2,343 research outputs found
New constraint on neutrino magnetic moment and neutrino millicharge from LUX-ZEPLIN dark matter search results
Elastic neutrino-electron scattering represents a powerful tool to investigate key neutrino properties. In view of the recent results released by the LUX-ZEPLIN collaboration, we provide a first determination of the limits achievable on the neutrino magnetic moment and neutrino millicharge, whose effect becomes non-negligible in some beyond the Standard Model theories. In this context, we evaluate and discuss the impact of different approximations to describe the neutrino interaction with atomic electrons. The new LUX-ZEPLIN data allows us to set a very competitive limit on the neutrino magnetic moment when compared to the other laboratory bounds, namely mu effv < 1.1 x 10-11 mu B at 90% C.L., which improves by a factor of 2.5 the Borexino collaboration limit and represents the second best world limit after the recent XENONnT result. Moreover, exploiting the so-called equivalent photon approximation, we obtain the most stringent limit on the neutrino millicharge, namely Iqeffv I < 1.5 x 10-13e0 at 90% C.L., which represents a great improvement with respect to the previous laboratory bounds
Measurement of the time resolution of the installed muon chambers with the 2008 cosmic runs
One of the main goals of the LHCb muon system commissioning is to access the detector performance and identify possible misbehaviors in the installed chambers: this is partially possible using cosmic ray muons tracked through the detector. In this note we focus on the measurement of the time resolution of the whole installed detector (M2-M5 stations) using the 2008 commissioning data. Results are compared with the expected performances
Proposal to Search for Heavy Neutral Leptons at the SPS
A new fixed-target experiment at the CERN SPS accelerator is proposed that
will use decays of charm mesons to search for Heavy Neutral Leptons (HNLs),
which are right-handed partners of the Standard Model neutrinos. The existence
of such particles is strongly motivated by theory, as they can simultaneously
explain the baryon asymmetry of the Universe, account for the pattern of
neutrino masses and oscillations and provide a Dark Matter candidate.
Cosmological constraints on the properties of HNLs now indicate that the
majority of the interesting parameter space for such particles was beyond the
reach of the previous searches at the PS191, BEBC, CHARM, CCFR and NuTeV
experiments. For HNLs with mass below 2 GeV, the proposed experiment will
improve on the sensitivity of previous searches by four orders of magnitude and
will cover a major fraction of the parameter space favoured by theoretical
models.
The experiment requires a 400 GeV proton beam from the SPS with a total of
2x10^20 protons on target, achievable within five years of data taking. The
proposed detector will reconstruct exclusive HNL decays and measure the HNL
mass. The apparatus is based on existing technologies and consists of a target,
a hadron absorber, a muon shield, a decay volume and two magnetic
spectrometers, each of which has a 0.5 Tm magnet, a calorimeter and a muon
detector. The detector has a total length of about 100 m with a 5 m diameter.
The complete experimental set-up could be accommodated in CERN's North Area.
The discovery of a HNL would have a great impact on our understanding of
nature and open a new area for future research
Aging measurements on triple-GEM detectors operated with CF4-based gas mixtures
We present the results of a global irradiation test of full size triple-GEM detectors operated with CF 4 -based gas mixtures. This study has been performed in the framework of an R&D activity on detectors for the innermost region of the first muon station of the LHCb experiment. The prototypes have been irradiated at the Calliope facility of the ENEA-Casaccia with a high intensity 1.25 MeV Îł 60 Co source. After the irradiation test the detectors performances have been measured with X-rays and with a 3 GeV pion beam at CERN. A SEM analysis on several samples of the detectors has been performed to complete the understanding of the physical processes occurring in a GEM detector during a strong irradiation
Production and performance of LHCb triple-GEM detectors equipped with the dedicated CARDIAC-GEM front-end electronics
The production of the triple-GEM detectors for the innermost region of the first muon station of the LHCb experiment has started in February 2006, and is foreseen to be completed by the end of July. The final design of the detector and the construction procedure and tools, as well as the quality controls are defined. The performances of each detector, composed by two triple-GEM chambers equipped with dedicated CARDIAC-GEM front-end electronics, are studied with a cosmic ray telescope. The cosmic ray telescope has been set up including all the final off-detector components
Performance of the Muon Identification at LHCb
The performance of the muon identification in LHCb is extracted from data
using muons and hadrons produced in J/\psi->\mu\mu, \Lambda->p\pi and
D^{\star}->\pi D0(K\pi) decays. The muon identification procedure is based on
the pattern of hits in the muon chambers. A momentum dependent binary
requirement is used to reduce the probability of hadrons to be misidentified as
muons to the level of 1%, keeping the muon efficiency in the range of 95-98%.
As further refinement, a likelihood is built for the muon and non-muon
hypotheses. Adding a requirement on this likelihood that provides a total muon
efficiency at the level of 93%, the hadron misidentification rates are below
0.6%.Comment: 17 pages, 10 figure
Measurement of the front-end dead-time of the LHCb muon detector and evaluation of its contribution to the muon detection inefficiency
A method is described which allows to deduce the dead-time of the front-end
electronics of the LHCb muon detector from a series of measurements performed
at different luminosities at a bunch-crossing rate of 20 MHz. The measured
values of the dead-time range from 70 ns to 100 ns. These results allow to
estimate the performance of the muon detector at the future bunch-crossing rate
of 40 MHz and at higher luminosity
Performance of the LHCb muon system with cosmic rays
The LHCb Muon system performance is presented using cosmic ray events
collected in 2009. These events allowed to test and optimize the detector
configuration before the LHC start. The space and time alignment and the
measurement of chamber efficiency, time resolution and cluster size are
described in detail. The results are in agreement with the expected detector
performance.Comment: Submitted to JINST and accepte
Performance of the LHCb muon system
The performance of the LHCb Muon system and its stability across the full
2010 data taking with LHC running at ps = 7 TeV energy is studied. The
optimization of the detector setting and the time calibration performed with
the first collisions delivered by LHC is described. Particle rates, measured
for the wide range of luminosities and beam operation conditions experienced
during the run, are compared with the values expected from simulation. The
space and time alignment of the detectors, chamber efficiency, time resolution
and cluster size are evaluated. The detector performance is found to be as
expected from specifications or better. Notably the overall efficiency is well
above the design requirementsComment: JINST_015P_1112 201
A facility to Search for Hidden Particles (SHiP) at the CERN SPS
A new general purpose fixed target facility is proposed at the CERN SPS
accelerator which is aimed at exploring the domain of hidden particles and make
measurements with tau neutrinos. Hidden particles are predicted by a large
number of models beyond the Standard Model. The high intensity of the SPS
400~GeV beam allows probing a wide variety of models containing light
long-lived exotic particles with masses below (10)~GeV/c,
including very weakly interacting low-energy SUSY states. The experimental
programme of the proposed facility is capable of being extended in the future,
e.g. to include direct searches for Dark Matter and Lepton Flavour Violation.Comment: Technical Proposa
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