The semiconductor pixel detector Timepix (256 × 256 pixels with pitch of 55 um) can be used for energy measurements. This measurements require knowledge of the energy calibration of each pixel of the ...matrix. Such a calibration is very nonlinear in the low energy range. A method already exists that uses radiation sources for calibration of each pixel of the matrix. The response of each pixel is measured and evaluated in order to acquire parameters for a surrogate calibration function. This method requires analysis of thousands of spectra and performing thousands of fits. A new calibration procedure has been designed that combines Timepix test pulse functionality and measurement with radiation sources. This procedure significantly reduces time needed for calibration. In the first part of the method a relative calibration is obtain by injecting a defined test charges into all pixels of the matrix. In the second phase a calibration precision is improved and converted to absolute scale by irradiating the detector with a source. After such a complex calibration, it is possible to perform a recalibration of the detector, without the need for a source. The new procedure is fully automatic and is built into a current control and data acquisition software for Timepix detectors as an extension module.
As with most software, developers tend to create interfaces which seem logical and user-friendly. The only problem is that 'logical' to one person is confusing to another. The best approach is try ...out several search engines and spend enough time trying sample searches that you get a feel for the degree to which it satisfies your needs. All of these sites have adequate help areas and should be your first stop. Hopefully, these tools will help you to spend less time aimlessly surfing and more time realizing the potential of the Internet.
Current plans call for two separate missions to deploy Medipix2-Technology-based detectors in space for the first time. NASA is planning to deploy 5 or more Radiation Environment Monitor (REM) units, ...each of which will contain a Medipix2 TimePix-based detector assembly, on the International Space Station (ISS) during the spring of 2012 as part of a Station Detailed Test Objective (SDTO). These units will be mounted on a single 8-layer printed circuit board containing a USB-based interface. The entire unit will have the form of a typical USB flash-memory device, and the USB interface will provide interactive control and data readout as well as the operating power. Each of the units will be separately plugged into one of the 21 Lenovo® T-61B laptops that are currently onboard the ISS. The purpose of this test is to acquire initial on-orbit data to allow feedback into the design of the next generation of Medipix device, which is intended to support the development of a portable, standalone, wireless and battery-powered personal space radiation dosimeter. The second mission, LUCID (Langton Ultimate Cosmic ray Intensity Detector) is part of a UK outreach project being conducted by the Simon Langton School for Boys in Canterbury, UK. A small instrument containing 5 detector assemblies, also containing the TimePix versions of the Medipix2 technology will be deployed on the upcoming UK TechDemoSat 1 mission, also planned for launch in 2012. These deployments have many similar embedded control software and ground-based analysis software requirements.
Synchrotron applications such as coherent X-ray diffraction and X-ray photon-correlation spectroscopy require detectors with a pixel pitch of 50 μm as highlighted by a survey with beamline scientists ...of Diamond Light Source synchrotron. Furthermore, the detector should also have a high frame rate, large dynamic range and large detection efficiency. The Medipix3 readout chip with a pixel pitch of 55 μm emerged as a good candidate to develop a new detector for the aforementioned applications. Additionally, it implements a new operating mode, referred to as Charge Summing Mode (CSM), with the purpose of eliminating charge-shared events. This mode can be very useful in this case, since the charge-sharing effect increases as the detector pixel size decreases. Also, its design is expected to be more radiation hard that its predecessor Medipix2. The present work focuses on the evaluation of the radiation hardness and the CSM operating mode of a Medipix3-based detector in order to develop a large area detector for synchrotron applications.
A search with the ATLAS detector is presented for the Standard Model Higgs boson produced by vector-boson fusion and decaying to a pair of bottom quarks, using 20.2 fb(-1) of LHC proton-proton ...collision data at root s - 8 TeV. The signal is searched for as a resonance in the invariant mass distribution of a pair of jets containing b-hadrons in vector-boson-fusion candidate events. The yield is measured to be -0.8 +/- 2.3 times the Standard Model cross-section for a Higgs boson mass of 125 GeV. The upper limit on the cross-section times the branching ratio is found to be 4.4 times the Standard Model cross-section at the 95% confidence level, consistent with the expected limit value of 5.4 (5.7) in the background-only (Standard Model production) hypothesis.
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