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265 records · Page 15
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on K2H2OsCCl5O2 by Materials Project

K4Os2CH4O3Cl10CO crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional and consists of four formaldehyde molecules and one K4Os2CH4O3Cl10 framework. In the K4Os2CH4O3Cl10 framework, there are four inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 7-coordinate geometry to two O2- and five Cl1- atoms. There are one shorter (2.64 Å) and one longer (2.82 Å) K–O bond lengths. There are a spread of K–Cl bond distances ranging from 3.08–3.37 Å. In the second K1+ site, K1+ is bonded in a 9-coordinate geometry to nine Cl1- atoms. There are a spread of K–Cl bond distances ranging from 3.17–3.79 Å. In the third K1+ site, K1+ is bonded in a 2-coordinate geometry to two O2- and seven Cl1- atoms. There are one shorter (2.69 Å) and one longer (2.74 Å) K–O bond lengths. There are a spread of K–Cl bond distances ranging from 3.12–3.67 Å. In the fourth K1+ site, K1+ is bonded in a 10-coordinate geometry to ten Cl1- atoms. There are a spread of K–Cl bond distances ranging from 3.16–3.85 Å. There are two inequivalent Os1+ sites. In the first Os1+ site, Os1+ is bonded in a distorted square pyramidal geometry to five Cl1- atoms. There are a spread of Os–Cl bond distances ranging from 2.36–2.49 Å. In the second Os1+ site, Os1+ is bonded in a distorted square pyramidal geometry to five Cl1- atoms. There are a spread of Os–Cl bond distances ranging from 2.36–2.52 Å. C4+ is bonded in a single-bond geometry to one O2- atom. The C–O bond length is 1.17 Å. There are four inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted water-like geometry to two K1+ and two H1+ atoms. In the second O2- site, O2- is bonded in a distorted water-like geometry to two K1+ and two H1+ atoms. In the third O2- site, O2- is bonded in a single-bond geometry to one C4+ and one Cl1- atom. The O–Cl bond length is 3.27 Å. There are ten inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a 1-coordinate geometry to three K1+ and one Os1+ atom. In the second Cl1- site, Cl1- is bonded in a 4-coordinate geometry to three K1+ and one Os1+ atom. In the third Cl1- site, Cl1- is bonded in a 4-coordinate geometry to three K1+ and one Os1+ atom. In the fourth Cl1- site, Cl1- is bonded in a 5-coordinate geometry to four K1+ and one Os1+ atom. In the fifth Cl1- site, Cl1- is bonded in a 6-coordinate geometry to four K1+, one Os1+, and one O2- atom. In the sixth Cl1- site, Cl1- is bonded in a 3-coordinate geometry to two K1+ and one Os1+ atom. In the seventh Cl1- site, Cl1- is bonded in a 1-coordinate geometry to three K1+ and one Os1+ atom. In the eighth Cl1- site, Cl1- is bonded in a 4-coordinate geometry to three K1+ and one Os1+ atom. In the ninth Cl1- site, Cl1- is bonded in a 1-coordinate geometry to four K1+ and one Os1+ atom. In the tenth Cl1- site, Cl1- is bonded in a 1-coordinate geometry to two equivalent K1+ and one Os1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Long-lived biνo at the LHC

We examine the detection prospects for a long-lived bi ν o, a pseudo-Dirac bino which is responsible for neutrino masses, at the LHC and at dedicated long-lived particle detectors. The bi ν o arises in U(1) R -symmetric supersymmetric models where the neutrino masses are generated through higher dimensional operators in an inverse seesaw mechanism. At the LHC the bi ν o is produced through squark decays and it subsequently decays to quarks, charged leptons and missing energy via its mixing with the Standard Model neutrinos. We consider long-lived bi ν os which escape the ATLAS or CMS detectors as missing energy and decay to charged leptons inside the proposed long-lived particle detectors FASER, CODEX-b, and MATHUSLA. We find the currently allowed region in the squark-bi ν o mass parameter space by recasting most recent LHC searches for jets+. We also determine the reach of MATHUSLA, CODEX-b and FASER. We find that a large region of parameter space involving squark masses, bi ν o mass and the messenger scale can be probed with MATHUSLA, ranging from bi ν o masses of 10 GeV-2 TeV and messenger scales 10 2 - 11 TeV for a range of squark masses.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Materials Data on OsN5Cl3 by Materials Project

