To what extent did the 2018 Senate candidates adapt their Twitter strategy to match electoral realities during the campaign? Previous literature on the political use of social media suggests that ...Twitter is a gauge of "word of mouth" popularity and can be seen as an indirect proxy for votes. As such, Senate candidates have an incentive to be strategic in their use of social media during the election season. Relying on the framework set forth by Gainous and Wagner (
2014
), we categorized senatorial candidates' tweets using an Artificial Neural Network and analyzed them over time to see if political party, presidential vote margin, incumbency and Senate race competitiveness predict the types of tweets that candidates were likely to send. Senate candidate tweets were also examined to determine under what conditions candidates opted to attack, stay quiet about, or align themselves with President Trump. We found that incumbents tended to talk about policy more and attack less, while challengers attacked their opponents to level the playing field. Democratic candidates followed a conventional strategy of tweeting about Trump where it made strategic sense, and using social media in competitive races to attack their opponents and to encourage supporters to get involved. Republicans followed a base-mobilization strategy consisting of aligning themselves with Trump and attacking their opponents when they were underdogs.
Abstract The resonant substructure of D 0 → π+π−π+π− decays is studied using data collected by the CLEO-c detector. An amplitude analysis is performed in order to disentangle the various intermediate ...state contributions. To limit the model complexity a data driven regularization procedure is applied. The prominent contributions are the decay modes D 0 → a 1(1260)+ π−, D 0 → σ f 0(1370) and D 0 → ρ(770)0 ρ(770)0. The broad resonances a 1(1260)+, π(1300)+ and a 1(1640)+ are studied in detail, including quasi-modelindependent parametrizations of their lineshapes. The mass and width of the a 1(1260)+ meson are determined to be m a1(1260)+ = 1225 ± 9 (stat) ± 17 (syst) ± 10 (model) MeV/c 2 and Γa1(1260)+ = 430 ± 24 (stat) ± 25 (syst) ± 18 (model) MeV. The amplitude model of D 0 → K + K −π+π− decays obtained from CLEO II.V, CLEO III, and CLEO-c data is revisited with improved lineshape parametrizations. The largest components are the decay modes D 0 → ϕ(1020)ρ(770)0, D 0 → K 1(1270)+ K − and D 0 → K(1400)+ K −. The fractional CP -even content of the decay D 0 → π+π−π+π− is calculated from the amplitude model to be F + 4π = 72.9 ± 0.9(stat) ± 1.5(syst) ± 1.0(model) %, consistent with that obtained from a previous model-independent measurement. For D 0 → K + K −π+π− decays, the CP -even fraction is measured for the first time and found to be F + KKππ = 75.3 ± 1.8 (stat) ± 3.3 (syst) ± 3.5 (model) %. The global decay rate asymmetries between D 0 and D ¯ 0 $$ {\overline{D}}^0 $$ decays are measured to be A C P 4 π = + 0.54 ± 1.04 stat ± 0.51 syst % $$ {\mathcal{A}}_{CP}^{4\uppi}=\left+0.54\pm 1.04\ \left(\mathrm{stat}\right)\pm 0.51\ \left(\mathrm{syst}\right)\right\% $$ and A C P KKππ = + 1.84 ± 1.74 stat ± 0.30 syst % $$ {\mathcal{A}}_{CP}^{KK\pi \pi}=\left+1.84\pm 1.74\ \left(\mathrm{stat}\right)\pm 0.30\ \left(\mathrm{syst}\right)\right\% $$ . A search for CP asymmetries in the amplitude components yields no evidence for CP violation in either decay mode.
Performance of a prototype TORCH time-of-flight detector Bhasin, S.; Blake, T.; Brook, N.H. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2023, Letnik:
1050
Journal Article
Recenzirano
Odprti dostop
TORCH is a novel time-of-flight detector, designed to provide charged particle identification of pions, kaons and protons in the momentum range 2–20 GeV/c over a 9.5 m flight path. A detector module, ...comprising a 10 mm thick quartz plate, provides a source of Cherenkov photons which propagate via total internal reflection to one end of the plate. Here, the photons are focused onto an array of custom-designed Micro-Channel Plate Photo-Multiplier Tubes (MCP-PMTs) which measure their positions and arrival times. The target time resolution per photon is 70 ps which, for 30 detected photons per charged particle, results in a 10–15 ps time-of-flight resolution. A 1.25 m length TORCH prototype module employing two MCP-PMTs has been developed, and tested at the CERN PS using a charged hadron beam of 8 GeV/c momentum. The construction of the module, the properties of the MCP-PMTs and the readout electronics are described. Measurements of the collected photon yields and single-photon time resolutions have been performed as a function of particle entry points on the plate and compared to expectations. These studies show that the performance of the TORCH prototype approaches the design goals for the full-scale detector.
TORCH pattern recognition and particle identification performance Garcia Martin, L.M.; Blake, T.; Brook, N.H. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2023, Letnik:
1055
Journal Article
Recenzirano
Odprti dostop
The TORCH detector aims to provide K/π (K/p) separation up to a momentum of about 10 (15) ▪ by measuring their time-of-flight at the LHCb detector. Prompt Cherenkov photons are produced in a quartz ...radiator bar of 10 mm thickness, and propagated via total internal reflection to the periphery of the detector, where they are focused onto an array of microchannel plate photomultipliers that measure the photon arrival time and position. Pattern recognition techniques are used to compare the likelihood that the detector image is due to a given particle hypothesis. Good performance is obtained even for very high detector occupancies.
