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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,189 records · Page 66
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Strip sensor performance in prototype modules built for ATLAS ITk

ATLAS experiment is preparing an upgrade of its detector for High-Luminosity LHC (HL-LHC) operation. The upgrade involves installation of the new all-silicon Inner Tracker (ITk). In the context of the ITk preparations, more than 80 strip modules were built with prototype barrel sensors. They were tested with electrical readout on a per-channel basis. In general, an excellent performance was observed, consistent with previous ASIC-level and sensor-level tests. However, the lessons learned included two phenomena important for the future phases of the project. First was the need to store and test the modules in a dry environment due to humidity sensitivity of the sensors. The second was an observation of high noise regions for 2 modules. The high noise regions were tested further in several ways, including monitoring the performance as a function of time and bias voltage. Additionally, direct sensor-level tests were performed on the affected channels. The inter-strip resistance and bias resistance tests showed low values, indicating a temporary loss of the inter-strip isolation. A subsequent recovery of the noise performance was observed. Here we present the test details, an analysis of how the inter-strip isolation affects the module noise, and the relationship with sensor-level quality control tests.

47 OTHER INSTRUMENTATION↗
DOE OSTI2023

A matched-filter approach to radio variability and transients: searching for orphan afterglows in the VAST Pilot Survey

Radio transient searches using traditional variability metrics struggle to recover sources whose evolution time-scale is significantly longer than the survey cadence. Motivated by the recent observations of slowly evolving radio afterglows at gigahertz frequency, we present the results of a search for radio variables and transients using an alternative matched-filter approach. We designed our matched-filter to recover sources with radio light curves that have a high-significance fit to power-law and smoothly broken power-law functions; light curves following these functions are characteristic of synchrotron transients, including ‘orphan’ gamma-ray burst afterglows, which were the primary targets of our search. Applying this matched-filter approach to data from Variables and Slow Transients Pilot Survey conducted using the Australian SKA Pathfinder, we produced five candidates in our search. Subsequent Australia Telescope Compact Array observations and analysis revealed that: one is likely a synchrotron transient; one is likely a flaring active galactic nucleus, exhibiting a flat-to-steep spectral transition over 4 months; one is associated with a starburst galaxy, with the radio emission originating from either star formation or an underlying slowly evolving transient; and the remaining two are likely extrinsic variables caused by interstellar scintillation. The synchrotron transient, VAST J175036.1–181454, has a multifrequency light curve, peak spectral luminosity, and volumetric rate that is consistent with both an off-axis afterglow and an off-axis tidal disruption event; interpreted as an off-axis afterglow would imply an average inverse beaming factor $\langle f^{-1}_{\text{b}} \rangle = 860^{+1980}_{-710}$, or equivalently, an average jet opening angle of $\langle \theta _{\textrm {j}} \rangle = 3^{+4}_{-1}\,$ deg.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1994

The detection of pulsed X-ray emission from a nearby radio pulsar

As part of a search for thermal surface radiation from nearby neutron stars, we have carried out a 45,000 s observation of the nearby radio pulsar PSR 1929+10 with the ROSAT PSPC. After background subtraction, a net of 420 +/- 25 photons in the 0.1 to 2.0 keV band were detected at the position of the pulsar, corresponding to a luminosity of 1.2 x 10(exp 30) ergs/sec for a source distance of 250 pc, or approximately 3 x 10(exp -4) of the pulsar's spin-down luminosity. We find coherent pulsations from PSR 1929+10 at the radio period of 0.2265 s. The folded light curve is well fitted by a sinusoidal oscillation with a pulsed fraction of about 30%. The total spectrum is fitted by a blackbody with a temperature T(sub infinity) approximately equals 3.2 x 10(exp 6) K; the implied emitting area has a radius of less than 50 m. The maximum of the X-ray light curve coincides with the radio pulse, suggesting that we are detecting the hot magnetic polar cap of the star. The temperature limit for the remainder of the stellar surface is T(sub infinity) less than 3 x 10(exp 5) K. The spatial distribution of the photons is consistent with the instrument point-spread function. We discuss the implications of these results for the temperature distribution over the surface of the star and use this detection to constrain various heating mechanisms for rotation-powered neutron stars. We also use a simple model of general relativistic light bending near the stellar surface in conjunction with the radio emission geometry and the X-ray pulsed fraction to derive a radius for the neutron star of R = 9 +/- 3 km.

