Data-taking Run Research Articles

ATLAS Run 2 searches for electroweak production of supersymmetric particles interpreted within the pMSSM

A summary of the constraints from searches performed by the ATLAS collaboration for the electroweak production of charginos and neutralinos is presented. Results from eight separate ATLAS searches are considered, each using 140 fb−1 of proton-proton data at a centre-of-mass energy of s\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\sqrt{s} $$\\end{document} = 13 TeV collected at the Large Hadron Collider during its second data-taking run. The results are interpreted in the context of the 19-parameter phenomenological minimal supersymmetric standard model, where R-parity conservation is assumed and the lightest supersymmetric particle is assumed to be the lightest neutralino. Constraints from previous electroweak, flavour and dark matter related measurements are also considered. The results are presented in terms of constraints on supersymmetric particle masses and are compared with limits from simplified models. Also shown is the impact of ATLAS searches on parameters such as the dark matter relic density and the spin-dependent and spin-independent scattering cross-sections targeted by direct dark matter detection experiments. The Higgs boson and Z boson ‘funnel regions’, where a low-mass neutralino would not oversaturate the dark matter relic abundance, are almost completely excluded by the considered constraints. Example spectra for non-excluded supersymmetric models with light charginos and neutralinos are also presented.

Improved limits on Fierz interference using asymmetry measurements from the Ultracold Neutron Asymmetry (UCNA) experiment

The Ultracold Neutron Asymmetry (UCNA) experiment was designed to measure the β-decay asymmetry parameter, A0, for free neutron decay. In the experiment, polarized ultracold neutrons are transported into a decay trap, and their β-decay electrons are detected with ≈4π acceptance into two detector packages which provide position and energy reconstruction. The experiment also has sensitivity to bn, the Fierz interference term in the neutron β-decay rate. In this work, we determine bn from the energy dependence of A0 using the data taken during the UCNA 2011–2013 run. In addition, we present the same type of analysis using the earlier 2010 A dataset. Motivated by improved statistics and comparable systematic errors compared to the 2010 data-taking run, we present a new bn measurement using the weighted average of our asymmetry dataset fits, to obtain bn=0.066±0.041stat±0.024syst which corresponds to a limit of −0.012<bn<0.144 at the 90% confidence level.Received 17 November 2019Accepted 25 February 2020DOI:https://doi.org/10.1103/PhysRevC.101.035503©2020 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasBeta decayElectroweak interactions in nuclear physicsNuclear tests of fundamental interactionsNuclear Physics

Electronics of the data acquisition system of the DANSS detector based on silicon photomultipliers

The electronics of the data acquisition system based on silicon photomultipliers is briefly described. The elements and modules of the system were designed and constructed at ITEP especially for the DANSS detector. Examples of digitized signals obtained with the presented electronic modules and selected results on processing of the DANSS engineering data-taking run in spring 2016 are given.

Development, Validation and Integration of the ATLAS Trigger System Software in Run 2

The trigger system of the ATLAS detector at the LHC is a combination of hardware, firmware, and software, associated to various sub-detectors that must seamlessly cooperate in order to select one collision of interest out of every 40,000 delivered by the LHC every millisecond. These proceedings discuss the challenges, organization and work flow of the ongoing trigger software development, validation, and deployment. The goal of this development is to ensure that the most up-to-date algorithms are used to optimize the performance of the experiment. The goal of the validation is to ensure the reliability and predictability of the software performance. Integration tests are carried out to ensure that the software deployed to the online trigger farm during data-taking run as desired. Trigger software is validated by emulating online conditions using a benchmark run and mimicking the reconstruction that occurs during normal data-taking. This exercise is computationally demanding and thus runs on the ATLAS high performance computing grid with high priority. Performance metrics ranging from low-level memory and CPU requirements, to distributions and efficiencies of high-level physics quantities are visualized and validated by a range of experts. This is a multifaceted critical task that ties together many aspects of the experimental effort and thus directly influences the overall performance of the ATLAS experiment.

