257 research outputs found
Scintillation hodoscopes for time-of-flight measurements
No full textThe performances of the TOF scintillation counters used in the SIGMA-AIAKS spectrometer are presented. The counters, made of NE110, are 150, 65 and 10 cm long, 10 cm wide and 1.5 cm thick. The time resolutions for minimum ionizing particles have been measured to be σt = 0.18 ns, 0.14 ns and 0.11 ns respectively. The main contribution to the resolution is given by the photoe collection statistics determined by the decay time of the scintillator and the difference of the optical paths in the counter. The scintillation counters, assembled into hodoscopes of 1.5 × 3.2 m2 and 0.65 × 0.8 m2 are used for identification of particles through the TOF. The algorithms of off-line data processing are also presented
Particulate matter emissions from biochar-amended soils as a potential tradeoff to the negative emission potential
No full text© 2016 The Author(s). Novel carbon sequestration strategies such as large-scale land application of biochar may provide sustainable pathways to increase the terrestrial storage of carbon. Biochar has a long residence time in the soil and hence comprehensive studies are urgently needed to quantify the environmental impacts of large-scale biochar application. In particular, black carbon emissions from soils amended with biochar may counteract the negative emission potential due to the impacts on air quality, climate, and biogeochemical cycles. We investigated, using wind tunnel experiments, the particulate matter emission potential of a sand and two agriculturally important soils amended with different concentrations of biochar, in comparison to control soils. Our results indicate that biochar application considerably increases particulate emissions possibly by two mechanisms-the accelerated emission of fine biochar particles and the generation and emission of fine biochar particles resulting from abrasion of large biochar particles by sand grains. Our study highlights the importance of considering the background soil properties (e.g., texture) and geomorphological processes (e.g., aeolian transport) for biochar-based carbon sequestration programs
Experimental Study of the Radiative Scattering PI-P-]PI-P-gamma at 43 GEV
No full textThe pion radiative scattering (x-p + x-py) has been studied at 43 GeV in the interval 0.2 lt, l 0.4 (GeV/c)2 of the momentum transfer squared to the proton and in the range of photon energy 2 < w < 40 GeV. Calculations based on Low theorem agree well with measured w, t, and m, (final xy-invariant mass) differential cross-sections. The results obtained extend the validity of Low approach to the radiative scattering at high energies
Direct Observation of PI-2(1680) in the RHO-0-PI-System
No full textIn the reaction of x- dissociation into a p+p-z'- system on a Cu nucleus, a clear enhancement in the poz- effective-mass distribution has been observed in the 1;2( 1680) region. Partial-wave analysis shows that this enhancement is due to the P-wave and has a resonant nature. Coherent and incoherent cross-sections for this enhancement have been measured
Search for single top quark production via contact interactions at LEP2
No full textSingle top quark production via four-fermion contact interactions associated to flavour-changing neutral currents was searched for in data taken by the DELPHI detector at LEP2. The data were accumulated at centre-ofmass energies ranging from 189 to 209 GeV, with an integrated luminosity of 598.1 pb−1. No evidence for a signal was found. Limits on the energy scale Λ, were set for scalar-, vector- and tensor-like coupling scenarios. © The Author(s) 2011
Study of the dependence of direct soft photon production on the jet characteristics in hadronic Z0 decays
No full textAn analysis of the direct soft photon production rate as a function of the parent jet characteristics is presented, based on hadronic events collected by the DELPHI experiment at LEP1. The dependences of the photon rates on the jet kinematic characteristics (momentum, mass, etc.) and on the jet charged, neutral and total hadron multiplicities are reported. Up to a scale factor of about four, which characterizes the overall value of the soft photon excess, a similarity of the observed soft photon behavior to that of the inner hadronic bremsstrahlung predictions is found for the momentum, mass, and jet charged multiplicity dependences. However for the dependence of the soft photon rate on the jet neutral and total hadron multiplicities a prominent difference is found for the observed soft photon signal as compared to the expected bremsstrahlung from final state hadrons. The observed linear increase of the soft photon production rate with the jet total hadron multiplicity and its strong dependence on the jet neutral multiplicity suggest that the rate is proportional to the number of quark pairs produced in the fragmentation process, with the neutral pairs being more effectively radiating than the charged ones. © 2010 The Author(s)
