3,995 research outputs found
Performance of the LHCb RICH detectors during the LHC Run II
The LHCb RICH system provides hadron identification over a wide momentum
range (2-100 GeV/c). This detector system is key to LHCb's precision flavour
physics programme, which has unique sensitivity to physics beyond the standard
model. This paper reports on the performance of the LHCb RICH in Run II,
following significant changes in the detector and operating conditions. The
changes include the refurbishment of significant number of photon detectors,
assembled using new vacuum technologies, and the removal of the aerogel
radiator. The start of Run II of the LHC saw the beam energy increase to 6.5
TeV per beam and a new trigger strategy for LHCb with full online detector
calibration. The RICH information has also been made available for all trigger
streams in the High Level Trigger for the first time.Comment: Updated authors' details and DO
Probing lepton flavour (universality) violation at NA62 and future kaon experiments
Recent results from the LHC's first run have revealed intriguing departures
from lepton flavour universality in the semi-leptonic decays of -mesons. We
discuss the complementary role that rare kaon decays can provide in testing new
physics explanations of these flavour anomalies. In the framework of minimal
flavour violation, we relate the chiral low-energy constants involved in
and (\ell = \mu \mbox{ or } e) with the
new physics Wilson coefficients of the effective Hamiltonian. We
comment on the determination of these low-energy constants at NA62 and future
kaon experiments, as well as the required improvements in sensitivity necessary
to test the -physics anomalies in the kaon sector.Comment: 6 pages, Presented at the International Conference on Kaon Physics
2016, 14-17 September 2016, Birmingham, U
The Future of RICH Detectors through the Light of the LHCb RICH
The limitations in performance of the present RICH system in the LHCb
experiment are given by the natural chromatic dispersion of the gaseous
Cherenkov radiator, the aberrations of the optical system and the pixel size of
the photon detectors. Moreover, the overall PID performance can be affected by
high detector occupancy as the pattern recognition becomes more difficult with
high particle multiplicities. This paper shows a way to improve performance by
systematically addressing each of the previously mentioned limitations. These
ideas are applied in the present and future upgrade phases of the LHCb
experiment. Although applied to specific circumstances, they are used as a
paradigm on what is achievable in the development and realisation of high
precision RICH detectors
Experimental investigation on the geometry of GHz states
Nonclassical correlations arising in complex quantum networks are attracting growing interest, both from afundamental perspective and for potential applications in information processing. In particular, in an entanglementswapping scenario a new kind of correlations arise, the so-called nonbilocal correlations that are incompatible withlocal realism augmented with the assumption that the sources of states used in the experiment are independent.In practice, however, bilocality tests impose strict constraints on the experimental setup and in particular to thepresence of shared reference frames between the parties. Here, we experimentally address this point showing thatfalse positive nonbilocal quantum correlations can be observed even though the sources of states are independent.To overcome this problem, we propose and demonstrate a scheme for the violation of bilocality that does notrequire shared reference frames and thus constitutes an important building block for future investigations ofquantum correlations in complex network
Photoelectron backscattering from silicon anodes of hybrid photodetector tubes
The impact of photoelectron backscattering on spectral distributions measured with hybrid photodetector tubes has been calculated. The calculations are based on the backscattering coefficient mu , the average number of photoelectrons N/sub phel/ emitted from the photocathode, and on the distribution of the fractional photoelectron energy q absorbed in silicon during the backscattering process. We obtained the following results: the average number of absorbed (measured) photoelectrons N/sub meas/ in the silicon anode amounts to ~88% of the incident N/sub phel/. Photoelectron- and gamma-absorption peaks are broadened by a factor 1.043 due to backscattering. As an example, for photomultiplier tubes, this broadening can amount to an average factor of 1.18 due to statistic and gain fluctuations on the dynode chain. (15 refs)
Hybrid photon detectors
Hybrid photon detectors detect light via vacuum photocathodes and accelerate the emitted photoelectrons by an electric field towards inversely polarized silicon anodes, where they are absorbed, thus producing electron-hole pairs. These, in turn, are collected and generate electronic signals on their ohmic contacts. This review first describes the characteristic properties of the main components of hybrid photon detectors: light entrance windows, photocathodes, and silicon anodes. Then, essential relations describing the trajectories of photoelectrons in electric and magnetic fields and their backscattering from the silicon anodes are derived. Depending on their anode configurations, three families of hybrid photon detectors are presented: hybrid photomultiplier tubes with single anodes for photon counting with high sensitivity and for gamma spectroscopy; multi-anode photon detector tubes with anodes subdivided into square or hexagonal pads for position-sensitive photon detection; imaging silicon pixel array tubes with finely segmented anodes for photon-sensitive imaging devices. Some of the hybrid photon detectors’ applications and achievements in radiation detection are discussed and compared with competing devices such as photomultipliers, image intensifiers, photodiodes, silicon drift chambers, charge coupled devices, visible light photon counters, and photographic emulsions
Storage and retrieval of vector beams of light in a multiple-degree-of-freedom quantum memory
The full structuration of light in the transverse plane, including intensity,
phase and polarization, holds the promise of unprecedented capabilities for
applications in classical optics as well as in quantum optics and information
sciences. Harnessing special topologies can lead to enhanced focusing, data
multiplexing or advanced sensing and metrology. Here we experimentally
demonstrate the storage of such spatio-polarization-patterned beams into an
optical memory. A set of vectorial vortex modes is generated via liquid crystal
cell with topological charge in the optic axis distribution, and preservation
of the phase and polarization singularities is demonstrated after retrieval, at
the single-photon level. The realized multiple-degree-of-freedom memory can
find applications in classical data processing but also in quantum network
scenarios where structured states have been shown to provide promising
attributes, such as rotational invariance
Kaon decay interferometry as meson dynamics probes
We discuss the time dependent interferences between and in the
decays in and , to be studied at interferometry machines
such as the -factory and LEAR. We emphasize the possibilities and the
advantages of using interferences, in comparison with width measurements, to
obtain information both on conserving and violating amplitudes.
Comparison with present data and suggestions for future experiments are made.Comment: 15 pages, in RevTex, Report INFNNA-IV-93-31, UTS-DFT-93-2
- …