We propose an experiment (Mu3e) to search for the lepton flavour violating decay mu+ -> e+e-e+. We aim for an ultimate sensitivity of one in 10^16 mu-decays, four orders of magnitude better than previous searches. This sensitivity is made possible by exploiting modern silicon pixel detectors providing high spatial resolution and hodoscopes using scintillating fibres and tiles providing precise timing information at high particle rates.
The MEG (Mu to Electron Gamma) experiment has been running at the Paul Scherrer Institut (PSI), Switzerland since 2008 to search for the decay meg by using one of the most intense continuous $mu^+$ beams in the world. This paper presents the MEG components: the positron spectrometer, including a thin target, a superconducting magnet, a set of drift chambers for measuring the muon decay vertex and the positron momentum, a timing counter for measuring the positron time, and a liquid xenon detector for measuring the photon energy, position and time. The trigger system, the read-out electronics and the data acquisition system are also presented in detail. The paper is completed with a description of the equipment and techniques developed for the calibration in time and energy and the simulation of the whole apparatus.
FASER is a proposed small and inexpensive experiment designed to search for light, weakly-interacting particles during Run 3 of the LHC from 2021-23. Such particles may be produced in large numbers along the beam collision axis, travel for hundreds of meters without interacting, and then decay to standard model particles. To search for such events, FASER will be located 480 m downstream of the ATLAS IP in the unused service tunnel TI12 and be sensitive to particles that decay in a cylindrical volume with radius R=10 cm and length L=1.5 m. FASER will complement the LHCs existing physics program, extending its discovery potential to a host of new, light particles, with potentially far-reaching implications for particle physics and cosmology. This document describes the technical details of the FASER detector components: the magnets, the tracker, the scintillator system, and the calorimeter, as well as the trigger and readout system. The preparatory work that is needed to install and operate the detector, including civil engineering, transport, and integration with various services is also presented. The information presented includes preliminary cost estimates for the detector components and the infrastructure work, as well as a timeline for the design, construction, and installation of the experiment.
The AMoRE (Advanced Mo-based Rare process Experiment) project is a series of experiments that use advanced cryogenic techniques to search for the neutrinoless double-beta decay of mohundred. The work is being carried out by an international collaboration of researchers from eight countries. These searches involve high precision measurements of radiation-induced temperature changes and scintillation light produced in ultra-pure Mo[100]-enriched and Ca[48]-depleted calcium molybdate ($mathrm{^{48depl}Ca^{100}MoO_4}$) crystals that are located in a deep underground laboratory in Korea. The mohundred nuclide was chosen for this zeronubb decay search because of its high $Q$-value and favorable nuclear matrix element. Tests have demonstrated that camo crystals produce the brightest scintillation light among all of the molybdate crystals, both at room and at cryogenic temperatures. $mathrm{^{48depl}Ca^{100}MoO_4}$ crystals are being operated at milli-Kelvin temperatures and read out via specially developed metallic-magnetic-calorimeter (MMC) temperature sensors that have excellent energy resolution and relatively fast response times. The excellent energy resolution provides good discrimination of signal from backgrounds, and the fast response time is important for minimizing the irreducible background caused by random coincidence of two-neutrino double-beta decay events of mohundred nuclei. Comparisons of the scintillating-light and phonon yields and pulse shape discrimination of the phonon signals will be used to provide redundant rejection of alpha-ray-induced backgrounds. An effective Majorana neutrino mass sensitivity that reaches the expected range of the inverted neutrino mass hierarchy, i.e., 20-50 meV, could be achieved with a 200~kg array of $mathrm{^{48depl}Ca^{100}MoO_4}$ crystals operating for three years.
The third generation of the Beijing Electron Spectrometer, BESIII, is an apparatus for high energy physics research. The hunting of new particles and the measurement of their properties or the research of rare processes are sought to understand if the measurements confirm the Standard Model and to look for physics beyond it. The detectors ensure the reconstruction of events belonging to the sub-atomic domain. The operation and the efficiency of the BESIII inner tracker is compromised due to the the radiation level of the apparatus. A new detector is needed to guarantee better performance and to improve the physics research. A cylindrical triple-GEM detector (CGEM) is an answer to this need: it will maintain the excellent performance of the inner tracker while improving the spatial resolution in the beam direction allowing a better reconstruction of secondary vertices. The technological challenge of the CGEM is related in its spatial limitation and the needed cylindrical shape. At the same time the detector has to ensure an efficiency close to 1 and a stable spatial resolution better than 150 $mu$m, independently from the track incident angle and the presence of 1 T magnetic field. In the years 2014-2018 the CGEM-IT has been designed and built. Through several test beam and simulations the optimal configuration from the geometrical and electrical points of view has been found. This allows to measure the position of the charged particle interacting with the CGEM-IT. Two algorithms have been used for this purpose, the charge centroid and the $mu$TPC, a new technique introduced by ATLAS in MicroMegas and developed here for the first time for triple-GEM detector. A complete triple-GEM simulation software has been developed to improve the knowledge of the detection processes. The software reproduces the CGEM-IT behavior in the BESIII offline software.
The GERDA collaboration is performing a search for neutrinoless double beta decay of ^{76}Ge with the eponymous detector. The experiment has been installed and commissioned at the Laboratori Nazionali del Gran Sasso and has started operation in November 2011. The design, construction and first operational results are described, along with detailed information from the R&D phase.