The TORCH time-of-flight detector Harnew, N.; Gao, R.; Hadavizadeh, T. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2023, Letnik:
1048
Journal Article
Recenzirano
Odprti dostop
TORCH is a large-area time-of-flight (ToF) detector, proposed for the Upgrade-II of the LHCb experiment. It will provide charged hadron identification over a 2–20 GeV/c momentum range, given a 9.5m ...flight distance from the LHC interaction point. To achieve this level of performance, a 15ps timing resolution per track is required. A TORCH prototype module having a 1250×660×10mm3 fused-silica radiator plate and equipped with two MCP-PMTs has been tested in a 8GeV/c CERN test-beam. Single-photon time resolutions of between 70–100ps have been achieved, dependent on the beam position in the radiator. The measured photon yields agree with expectations.
Status of the TORCH time-of-flight project Harnew, N.; Bhasin, S.; Blake, T. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2020, Letnik:
952
Journal Article
Recenzirano
Odprti dostop
TORCH is a time-of-flight detector, designed to provide charged π∕K particle identification up to a momentum of 10GeV/c for a 10m flight path. To achieve this level of performance, a time resolution ...of 15 ps per incident particle is required. TORCH uses a plane of quartz of 1 cm thickness as a source of Cherenkov photons, which are then focussed onto square Micro-Channel Plate Photomultipliers (MCP-PMTs) of active area 53 × 53mm2, segmented into 8 × 128 pixels equivalent. A small-scale TORCH demonstrator with a customised MCP-PMT and associated readout electronics has been successfully operated in a 5GeV/c mixed pion/proton beam at the CERN PS facility. Preliminary results indicate that a single-photon resolution better than 100ps can be achieved. The expected performance of a full-scale TORCH detector for the Upgrade II of the LHCb experiment is also discussed.
The TORCH detector R&D: Status and perspectives Gys, T.; Brook, N.; García, L. Castillo ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2017, Letnik:
876
Journal Article
Recenzirano
Odprti dostop
TORCH (Timing Of internally Reflected CHerenkov photons) is a time-of-flight detector for particle identification at low momentum. It has been originally proposed for the LHCb experiment upgrade. ...TORCH is using plates of quartz radiator in a modular design. A fraction of the Cherenkov photons produced by charged particles passing through this radiator propagate by total internal reflection, they emerge at the edges and are subsequently focused onto fast, position-sensitive single-photon detectors. The recorded position and arrival time of the photons are used to precisely reconstruct their trajectory and propagation time in the quartz. The on-going R&D programme aims at demonstrating the TORCH basic concept through the realization of a full detector module and has been organized on the following main development lines: micro-channel plate photon detectors featuring the required granularity and lifetime, dedicated fast front-end electronics preserving the picosecond timing information provided by single photons, and high-quality quartz radiator and focussing optics minimizing photon losses. The present paper reports on the TORCH results successfully achieved in the laboratory and in charged particle beam tests. It will also introduce the latest developments towards a final full-scale module prototype.
Beam tests of a large-scale TORCH time-of-flight demonstrator Hancock, T.H.; Bhasin, S.; Blake, T. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2020, Letnik:
958
Journal Article
Recenzirano
Odprti dostop
The TORCH time-of-flight detector is designed to provide particle identification in the momentum range 2−10GeV∕c over large areas. The detector exploits prompt Cherenkov light produced by charged ...particles traversing a 10mm thick quartz plate. The photons propagate via total internal reflection and are focused onto a detector plane comprising position-sensitive Micro-Channel Plate Photo-Multiplier Tubes (MCP-PMT) detectors. The goal is to achieve a single-photon timing resolution of 70ps, giving a timing precision of 15ps per charged particle by combining the information from around 30 detected photons. The MCP-PMT detectors have been developed with a commercial partner (Photek Ltd, UK), leading to the delivery of a square tube of active area 53×53mm2 with a granularity of 8×128pixels equivalent. A large-scale demonstrator of TORCH, having a quartz plate of dimensions 660×1250×10mm3 and read out by a pair of MCP-PMTs with custom readout electronics, has been verified in a test beam campaign at the CERN PS. Preliminary results indicate that the required performance is close to being achieved. The anticipated performance of a full-scale TORCH detector at the LHCb experiment is presented.
TORCH is a time-of-flight detector designed to perform particle identification over the momentum range 2–10 GeV/c for a 10 m flight path. The detector exploits prompt Cherenkov light produced by ...charged particles traversing a quartz plate of 10mm thickness. Photons are then trapped by total internal reflection and directed onto a detector plane instrumented with customised position-sensitive Micro-Channel Plate Photo-Multiplier Tube (MCP-PMT) detectors. A single-photon timing resolution of 70ps is targeted to achieve the desired separation of pions and kaons, with an expectation of around 30 detected photons per track. Studies of the performance of a small-scale TORCH demonstrator with a radiator of dimensions 120×350×10mm3 have been performed in two test-beam campaigns during November 2017 and June 2018. Single-photon time resolutions ranging from 104.3ps to 114.8ps and 83.8ps to 112.7ps have been achieved for MCP-PMTs with granularity 4 × 64 and 8 × 64 pixels, respectively. Photon yields are measured to be within ∼10% and ∼30% of simulation, respectively. Finally, the outlook for future work with planned improvements is presented.
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