75 research outputs found
FASER: ForwArd Search ExpeRiment at the LHC
FASER, the ForwArd Search ExpeRiment, is a proposed 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 in large numbers
in the far-forward region and then 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 describe the FASER program. In its first stage, FASER is an extremely
compact and inexpensive detector, sensitive to decays in a cylindrical region
of radius R = 10 cm and length L = 1.5 m. FASER is planned to be constructed
and installed in Long Shutdown 2 and will collect data during Run 3 of the 14
TeV LHC from 2021-23. If FASER is successful, FASER 2, a much larger successor
with roughly R ~ 1 m and L ~ 5 m, could be constructed in Long Shutdown 3 and
collect data during the HL-LHC era from 2026-35. FASER and FASER 2 have the
potential to discover dark photons, dark Higgs bosons, heavy neutral leptons,
axion-like particles, and many other long-lived particles, as well as provide
new information about neutrinos, with potentially far-ranging implications for
particle physics and cosmology. We describe the current status, anticipated
challenges, and discovery prospects of the FASER program.Comment: 13 pages, 4 figures, submitted as Input to the European Particle
Physics Strategy Update 2018-2020 and draws on FASER's Letter of Intent,
Technical Proposal, and physics case documents (arXiv:1811.10243,
arXiv:1812.09139, and arXiv:1811.12522
Characterization of the demonstrator of the fast silicon monolithic ASIC for the TT-PET project
The TT-PET collaboration is developing a small animal TOF-PET scanner based
on monolithic silicon pixel sensors in SiGe BiCMOS technology. The demonstrator
chip, a small-scale version of the final detector ASIC, consists of a 3 x 10
pixel matrix integrated with the front-end, a 50 ps binning TDC and read out
logic. The chip, thinned down to 100 {\mu}m and backside metallized, was
operated at a voltage of 180 V. The tests on a beam line of minimum ionizing
particles show a detection efficiency greater than 99.9 % and a time resolution
down to 110 ps
Technical Proposal for FASER: ForwArd Search ExpeRiment at the LHC
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 LHC's 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.Comment: 82 pages, 62 figures; submitted to the CERN LHCC on 7 November 201
FASER's Physics Reach for Long-Lived Particles
FASER,the ForwArd Search ExpeRiment,is a proposed 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 (HNLs); light B-L
and gauge bosons; axion-like particles (ALPs) that are coupled
dominantly to photons, fermions, and gluons through non-renormalizable
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
Nox2-deficient Tregs improve heart transplant outcomes via their increased graft recruitment and enhanced potency.
Nox2 is a ROS-generating enzyme, deficiency of which increases suppression by Tregs in vitro and in an in vivo model of cardiac remodelling. Since Tregs have emerged as a candidate therapy in autoimmunity and transplantation, we hypothesised that Nox2 deficiency in Tregs in recipient mice may improve outcomes in a heart transplant model. A novel B6129 mouse model with Treg-targeted Nox2 deletion (Nox2fl/flFoxP3Cre+) was generated and transplanted with hearts from CB6F1 donors. As compared to littermate controls, Nox2fl/flFoxP3Cre+ mice had lower plasma levels of alloantibodies and troponin-I, reduced levels of IFN-Îł in heart allograft homogenates and diminished cardiomyocyte necrosis and allograft fibrosis. Single cell analyses of allografts revealed higher absolute numbers of Tregs and lower CD8+ T cell infiltration in Nox2-deficient recipients compared to Nox2-replete mice. Mechanistically, in addition to a greater suppression of CD8+CD25- T effector cell proliferation and IFN-Îł production, Nox2-deficient Tregs expressed higher levels of CCR4 and CCR8, driving cell migration to allografts; this was associated with increased expression of miR214-3p. These data indicate that Nox2 deletion in Tregs enhances their suppressive ability and migration to heart allografts. Therefore, Nox2 inhibition in Tregs may be a useful approach to improve their therapeutic efficacy
First Direct Observation of Collider Neutrinos with FASER at the LHC
We report the first direct observation of neutrino interactions at a particle
collider experiment. Neutrino candidate events are identified in a 13.6 TeV
center-of-mass energy collision data set of 35.4 fb using the
active electronic components of the FASER detector at the Large Hadron
Collider. The candidates are required to have a track propagating through the
entire length of the FASER detector and be consistent with a muon neutrino
charged-current interaction. We infer neutrino interactions
with a significance of 16 standard deviations above the background-only
hypothesis. These events are consistent with the characteristics expected from
neutrino interactions in terms of secondary particle production and spatial
distribution, and they imply the observation of both neutrinos and
anti-neutrinos with an incident neutrino energy of significantly above 200 GeV.Comment: Submitted to PRL on March 24 202
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