This paper describes the apparatus and the procedures implemented to test the front-end (FE) electronics of the LHCb muon detector multi wire proportional chambers (MWPC). Aim of the test procedure ...is to diagnose every FE channel of a given chamber by performing an analysis of the noise rate versus threshold and of the performances at the operational thresholds. Measurements of the key noise parameters, obtained while performing quality tests on the MWPC chambers before the installation on the experiment, are presented. The test suite proved to be an automatic, fast and user-friendly system for mass production tests of chambers. It provided the electronic identification of every chamber and FE board, and the storage and bookkeeping of test results that will be made available to the experiment control system during data taking.
On August 17, 2017, the first gravitational wave signal from a binary neutron star inspiral (GW170817) was detected by Advanced LIGO and Advanced VIRGO. Here we present radioactive β-decay rates of ...three independent sources 44Ti, 60Co and 137Cs, monitored during the same period by a precision experiment designed to investigate the decay of long-lived radioactive sources. We do not find any significant correlations between decay rates in a 5 h time interval following the GW170817 observation. This contradicts a previous claim published in this journal of an observed 2.5σ Pearson Correlation between fluctuations in the number of observed decays from two β-decaying isotopes (32Si and 36Cl) in the same time interval. By correcting for the choice of an arbitrary time interval, we find no evidence of a correlation above 1.5σ confidence. In addition, we argue that such analyses on correlations in arbitrary time intervals should always correct for the so-called Look-Elsewhere effect by quoting the global significance.
The measurement of charmonium states produced in proton-neon ($p\text {Ne}$) collisions by the LHCb experiment in its fixed-target configuration is presented. The production of ${{J} ...\hspace{-1.66656pt}/\hspace{-1.111pt}\psi }$ and $\psi {(2S)}$ mesons is studied with a beam of 2.5$\mathrm{\,Te\hspace{-1.00006pt}V}$ protons colliding on gaseous neon targets at rest, corresponding to a nucleon-nucleon centre-of-mass energy $\sqrt{s_{\scriptscriptstyle \text {NN}}} =68.5\mathrm{\,Ge\hspace{-1.00006pt}V} $. The data sample corresponds to an integrated luminosity of $21.7\pm 1.4 $ nb$^{-1}$. The ${{J} \hspace{-1.66656pt}/\hspace{-1.111pt}\psi }$ and $\psi {(2S)}$ hadrons are reconstructed in $\mu ^+\mu ^-$ final states. The ${{J} \hspace{-1.66656pt}/\hspace{-1.111pt}\psi }$ production cross-section per target nucleon in the centre-of-mass rapidity range $y^\star \in -2.29, 0$ is found to be $506 \pm 8 \pm 46 \text { nb/nucleon}$. The ratio of ${{J} \hspace{-1.66656pt}/\hspace{-1.111pt}\psi }$ and $D^0$ cross-sections is evaluated to $(1.06 \pm 0.02 \pm 0.09)\%$. The $\psi {(2S)}$ to ${{J} \hspace{-1.66656pt}/\hspace{-1.111pt}\psi }$ relative production rate is found to be $(1.67 \pm 0.27\pm 0.10)\%$ in good agreement with other measurements involving beam and target nuclei of similar sizes.
We report on finding no correlation between the two strongest observed Solar flares in September 2017 and the decay rates of 60Co, 44Ti and 137Cs sources, which are continuously measured by two ...independent NaI(Tl) detector setups. We test for variations in the number of observed counts with respect to the number of expected counts over multiple periods with timescales varying from 1 to 109 h around the Solar flare. No excess or deficit exceeds the 2σ global significance. We set a conservative lower limit on the decay rate deviation over an 84 h period around the two correlated Solar flares in September 2017 to 0.062% with 2σ confidence. A fractional change of ∼0.1% in the decay rate of 54Mn over a period of 84 h was claimed with 7σ significance during multiple Solar flares in December 2006. We exclude such an effect at 4.7σ significance.
A search for Formula omitted violation in charmless four-body decays of Formula omitted and Formula omitted baryons with a proton and three charged mesons in the final state is performed. To cancel ...out production and detection charge-asymmetry effects, the search is carried out by measuring the difference between the Formula omitted asymmetries in a charmless decay and in a decay with an intermediate charmed baryon with the same particles in the final state. The data sample used was recorded in 2011 and 2012 with the LHCb detector and corresponds to an integrated luminosity of Formula omitted. A total of 18 Formula omitted asymmetries are considered, either accounting for the full phase space of the decays or exploring specific regions of the decay kinematics. No significant Formula omitted-violation effect is observed in any of the measurements.
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