracker (STAR-SVT) is a three-barrel microvertex detector based upon silicon drift detector (SDD) technology. As designed for the STAR-SVT, (SDDs) are capable of providing unambiguous two-dimensional hit position measurements with resolutions on the order of 20 μm in each coordinate. In addition, a high-resolution energy loss measurement in the three layers of the SVT enables good particle identification. We describe features of the design of the STAR-SVT SDDs and electronics that are motivated by such characteristics. We also detail the mechanical structure, assembly procedures, and performance characteristics of the completed device. [Copyright &y& Elsevier]

The muon spectrometer of the ATLAS detector for the Large Hadron Collider is designed to provide a muon transverse momentum resolution of 2%–10% for momenta between 6 GeV and 1 TeV over a pseudo-rapidity range of |η|⩽2.7. This required the development of precision drift chambers with a track position resolution of 40 μm, the Monitored Drift Tube (MDT) chambers. We report about the construction of the three main types of MDT chambers for ATLAS, test results and the first production experience. [Copyright &y& Elsevier]

The current status of the STAR Silicon Vertex Tracker (SVT) is presented. The performance of the Silicon Drift Detectors (SDD) is discussed. Results for a recent 15 layer SDD tracker which prototypes all components of the SVT are presented. The enhanced physics capabilities of the STAR detector due to the addition of the SVT are addressed. [Copyright &y& Elsevier]

Abstract: ATLAS is a general purpose experiment aimed at studying high-energy particle interactions at the Large Hadron Collider (LHC). This paper describes the evolution of the Controls and Configuration system of the ATLAS Trigger and Data Acquisition from the Technical Design Report to the first events taken with circulating beams. We present the lessons learned during the development. [ABSTRACT FROM AUTHOR]

Abstract: The ATLAS muon spectrometer uses tracking chambers consisting of up to 5m long drift tubes filled with at 3bar. The chambers are run in a average toroidal magnetic field of 0.4T created by 8 air core coils. They provide a track-point accuracy of if the space-to-drift-time relationship is known with accuracy. The magnetic field B influences the electron drift inside the tubes: the maximum drift time increases by . B varies by up to along the tubes of the chambers mounted near the magnet coils which translates into a variation of of up to 45ns. The dependence of on B must be taken into account. Test-beam measurements show that the electron drift in case of can be modelled with the required accuracy by a Langevin equation with a friction term which is slightly non-linear in the drift velocity. [Copyright &y& Elsevier]

Abstract: The muon spectrometer of the ATLAS experiment at the Large Hadron Collider is designed to measure the muon momenta of up to 1TeV/c with a resolution of better than 10% in a toroidal magnetic field of superconducting air–core magnets. The muon track sagitta is measured in three layers of pressurized drift-tube chambers. The precision muon chambers have to be aligned with an accuracy of better than in the track bending plane. An optical alignment system monitors movements of the muon chambers with a precision of few microns. In order to determine the chamber positions in the spectrometer, the initial chamber positions have to be measured with accuracy using straight muon tracks from proton–proton collisions in a dedicated run of the ATLAS detector with the toroid magnets turned off. A Least Square algorithm has been developed which determines the misalignment parameters of a complete azimuthal sector of the barrel part of the muon spectrometer. It has been tested with straight cosmic muon tracks during the commissioning of the ATLAS experiment. Simulations show that the required alignment accuracy is reached with 100,000 muons per sector originating from the interaction point with transverse momentum greater than 10GeV. About half of the barrel chambers have already been aligned with accuracy using cosmic muons. [Copyright &y& Elsevier]