Irradiation aging of the CMS Drift Tube muon detector Ferrero, D.D. Redondo; Maestre, J. Alcaraz; González, B. Álvarez ...
Radiation physics and chemistry (Oxford, England : 1993),
07/2020, Letnik:
172
Journal Article
Recenzirano
During the High Luminosity LHC, the Drift Tube chambers installed in the CMS detector need to operate with an integrated dose ten times higher than expected at the LHC due to the increase in ...integrated luminosity from 300 fb-1 to 3000 fb-1. Irradiations have been performed to assess the performance of the detector under such conditions and to characterize the radiation aging of the detector. The presented analysis focuses on the behaviour of the high voltage currents and the dose measurements needed to extrapolate the results to High Luminosity conditions, using data from the photon irradiation campaign at GIF++ in 2016 as well as the efficiency analysis from the irradiation campaign started in 2017. Although the single-wire loss of high voltage gain observed of 70% is very high, the muon reconstruction efficiency is expected to decrease less than 20% during the full duration of High Luminosity LHC in the areas under highest irradiation.
•The High Luminosity Large Hadron Collider will have increased radiation levels.•Exposure to radiation reduces the performance of gaseous detectors.•Drift Tube detectors are being characterized for future operation.
Single photons detected by the DELPHI experiment at LEP2 in the years 1997–2000 are reanalysed to investigate the existence of a single extra dimension in a modified ADD scenario with slightly warped ...large extra dimensions. The data collected at centre-of-mass energies between 180 and 209 GeV for an integrated luminosity of ∼650 pb
−1
agree with the predictions of the Standard Model and allow a limit to be set on graviton emission in one large extra dimension. The limit obtained on the fundamental mass scale
M
D
is 1.69 TeV/
c
2
at 95% CL, with an expected limit of 1.71 TeV/
c
2
.
We report on measurements of the decays of B¯ mesons into the semileptonic final states B¯→D^(*)π^(+)π^(-)ℓ^(-)ν¯, where D^(*) represents a D or D^(*) meson and ℓ^(-) is an electron or a muon. These ...measurements are based on 471×10^(6) BB ¯ pairs recorded with the BABAR detector at the SLAC asymmetric B factory PEP-II. We determine the branching fraction ratios R_{π^{+}π^{-}}^{(*)}=B(Bover ¯→D^{(*)}π^{+}π^{-}ℓ^{-}νover ¯)/B(Bover ¯→D^{(*)}ℓ^{-}νover ¯) using events in which the second B meson is fully reconstructed. We find R_{π^{+}π^{-}}=0.067±0.010±0.008 and R_{π^{+}π^{-}}^{*}=0.019±0.005±0.004, where the first uncertainty is statistical and the second is systematic. Based on these results and assuming isospin invariance, we estimate that Bover ¯→D^{(*)}ππℓ^{-}νover ¯ decays, where π denotes either a π^{±} and π^{0} meson, account for up to half the difference between the measured inclusive semileptonic branching fraction to charm hadrons and the corresponding sum of previously measured exclusive branching fractions.
Moments of the hadronic invariant mass and of the lepton energy spectra in semileptonic B decays have been determined with the data recorded by the DELPHI detector at LEP. From measurements of the ...inclusive b-hadron semileptonic decays, and imposing constraints from other measurements on b- and c-quark masses, the first three moments of the lepton energy distribution and of the hadronic mass distribution, have been used to determine parameters which enter into the extraction of |V_cb| from the measurement of the inclusive b-hadron semileptonic decay width. The values obtained in the kinetic scheme are: m_b(1 GeV) = 4.591 +/- 0.062 +/- 0.039 +/- 0.005 GeV/c^2 m_c(1 GeV) = 1.170 +/- 0.093 +/- 0.055 +/- 0.005 GeV/c^2 mu_{pi}^2(1 GeV) = 0.399 +/- 0.048 +/- 0.034 +/- 0.087 GeV^2 \tilde{\rho}_D^3 = 0.053 +/- 0.017 +/- 0.011 +/- 0.026 GeV^3, and include corrections at order 1/m_b^3. Using these results, and present measurements of the inclusive semileptonic decay partial width of b-hadrons at LEP, an accurate determination of |V_cb| is obtained: |V_cb| = 0.0421 x (1 +/- 0.014 (meas.) +/- 0.014 (fit) +/- 0.015 (th.)).
