Sökning: "Natural experiment"

Visar resultat 21 - 25 av 1474 avhandlingar innehållade orden Natural experiment.

1. 21. Spatial and temporal aspects of intense attosecond pulses for pump-probe experiments

   Författare :Hampus Wikmark; Atomfysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; ultrafast lasers; ultrafast optics; attosecond pulses; pump-probe experiments; XUV light; XUV focusing; wavefront sensing; XUV optics; X-ray optics; Fysicumarkivet A:2019:Wikmark; ultrasnabba lasrar; attosekundspulser; pump-prob-experiment; XUV-ljus; vågfrontmätningar; XUV-optik; Röntgen-optik;

   Sammanfattning : Nuclear and electronic dynamics in atoms and molecules are the foundation of many physical processes and chemical reactions. Often, these dynamics take place on timescales so much shorter than those commonly encountered that they are called ultrafast. LÄS MER

3. 22. Semi-natural meadows in southern Sweden - changes over time and the relationship between nitrogen supply and management

   Författare :Gudrun A I Berlin; Biologiska institutionen; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Plant community dynamic; Nitrogen; Mowing; Meadows; Management; Long-term study; Landscape changes; Field experiment; Community diversity; Fertilisation; Species changes; Species turnover; Plant ecology; Växtekologi;

   Sammanfattning : In this thesis, I have studied continuously managed semi-natural meadows in south-central Sweden. The purpose was 1) to make a survey of meadow vegetation in the region 2) to compare two investigations of the vegetation, one from 1963-1966 and one from 1990 3) to investigate experimentally in the field how increased nitrogen supply rate as well as changed management intensity effects the nitrogen economy and species richness in two meadow communities. LÄS MER

4. 23. Calibration of b-tagging and search for Dark Matter : Calibration of b-tagging efficiency and search for Dark Matter production in association with heavy flavour quarks with the ATLAS experiment

   Författare :Anna Shcherbakova; Sara Strandberg; Oscar Gonzalez Lopez; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; ATLAS; ATLAS experiment; physics analysis; LHC; Large Hadron Collider; Dark Matter; b-tagging; fysik; Physics;

   Sammanfattning : The Large Hadron Collider (LHC) is the most powerful and complex particle accelerator ever built. The ATLAS and the CMS are the two multipurpose particle detectors at the LHC, designed to cover a wide range of physics measurements. LÄS MER

5. 24. Three Pion Interferometry in the NA44 Experiment

   Författare :Janus Schmidt-Sörensen; Kärnfysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; quantum field theory; heavy-ion physics; bose-einstein; Elementary particle physics; interferometry; Elementarpartikelfysik; kvantfältteori; Fysicumarkivet A:1999:Schmidt-Sörensen;

   Sammanfattning : This thesis presents a three-particle correlation analysis with pions originating from Sulphur-Lead and Lead-Lead collisions at 200 and 158 GeV/c per nucleon respectively, taken by the CERN heavy-ion experiment NA44. The genuine three-body correlation is suppressed in both colliding systems which indicates that the particle production source is partly coherent. LÄS MER

7. 25. Single-Photon Events in the DELPHI Experiment

   Författare :Elisabeth Falk; Partikel- och kärnfysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; kvantfältteori; Elementarpartikelfysik; quantum field theory; DELPHI; STIC; LEP; single-photon events; PS; off-energy electrons; silicon-strip detector; coherent noise; emittance; Elementary particle physics; fast wire scanner; High energy interactions; cosmic rays; Kosmisk strålning; högenergi; Fysicumarkivet A:1998:Falk Harris;

   Sammanfattning : A series of studies pertaining to the STIC calorimeter at the DELPHI experiment at LEP is presented, and a new generation of fast wire scanners for emittance measurements at PS is described. The STIC studies are centered around a single-photon analysis, in which the reaction e+ e- -> gamma + invisible particles was studied at center-of-mass energies of 161, 172 and 183 GeV. LÄS MER