MATHUSLA detector development

The MATHUSLA collaboration has proposed to construct a large area detector on the surface above the CMS experiment. Such a detector would search for long-lived exotic particles produced in the collisions at the LHC. In order to maximize acceptance and sensitivity, MATHUSLA intends to instrument a large surface area with multiple layers of scintillator bars. The massive scale of the detector requires a high level of modularity and cost efficiency in the design. To achieve these goals, MATHUSLA will use extruded scintillator bars with WaveLength Shifting Fibre (WLSF) threaded through for light collection. This results in a basic detector unit of two 2.5 m long scintillator bars threaded with a WLSF that terminate at SiPMs on either end. These units are combined into increasingly larger mechanical assemblies to construct the modular MATHUSLA detector layers. At the University of Victoria we are making use of a desktop darkbox as well as MATHUSLA prototype detector made of 4 MATHUSLA-like layers of scintillator to characterize the performance of the various WLSF compounds, SiPMs, and scintillator dimensions

Effects of base-flow variations on the secondary instability in the wake of a circular cylinder

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Development of a new Front End electronics in Silicon and Silicon-Germanium technology for the Resistive Plate Chamber detector for high rate experiments

The upgrade of the Resistive Plate Chamber (RPC) detector, in order to increase the detector rate capability and to be able to work efficiently in high rate environment, consists in the reduction of the operating voltage along with the detection of signals which are few hundred {\mu}V small. The approach chosen by this project to achieve this objective is to develop a new kind of Front End electronics which, thanks to a mixed technology in Silicon and Silicon-Germanium, enhance the detector performances increasing its rate capability. The Front End developed is composed by a preamplifier in Silicon BJT technology with a very low inner noise (1000 $e^{-}$ rms) and an amplification factor of 0.3-0.4 mV/fC and a new kind of discriminator in SiGe HJT technology which allows a minimum threshold of the order of 0.5 mV. The performances of this kind of Front End will be shown. The results are obtained by using the CERN H8 beamline with a full-size RPC chamber of 1 mm gas gap and 1.2 mm thickness of electrodes equipped with this kind of Front End electronics.Comment: 14th Workshop on Resistive Plate Chambers and Related Detectors 19-23 February, 2018 Puerto Vallarta, Jalisco state, Mexic

The MATHUSLA Test Stand

The rate of muons from LHC $pp$ collisions reaching the surface above the ATLAS interaction point is measured and compared with expected rates from decays of $W$ and $Z$ bosons and $b$- and $c$-quark jets. In addition, data collected during periods without beams circulating in the LHC provide a measurement of the background from cosmic ray inelastic backscattering that is compared to simulation predictions. Data were recorded during 2018 in a 2.5 $\times$ 2.5 $\times$ 6.5~$\rm{m}^3$ active volume MATHUSLA test stand detector unit consisting of two scintillator planes, one at the top and one at the bottom, which defined the trigger, and six layers of RPCs between them, grouped into three $(x,y)$-measuring layers separated by 1.74 m from each other. Triggers selecting both upward-going tracks and downward-going tracks were used.Comment: 18 pages, 11 figures, 1 tabl

A new RPCs generation for astroparticle physics

The Resistive Plate Chambers (RPCs) can be extensively used in Cosmic Ray Physics and Gamma- Ray Astronomy. Indeed, the ARGO-YBJ detector, a 7000 m2 full coverage RPC carpet, was operated at YangBaJing (Tibet, 4300 m asl) with very low maintenance and excellent performance for more than a decade. It provided: high efficiency detection of low energy showers, down to 100 GeV, by means of the dense read-out sampling; wide energy range investigated, 100 GeV – 10 PeV, by means of the combined digital/charge read-outs; good energy and angular resolutions with unprecedented details in the shower core region. The RPC-based flare hunter we propose is therefore based on the experience of the ARGO-YBJ experiment. A new RPC generation dedicated to cosmic ray experiments is in preparation, the main differences from ARGO-YBJ being the avalanche mode operation instead of streamer and the gas closed loop that strongly reduces the fresh gas consumption. This contribution shows experimental results on several new generation prototypes that were built in view of a test experiment to be performed in the South hemisphere. The experiment can be carried out either as standalone or by installing the RPC layer on top of a water Cherenkov detector. The purpose of this hybrid detector would be to combine the RPC capability of imaging the shower front, down to few keV/hit, with the Cherenkov capability of integrating all signals produced by the shower in several radiation lengths of water. In both cases the RPCs would strongly increase the sensitivity to the observation of flaring phenomena like GRBs or AGNs below the TeV

Cosmic-ray searches with the MATHUSLA detector

The performance of the proposed MATHUSLA detector as an instrument for studying the physics of cosmic rays by measuring extensive air showers is presented. The MATHUSLA detector is designed to observe and study the decay of long-lived particles produced at the pp interaction point of the CMS detector at CERN during the HL-LHC data-taking period. The proposed MATHUSLA detector will be composed of many layers of long scintillating bars that cannot measure more than one hit per bar and correctly report the hit coordinate in case of multiple hits. This study shows that adding a layer of RPC detectors with both analogue and digital readout significantly enhances the capabilities of MATHUSLA to measure the local densities and arrival times of charged particles at the front of air showers. We discuss open issues in cosmic-ray physics that the proposed MATHUSLA detector with an additional layer of RPC detectors could address and conclude by comparing with other air-shower facilities that measure cosmic rays in the PeV energy range.Comment: 64 pages, 58 figure

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements