Sökning: "luminosity function"

Visar resultat 1 - 5 av 16 avhandlingar innehållade orden luminosity function.

1. 1. The faintest stars : A study of white, red and brown dwarfs

   Författare :Leif Festin; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; brown dwarfs; white dwarfs; M dwarf; low luminosity; luminosity function; mass function; Pleiades; Astronomi; Astronomy and astrophysics; Astronomi och astrofysik; astronomi; Astronomy;

   Sammanfattning : The local space density of the faintest stars, including M dwarfs, white dwarfs and brown dwarfs has been studied by two different methods.By using dark nebulae as opaque outer screens, the luminosity functions of M dwarfs and white dwarfs were studied as volume-limited and dynamically unbiassed foreground samples. LÄS MER

3. 2. Crowded Field Photometry and Luminosity Function Analysis as Probes of Galactic Evolution

   Författare :Ralph Snel; Astronomi - Genomgår omorganisation; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; observational; Methods: data analysis; statistical - Techniques: photometric - Stars: luminosity function; imaging; evolution - Galaxies: stellar content; mass function; space research; cosmic chemistry; Astronomi; rymdvetenskap; kosmisk kemi; Fysicumarkivet A:1998:Snel;

   Sammanfattning : Crowded field photometry is a powerful method to investigate stellar evolutionary processes in astrophysically interesting regions such as nearby external galaxies and globular cluster cores. While detectors are approaching the physical limits for photon detection, data analysis methods for crowded stellar fields are not yet equally sophisticated. LÄS MER

4. 3. Hadronic Structure Measurements of the Photon by DELPHI at LEP II

   Författare :Andreas Nygren; Partikel- och kärnfysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Elementarpartikelfysik; DELPHI; LEP; VSAT; luminosity; two-photon physics; cross section; double tag; bhabha; background; structure function; kvantfältteori; quantum field theory; Elementary particle physics; Fysicumarkivet A:2001:Nygren;

   Sammanfattning : This thesis is mainly an analysis of data taken by the VSAT detector in the DELPHI experiment at the LEP II collider at CERN. The analysis spans from 1998 to 2000, with a center of mass energy ranging from 189 to 206 GeV. LÄS MER

5. 4. Luminosity evaluation and fragmentation studies for the DELPHI experiment at LEP

   Författare :Christina Zacharatou Jarlskog; Partikel- och kärnfysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; luminosity; hadronization; Z boson; strong coupling constant; Elementary particle physics; Elementarpartikelfysik; quantum field theory; Fysicumarkivet A:2001:Jarlskog; LEP; DELPHI; kvantfältteori; Physics; Fysik;

   Sammanfattning : The first subject addressed in this thesis is the contribution of the VSAT luminosity to the lineshape analysis, i.e. to the extraction of the mass and width of the Z0 boson from LEP1 DELPHI data. The VSAT detector has contributed to the lineshape parameter determination by providing a relative luminosity measurement of high accuracy. LÄS MER

7. 5. Measurements of luminosity and a search for dark matter in the ATLAS experiment

   Författare :Patrawan Pasuwan; Sara Strandberg; Christophe Clement; Erin O'Sullivan; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; particle physics; ATLAS; luminosity; track counting; dark matter; simplified model; fysik; Physics;

   Sammanfattning : This licentiate thesis presents contributions to the luminosity measurement from the data recorded by the ATLAS detector in 2017 using a track-counting technique, as well as a search for dark matter in the ATLAS experiment using 139 fb-1 of √s = 13 TeV pp collision data delivered by the LHC from 2015 to 2018. Track-counting luminosity measurements in low-luminosity operations are performed to study the effect of low collision rates on luminosity determination. LÄS MER