Data preservation at the Fermilab Tevatron

The Fermilab Tevatron collider's data-taking run ended in September 2011, yielding a dataset with rich scientific potential. The CDF and D0 experiments each have approximately 9PB of collider and simulated data stored on tape. A large computing infrastructure consisting of tape storage, disk cache, and distributed grid computing for physics analysis with the Tevatron data is present at Fermilab. The Fermilab Run II data preservation project intends to keep this analysis capability sustained through the year 2020 and beyond. To achieve this goal, we have implemented a system that utilizes virtualization, automated validation, and migration to new standards in both software and data storage technology and leverages resources available from currently-running experiments at Fermilab. These efforts have also provided useful lessons in ensuring long-term data access for numerous experiments, and enable high-quality scientific output for years to come.

Data preservation at the Fermilab Tevatron

The Fermilab Tevatron collider's data-taking run ended in September 2011, yielding a dataset with rich scientific potential. The CDF and DO experiments each have nearly 9 PB of collider and simulated data stored on tape. A large computing infrastructure consisting of tape storage, disk cache, and distributed grid computing for physics analysis with the Tevatron data is present at Fermilab. The Fermilab Run II data preservation project intends to keep this analysis capability sustained through the year 2020 or beyond. To achieve this, we are implementing a system that utilizes virtualization, automated validation, and migration to new standards in both software and data storage technology as well as leveraging resources available from currently-running experiments at Fermilab. These efforts will provide useful lessons in ensuring long-term data access for numerous experiments throughout high-energy physics, and provide a roadmap for high-quality scientific output for years to come.

HARPO: beam characterization of a TPC for gamma-ray polarimetry and high angular-resolution astronomy in the MeV-GeV range

A time projection chamber (TPC) can be used to measure the polarization of gamma rays with excellent angular precision and sensitivity in the MeV-GeV energy range through the conversion of photons to e+e− pairs.The Hermetic ARgon POlarimeter (HARPO) prototype was built to demonstrate this concept. It was recently tested in the polarized photon beam at the NewSUBARU facility in Japan. We present this data-taking run, which demonstrated the excellent performance of the HARPO TPC.

Construction and test of the cylindrical-GEM detectors for the KLOE-2 Inner Tracker

The upgrade of the KLOE detector at DAFNE, the Φ-factory at the Laboratori Nazionali di Frascati, foresees the insertion of an Inner Tracker around the interaction region, composed of four layers with diameters from 26cm to 41cm and an active length of 70cm. Each layer is realized as a cylindrical triple-GEM detector, a solution that allows to keep the total material of the Inner Tracker below 2% of a radiation length, which is of utmost importance to limit the multiple scattering of low-momentum tracks and to minimize dead spaces, thus maximizing the detector's active area. The peculiar read-out pattern with X and V strips provides a spatial resolution of about 200μm and 400μm for azimuthal and longitudinal coordinates, respectively.After 2 years, the construction of the Inner Tracker has been completed and the detector is ready to be inserted in the KLOE apparatus for a next data-taking run. The details of the manufacturing procedure as well as the results of validation tests are reported.

A SURVEY OF LATEST RESULTS FROM THE CDF EXPERIMENT

In 2001 the CDF experiment began a data-taking run at the highest centre-of-mass energies in the world. Expectations were high that this data would lead to an increased understanding of top physics and possible discovery of the Higgs boson and non-Standard Model particles. In this review we describe the aims and scope of this data-taking run, some of the upgrades carried out on CDF and our current experimental status. We briefly discuss the breadth of the CDF physics programme, before describing selected topics in quantum chromodynamics, heavy quark, electroweak and exotic physics. Latest results and projected ultimate experimental reach will be shown.