(OsN)2N2(N2Cl)2(NCl2)2 crystallizes in the orthorhombic Pnma space group. The structure is zero-dimensional and consists of four ammonia molecules, four azanylidyneosmium molecules, four dichloramine molecules, and four N2Cl clusters. In each N2Cl cluster, N+0.20+ is bonded in a single-bond geometry to one Cl1- atom. The N–Cl bond length is 1.70 Å. Cl1- is bonded in a linear geometry to two equivalent N+0.20+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K2H3OsN2O7 by Materials Project

(K2OsN2O7)2(H2)3 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional and consists of twelve hydrogen molecules and one K2OsN2O7 framework. In the K2OsN2O7 framework, there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of K–O bond distances ranging from 2.76–2.87 Å. In the second K1+ site, K1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of K–O bond distances ranging from 2.70–3.02 Å. Os7+ is bonded to four O2- atoms to form distorted edge-sharing OsO4 trigonal pyramids. There are a spread of Os–O bond distances ranging from 1.77–1.97 Å. There are two inequivalent N1+ sites. In the first N1+ site, N1+ is bonded in a bent 120 degrees geometry to two O2- atoms. Both N–O bond lengths are 1.26 Å. In the second N1+ site, N1+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.25 Å) and one longer (1.27 Å) N–O bond length. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a water-like geometry to two equivalent Os7+ atoms. In the second O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent K1+ and one N1+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to one K1+ and one N1+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to two K1+ and one N1+ atom. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to two K1+ and one Os7+ atom. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to three K1+ and one N1+ atom. In the seventh O2- site, O2- is bonded in a distorted single-bond geometry to two K1+ and one Os7+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Climate model projections from the Scenario Model Intercomparison Project (ScenarioMIP) of CMIP6

Abstract. The Scenario Model Intercomparison Project (ScenarioMIP) defines and coordinates the main set of future climate projections, based on concentration-driven simulations, within the Coupled Model Intercomparison Project phase 6 (CMIP6). This paper presents a range of its outcomes by synthesizing results from the participating global coupled Earth system models. We limit our scope to the analysis of strictly geophysical outcomes: mainly global averages and spatial patterns of change for surface air temperature and precipitation. We also compare CMIP6 projections to CMIP5 results, especially for those scenarios that were designed to provide continuity across the CMIP phases, at the same time highlighting important differences in forcing composition, as well as in results. The range of future temperature and precipitation changes by the end of the century (2081–2100) encompassing the Tier 1 experiments based on the Shared Socioeconomic Pathway (SSP) scenarios (SSP1-2.6, SSP2-4.5, SSP3-7.0 and SSP5-8.5) and SSP1-1.9 spans a larger range of outcomes compared to CMIP5, due to higher warming (by close to 1.5 ∘C) reached at the upper end of the 5 %–95 % envelope of the highest scenario (SSP5-8.5). This is due to both the wider range of radiative forcing that the new scenarios cover and the higher climate sensitivities in some of the new models compared to their CMIP5 predecessors. Spatial patterns of change for temperature and precipitation averaged over models and scenarios have familiar features, and an analysis of their variations confirms model structural differences to be the dominant source of uncertainty. Models also differ with respect to the size and evolution of internal variability as measured by individual models' initial condition ensemble spreads, according to a set of initial condition ensemble simulations available under SSP3-7.0. These experiments suggest a tendency for internal variability to decrease along the course of the century in this scenario, a result that will benefit from further analysis over a larger set of models. Benefits of mitigation, all else being equal in terms of societal drivers, appear clearly when comparing scenarios developed under the same SSP but to which different degrees of mitigation have been applied. It is also found that a mild overshoot in temperature of a few decades around mid-century, as represented in SSP5-3.4OS, does not affect the end outcome of temperature and precipitation changes by 2100, which return to the same levels as those reached by the gradually increasing SSP4-3.4 (not erasing the possibility, however, that other aspects of the system may not be as easily reversible). Central estimates of the time at which the ensemble means of the different scenarios reach a given warming level might be biased by the inclusion of models that have shown faster warming in the historical period than the observed. Those estimates show all scenarios reaching 1.5 ∘C of warming compared to the 1850–1900 baseline in the second half of the current decade, with the time span between slow and fast warming covering between 20 and 27 years from present. The warming level of 2 ∘C of warming is reached as early as 2039 by the ensemble mean under SSP5-8.5 but as late as the mid-2060s under SSP1-2.6. The highest warming level considered (5 ∘C) is reached by the ensemble mean only under SSP5-8.5 and not until the mid-2090s.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Techno-economic assessment of emissions mitigation technologies for post-combustion CO2 capture using AMP/PZ

