498 research outputs found
Directional Sensitivity of the NEWSdm Experiment to Cosmic Ray Boosted Dark Matter
We present a study of a directional search for Dark Matter boosted forward
when scattered by cosmic-ray nuclei, using a module of the NEWSdm experiment.
The boosted Dark Matter flux at the edge of the Earth's atmosphere is expected
to be pointing to the Galactic Center, with a flux 15 to 20 times larger than
in the transverse direction.
The module of the NEWSdm experiment consists of a 10 kg stack of Nano Imaging
Trackers, i.e.~newly developed nuclear emulsions with AgBr crystal sizes down
to a few tens of nanometers. The module is installed on an equatorial
telescope. The relatively long recoil tracks induced by boosted Dark Matter,
combined with the nanometric granularity of the emulsion, result in an
extremely low background. This makes an installation at the INFN Gran Sasso
laboratory, both on the surface and underground, viable. A comparison between
the two locations is made. The angular distribution of nuclear recoils induced
by boosted Dark Matter in the emulsion films at the surface laboratory is
expected to show an excess with a factor of 3.5 in the direction of the
Galactic Center. This excess allows for a Dark Matter search with directional
sensitivity. The surface laboratory configuration prevents the deterioration of
the signal in the rock overburden and it emerges as the most powerful approach
for a directional observation of boosted Dark Matter with high sensitivity. We
show that, with this approach, a 10 kg module of the NEWSdm experiment exposed
for one year at the Gran Sasso surface laboratory can probe Dark Matter masses
between 1 keV/c and 1 GeV/c and cross-section values down to
~cm with a directional sensitive search.Comment: 15 pages, 14 figures, updated references, clarified discussion in
intro section. Submitted to JCA
Observation of Collider Muon Neutrinos with the SND@LHC Experiment
We report the direct observation of muon neutrino interactions with the SND@LHC detector at the Large Hadron Collider. A dataset of proton-proton collisions at
√
s
=
13.6
TeV
collected by SND@LHC in 2022 is used, corresponding to an integrated luminosity of
36.8
fb
−
1
. The search is based on information from the active electronic components of the SND@LHC detector, which covers the pseudorapidity region of
7.2
<
η
<
8.4
, inaccessible to the other experiments at the collider. Muon neutrino candidates are identified through their charged-current interaction topology, with a track propagating through the entire length of the muon detector. After selection cuts, 8
ν
μ
interaction candidate events remain with an estimated background of 0.086 events, yielding a significance of about 7 standard deviations for the observed
ν
μ signal
Observation of Collider Muon Neutrinos with the SND@LHC Experiment
We report the direct observation of muon neutrino interactions with the SND@LHC detector at the Large Hadron Collider. A dataset of proton-proton collisions at s=13.6 TeV collected by SND@LHC in 2022 is used, corresponding to an integrated luminosity of 36.8 fb-1. The search is based on information from the active electronic components of the SND@LHC detector, which covers the pseudorapidity region of 7.2<8.4, inaccessible to the other experiments at the collider. Muon neutrino candidates are identified through their charged-current interaction topology, with a track propagating through the entire length of the muon detector. After selection cuts, 8 νμ interaction candidate events remain with an estimated background of 0.086 events, yielding a significance of about 7 standard deviations for the observed νμ signal
Measurement of the muon flux at the SND@LHC experiment
The Scattering and Neutrino Detector at the LHC (SND@LHC) started taking data at the beginning of Run 3 of the LHC. The experiment is designed to perform measurements with neutrinos produced in proton-proton collisions at the LHC in an energy range between 100 GeV and 1 TeV. It covers a previously unexplored pseudo-rapidity range of 7.2 < η< 8.4 . The detector is located 480 m downstream of the ATLAS interaction point in the TI18 tunnel. It comprises a veto system, a target consisting of tungsten plates interleaved with nuclear emulsion and scintillating fiber (SciFi) trackers, followed by a muon detector (UpStream, US and DownStream, DS). In this article we report the measurement of the muon flux in three subdetectors: the emulsion, the SciFi trackers and the DownStream Muon detector. The muon flux per integrated luminosity through an 18 × 18 cm 2 area in the emulsion is: 1.5±0.1(stat)×104fb/cm2. The muon flux per integrated luminosity through a 31 × 31 cm 2 area in the centre of the SciFi is: 2.06±0.01(stat)±0.12(sys)×104fb/cm2 The muon flux per integrated luminosity through a 52 × 52 cm 2 area in the centre of the downstream muon system is: 2.35±0.01(stat)±0.10(sys)×104fb/cm2 The total relative uncertainty of the measurements by the electronic detectors is 6 % for the SciFi and 4 % for the DS measurement. The Monte Carlo simulation prediction of these fluxes is 20–25 % lower than the measured values