Status of TAMA300

The project of a laser interferometer gravitational wave detector TAMA300 is in progress. Stable operation of the power-recycled Fabry–Perot Michelson interferometer with improved sensitivity was established. The eighth data-taking run was held as an international full coincidence run with the Laser Interferometer Gravitational Wave Observatory (LIGO). We achieved an observation time of more than 1000 h with a duty cycle of more than 80%. This run can be compared with the previous run without power recycling for stability. The alignment control system was essential to keep the condition of the interferometer optimum not only for test-mass mirrors but also for a recycling mirror.

Recent results and current status of the muon g – 2 experiment at BNL

The muon (g – 2) experiment E821 is currently in progress at Brookhaven National Laboratory. Four data-taking runs for positive muons and one run for negative muons were successfully accomplished in 1997–2000 and 2001, respectively. Results of the 1997–2000 runs have been published, thus completing our experiment for µ+. Data analysis for the 2001 run for µ – is currently in progress. To provide measurement of aµ– = ½(g – 2)µ– at the same level of accuracy as for aµ+ = ½(g – 2)µ+, we would need one more data-taking run. PACS Nos.: 31.15Pf, 31.30Jv, 32.10Hq

Current status of TAMA

TAMA300, an interferometric gravitational-wave detector with 300 m baseline length, has been developed and operated with sufficient sensitivity to detect gravitational-wave events within our galaxy and sufficient stability for observations. The interferometer was operated for over 24 h stably and continuously. With a strain-equivalent noise level of h ∼ 5 × 10−21 Hz−1/2, a signal-to-noise ratio (SNR) of 30 is expected for gravitational waves generated by a coalescence of 1.4 M⊙−1.4 M⊙ binary neutron stars at 10 kpc distance. In the summer of 2000, we carried out a two-week data-taking run, called data taking 4 (DT4), collecting 160 h of data to be analysed in the search for gravitational waves. In this paper, we review the design of the TAMA300 interferometer and the results of DT4. In addition, improvements after DT4 and recent results are also reported.

Stable operation of a 300-m laser interferometer with sufficient sensitivity to detect gravitational-wave events within our galaxy.

TAMA300, an interferometric gravitational-wave detector with 300-m baseline length, has been developed and operated with sufficient sensitivity to detect gravitational-wave events within our galaxy and sufficient stability for observations; the interferometer was operated for over 10 hours stably and continuously. With a strain-equivalent noise level of h approximately 5x10(-21)/sqrt[Hz], a signal-to-noise ratio of 30 is expected for gravitational waves generated by a coalescence of 1.4M-1.4M binary neutron stars at 10 kpc distance. We evaluated the stability of the detector sensitivity with a 2-week data-taking run, collecting 160 hours of data to be analyzed in the search for gravitational waves.

RAMPEX — a new spin experiment

Experiment RAMPEX — Russian-AMerican Polarization EXperiment — is dedicated to studies of one-spin asymmetries which have twist-3 and also twist-2 origin, in hard and semi-hard inclusive processes on the polarized propane-diol target. A special consideration has been given for the prospects of using polarized 3He target. This studies will be performed at the Serpukhov accelerator at 70 GeV/ c (p beam) and 40 GeV/ c ( π − beam). The first data-taking run is being planned for Fall'97.

Operational experience with a large detector system using silicon strip detectors with double sided readout

A large system of silicon strip detectors with double sided readout has been successfully commissioned over the course of the last year at the e +e − collider LEP. The readout of this 73 728 channel system is performed with custom designed VLSI charge sensitive amplifier chips (CAMEX64A). An overall point resolution of 12 μm on both sides has been acheived for the complete system. The most important difficulties during the run were beam losses into the detector, and a chemical agent deposited onto the electronics; however, the damage from these sources was understood and brought under control. This and other results of the 1991 data-taking run are described with special emphasis on the operational experience.

Performance of the UA2 scintillating-fibre detector

A large scintillating-fibre detector consisting of ≈ 60 000 scintillating plastic fibres of 1 mm diameter and 2.4 m length has been used successfully as a tracking and preshower detector in the UA2 experiment at CERN. The detector readout and the results from the p p data-taking run are described.