Minimizing the environmental impacts of amine-based post-combustion carbon capture technologies is essential for meeting environmental permitting regulations and ensuring public acceptance. Experimental test campaigns at the CO₂ capture pilot plant in Niederaussem using CESAR1 demonstrated that integrating available emission abatement technologies can significantly reduce the concentration of amines and degradation products in CO₂-depleted flue gas to below the detection limit of an infrared spectrometer. The study confirmed that proprietary dry bed technology (OEASE Aerozone™) or a second water wash can lower AMP and PZ emissions to below 1 mg/Nm³. However, to achieve very low NH₃ emissions below 2 mg/Nm³, an acid or other chemically active wash downstream of the water wash is required. A configuration with a dry bed or a double water wash results in a carbon capture cost (CCC) of 44 €/tCO₂, and a CO₂ avoided cost (CAC) of 86 €/tCO₂. A configuration with an acid wash increases the CCC to 47 €/tCO₂ and the CAC to 90 €/tCO₂ due to the amine losses in the acid waste and its treatment.

CO2 capture↗
DOE OSTI2020

Materials Data on Te7OsO5F32 by Materials Project

OsTe6O5F27TeF5 crystallizes in the triclinic P-1 space group. The structure is one-dimensional and consists of two TeF5 clusters and two OsTe6O5F27 ribbons oriented in the (0, 1, 0) direction. In each TeF5 cluster, Te+4.86+ is bonded in a square pyramidal geometry to five F1- atoms. There are a spread of Te–F bond distances ranging from 1.87–1.96 Å. There are five inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the second F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the third F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the fourth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the fifth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In each OsTe6O5F27 ribbon, Os8+ is bonded in a 6-coordinate geometry to five O2- and one F1- atom. There are a spread of Os–O bond distances ranging from 1.68–1.94 Å. The Os–F bond length is 2.34 Å. There are six inequivalent Te+4.86+ sites. In the first Te+4.86+ site, Te+4.86+ is bonded in a 3-coordinate geometry to three F1- atoms. There are a spread of Te–F bond distances ranging from 1.93–2.41 Å. In the second Te+4.86+ site, Te+4.86+ is bonded in a 4-coordinate geometry to four F1- atoms. There are a spread of Te–F bond distances ranging from 1.87–2.18 Å. In the third Te+4.86+ site, Te+4.86+ is bonded in an octahedral geometry to one O2- and five F1- atoms. The Te–O bond length is 1.96 Å. There are a spread of Te–F bond distances ranging from 1.87–1.89 Å. In the fourth Te+4.86+ site, Te+4.86+ is bonded in an octahedral geometry to one O2- and five F1- atoms. The Te–O bond length is 1.95 Å. There are a spread of Te–F bond distances ranging from 1.85–1.90 Å. In the fifth Te+4.86+ site, Te+4.86+ is bonded in an octahedral geometry to one O2- and five F1- atoms. The Te–O bond length is 1.96 Å. There are a spread of Te–F bond distances ranging from 1.87–1.90 Å. In the sixth Te+4.86+ site, Te+4.86+ is bonded in an octahedral geometry to one O2- and five F1- atoms. The Te–O bond length is 1.94 Å. There are a spread of Te–F bond distances ranging from 1.87–1.95 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one Os8+ and one Te+4.86+ atom. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Os8+ and one Te+4.86+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to one Os8+ and one Te+4.86+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one Os8+ atom. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to one Os8+ and one Te+4.86+ atom. There are twenty-seven inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ and one F1- atom. The F–F bond length is 2.55 Å. In the second F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ and one F1- atom. The F–F bond length is 2.91 Å. In the third F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the fourth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the fifth F1- site, F1- is bonded in a distorted single-bond geometry to one Te+4.86+ atom. In the sixth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the seventh F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the eighth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ and one F1- atom. The F–F bond length is 2.62 Å. In the ninth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the tenth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the eleventh F1- site, F1- is bonded in a distorted bent 120 degrees geometry to two Te+4.86+ atoms. In the twelfth F1- site, F1- is bonded in a 2-coordinate geometry to one Os8+ and one Te+4.86+ atom. In the thirteenth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the fourteenth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the fifteenth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the sixteenth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the seventeenth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the eighteenth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the nineteenth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the twentieth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the twenty-first F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the twenty-second F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ and one F1- atom. The F–F bond length is 2.83 Å. In the twenty-third F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the twenty-fourth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the twenty-fifth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the twenty-sixth F1- site, F1- is bonded in a 4-coordinate geometry to four F1- atoms. In the twenty-seventh F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Search for pairs of scalar leptoquarks decaying into quarks and electrons or muons in $ \sqrt{s}$ = 13 TeV pp collisions with the ATLAS detector

