Igor Bayshev

We present the FP420 R&D project, which has been studying the key aspects of the development and installation of a silicon tracker and fast-timing detectors in the LHC tunnel at 420 m from the interaction points of the ATLAS and CMS experiments. These detectors would measure precisely very forward protons in conjunction with the corresponding central detectors as a means to study Standard Model (SM) physics, and to search for and characterise new physics signals. This report includes a detailed description of the physics case for the detector and, in particular, for the measurement of Central Exclusive Production, pp→p+ϕ+p, in which the outgoing protons remain intact and the central system ϕ may be a single particle such as a SM or MSSM Higgs boson. Other physics topics discussed are γγ and γp interactions, and diffractive processes. The report includes a detailed study of the trigger strategy, acceptance, reconstruction efficiencies, and expected yields for a particularpp→pHp measurement with Higgs boson decay in theb mode. The document also describes the detector acceptance as given by the LHC beam optics between the interaction points and the FP420 location, the machine backgrounds, the new proposed connection cryostat and the moving (``Hamburg'') beam-pipe at 420 m, and the radio-frequency impact of the design on the LHC. The last part of the document is devoted to a description of the 3D silicon sensors and associated tracking performances, the design of two fast-timing detectors capable of accurate vertex reconstruction for background rejection at high-luminosities, and the detector alignment and calibration strategy.

Monte Carlo radiation transport codes are used by the CMS Beam Radiation Instrumentation and Luminosity (BRIL) project to estimate the radiation levels due to proton–proton collisions and machine induced background. Results are used by the CMS collaboration for various applications: comparison with detector hit rates, pile-up studies, predictions of radiation damage based on various models (Dose, NIEL, DPA), shielding design, estimations of residual dose environment. Simulation parameters, and the maintenance of the input files are summarized, and key results are presented. Furthermore, an overview of additional programs developed by the BRIL project to meet the specific needs of CMS community is given.

Thermal neutron counters inside moderating shells are used widely at high energy accelerators. Response of these detectors to neutrons of different energy depends on material, size and shape of moderator. Radiators and absorbers can also modify this response significantly. The main application of counters in moderators is neutron dosimetry. Some dedicated sets of these detectors Bonner spheres) are even used sometimes to estimate neutron spectra. Monitoring of fast neutrons at modern accelerator and experimental facilities is very important to keep radiation damage of electronic components under control. One more step towards fast neutron measurements with thermal neutron counters in moderators is reported here. A set of neutron transport simulations is done to optimize moderator/radiator/absorber assemblies for higher sensitivity to neutrons with energies above 100 kev along with much lower sensitivity at lower energies. The resulting pair of the main and complementary monitors is designed.