Yancopoulos, S.↗
NASA NTRS1994

The Orion OB1 association. 1: Stellar content

Walfraven photometry of established and probable members of the Orion OB1 association is presented. Effective temperature, surface gravity, luminosity and mass are derived for all stars, using atmosphere model by Kurucz (1979). Absolute magnitudes are calculated using the Straizys and Kuriliene (1981) tables. Distance moduli and visual extinctions are determined. A comparison of the visual extinctions to IRAS 100 micrometers data shows that the near edge of the Orion A and B clouds lies at a distance of approximately 320 pc, while the far edge is at approximately 500 pc. A method for deriving the ages of the subgroups by comparing theoretical isochrones to the observations in the log g, log T(sub eff) plane is presented. The derived ages suggest, contrary to earlier studies, that subgroup 1b is younger than 1c, which can possibly be explained by past geometries of the system of stars and gas. The initial mass function for Orion OB1 is derived with the aid of the Kolmogorov-Smirnoff test. Through extensive simulations, we show that it is very difficult to derive accurately the Initial Mass Function (IMF) from the available data. To within somewhat weak limits the IMF is found to be of the form xi(log M) = AM(exp -1.7 +/- 0.2) for all subgroups. The energy output of the subgroups in the form of stellar winds and supernovae is calculated and compared to the observed size and expansion velocity of the Orion-Eridanus bubble. It is shown that the energy output of the association can account for the morphology and kinematics of the interstellar medium (ISM).

Brown, A. G. A.↗
DOE OSTI2022

Search for high-mass resonances decaying to a jet and a Lorentz-boosted resonance in proton-proton collisions at s = 13 TeV

A search is reported for high-mass hadronic resonances that decay to a parton and a Lorentz-boosted resonance, which in turn decays into a pair of partons. The search is based on data collected with the CMS detector at the LHC in proton-proton collisions at $\sqrt{s}$ = 13 TeV, corresponding to an integrated luminosity of 138 fb$^{-1}$. The boosted resonance is reconstructed as a single wide jet with substructure consistent with a two-body decay. The high-mass resonance is thus considered as a dijet system. The jet substructure information and the kinematic properties of cascade resonance decays are exploited to disentangle the signal from the large quantum chromodynamics multijet background. The dijet mass spectrum is analyzed for the presence of new high-mass resonances, and is found to be consistent with the standard model background predictions. Results are interpreted in a warped extra dimension model where the high-mass resonance is a Kaluza-Klein gluon, the boosted resonance is a radion, and the final state partons are all gluons. Limits on the production cross section are set as a function of the Kaluza-Klein gluon and radion masses. These limits exclude at 95% confidence level models with Kaluza-Klein gluon masses in the range from 2.0 to 4.3 TeV and radion masses in the range from 0.20 to 0.74 TeV. By exploring a novel experimental signature, the observed limits on the Kaluza-Klein gluon mass are extended by up to about 1 TeV compared to previous searches.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Associated production of prompt $J/ψ$ and Υ mesons in $pp$ collisions at $\sqrt{s}$ = 13 TeV

The associated production of prompt J/ψ and Υ mesons in pp collisions at a centre-of-mass energy of $\sqrt{s}$ = 13 TeV is studied using LHCb data, corresponding to an integrated luminosity of 4 fb -1 . The measurement is performed for J/ψ (Υ) mesons with a transverse momentum p T < 10 (30) GeV/c in the rapidity range 2.0 < y < 4.5. In this kinematic range, the cross-section of the associated production of prompt J/ψ and Υ(1S) mesons is measured to be 133 ± 22 ± 7 ± 3 pb, with a signifcance of 7.9 σ, and that of prompt J/ψ and Υ(2S) mesons to be 76 ± 21 ± 4 ± 7 pb, with a signifcance of 4.9 σ. The frst uncertainty is statistical, the second systematic, and the third due to uncertainties on the used branching fractions. This is the frst observation of the associated production of J/ψ and Υ(1S) in proton-proton collisions. Diferential cross-sections are measured as functions of variables that are sensitive to kinematic correlations between the J/ψ and Υ(1S) mesons. The efective cross-sections of the associated production of prompt J/ψ and Υ mesons are obtained and found to be compatible with measurements using other particle productions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Measurement of properties of B$^0_\mathrm{s}\to\mu^+\mu^-$ decays and search for B$^0\to\mu^+\mu^-$ with the CMS experiment

