A large-scale Scintillating Fibre Tracker has been developed and constructed for the current LHCb Upgrade 1. The high radiation by fast neutrons reduces the light yield of the detector in the course ...of LHC Run 3, and is challenging the tracker’s hit detection efficiency. To mitigate radiation-induced ageing effects, the central fibre mats and photodetectors will be replaced during the next long shutdown (2026–2028). For this purpose, microlens-enhanced silicon photomultipliers with an improved photon detection efficiency are being developed. The first prototypes have been produced based on the outcome of dedicated simulation studies, and the results of the first light yield measurements are presented.
We have measured the 3d→2p transition x rays of kaonic ^{3}He and ^{4}He atoms using superconducting transition-edge-sensor microcalorimeters with an energy resolution better than 6 eV (FWHM). We ...determined the energies to be 6224.5±0.4(stat)±0.2(syst) eV and 6463.7±0.3(stat)±0.1(syst) eV, and widths to be 2.5±1.0(stat)±0.4(syst) eV and 1.0±0.6(stat)±0.3(stat) eV, for kaonic ^{3}He and ^{4}He, respectively. These values are nearly 10 times more precise than in previous measurements. Our results exclude the large strong-interaction shifts and widths that are suggested by a coupled-channel approach and agree with calculations based on optical-potential models.
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
)
×
10
4
fb/cm
2
.
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
)
×
10
4
fb/cm
2
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
)
×
10
4
fb/cm
2
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.
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¯μ
The kaonic deuterium measurement at J-PARC and DAΦNE will provide a piece of information still missing to the antikaon-nucleon interaction close to threshold, providing valuable information to answer ...one of the most fundamental problems in hadron physics today - to the yet unsolved puzzle of how the hadron mass is generated. For this a new X-ray detector system has been developed to measure the shift and width of the 2p → 1s transition of kaonic deuterium with a precision of 60 eV and 140 eV, respectively.
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 sqrts=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.
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