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A bstract We describe a proposal to add a set of very forward detectors to the CMS experiment for the high-luminosity era of the Large Hadron Collider to search for beyond the standard model long-lived particles, such as dark photons, heavy neutral leptons, axion-like particles, and dark Higgs bosons. The proposed subsystem is called FACET for F orward- A perture C MS E x T ension, and will be sensitive to any particles that can penetrate at least 50 m of magnetized iron and decay in an 18 m long, 1 m diameter vacuum pipe. The decay products will be measured in detectors using identical technology to the planned CMS Phase-2 upgrade.

A bstract The discovery by the ATLAS and CMS experiments of a new boson with mass around 125 GeV and with measured properties compatible with those of a Standard-Model Higgs boson, coupled with the absence of discoveries of phenomena beyond the Standard Model at the TeV scale, has triggered interest in ideas for future Higgs factories. A new circular e + e − collider hosted in a 80 to 100 km tunnel, TLEP, is among the most attractive solutions proposed so far. It has a clean experimental environment, produces high luminosity for top-quark, Higgs boson, W and Z studies, accommodates multiple detectors, and can reach energies up to the threshold and beyond. It will enable measurements of the Higgs boson properties and of Electroweak Symmetry-Breaking (EWSB) parameters with unequalled precision, offering exploration of physics beyond the Standard Model in the multi-TeV range. Moreover, being the natural precursor of the VHE-LHC, a 100 TeV hadron machine in the same tunnel, it builds up a long-term vision for particle physics. Altogether, the combination of TLEP and the VHE-LHC offers, for a great cost effectiveness, the best precision and the best search reach of all options presently on the market. This paper presents a first appraisal of the salient features of the TLEP physics potential, to serve as a baseline for a more extensive design study.

Particle Flow Algorithms (PFAs) attempt to measure each particle in a hadronic jet individually, using the detector subsystem that provides the best energy/momentum resolution. Calorimeters that can exploit the power of PFAs emphasize spatial granularity over single particle energy resolution. In this context, the CALICE Collaboration developed the Digital Hadron Calorimeter (DHCAL). The DHCAL uses Resistive Plate Chambers (RPCs) as active media and is read out with 1 × 1 cm 2 pads and digital (1-bit) resolution. In order to obtain a unique dataset of electromagnetic and hadronic interactions with unprecedented spatial resolution, the DHCAL went through a broad test beam program. In addition to conventional calorimetry, the DHCAL offers detailed measurements of event shapes, rigorous tests of simulation models and various analytical tools to improve calorimetric performance. Here we report on the results from the analysis of DHCAL data and comparisons with the Monte Carlo simulations.

Secondary electron emission is the primary signal formation and/or amplification technique utilized in accelerator beam monitors and photomultiplier tubes where incident energetic particles cause ejection of additional electrons from a secondary emission surface. The materials employed as surfaces for secondary electron emission have demonstrated exceptional resistance to radiation, making them suitable for serving as the active media in radiation-hard calorimeters. With this motivation, we developed dedicated secondary electron emission sensor modules, tested them with particle beams and developed Monte Carlo simulations to predict the performance of large-scale calorimeters. Here, the details of the sensor modules and the results of the beam tests and simulations will be discussed. Recently, we have applied high secondary emission yield materials, Al 2 O 3 and TiO 2 , as surface coatings on the anode plates of one-glass resistive plate chambers developing the so-called hybrid resistive plate chambers. The beam test results manifestly show the contribution of the secondary emission layer on the overall electron multiplication in the gas gap. The measurements also enable preliminary assessment of the secondary emission principle in thin Al 2 O 3 and TiO 2 layers in a particle shower/avalanche environment and the development of Monte Carlo simulations. Here we describe the details of the direct utilization of the secondary electron emission surfaces and the impact of the findings on future implementations.

Optical scintillating bers lose their transparencies when exposed to radiation. Nearly all studies of radiation damage to optical bers so far only characterize this darkening with a single period of irradiation. Following the irradiation, bers undergo room temperature annealing, and regain some of their transparencies. We tested the irradiation-recovery characteristics of scintillating fibers in four consecutive cycles. In addition, three optical scintillating bers were irradiated at 22 Gy per minute for over 15 hours, and their transmittance were measured each minute by pulsing a light source through the bers. Here, we report on the in-situ characterization of the transmittance vs radiation exposure, allowing future applications to better predict the lifetime of the scintillating bers.