Results are reported for the $ {\mathrm{B}}_{\mathrm{s}}^0 $→ μ$^{+}$μ$^{−}$ branching fraction and effective lifetime and from a search for the decay B$^{0}$→ μ$^{+}$μ$^{−}$. The analysis uses a data sample of proton-proton collisions accumulated by the CMS experiment in 2011, 2012, and 2016, with center-of-mass energies (integrated luminosities) of 7 TeV (5 fb$^{−1}$), 8 TeV (20 fb$^{−1}$), and 13 TeV (36 fb$^{−1}$). The branching fractions are determined by measuring event yields relative to B$^{+}$→ J/ψK$^{+}$ decays (with J/ψ → μ$^{+}$μ$^{−}$), which results in the reduction of many of the systematic uncertainties. The decay $ {\mathrm{B}}_{\mathrm{s}}^0 $→ μ$^{+}$μ$^{−}$ is observed with a significance of 5.6 standard deviations. The branching fraction is measured to be $ \mathrm{\mathcal{B}}\left({\mathrm{B}}_{\mathrm{s}}^0\to {\upmu}^{+}{\upmu}^{-}\right)=\left[2.9\pm 0.7\left(\exp \right)\pm 0.2\left(\mathrm{frag}\right)\right]\times {10}^{-9} $, where the first uncertainty combines the experimental statistical and systematic contributions, and the second is due to the uncertainty in the ratio of the $ {\mathrm{B}}_{\mathrm{s}}^0 $ and the B$^{+}$ fragmentation functions. No significant excess is observed for the decay B$^{0}$→ μ$^{+}$μ$^{−}$, and an upper limit of ℬ(B$^{0}$ → μ$^{+}$μ$^{−}$) < 3.6 × 10$^{−10}$ is obtained at 95% confidence level. The $ {\mathrm{B}}_{\mathrm{s}}^0 $→ μ+μ− effective lifetime is measured to be $ {\tau}_{\upmu^{+}{\upmu}^{-}}={1.70}_{-0.44}^{+0.61} $ ps. These results are consistent with standard model predictions.[graphic not available: see fulltext]

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Inclusive search for highly boosted Higgs bosons decaying to bottom quark-antiquark pairs in proton-proton collisions at $\sqrt{s} =$ 13 TeV

A search for standard model Higgs bosons (H) produced with transverse momentum (p$_{T}$) greater than 450 GeV and decaying to bottom quark-antiquark pairs ($ \mathrm{b}\overline{\mathrm{b}} $) is performed using proton-proton collision data collected by the CMS experiment at the LHC at $ \sqrt{s} $ = 13 TeV. The data sample corresponds to an integrated luminosity of 137 fb$^{−1}$. The search is inclusive in the Higgs boson production mode. Highly Lorentz-boosted Higgs bosons decaying to $ \mathrm{b}\overline{\mathrm{b}} $ are reconstructed as single large-radius jets, and are identified using jet substructure and a dedicated b tagging technique based on a deep neural network. The method is validated with Z →$ \mathrm{b}\overline{\mathrm{b}} $ decays. For a Higgs boson mass of 125 GeV, an excess of events above the background assuming no Higgs boson production is observed with a local significance of 2.5 standard deviations (σ), while the expectation is 0.7. The corresponding signal strength and local significance with respect to the standard model expectation are μ$_{H}$ = 3.7 ± 1.2(stat)$ {}_{-0.7}^{+0.8} $(syst)$ {}_{-0.5}^{+0.8} $(theo) and 1.9 σ. Additionally, an unfolded differential cross section as a function of Higgs boson p$_{T}$ for the gluon fusion production mode is presented, assuming the other production modes occur at the expected rates.[graphic not available: see fulltext]

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Speeding up particle track reconstruction using a parallel Kalman filter algorithm

