The ForwArd Search ExpeRiment (FASER) is an approved experiment dedicated to searching for light, extremely weakly interacting particles at the LHC. Such particles may be produced in the LHC's ...high-energy collisions and travel long distances through concrete and rock without interacting. They may then decay to visible particles in FASER, which is placed 480 m downstream of the ATLAS interaction point. In this work we briefly describe the FASER detector layout and the status of potential backgrounds. We then present the sensitivity reach for FASER for a large number of long-lived particle models, updating previous results to a uniform set of detector assumptions, and analyzing new models. In particular, we consider all of the renormalizable portal interactions, leading to dark photons, dark Higgs bosons, and heavy neutral leptons; light B−L and Li−Lj gauge bosons; axionlike particles that are coupled dominantly to photons, fermions, and gluons through nonrenormalizable operators; and pseudoscalars with Yukawa-like couplings. We find that FASER and its follow-up, FASER 2, have a full physics program, with discovery sensitivity in all of these models and potentially far-reaching implications for particle physics and cosmology.
A
bstract
In the DsTau experiment at the CERN SPS (NA65), an independent and direct way to measure tau neutrino production following high energy proton interactions was proposed. As the main source ...of tau neutrinos is a decay of
D
s
mesons, produced in proton-nucleus interactions, the project aims at measuring a differential cross section of this reaction. The experimental method is based on a use of high resolution emulsion detectors for effective registration of events with short lived particle decays. Here we present the motivation of the study, details of the experimental technique, and the first results of the analysis of the data collected during test runs, which prove feasibility of the full scale study of the process in future.
The use of muon tomography in geoscience projects has been continuously increasing over the past few years. This led to a variety of applications that often use custom-tailored solutions for data ...acquisition and processing. The respective know-how is splintered and mainly available in a semi-published state in various physics departments that developed these methods. This complicates the design of new studies and the decision whether muon tomography is a suitable tool and feasible for a specific geoscientific question. In this study we review the current state of how muon tomography has been applied in the field of geosciences with the goal of equipping interested geoscientists with the basic knowledge on the physical basics that constitute muon tomography. After an explanation of how muons are produced, how they traverse matter and how they are recorded, a showcase is made of recent applications. These studies show the variety of how muon tomography can be applied in experiments, such that interested readers may implement this technology for their own research. Finally, we provide a guide to best practice to help interested geoscientists decide if and how muon tomography could be implemented in their own research. We believe that through a better mutual understanding, new interdisciplinary collaborations can be initiated that advance the whole field of muon tomography.
The FASER experiment at the Large Hadron Collider (LHC), on top of the search for light weakly-interacting new particles, proposed a new detector (FASERν) to study neutrinos at the highest man-made ...energies and got approval by CERN in December 2019. With FASERν, the three-flavor neutrino cross-sections will be measured in the currently unexplored energy range between 350 GeV and 5 TeV. During Run 3 of the LHC starting from 2022, we will deploy an emulsion detector with a target mass of 1.1 tons, coupled with the FASER magnetic spectrometer. This would yield roughly 1,300 electron neutrinos, 8,000 muon neutrinos, and 30 tau neutrinos interacting in the detector. Here we present the status and plan of FASERν, as well as the neutrino detection in the 2018 data.
T cells are actively scanning pMHC-presenting cells in lymphoid organs and nonlymphoid tissues (NLTs) with divergent topologies and confinement. How the T cell actomyosin cytoskeleton facilitates ...this task in distinct environments is incompletely understood. Here, we show that lack of Myosin IXb (Myo9b), a negative regulator of the small GTPase Rho, led to increased Rho-GTP levels and cell surface stiffness in primary T cells. Nonetheless, intravital imaging revealed robust motility of Myo9b
CD8
T cells in lymphoid tissue and similar expansion and differentiation during immune responses. In contrast, accumulation of Myo9b
CD8
T cells in NLTs was strongly impaired. Specifically, Myo9b was required for T cell crossing of basement membranes, such as those which are present between dermis and epidermis. As consequence, Myo9b
CD8
T cells showed impaired control of skin infections. In sum, we show that Myo9b is critical for the CD8
T cell adaptation from lymphoid to NLT surveillance and the establishment of protective tissue-resident T cell populations.
In recent years, the use of radiographic inspection with cosmic-ray muons has spread into multiple research and industrial fields. This technique is based on the high-penetration power of cosmogenic ...muons. Specifically, it allows the resolution of internal density structures of large-scale geological objects through precise measurements of the muon absorption rate. So far, in many previous works, this muon absorption rate has been considered to depend solely on the density of traversed material (under the assumption of a standard rock) but the variation in chemical composition has not been taken seriously into account. However, from our experience with muon tomography in Alpine environments, we find that this assumption causes a substantial bias in the muon flux calculation, particularly where the target consists of high {Z2∕A} rocks (like basalts and limestones) and where the material thickness exceeds 300 m. In this paper, we derive an energy loss equation for different minerals and we additionally derive a related equation for mineral assemblages that can be used for any rock type on which mineralogical data are available. Thus, for muon tomography experiments in which high {Z2∕A} rock thicknesses can be expected, it is advisable to plan an accompanying geological field campaign to determine a realistic rock model.
Intravital multiphoton microscopy has become one of the central tools used in the investigation of dynamic cellular activity and function in living animals under nearly physiological conditions and ...is particularly important for studying the dynamic immune system. During intravital imaging in mice, periodic motion of tissue caused by respiration, induces significant shifts of the imaged region. In slow laser scanning imaging modalities, such as multiphoton microscopy, this movement can lead to considerable distortion and discontinuity in three dimensions of the acquired images. Here, we introduce VivoFollow 2, a toolkit that concurrent with image acquisition performs a precise measurement of the respective image distortion, enabling subsequent automated correction of the imaging data. Recovery of one three-dimensional image stack, corresponding to the tomographic tissue sectioning by the optical plane from each single raw image stack, preserves the time continuity within each image stack. Implementation of VivoFollow 2 thus enables a minimization of motion artifacts in tissues exposed to periodic movements and allows for long-term time-lapse imaging and subsequent precise image analysis of the dynamics of cellular and humoral factors in vivo.
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