A network of 16 Medipix-2 (MPX) silicon pixel devices was installed in the ATLAS detector cavern at CERN. It was designed to measure the composition and spectral characteristics of the radiation field in the ATLAS experiment and its surroundings. This study demonstrates that the MPX network can also be used as a self-sufficient luminosity monitoring system. The MPX detectors collect data independently of the ATLAS data-recording chain, and thus they provide independent measurements of the bunch-integrated ATLAS/LHC luminosity. In particular, the MPX detectors located close enough to the primary interaction point are used to perform van der Meer calibration scans with high precision. Results from the luminosity monitoring are presented for 2012 data taken at TeV proton-proton collisions. The characteristics of the LHC luminosity reduction rate are studied and the effects of beam-beam (burn-off) and beam-gas (single bunch) interactions are evaluated. The systematic variations observed in the MPX luminosity measurements are below 0.3% for one minute intervals.

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Results of detailed simulations of the charge transfer inefficiency of a prototype serial readout CCD chip are reported. The effect of radiation damage on the chip operating in a particle detector at high frequency at a future accelerator is studied, specifically the creation of two electron trap levels, 0.17 eV and 0.44 eV below the bottom of the conduction band. Good agreement is found between simulations using the ISE-TCAD DESSIS program and an analytical model for the former level but not for the latter. Optimum operation is predicted to be at about 250 K where the effects of the traps is minimal; this being approximately independent of readout frequency in the range 7-50 MHz. The work has been carried out within the Linear Collider Flavour Identification (LCFI) collaboration in the context of the International Linear Collider (ILC) project. Results of detailed simulations of the charge transfer inefficiency of a prototype serial readout CCD chip are reported. The effect of radiation damage on the chip operating in a particle detector at high frequency at a future accelerator is studied, specifically the creation of two electron trap levels, 0.17 eV and 0.44 eV below the bottom of the conduction band. Good agreement is found between simulations using the ISE-TCAD DESSIS program and an analytical model for the former level but not for the latter. Optimum operation is predicted to be at about 250 K where the effects of the traps is minimal; this being approximately independent of readout frequency in the range 7-50 MHz. The work has been carried out within the Linear Collider Flavour Identification (LCFI) collaboration in the context of the International Linear Collider (ILC) project.

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A luminosity determination based on thermal neutron counting with six MPX silicon pixel devices installed in the ATLAS cavern is presented. Recently, the ATLAS Collaboration published final √ s = 8 TeV luminosity results. This made possible to perform a detailed comparison and verify the potential of the thermal neutron counting as a novel method for luminosity measurements to supplement the well-established presently used procedures. This measurement is unique to the MPX network and has the advantage that the neutrons, which pass the MPX devices, cannot result from activation processes of material nearby. Good agreement is found between the MPX neutron counting results and the ATLAS reference luminosity. The differences between the ATLAS and MPX luminosity measurements are described by a Gaussian distribution with width of 1.5%. K: Beam-line instrumentation (beam position and profile monitors; beam-intensity monitors; bunch length monitors); Instrumentation for particle accelerators and storage rings -high energy (linear accelerators, synchrotrons); Neutron detectors (cold, thermal, fast neutrons); Performance of High Energy Physics Detectors 1Corresponding author.