One of the most computationally difficult problems expected for the High-Luminosity Large Hadron Collider (HL-LHC) is determining the trajectory of charged particles during event reconstruction. Algorithms used at the LHC today rely on Kalman filtering, which builds physical trajectories incrementally while incorporating material effects and error estimation. Recognizing the need for faster computational throughput, we have adapted Kalman-filter-based methods for highly parallel, many-core SIMD architectures that are now prevalent in high-performance hardware. In this paper, we discuss the design and performance of the improved tracking algorithm, referred to as mkFit. A key piece of the algorithm is the Matriplex library, containing dedicated code to optimally vectorize operations on small matrices. The physics performance of the mkFit algorithm is comparable to the nominal CMS tracking algorithm when reconstructing tracks from simulated proton-proton collisions within the CMS detector. We study the scaling of the algorithm as a function of the parallel resources utilized and find large speedups both from vectorization and multi-threading. mkFit achieves a speedup of a factor of 6 compared to the nominal algorithm when run in a single-threaded application within the CMS software framework.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2022

Photometric Objects around Cosmic Webs (PAC) Delineated in a Spectroscopic Survey. I. Methods

We provide a method for estimating the projected density distribution ${\bar{n}}_{2}{w}_{p}({r}_{p})$ of photometric objects around spectroscopic objects in a spectroscopic survey. This quantity describes the distribution of photometric sources with certain physical properties (e.g., luminosity, mass, and color) around cosmic webs (PAC) traced by the spectroscopic objects. The method can make full use of current and future deep and wide photometric surveys to explore the formation of galaxies up to medium redshift (z s < 2) 3 with the aid of cosmological spectroscopic surveys that sample only a fairly limited species of objects (e.g., emission line galaxies). As an example, we apply the PAC method to the CMASS spectroscopic and HSC-SSP PDR2 photometric samples to explore the distribution of galaxies for a wide range of stellar masses from 10 9.0 to 10 12.0 M ⊙ around massive galaxies at z s ≈ 0.6. Using the abundance-matching method, we model ${\bar{n}}_{2}{w}_{p}({r}_{p})$ in N-body simulation using Markov chain Monte Carlo sampling, and we accurately measure the stellar–halo mass relation and stellar mass function for the whole mass range. We can also measure the conditional stellar mass function of satellites for central galaxies of different mass. The PAC method has many potential applications for studying the evolution of galaxies.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Search for high mass dijet resonances with a new background prediction method in proton-proton collisions at $\sqrt{s} =$ 13 TeV

A search for narrow and broad resonances with masses greater than 1.8 TeV decaying to a pair of jets is presented. The search uses proton-proton collision data at $ \sqrt{s} $ = 13 TeV collected at the LHC, corresponding to an integrated luminosity of 137 fb$^{−1}$. The background arising from standard model processes is predicted with the fit method used in previous publications and with a new method. The dijet invariant mass spectrum is well described by both data-driven methods, and no significant evidence for the production of new particles is observed. Model independent upper limits are reported on the production cross sections of narrow resonances, and broad resonances with widths up to 55% of the resonance mass. Limits are presented on the masses of narrow resonances from various models: string resonances, scalar diquarks, axigluons, colorons, excited quarks, color-octet scalars, W′ and Z′ bosons, Randall-Sundrum gravitons, and dark matter mediators. The limits on narrow resonances are improved by 200 to 800 GeV relative to those reported in previous CMS dijet resonance searches. The limits on dark matter mediators are presented as a function of the resonance mass and width, and on the associated coupling strength as a function of the mediator mass. These limits exclude at 95% confidence level a dark matter mediator with a mass of 1.8 TeV and width 1% of its mass or higher, up to one with a mass of 4.8 TeV and a width 45% of its mass or higher.[graphic not available: see fulltext]

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS2001

Time Series Analysis of the UV Flickering in AGN

Many active galactic nuclei (AGN) exhibit large-amplitude luminosity fluctuations on short timescales. The fluctuations lead to a profound conclusion: The size of the emitting region is remarkably small. This observational fact is one of the pillars supporting the AGN paradigm: Prodigious amounts of gravitational potential energy are liberated in an accretion disk around a supermassive black hole. The goals of the research were to extract from the IUE Archive the very best observational characterizations of AGN flickering, and to use these to test and develop models for AGN variability. We hoped to answer these specific questions: 1) What does the intrinsic flickering continuum spectrum look like? 2) What do the intrinsic flickering emission-line profiles look like? 3) What is the power spectrum of the flickering? 4) What is the wavelength dependence of the power spectrum? 5) Is the flickering spectrum timescale dependent? and 6) What do the high-order cross correlation functions look like? A short summary of the papers produced by this research is presented.

