92 research outputs found

    Investigation into leaching of phenol and methylphenols applying the column test and the serial batch test

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    Within the framework of the Terms of Reference Plan for normalization commission 39011 on Leaching characteristics of building and waste materials, the National Institute of Public Health and the Environment (RIVM) is developing a set of leaching tests for various organic compounds. Laboratory investigations were performed for leaching tests of phenol and methylphenols (cresols) to assess the practical feasibility of the experimental set-up, the level of emissions and the reproducibility of the experiments. Additional experiments were performed to investigate the losses of phenols during the test. Leaching tets for phenols, based on Dutch pre-NVN 7344 and 7350, were performed on four different soils. The materials contained high levels of contaminants to ensure detectable leached quantities. With reference to the performance, the methods could be applied for phenols as well. In three of the soils, a high emission could be observed, especially in the first fractions of the eluates. For one soil, no leaching was found at all. Apparently, the phenols were not available as a result of an unknown characteristic element in that specific soil. The levels of emission from the (highly contaminated) materials were high in the range from 30 to 60 % relative to the soil concentrations. Levels were higher than ealier was found for PCBs and EOX, probably as a result of the higher water solubility of the phenols. Standard deviations (n=2) were good for most leaching test (2-20%).In het kader van het Taakstellend Plan ter ondersteuning van de normcommissie 390 11 Uitloogkarakterisering van bouw- en afvalstoffen (TSP), is onderzoek uitgevoerd ten behoeve van de uitloogproeven voor fenol en cresolen (methylfenolen).Uitloogproeven voor fenolen, gebaseerd op de ontwerpnormen 7344 en 7350 (kolom- en cascadeproeven voor PAK's, PCB's en EOX), zijn in tweevoud uitgevoerd op een viertal verschillende grondmonsters. Dit betrof in alle gevallen grondmonsters, omdat in de praktijk geen andere bouw- en afvalstoffen met fenolen-verontreiniging beschikbaar waren. Voor de onderzochte materialen is gekozen voor een hoog gehalte van de te onderzoeken contaminanten, omdat hierdoor gewaarborgd is, dat in de eluaten van de uitloogproeven voldoende hoge concentraties gemeten kunnen worden. Het doel van de werkzaamheden was gelegen in het vaststellen van de praktische uitvoerbaarheid van de proef, het niveau van de emissies en de herhaalbaarheid van de proef. In technisch opzicht blijken de ontwerpvoornormen praktisch uitvoerbaar. Het vooronderzoek naar het verliezen van fenolen aan onderdelen of gebruikte materialen van de proefopstellingen tijdens de uitvoering van de uitloogproeven, gaf aan dat er geen verliezen optreden, zodat de bovenstaande normen zonder verdere aanpassingen gevolgd zijn. Het verlies van de fenolen, dat tijdens het materialenonderzoek op basis van de massabalans is geconstateerd, geeft wel aanleiding tot een aanpassing van de methodiek, met name in de opvang en conservering (koeling) van de verschillende frakties. De emissies van de fenolen, die bepaald zijn met de kolomproef, liggen voor de verschillende component-materiaal combinaties ten opzichte van de uitgangsconcentraties in de materialen in een gebied tussen 30 en 60%. Voor de cascadeproef liggen deze waarden gelijk of hoger tot 80-90%. De gevonden waarden zijn veel hoger dan die in voorafgaand RIVM onderzoek betreffende de stofgroepen PCB's en EOX zijn vastgesteld. Tevens blijken de fenolen steeds snel, in de eerste fraktie(s) uit te logen in gronden waarin deze op basis van de (grond)eigenschappen redelijk beschikbaar zijn. Dit kan grotendeels verklaard worden uit de hogere wateroplosbaarheid van de fenolen. De relatieve standaarddeviaties (RSD) van de in tweevoud uitgevoerd kolom- en cascadeproeven waren over het algemeen goed (2-20%). Er zijn onvoldoende materialen onderzocht om een algemene uitspraak te kunnen doen over de uitloging van fenolen, mede omdat bij drie van de vier uitloogproeven een zeer forse uitloging optrad en bij een materiaal in het geheel niet. In ieder geval lijkt het niet bepaald te worden door de kolomproef

    Measurement of the top-quark mass in tt¯ events with dilepton final states in pp collisions at √s = 7 TeV