A search for new-physics resonances decaying into a lepton and a jet performed by the ATLAS experiment is presented. Scalar leptoquarks pair-produced in pp collisions at s = 13 TeV at the Large Hadron Collider are considered using an integrated luminosity of 139 fb-1, corresponding to the full Run 2 dataset. They are searched for in events with two electrons or two muons and two or more jets, including jets identified as arising from the fragmentation of c- or b-quarks. The observed yield in each channel is consistent with the Standard Model background expectation. Leptoquarks with masses below 1.8 TeV and 1.7 TeV are excluded in the electron and muon channels, respectively, assuming a branching ratio into a charged lepton and a quark of 100%, with minimal dependence on the quark flavour. Upper limits on the aforementioned branching ratio are also given as a function of the leptoquark mass.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

225 Ac-MACROPATATE: A Novel α-Particle Peptide Receptor Radionuclide Therapy for Neuroendocrine Tumors

Neuroendocrine tumors (NETs) express somatostatin receptors (SSTRs) 2 and 5. Modified variants of somatostatin, the cognate ligand for SSTR2 and SSTR5, are used in treatment for metastatic and locoregional disease. Peptide receptor radionuclide therapy with 177 Lu-DOTATATE (DOTA-octreotate), a β-particle–emitting somatostatin derivative, has demonstrated survival benefit in patients with SSTR-positive NETs. Despite excellent results, a subset of patients has tumors that are resistant to treatment, and alternative agents are needed. Targeted α-particle therapy has been shown to kill tumors that are resistant to targeted β-particle therapy, suggesting that targeted α-particle therapy may offer a promising treatment option for patients with 177 Lu-DOTATATE–resistant disease. Although DOTATATE can chelate the clinically relevant α-particle–emitting radionuclide 225 Ac, the labeling reaction requires high temperatures, and the resulting radioconjugate has suboptimal stability. Methods: We designed and synthesized MACROPATATE (MACROPA-octreotate), a novel radioconjugate capable of chelating 225 Ac at room temperature, and assessed its in vitro and in vivo performance. Results: MACROPATATE demonstrated comparable affinity to DOTATATE (dissociation constant, 21 nM) in U2-OS-SSTR2, a SSTR2-positive transfected cell line. 225 Ac-MACROPATATE demonstrated superior serum stability at 37°C over time compared with 225 Ac-DOTATATE. Biodistribution studies demonstrated higher tumor uptake of 225 Ac-MACROPATATE than of 225 Ac-DOTATATE in mice engrafted with subcutaneous H69 NETs. Therapy studies showed that 225 Ac-MACROPATATE exhibits significant antitumor and survival benefit compared with saline control in mice engrafted with SSTR-positive tumors. However, the increased accumulation of 225 Ac-MACROPATATE in liver and kidneys and subsequent toxicity to these organs decreased its therapeutic index compared with 225 Ac-DOTATATE. Conclusion: 225 Ac-MACROPATATE and 225 Ac-DOTATATE exhibit favorable therapeutic efficacy in animal models. Because of elevated liver and kidney accumulation and lower administered activity for dose-limiting toxicity of 225 Ac-MACROPATATE, 225 Ac-DOTATATE was deemed the superior agent for targeted α-particle peptide receptor radionuclide therapy.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2020