Robinson, Edward L.↗
DOE OSTI2021

Search for pair production of third-generation scalar leptoquarks decaying into a top quark and a τ-lepton in pp collisions at $\sqrt{s}$ = 13 TeV with the ATLAS detector

A search for pair production of third-generation scalar leptoquarks decaying into a top quark and a τ-lepton is presented. The search is based on a dataset of pp collisions at $\sqrt{s}$ = 13 TeV recorded with the ATLAS detector during Run 2 of the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb -1 . Events are selected if they have one light lepton (electron or muon) and at least one hadronically decaying τ -lepton, or at least two light leptons. In addition, two or more jets, at least one of which must be identified as containing b-hadrons, are required. Six final states, defined by the multiplicity and flavour of lepton candidates, are considered in the analysis. Each of them is split into multiple event categories to simultaneously search for the signal and constrain several leading backgrounds. The signal-rich event categories require at least one hadronically decaying τ-lepton candidate and exploit the presence of energetic final-state objects, which is characteristic of signal events. No significant excess above the Standard Model expectation is observed in any of the considered event categories, and 95% CL upper limits are set on the production cross section as a function of the leptoquark mass, for different assumptions about the branching fractions into tτ and bν. Scalar leptoquarks decaying exclusively into tτ are excluded up to masses of 1.43 TeV while, for a branching fraction of 50% into tτ, the lower mass limit is 1.22 TeV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Search for new physics using effective field theory in 13 TeV pp collision events that contain a top quark pair and a boosted Z or Higgs boson

A data sample containing top quark pairs ($\mathrm{t\bar{t}}$) produced in association with a Lorentz-boosted Z or Higgs boson is used to search for signs of new physics using effective field theory. The data correspond to an integrated luminosity of 138 fb$^{-1}$ of proton-proton collisions produced at a center-of-mass energy of 13 TeV at the LHC and collected by the CMS experiment. Selected events contain a single lepton and hadronic jets, including two identified with the decay of bottom quarks, plus an additional large-radius jet with high transverse momentum identified as a Z or Higgs boson decaying to a bottom quark pair. Machine learning techniques are employed to discriminate between $\mathrm{t\bar{t}}$Z or $\mathrm{t\bar{t}}$H events and events from background processes, which are dominated by $\mathrm{t\bar{t}}$ + jets production. No indications of new physics are observed. The signal strengths of boosted $\mathrm{t\bar{t}}$Z and $\mathrm{t\bar{t}}$H production are measured, and upper limits are placed on the $\mathrm{t\bar{t}}$Z and $\mathrm{t\bar{t}}$H differential cross sections as functions of the Z or Higgs boson transverse momentum. The effects of new physics are probed using a framework in which the standard model is considered to be the low-energy effective field theory of a higher energy scale theory. Eight possible dimension-six operators are added to the standard model Lagrangian and their corresponding coefficients are constrained via fits to the data.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Measurement of the polarisation of single top quarks and antiquarks produced in the $t$-channel at $ \sqrt{s} $ = 13 TeV and bounds on the $tWb$ dipole operator from the ATLAS experiment

A simultaneous measurement of the three components of the top-quark and top-antiquark polarisation vectors in t-channel single-top-quark production is presented. This analysis is based on data from proton–proton collisions at a centre-of-mass energy of 13 TeV corresponding to an integrated luminosity of 139 fb –1 , collected with the ATLAS detector at the LHC. Selected events contain exactly one isolated electron or muon, large missing transverse momentum and exactly two jets, one being b-tagged. Stringent selection requirements are applied to discriminate t-channel single-top-quark events from the background contributions. The top-quark and top-antiquark polarisation vectors are measured from the distributions of the direction cosines of the charged-lepton momentum in the top-quark rest frame. The three components of the polarisation vector for the selected top-quark event sample are P x' = 0.01 ± 0.18, P y' = –0.029 ± 0.027, P z' = 0.91 ± 0.10 and for the top-antiquark event sample they are P x' = –0.02 ± 0.20, P y' = –0.007 ± 0.051, P z' = 0.79 ± 0.16. Normalised differential cross-sections corrected to a fiducial region at the stable-particle level are presented as a function of the charged-lepton angles for top-quark and top-antiquark events inclusively and separately. These measurements are in agreement with Standard Model predictions. The angular differential cross-sections are used to derive bounds on the complex Wilson coefficient of the dimension-six O tW operator in the framework of an effective field theory. The obtained bounds are C tW ϵ [–0.9, 1.4] and C itW ϵ [–0.8, 0.2], both at 95% confidence level.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Synchrotron light source X-ray detection with Low-Gain Avalanche Diodes