JEM-EUSO is an international program for the development of space-based Ultra-High Energy Cosmic Ray observatories. The program consists of a series of missions which are either under development or in the data analysis phase. All instruments are based on a wide-field-of-view telescope, which operates in the near-UV range, designed to detect the fluorescence light emitted by extensive air showers in the atmosphere. We describe the simulation software ESAF in the framework of the JEM-EUSO program and explain the physical assumptions used. We present here the implementation of the JEM-EUSO, POEMMA, K-EUSO, TUS, Mini-EUSO, EUSO-SPB1 and EUSO-TA configurations in ESAF. For the first time ESAF simulation outputs are compared with experimental data.

PEN and PET (polyethylene naphthalate and teraphthalate) are common plastics used for drink bottles and plastic food containers. They are also good scintillators. Their ubiquity has made them of interest for high energy physics applications, as generally plastic scintillators can be very expensive. However, detailed studies on the performance of the scintillators has not yet been performed. At various tests, we measured the light yield and timing properties of PEN and PET with Fermilab and CERN test beams. We also irradiated several samples to varying gamma doses and investigated their recovery mechanisms. Here we report on the measurements performed over the past few years in order to characterize the scintillation properties of PEN and PET and discuss possible future implementations.

A novel design of Resistive Plate Chambers (RPCs), using only a single resistive plate, was developed and tested. Based on this design, prototype chambers of size ranging from 10 cm × 10 cm to 32 cm × 48 cm were constructed and tested with cosmic rays and particle beams. The tests confirmed the viability of this new approach for calorimetric applications where the particle rates do not exceed 1 kHz/cm 2 , such as CALICE digital calorimeters. The chambers also have improved single-particle response, such as a pad multiplicity close to unity. In addition to this development, we probed a new technique to mitigate limitations associated with common RPC gases compatible with the environment. The technique is based on electron multiplication in a thin layer of high secondary electron yield material coating on the anode plane. Here we report on the construction of various different glass RPC designs, and their performance measurements in laboratory tests and with particle beams.

Future collider experiments and the upgrade of the existing large-scale experiments impose unprece-dented radiation conditions for the calorimeter systems, particularly in the forward region. The calorimeters envisaged for these operating conditions must be sufficiently radiation-hard and robust in order to perform as expected for the entire lifetime of the experiments. In this context, a novel calorimeter design utilizing quartz-Cherenkov calorimetry, termed Q-Wall has been developed. The Q-Wall concept is a sampling calorimeter that alternates between plates of absorber (Fe, Pb, W, etc.) and active planes. The active planes comprise compact arrays of PMTs with either very thick quartz windows or fused silica pads optically coupled to traditional PMT windows. In these active elements, charged particles with β > 0.685 produce Cherenkov radiation which im-pinges directly onto the photocathode of the PMT. The Q-Wall concept holds the promise of a very fast and highly granular tracking calorimeter suitable for high radiation environments. A prototype module of Q-Wall was constructed and tested at CERN test beam. The prototype consisted of three photodetector setups: multianode PMTs directly coupled to ultraviolet-transmitting (UVT) plexiglass in a 2 x 2 and 3 x 3 configuration, an 8 x 8 array of SiPMs coupled to a 5 x 5 array of borosilicate glass cubes, and a 3 x 3 array of SiPMs connected to a 3 x 3 array of borosilicate glass cubes. Here we report on the results of these tests and compare them with electromagnetic shower development simulations with Geant4.

Microstructural changes in porous cordierite caused by machining were characterized using microtensile testing, X-ray computed tomography, and scanning electron microscopy. Young’s moduli and Poisson’s ratios were determined on ~215- to 380-μm-thick machined samples by combining digital image correlation and microtensile loading. The results provide evidence for an increase in microcrack density and decrease of Young’s modulus due to machining of the thin samples extracted from diesel particulate filter honeycombs. This result is in contrast to the known effect of machining on the strength distribution of bulk, monolithic ceramics.