Based on the full BABAR data sample, we report improved measurements of the ratios R(D(*))=B(B̄→D(*)τ⁻ν¯τ)/B(B̄→D(*)ll¯ν¯l), where l is either e or μ. These ratios are sensitive to new physics ...contributions in the form of a charged Higgs boson. We measure R(D)=0.440±0.058±0.042 and R(D*)=0.332±0.024±0.018, which exceed the standard model expectations by 2.0σ and 2.7σ, respectively. Taken together, our results disagree with these expectations at the 3.4σ level. This excess cannot be explained by a charged Higgs boson in the type II two-Higgs-doublet model.
The DELPHI detector at LEP has been used to measure multi-muon bundles originating from cosmic ray interactions with air. The cosmic events were recorded in “parasitic mode” between individual e
+e
− ...interactions and the total live time of this data taking is equivalent to 1.6
×
10
6
s. The DELPHI apparatus is located about 100
m underground and the 84 metres rock overburden imposes a cutoff of about 52
GeV/c on muon momenta. The data from the large volume Hadron Calorimeter allowed the muon multiplicity of 54,201 events to be reconstructed. The resulting muon multiplicity distribution is compared with the prediction of the Monte Carlo simulation based on CORSIKA/QGSJET01. The model fails to describe the abundance of high multiplicity events. The impact of QGSJET internal parameters on the results is also studied.
Moments of the hadronic invariant mass and of the lepton energy spectra in semileptonic B decays have been determined with the data recorded by the DELPHI detector at LEP. From measurements of the ...inclusive b-hadron semileptonic decays, and imposing constraints from other measurements on b- and c-quark masses, the first three moments of the lepton energy distribution and of the hadronic mass distribution, have been used to determine parameters which enter into the extraction of |Vcb| from the measurement of the inclusive b-hadron semileptonic decay width. The values obtained in the kinetic scheme are:\(\begin{array}{*{20}l}{{m_{b} {\left( {1\;{\text{GeV}}} \right)}} \hfill} & { = \hfill} & {{4.591 \pm 0.062 \pm 0.039 \pm 0.005\;{\text{GeV/c}}^{2} ,} \hfill} \\{{m_{c} {\left( {1\;{\text{GeV}}} \right)}} \hfill} & { = \hfill} & {{1.170 \pm 0.093 \pm 0.055 \pm 0.005\;{\text{GeV/c}}^{{\text{2}}} {\text{,}}} \hfill} \\{{\mu ^{2}_{\pi } {\left( {1\;{\text{GeV}}} \right)}} \hfill} & { = \hfill} & {{0.399 \pm 0.048 \pm 0.034 \pm 0.087\;{\text{GeV}}^{{\text{2}}} {\text{,}}} \hfill} \\{{ \ifmmode\expandafter\tilde\else\expandafter\~\fi{\rho }^{3}_{D} } \hfill} & { = \hfill} & {{0.053 \pm 0.017 \pm 0.011 \pm 0.026\;{\text{GeV}}^{{\text{3}}} ,} \hfill} \\\end{array} \)and include corrections at order 1/mb3. Using these results, and present measurements of the inclusive semileptonic decay partial width of b-hadrons at LEP, an accurate determination of |Vcb| is obtained: \({\left| {V_{{cb}} } \right|} = 0.0421 \times {\left( {1 \pm 0.014_{{{\text{meas}}{\text{.}}} \pm 0.014_{{{\text{fit}}} \pm 0.015_{{{\text{th}}{\text{.}}} } \right)}\)
The data taken by
Delphi
at centre-of-mass energies between 189 and 209 GeV are used to place limits on the
CP
-conserving trilinear gauge boson couplings
,
λ
γ
and Δ
κ
γ
associated to
W
+
W
−
and ...single
W
production at
Lep2
. Using data from the
jj
ℓ
ν
,
jjjj
,
jjX
and
ℓ
X
final states, where
j
,
ℓ
and
X
represent a jet, a lepton and missing four-momentum, respectively, the following limits are set on the couplings when one parameter is allowed to vary and the others are set to their Standard Model values of zero:
Results are also presented when two or three parameters are allowed to vary. All observations are consistent with the predictions of the Standard Model and supersede the previous results on these gauge coupling parameters published by
Delphi
.
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