Results and Perspectives from the First Two Years of Neutrino Physics at the LHC by the SND@LHC Experiment
After rapid approval and installation, the SND@LHC Collaboration was able to gather data successfully in 2022 and 2023. Neutrino interactions from νμs originating at the LHC IP1 were observed. Since muons constitute the major background for neutrino interactions, the muon flux entering the acceptance was also measured. To improve the rejection power of the detector and to increase the fiducial volume, a third Veto plane was recently installed. The energy resolution of the calorimeter system was measured in a test beam. This will help with the identification of νe interactions that can be used to probe charm production in the pseudo-rapidity range of SND@LHC (7.2 < η < 8.4). Events with three outgoing muons have been observed and are being studied. With no vertex in the target, these events are very likely from muon trident production in the rock before the detector. Events with a vertex in the detector could be from trident production, photon conversion, or positron annihilation. To enhance SND@LHC’s physics case, an upgrade is planned for HL-LHC that will increase the statistics and reduce the systematics. The installation of a magnet will allow the separation of νμ from ν¯μWe acknowledge the support for the construction and operation of the SND@LHC detector provided by the following funding agencies: CERN; the Bulgarian Ministry of Education and Science within the National Roadmap for Research Infrastructures 2020–2027 (object CERN); ANID—Millennium Program—ICN2019_044 (Chile); the Deutsche Forschungsgemeinschaft (DFG, ID 496466340); the Italian National Institute for Nuclear Physics (INFN); JSPS, MEXT, the Global COE program of Nagoya University, the Promotion and Mutual Aid Corporation for Private Schools of Japan for Japan; the National Research Foundation of Korea with grant numbers 2021R1A2C2011003, 2020R1A2C1099546, 2021R1F1A1061717, and 2022R1A2C100505; Fundação para a Ciência e a Tecnologia, FCT (Portugal), CERN/FIS-INS/0028/2021; the Swiss National Science Foundation (SNSF); TENMAK for Turkey (Grant No. 2022TENMAK(CERN) A5.H3.F2-1). M. Climesu, H. Lacker and R. Wanke are funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation), Project 496466340. We acknowledge the funding of individuals by Fundação para a Ciência e a Tecnologia, FCT (Portugal) with grant numbers CEECIND/01334/2018, CEECINST/00032/2021 and PRT/BD/153351/2021.CERNBulgarian Ministry of Education and ScienceANID—Millennium ProgramDeutsche ForschungsgemeinschaftItalian National Institute for Nuclear Physics (INFN)JSPS, MEXT, the Global COE program of Nagoya University, the Promotion and Mutual Aid Corporation for Private Schools of Japan for JapanNational Research Foundation of KoreaFundação para a Ciência e a Tecnologia, FCT (Portugal)Swiss National Science Foundation (SNSF)TENMAK for TurkeyPeer Reviewe
SND@LHC: The Scattering and Neutrino Detector at the LHC
SND@LHC is a compact and stand-alone experiment designed to perform measurements with neutrinos produced at the LHC in the pseudo-rapidity region of . The experiment is located 480 m downstream of the ATLAS interaction point, in the TI18 tunnel. The detector is composed of a hybrid system based on an 830 kg target made of tungsten plates, interleaved with emulsion and electronic trackers, also acting as an electromagnetic calorimeter, and followed by a hadronic calorimeter and a muon identification system. The detector is able to distinguish interactions of all three neutrino flavours, which allows probing the physics of heavy flavour production at the LHC in the very forward region. This region is of particular interest for future circular colliders and for very high energy astrophysical neutrino experiments. The detector is also able to search for the scattering of Feebly Interacting Particles. In its first phase, the detector will operate throughout LHC Run 3 and collect a total of 250