A study of the b-quark fragmentation function with the DELPHI detector at LEP I and an averaged distribution obtained at the Z Pole
No full textThe nature of b-quark jet hadronisation has been investigated using data taken at the Z peak by the DELPHI detector at LEP. Two complementarymethods are used to reconstruct the energy of weakly decaying b-hadrons, EweakB. The average value of xweakB = EweakB/Ebeam is measured to be 0.699 ± 0.011. The resulting xweakB distribution is then analysed in the framework of two choices for the perturbative contribution (parton shower and Next to Leading Log QCD calculation) in order to extract measurements of the non-perturbative contribution to be used in studies of bhadron production in other experimental environments than LEP. In the parton shower framework, data favour the Lund model ansatz and corresponding values of its parameters have been determined within PYTHIA 6.156 from DELPHI data: a=1.84+0.23-0.21 and b=0.642+0.073-0.063 GeV-2, with a correlation factor ρ=92.2%. Combining the data on the b-quark fragmentation distributions with those obtained at the Z peak by ALEPH, OPAL and SLD, the average value of xweakB is found to be 0.7092 ± 0.0025 and the non-perturbative fragmentation component is extracted. Using the combined distribution, a better determination of the Lund parameters is also obtained: a = 1.48+0.11-0.10 and b = 0.509+0.024-0.023 GeV-2, with a correlation factor ρ 92.6%. © The Author(s) 2011
Searches for invisibly decaying Higgs bosons with the DELPHI detector at LEP
No full textGeneral rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Download date: 29 Jun 2019 Digital Object Identifier (DOI) 10.1140/epjc/s2003-01469-8 Eur. Phys. J. C 32, 475-492 (2004) Abstract. Searches for HZ production with the Higgs boson decaying into an invisible final state were performed using the data collected by the DELPHI experiment at centre-of-mass energies between 188 GeV and 209 GeV. Both hadronic and leptonic final states of the Z boson were analysed. In addition to the search for a heavy Higgs boson, a dedicated search for a light Higgs boson down to 40 GeV/c 2 was performed. No signal was found. Assuming the Standard Model HZ production cross-section, the mass limit for invisibly decaying Higgs bosons is 112.1 GeV/c 2 at 95% confidence level. An interpretation in the Minimal Supersymmetric extension of the Standard Model (MSSM) and in a Majoron model is also given
Kaon interference in the hadronic decays of the Z
No full textLink to publication Citation for published version (APA): Abreu, P., Agasi, E. E., Boudinov, E., Hao, W., Holthuizen, D. J., Kluit, P. M., ... van Eldik, J. E. (1996). Kaon interference in the hadronic decays of the Z. Physics Letters B, 379, 330. https://doi.org/10.1016/0370-2693(96)00572-2 General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. EB ELSEWJER PHYSICS LETTERS B Physics Letters B 379 (1996) [330][331][332][333][334][335][336][337][338][339][340] Kaon interference in the hadronic decays of the Z" Abstract The first measurement of like-sign charged kaon correlations in hadronic decays of the p is presented, based on data collected by the DELPHI detector. The charged kaons are identified by means of ring imaging Cherenkov detectors. A significant enhancement at small values of the four:momentum difference is observed in the ratio of like-sign to unlikesign KK pairs and in the ratio of like-sign pairs to a simulated reference sample. An update of the measurement of KiK:!, interference is also presented. An enhancement is found in the production of pairs of Ki of similar momenta, as compared with a simulated reference sample. The measured Bose-Einstein correlation parameters A and r are similar for charged and neutral kaon pairs. The value of the Bose-Einstein correlation strength A is consistent with unity. ' On leave of absence from IHEP Serpukhov
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