Electronic structure and photophysics of a supermolecular iron complex having a long MLCT-state lifetime and panchromatic absorption

Exploiting earth-abundant iron-based metal complexes as high-performance photosensitizers demands long-lived electronically excited metal-to-ligand charge-transfer (MLCT) states, but these species suffer typically from femtosecond timescale charge-transfer (CT)-state quenching by low-lying nonreactive metal-centered (MC) states. Here, we engineer supermolecular Fe(II) chromophores based on the bis(tridentate-ligand)metal(II)-ethyne-(porphinato)zinc(II) conjugated framework, previously shown to give rise to highly delocalized low-lying 3 MLCT states for other Group VIII metal (Ru, Os) complexes. Electronic spectral, potentiometric, and ultrafast pump–probe transient dynamical data demonstrate that a combination of a strong σ-donating tridentate ligand and a (porphinato)zinc(II) moiety with low-lying π*-energy levels, sufficiently destabilize MC states and stabilize supermolecular MLCT states to realize Fe(II) complexes that express 3 MLCT state photophysics reminiscent of their heavy-metal analogs. The resulting Fe(II) chromophore archetype, FeNHCPZn, features a highly polarized CT state having a profoundly extended 3MLCT lifetime (160 ps), 3 MLCT phosphorescence, and ambient environment stability. Density functional and domain-based local pair natural orbital coupled cluster [DLPNO-CCSD(T)] theory reveal triplet-state wavefunction spatial distributions consistent with electronic spectroscopic and excited-state dynamical data, further underscoring the dramatic Fe metal-to-extended ligand CT character of electronically excited FeNHCPZn. This design further prompts intense panchromatic absorptivity via redistributing high-energy absorptive oscillator strength throughout the visible spectral domain, while maintaining a substantial excited-state oxidation potential for wide-ranging photochemistry––highlighted by the ability of FeNHCPZn to photoinject charges into a SnO 2 /FTO electrode in a dye-sensitized solar cell (DSSC) architecture. Concepts enumerated herein afford opportunities for replacing traditional rare-metal–based emitters for solar-energy conversion and photoluminescence applications.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2020

Performance of the ATLAS muon triggers in Run 2

The performance of the ATLAS muon trigger system is evaluated with proton-proton ( pp ) and heavy-ion (HI) collision data collected in Run 2 during 2015–2018 at the Large Hadron Collider. It is primarily evaluated using events containing a pair of muons from the decay of Z bosons to cover the intermediate momentum range between 26 GeV and 100 GeV. Overall, the efficiency of the single-muon triggers is about 68% in the barrel region and 85% in the endcap region. The p T range for efficiency determination is extended by using muons from decays of J ψ mesons, W bosons, and top quarks. The performance in HI collision data is measured and shows good agreement with the results obtained in pp collisions. The muon trigger shows uniform and stable performance in good agreement with the prediction of a detailed simulation. Dedicated multi-muon triggers with kinematic selections provide the backbone to beauty, quarkonia, and low-mass physics studies. The design, evolution and performance of these triggers are discussed in detail.

47 OTHER INSTRUMENTATION↗
DOE OSTI2020

Materials Data on Ir2Os(NCl)10 by Materials Project

OsCl6(IrN3Cl2)2(N2)2 crystallizes in the monoclinic C2/m space group. The structure is zero-dimensional and consists of two hexachloroosmium molecules, four nitrogen molecules, and four IrN3Cl2 clusters. In each IrN3Cl2 cluster, Ir4+ is bonded in a tetrahedral geometry to three N+0.60- and one Cl1- atom. There is two shorter (1.73 Å) and one longer (2.00 Å) Ir–N bond length. The Ir–Cl bond length is 2.27 Å. There are two inequivalent N+0.60- sites. In the first N+0.60- site, N+0.60- is bonded in a bent 120 degrees geometry to one Ir4+ and one Cl1- atom. The N–Cl bond length is 1.67 Å. In the second N+0.60- site, N+0.60- is bonded in a single-bond geometry to one Ir4+ atom. There are two inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one N+0.60- atom. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one Ir4+ atom.

36 MATERIALS SCIENCE↗
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↗