Studies of and production in and Pb collisions
The production of and mesons is studied in proton-proton and
proton-lead collisions collected with the LHCb detector. Proton-proton
collisions are studied at center-of-mass energies of and ,
and proton-lead collisions are studied at a center-of-mass energy per nucleon
of . The studies are performed in center-of-mass rapidity
regions (forward rapidity) and
(backward rapidity) defined relative to the proton beam direction. The
and production cross sections are measured differentially as a function
of transverse momentum for and , respectively. The differential cross sections are used to
calculate nuclear modification factors. The nuclear modification factors for
and mesons agree at both forward and backward rapidity, showing
no significant evidence of mass dependence. The differential cross sections of
mesons are also used to calculate cross section ratios,
which show evidence of a deviation from the world average. These studies offer
new constraints on mass-dependent nuclear effects in heavy-ion collisions, as
well as and meson fragmentation.Comment: All figures and tables, along with machine-readable versions and any
supplementary material and additional information, are available at
https://lhcbproject.web.cern.ch/Publications/p/LHCb-PAPER-2023-030.html (LHCb
public pages
Observation of Cabibbo-suppressed two-body hadronic decays and precision mass measurement of the baryon
The first observation of the singly Cabibbo-suppressed
and decays
is reported, using proton-proton collision data at a centre-of-mass energy of
, corresponding to an integrated luminosity of , collected with the LHCb detector between 2016 and 2018. The
branching fraction ratios are measured to be
,
. In addition, using the
decay channel, the baryon
mass is measured to be , improving the
precision of the previous world average by a factor of four.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-011.html (LHCb
public pages
Measurement of boson production cross-section in collisions at TeV
The first measurement of the boson production cross-section at
centre-of-mass energy TeV in the forward region is reported,
using collision data collected by the LHCb experiment in year 2017,
corresponding to an integrated luminosity of . The
production cross-section is measured for final-state muons in the
pseudorapidity range . The integrated cross-section is determined to be for the di-muon invariant
mass in the range . This result and the
differential cross-section results are in good agreement with theoretical
predictions at next-to-next-to-leading order in the strong coupling.
Based on a previous LHCb measurement of the boson production
cross-section in Pb collisions at TeV, the nuclear
modification factor is measured for the first time at this
energy. The measured values are in the forward region () and
in the backward region
(), where represents the muon rapidity in
the centre-of-mass frame.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-010.html (LHCb
public pages
Fraction of decays in prompt production measured in pPb collisions at TeV
The fraction of and decays in the prompt
yield, , is measured by
the LHCb detector in pPb collisions at TeV. The study
covers the forward () and backward () rapidity
regions, where is the rapidity in the nucleon-nucleon
center-of-mass system. Forward and backward rapidity samples correspond to
integrated luminosities of 13.6 0.3 nb and 20.8 0.5
nb, respectively. The result is presented as a function of the
transverse momentum in the range 1 GeV/.
The fraction at forward rapidity is compatible with the LHCb
measurement performed in collisions at TeV, whereas the
result at backward rapidity is 2.4 larger than in the forward region
for GeV/. The increase of at low at backward rapidity is compatible with the suppression of the
(2S) contribution to the prompt yield. The lack of in-medium
dissociation of states observed in this study sets an upper limit of
180 MeV on the free energy available in these pPb collisions to dissociate or
inhibit charmonium state formation.Comment: All figures and tables, along with machine-readable versions and any
supplementary material and additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-028.html (LHCb
public pages
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