Ageing in the LHCb outer tracker: Aromatic hydrocarbons and wire cleaning Tuning, N.; Bachmann, S.; Bagaturia, Y. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2011, Letnik:
656, Številka:
1
Journal Article
Recenzirano
The LHCb Outer Tracker straw tubes have shown to suffer from gain loss after irradiation in the laboratory at moderate intensities. Under irradiation an insulating layer is formed on the anode wire. ...The ageing is caused by contamination of the counting gas due to outgassing of the plastifier di-isopropyl-naphthalene in araldite AY103-1 used at construction. This paper presents irradiation results with and without the plastifier, together with the mass spectra of the glue samples. In addition, the effects of wire heating and large currents are presented.
The LHCb Outer Tracker (OT) detector has shown to suffer from gain loss after irradiation in the laboratory at moderate intensities. Under irradiation an insulating layer is formed on the anode wire. ...The ageing is caused by contamination of the counting gas due to outgassing of the glue used in construction namely araldite AY103-1. The gain loss is concentrated upstream the gas flow, and at moderate irradiation intensity only. The ageing rate is reduced by longterm flushing and by the addition of a few percent of
O
2
to the gas mixture. Furthermore, applying a large positive high voltage (beyond the amplification regime) removes the insulating deposits without damaging the wire surface. This paper presents both the characteristics of the ageing phenomenon and the beneficial treatments.
A first alignment of the LHCb Vertex Locator has been obtained from beam induced tracks at the LHC. A 450
GeV/
c protons were collided on a beam absorber during the LHC synchronisation tests of the ...anti-clockwise beam in August and September 2008. The resulting particle tracks have been reconstructed by the Vertex Locator. This was the first full reconstruction of tracks induced by the LHC beam. The quality of the data obtained is discussed. A total of 2200 tracks were reconstructed from the full data sample, and a first spatial alignment was obtained. The detector is aligned to an accuracy of
5
μ
m
in the sensor plane. The results confirm that all detector modules have not been displaced from their surveyed positions by more than
10
μ
m
.
The quantum numbers of the X(3872) meson are determined to be J(PC)=1(++) based on angular correlations in B(+)→X(3872)K(+) decays, where X(3872)→π(+)π(-)J/ψ and J/ψ→μ(+)μ(-). The data correspond to ...1.0 fb(-1) of pp collisions collected by the LHCb detector. The only alternative assignment allowed by previous measurements J(PC)=2(-+) is rejected with a confidence level equivalent to more than 8 Gaussian standard deviations using a likelihood-ratio test in the full angular phase space. This result favors exotic explanations of the X(3872) state.
First LHC beam induced tracks reconstructed in the LHCb VELO Parkes, C.; Borghi, S.; Bates, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/2009, Letnik:
604, Številka:
1
Journal Article
Recenzirano
The Vertex Locator of the LHCb experiment has been used to fully reconstruct beam induced tracks at the LHC. A beam of protons was collided with a beam absorber during the LHC synchronisation test of ...the anti-clockwise beam on the weekend 22nd–24th August 2008. The resulting particles have been observed by the Vertex Locator. The LHCb Vertex Locator is a silicon micro-strip detector containing 21 planes of modules. Tracks were observed passing through up to 19 modules (38 silicon sensors). A total of over 700 tracks were reconstructed, and are being used to study the calibration and alignment of the detector.
A search for heavy Majorana neutrinos produced in the B- → π+ μ- μ- decay mode is performed using 3 fb(-1) of integrated luminosity collected with the LHCb detector in pp collisions at ...center-of-mass energies of 7 and 8 TeV at the LHC. Neutrinos with masses in the range 250 to 5000 MeV and lifetimes from zero to 1000 ps are probed. In the absence of a signal, upper limits are set on the branching fraction B(B- → π+ μ- μ-) as functions of neutrino mass and lifetime. These limits are on the order of 10(-9) for short neutrino lifetimes of 1 ps or less. Limits are also set on the coupling between the muon and a possible fourth-generation neutrino.
During 2011 the LHCb experiment at CERN collected 1.0 fb
−1
of
pp
collisions. Due to the large heavy quark production cross-sections, these data provide unprecedented samples of heavy flavoured ...hadrons. The first results from LHCb have made a significant impact on the flavour physics landscape and have definitively proved the concept of a dedicated experiment in the forward region at a hadron collider. This document discusses the implications of these first measurements on classes of extensions to the Standard Model, bearing in mind the interplay with the results of searches for on-shell production of new particles at ATLAS and CMS. The physics potential of an upgrade to the LHCb detector, which would allow an order of magnitude more data to be collected, is emphasised.
(ProQuest: ... denotes formulae and/or non-USASCII text omitted) Measurements of b hadron production ratios in proton-proton collisions at a center-of-mass energy of 7 TeV with an integrated ...luminosity of 3 pb super(-1) are presented. We study the ratios of strange B meson to light B meson production functionof sub(s)/(functionof sub(u) + functionof sub(d)) and ... baryon to light B meson production functionof sub(Lambda)b/(functionof sub(u) + functionof sub(d)) as a function of the charmed hadron-muon pair transverse momentum p sub(T) and the b hadron pseudorapidity eta, for p sub(T) between 0 and 14 GeV and eta between 2 and 5. We find that functionof sub(s)/(functionof sub(u) + functionof sub(d)) is consistent with being independent of p sub(T) and eta, and we determine ..., where the first error is statistical and the second systematic. The corresponding ratio functionof sub(Lambda)b/(functionof sub(u) + functionof sub(d)) is found to be dependent upon the transverse momentum of the charmed hadron-muon pair, functionof sub(Lambda)b/(functionof sub(u) + functionof sub(d)) = (0.404 + or - 0.017(stat) + or - 0.027(syst) + or - 0.105(Br)), where Br reflects an absolute scale uncertainty due to the poorly x 1 - (0.031 + or - 0.004(stat) + or - 0.003(syst)) x p sub(T)(GeV) known branching fraction ... We extract the ratio of strange B meson to light neutral B meson production functionof sub(s)/functionof sub(d) by averaging the result eported here with two previous measurements derived from the relative abundances of ... to B super(0 arrow right )D super(+)K super(-) and B super(0) arrow right a D super(+)pi super(-). We obtain ...
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