Abstract Low Gain Avalanche Diodes (LGADs) represent the state-of-the-art in timing measurements and will instrument the future Timing Detectors of ATLAS and CMS for the High-Luminosity LHC. While initially conceived as a sensor for charged particles, the intrinsic gain of LGADs makes it possible to detect low-energy X-rays with good energy resolution and excellent time resolution (tens of picoseconds). Using the Stanford Synchrotron Radiation Lightsource (SSRL) at SLAC, several LGADs designs were characterized with energies from 5 to 70 keV. The SSRL provides 10 ps pulsed X-ray bunches separated by 2 ns intervals with an energy dispersion (ΔE/E) of 10 -4 . LGADs from Hamamatsu Photonics (HPK) and Brookhaven National Laboratory (BNL) with different thicknesses ranging from 20 μm to 50 μm and different gain layer designs were read out using fast amplification boards and digitized with a high bandwidth and high sampling rate oscilloscope. PIN devices from HPK and AC-LGADs from BNL were characterized as well. A systematic and detailed characterization of the devices' energy linearity, resolution, and time resolution as a function of X-ray energy was performed for different biasing voltages at room temperature and are reported in this work. The charge collection and multiplication mechanism were simulated using Geant4 and TCAD Sentaurus, providing an important handle for interpreting the data.

Instruments & Instrumentation↗
DOE OSTI2024

Search for high-mass resonances in final states with a τ-lepton and missing transverse momentum with the ATLAS detector

A search for high-mass resonances decaying into a τ-lepton and a neutrino using proton-proton collisions at a center-of-mass energy of $\sqrt{s}$ =13 TeV is presented. The full run 2 data sample corresponding to an integrated luminosity of 139 fb -1 recorded by the ATLAS experiment in the years 2015–2018 is analyzed. The τ-lepton is reconstructed in its hadronic decay modes and the total transverse momentum carried out by neutrinos is inferred from the reconstructed missing transverse momentum. The search for new physics is performed on the transverse mass between the τ-lepton and the missing transverse momentum. No excess of events above the Standard Model expectation is observed and upper exclusion limits are set on the W' →τ⁢v production cross section. Heavy W' vector bosons with masses up to 5.0 TeV are excluded at 95% confidence level, assuming that they have the same couplings as the Standard Model W boson. For nonuniversal couplings, W' bosons are excluded for masses less than 3.5–5.0 TeV, depending on the model parameters. In addition, model-independent limits on the visible cross section times branching ratio are determined as a function of the lower threshold on the transverse mass of the τ-lepton and missing transverse momentum.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Production and tests of the ADDC for the Micromegas detector of the ATLAS New Small Wheel

The Large Hadron Collider (LHC) at CERN will perform a series of upgrades to allow luminosity increases during the next physics runs expected from 2022 on. These will also significantly increase the trigger rates of all the detectors. As part of the ATLAS Phase-I upgrade, the current Small Wheel muon detectors will be replaced with state-of-the-art New Small Wheel (NSW) detectors to cope with the increased luminosity of the LHC. The Address in Real Time Data Driver Card (ADDC) is designed to transmit the trigger data from the resistive Micro-Mesh Gaseous Structure (Micromegas) detectors of the NSW. The ART ASIC on the ADDC is a customdesigned chip to receive theAddress in Real Time (ART) signals from theVMMfront-end ASIC and perform hit-selection processing. The processed trigger data is then sent to the Trigger Processor (TP) through optical links. A total of 512 ADDCs will be installed on the detector close to the front-end boards. Therefore, those cards must be able to work properly in a high radiation and magnetic field environment. Furthermore, after four rounds of prototyping, the ADDC production was launched in January of 2019. 600 ADDC boards have been produced and tested with an automated test stand. This test setup can simulate the front-end signals and provide "Level-1 Data Driver Card" (L1DDC) functions as well as part of the TP functions. Thus, the ADDC functionality and stability can be verified without the remaining NSW electronics. This paper describes the ADDC hardware prototype development, radiation and integration testing, and the ADDC automated production test procedure.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