Latest results from the TORCH R&D Project Gys, T.; Brook, N.; Castillo García, L. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2018, Volume:
912
Journal Article
Peer reviewed
TORCH (Timing Of internally Reflected CHerenkov photons) is a precision time-of-flight detector for particle identification at low momentum. It uses Cherenkov photons produced by charged particles ...passing through a quartz radiator plate. Some of these photons propagate by total internal reflection, they emerge at the edges and are subsequently focused onto photon detectors. The recorded positions and arrival times of the photons are used to precisely reconstruct their trajectory and propagation time in the quartz. This allows to determine the crossing time of the particles through the plate. The TORCH design requires the development of fast photon detectors with fine and asymmetric anode segmentation. The overall per-photon time precision must be better than 70 ps after signal processing and photon path reconstruction in the quartz. In addition, the photon detectors must survive several years of high illumination levels. The on-going R&D programme aims at demonstrating the TORCH basic concept through the realization of a detector module equipped with custom photon detectors featuring the required granularity and lifetime, with dedicated fast front-end electronics and with high-quality quartz radiator and focussing optics. This paper will report on the latest TORCH results achieved in the laboratory and in charged particle beam tests. It will also introduce the developments towards a full-scale module prototype.
Performance of 8- and 12-dynode stage multianode photo-multipliers Bibby, J.H.; Buckley, A.; Chamonal, R.J.U. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2006, Volume:
567, Issue:
1
Journal Article
Peer reviewed
We report on studies of 64-channel Multianode Photo-Multiplier Tubes (MaPMTs) as photo-detectors for Ring Imaging CHerenkov (RICH) counters. The newly available 8-dynode stage MaPMT was tested in ...particle beams at CERN. The MaPMT signals were read out directly with the Beetle1.2 chip which was designed for the LHCb environment and operates at 40
MHz. The photon yield and signal losses were determined for a cluster of
3
×
3
close-packed MaPMTs. The performance of the 8-dynode stage MaPMT was compared to that of the 12-dynode stage MaPMT which has a larger intrinsic gain.
A cluster of multi-anode photomultiplier tubes (MaPMTs) equipped with focusing lenses in front of the tubes was tested in a prototype ring imaging Cherenkov (RICH) detector in a charged particle ...beam. The readout electronics were capable of capturing the data at 40
MHz. The effects due to charged particles and magnetic field on the MaPMT performance were also studied. The results are used to evaluate the MaPMT as a possible photodetector for the LHCb RICH detectors.
Abstract A combination of measurements sensitive to the CKM angle γ from LHCb is performed. The inputs are from analyses of time-integrated B + arrow right DK +, B 0 arrow right DK 0, B 0 arrow right ...DK +pi- and B + arrow right DK +pi+pi- tree-level decays. In addition, results from a time-dependent analysis of B s 0 arrow rightD s K ± decays are included. The combination yields γ=(72.2 -7.3 +6.8 )°, where the uncertainty includes systematic effects. The 95.5% confidence level interval is determined to be γ 55.9, 85.2°. A second combination is investigated, also including measurements from B + arrow right Dpi+ and B + arrow right Dpi+pi-pi+ decays, which yields compatible results. Figure not available: see fulltext.
An array of Multi-anode Photomultiplier Tubes (MaPMT) was evaluated for use in the LHCb Ring Imaging Cherenkov (RICH) detectors using a prototype RICH detector in a charged particle beam. The MaPMT ...performance was measured with different radiator gases with and without lenses. The performance of the MaPMTs in terms of photon yield and pixel cross-talk is presented.
Two new algorithms for use in the analysis of Formula: see text collision are developed to identify the flavour of Formula: see text mesons at production using pions and protons from the ...hadronization process. The algorithms are optimized and calibrated on data, using Formula: see text decays from Formula: see text collision data collected by LHCb at centre-of-mass energies of 7 and 8 TeV . The tagging power of the new pion algorithm is 60% greater than the previously available one; the algorithm using protons to identify the flavour of a Formula: see text meson is the first of its kind.
The decays Formula: see text and Formula: see text are observed for the first time using a data sample corresponding to an integrated luminosity of 3.0 fbFormula: see text, collected by the LHCb ...experiment in proton-proton collisions at the centre-of-mass energies of 7 and 8Formula: see text. The branching fractions relative to that of Formula: see text are measured to be Formula: see textwhere the first uncertainties are statistical and the second are systematic.
Quenching the scintillation in CF4 Cherenkov gas radiator Blake, T.; D׳Ambrosio, C.; Easo, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2015, Volume:
791
Journal Article
Peer reviewed
Open access
CF4 is used as a Cherenkov gas radiator in one of the Ring Imaging Cherenkov detectors at the LHCb experiment at the CERN Large Hadron Collider. CF4 is well known to have a high scintillation photon ...yield in the near and far VUV, UV and in the visible wavelength range. A large flux of scintillation photons in our photon detection acceptance between 200 and 800nm could compromise the particle identification efficiency. We will show that this scintillation photon emission system can be effectively quenched, consistent with radiationless transitions, with no significant impact on the photons resulting from Cherenkov radiation.
The first measurements of the forward-backward asymmetry of the dimuon pair (A_{FB}), the triple-product asymmetry (A_{2ϕ}), and the charge-parity-conjugation asymmetry (A_{CP}), in ...D^{0}→π^{+}π^{-}μ^{+}μ^{-} and D^{0}→K^{+}K^{-}μ^{+}μ^{-} decays are reported. They are performed using data from proton-proton collisions collected with the LHCb experiment from 2011 to 2016, corresponding to a total integrated luminosity of 5 fb^{-1}. The asymmetries are measured to be A_{FB}(D^{0}→π^{+}π^{-}μ^{+}μ^{-})=(3.3±3.7±0.6)%, A_{2ϕ}(D^{0}→π^{+}π^{-}μ^{+}μ^{-})=(-0.6±3.7±0.6)%, A_{CP}(D^{0}→π^{+}π^{-}μ^{+}μ^{-})=(4.9±3.8±0.7)%, A_{FB}(D^{0}→K^{+}K^{-}μ^{+}μ^{-})=(0±11±2)%, A_{2ϕ}(D^{0}→K^{+}K^{-}μ^{+}μ^{-})=(9±11±1)%, A_{CP}(D^{0}→K^{+}K^{-}μ^{+}μ^{-})=(0±11±2)%, where the first uncertainty is statistical and the second systematic. The asymmetries are also measured as a function of the dimuon invariant mass. The results are consistent with the standard model predictions.
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