18 research outputs found
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
First neutrino interaction candidates at the LHC
FASER at the CERN Large Hadron Collider (LHC) is designed to directly
detect collider neutrinos for the first time and study their cross sections at
TeV energies, where no such measurements currently exist. In 2018, a pilot
detector employing emulsion films was installed in the far-forward region of
ATLAS, 480 m from the interaction point, and collected 12.2 fb of
proton-proton collision data at a center-of-mass energy of 13 TeV. We describe
the analysis of this pilot run data and the observation of the first neutrino
interaction candidates at the LHC. This milestone paves the way for high-energy
neutrino measurements at current and future colliders.Comment: Auxiliary materials are available at
https://faser.web.cern.ch/fasernu-first-neutrino-interaction-candidate
The FASER Detector
FASER, the ForwArd Search ExpeRiment, is an experiment dedicated to searching
for light, extremely weakly-interacting particles at CERN's Large Hadron
Collider (LHC). Such particles may be produced in the very forward direction of
the LHC's high-energy collisions and then decay to visible particles inside the
FASER detector, which is placed 480 m downstream of the ATLAS interaction
point, aligned with the beam collisions axis. FASER also includes a
sub-detector, FASER, designed to detect neutrinos produced in the LHC
collisions and to study their properties. In this paper, each component of the
FASER detector is described in detail, as well as the installation of the
experiment system and its commissioning using cosmic-rays collected in
September 2021 and during the LHC pilot beam test carried out in October 2021.
FASER will start taking LHC collision data in 2022, and will run throughout LHC
Run 3
Machine Detector Interface for FASER
The ForwArd Search ExpeRiment (FASER) is a planned small-scale experiment designed for the search of light and weakly-interacting particles at the Large Hadron Collider (LHC). The FASER detector will be located along the beam collision axis, m downstream from the ATLAS interaction point (IP), in an unused service tunnel. A full Geant4 model of the LHC accelerator as well as the surrounding tunnel complex has been developed to simulate the propagation of the products of the proton-proton collisions from the ATLAS IP to the FASER detector. The simulation also handles radiation from LHC beam induced background sources. The simulated fluences of Standard Model particles, which constitute the main signal and background of the experiment are presented
Studying neutrinos at the LHC: FASER and its impact to the cosmic-ray physics
Studies of high energy proton interactions have been basic inputs to understand the cosmic-ray spectra observed on the earth. Yet, the experimental knowledge with controlled beams has been limited. In fact, uncertainties of the forward hadron production are very large due to the lack of experimental data. The FASER experiment is proposed to measure particles, such as neutrinos and hypothetical dark-sector particles, at the forward location of the 14 TeV proton-proton collisions at the LHC. As it corresponds to 100-PeV proton interactions in fixed target mode, a precise measurement by FASER would provide information relevant for PeV-scale cosmic rays. By studying three flavor neutrinos with the dedicated neutrino detector (FASER), FASER will lead to a quantitative understanding of prompt neutrinos, which is an important background towards the astrophysical neutrino observation by neutrino telescopes such as IceCube. In particular, the electron and tau neutrinos have strong links with charmed hadron production. And, the FASER measurements may also shed light on the unresolved muon puzzle at the high energy. FASER is going to start taking data in 2022. We expect about 8000 numu, 1300 nue and 20 nutau CC interactions at the TeV energy scale during Run 3 of the LHC operation (2022-2024) with a 1.1 tons emulsion-based neutrino detector. We report here the overview and prospect of the FASER experiment in relation to the cosmic-ray physics, together with the first LHC neutrino candidates that we caught in the pilot run held in 2018
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The tracking detector of the FASER experiment
FASER is a new experiment designed to search for new light weakly-interacting
long-lived particles (LLPs) and study high-energy neutrino interactions in the
very forward region of the LHC collisions at CERN. The experimental apparatus
is situated 480 m downstream of the ATLAS interaction-point aligned with the
beam collision axis. The FASER detector includes four identical tracker
stations constructed from silicon microstrip detectors. Three of the tracker
stations form a tracking spectrometer, and enable FASER to detect the decay
products of LLPs decaying inside the apparatus, whereas the fourth station is
used for the neutrino analysis. The spectrometer has been installed in the LHC
complex since March 2021, while the fourth station is not yet installed. FASER
will start physics data taking when the LHC resumes operation in early 2022.
This paper describes the design, construction and testing of the tracking
spectrometer, including the associated components such as the mechanics,
readout electronics, power supplies and cooling system
The trigger and data acquisition system of the FASER experiment
The FASER experiment is a new small and inexpensive experiment that is placed 480 meters downstream of the ATLAS experiment at the CERN LHC. FASER is designed to capture decays of new long-lived particles, produced outside of the ATLAS detector acceptance. These rare particles can decay in the FASER detector together with about 500–1000 Hz of other particles originating from the ATLAS interaction point. A very high efficiency trigger and data acquisition system is required to ensure that the physics events of interest will be recorded. This paper describes the trigger and data acquisition system of the FASER experiment and presents performance results of the system acquired during initial commissioning
The tracking detector of the FASER experiment
FASER is a new experiment designed to search for new light weakly-interacting long-lived particles (LLPs) and study high-energy neutrino interactions in the very forward region of the LHC collisions at CERN. The experimental apparatus is situated 480 m downstream of the ATLAS interaction-point aligned with the beam collision axis. The FASER detector includes four identical tracker stations constructed from silicon microstrip detectors. Three of the tracker stations form a tracking spectrometer, and enable FASER to detect the decay products of LLPs decaying inside the apparatus, whereas the fourth station is used for the neutrino analysis. The spectrometer has been installed in the LHC complex since March 2021, while the fourth station is not yet installed. FASER will start physics data taking when the LHC resumes operation in early 2022. This paper describes the design, construction and testing of the tracking spectrometer, including the associated components such as the mechanics, readout electronics, power supplies and cooling system
The trigger and data acquisition system of the FASER experiment
The FASER experiment is a new small and inexpensive experiment that is placed
480 meters downstream of the ATLAS experiment at the CERN LHC. FASER is
designed to capture decays of new long-lived particles, produced outside of the
ATLAS detector acceptance. These rare particles can decay in the FASER detector
together with about 500-1000 Hz of other particles originating from the ATLAS
interaction point. A very high efficiency trigger and data acquisition system
is required to ensure that the physics events of interest will be recorded.
This paper describes the trigger and data acquisition system of the FASER
experiment and presents performance results of the system acquired during
initial commissioning