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    Open Access: This article is distributed under the terms of the Creative Commons Attribution License.-- Chatrchyan, S. et al.The top-quark mass is measured in proton-proton collisions at s√=7 TeV using a data sample corresponding to an integrated luminosity of 5.0 fb−1 collected by the CMS experiment at the LHC. The measurement is performed in the dilepton decay channel tt¯→(ℓ+Μℓb)(â„“âˆ’ÎœÂŻÂŻâ„“bÂŻ), where ℓ=e,ÎŒ. Candidate top-quark decays are selected by requiring two leptons, at least two jets, and imbalance in transverse momentum. The mass is reconstructed with an analytical matrix weighting technique using distributions derived from simulated samples. Using a maximum-likelihood fit, the top-quark mass is determined to be 172.5±0.4 (stat.)±1.5 (syst.) GeV.Acknowledge support from BMWF and FWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); MoER, SF0690030s09 and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland); CEA and CNRS/IN2P3 (France);BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); MSI (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MON, RosAtom, RAS and RFBR (Russia); MSTD (Serbia); SEIDI and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); ThEP, IPST and NECTEC (Thailand); TUBITAK and TAEK (Turkey); NASU (Ukraine); STFC (United Kingdom); DOE and NSF (USA). Individuals have received support from the Marie-Curie program and the European Research Council (European Union); the Leventis Foundation; the A. P. Sloan Foundation; the Alexander von Humboldt Foundation; the Austrian Science Fund (FWF); the Belgian Federal Science Policy Office; the Fonds pour la Formation Ă  la Recherche dans l’Industrie et dans l’Agriculture (FRIA-Belgium); the Agentschap voor Innovatie door Wetenschap en Technologie (IWTBelgium); the Ministry of Education, Youth and Sports (MEYS) of Czech Republic; the Council of Science and Industrial Research, India; the Compagnia di San Paolo (Torino); and the HOMING PLUS program of Foundation for Polish Science, cofinanced from European Union, Regional Development Fund.Peer Reviewe

    Search for invisible decays of the Higgs boson produced via vector boson fusion in proton-proton collisions at root s=13 TeV

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    Search for Higgs Boson Pair Production in the Four b Quark Final State in Proton-Proton Collisions at root s=13 TeV

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    Measurement of the Higgs boson width and evidence of its off-shell contributions to ZZ production

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    Since the discovery of the Higgs boson in 2012, detailed studies of its properties have been ongoing. Besides its mass, its width—related to its lifetime—is an important parameter. One way to determine this quantity is to measure its off-shell production, where the Higgs boson mass is far away from its nominal value, and relating it to its on-shell production, where the mass is close to the nominal value. Here we report evidence for such off-shell contributions to the production cross-section of two Z bosons with data from the CMS experiment at the CERN Large Hadron Collider. We constrain the total rate of the off-shell Higgs boson contribution beyond the Z boson pair production threshold, relative to its standard model expectation, to the interval [0.0061, 2.0] at the 95% confidence level. The scenario with no off-shell contribution is excluded at a p-value of 0.0003 (3.6 standard deviations). We measure the width of the Higgs boson as ΓH=3.2+2.4−1.7MeV, in agreement with the standard model expectation of 4.1 MeV. In addition, we set constraints on anomalous Higgs boson couplings to W and Z boson pairs

    Performance of the CMS muon trigger system in proton-proton collisions at root s=13 TeV

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    The muon trigger system of the CMS experiment uses a combination of hardware and software to identify events containing a muon. During Run 2 (covering 2015–2018) the LHC achieved instantaneous luminosities as high as 2 × 1034 while delivering proton-proton collisions at √(s) = 13. The challenge for the trigger system of the CMS experiment is to reduce the registered event rate from about 40MHz to about 1kHz. Significant improvements important for the success of the CMS physics program have been made to the muon trigger system via improved muon reconstruction and identification algorithms since the end of Run 1 and throughout the Run 2 data-taking period. The new algorithms maintain the acceptance of the muon triggers at the same or even lower rate throughout the data-taking period despite the increasing number of additional proton-proton interactions in each LHC bunch crossing. In this paper, the algorithms used in 2015 and 2016 and their improvements throughout 2017 and 2018 are described. Measurements of the CMS muon trigger performance for this data-taking period are presented, including efficiencies, transverse momentum resolution, trigger rates, and the purity of the selected muon sample. This paper focuses on the single- and double-muon triggers with the lowest sustainable transverse momentum thresholds used by CMS. The efficiency is measured in a transverse momentum range from 8 to several hundred

    Observation of triple J/ψ meson production in proton-proton collisions

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    Data availability: Tabulated results are provided in the HEPData record for this analysis71. Release and preservation of data used by the CMS Collaboration as the basis for publications is guided by the CMS policy as stated in CMS data preservation, re-use and open access policy.Code availability: The CMS core software is publically available at https://github.com/cms-sw/cmssw.Copyright . Protons consist of three valence quarks, two up-quarks and one down-quark, held together by gluons and a sea of quark-antiquark pairs. Collectively, quarks and gluons are referred to as partons. In a proton-proton collision, typically only one parton of each proton undergoes a hard scattering – referred to as single-parton scattering – leaving the remainder of each proton only slightly disturbed. Here, we report the study of double- and triple-parton scatterings through the simultaneous production of three J/ψ mesons, which consist of a charm quark-antiquark pair, in proton-proton collisions recorded with the CMS experiment at the Large Hadron Collider. We observed this process – reconstructed through the decays of J/ψ mesons into pairs of oppositely charged muons – with a statistical significance above five standard deviations. We measured the inclusive fiducial cross-section to be 272+141−104(stat)±17(syst)fb, and compared it to theoretical expectations for triple-J/ψ meson production in single-, double- and triple-parton scattering scenarios. Assuming factorization of multiple hard-scattering probabilities in terms of single-parton scattering cross-sections, double- and triple-parton scattering are the dominant contributions for the measured process.SCOAP3.Change history: 27 February 2023A Correction to this paper has been published: https://doi.org/10.1038/s41567-023-01992-
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