Sökning: "Compton"

Visar resultat 16 - 20 av 25 avhandlingar innehållade ordet Compton.

1. 16. Microphysical Conditioning of Gamma-Ray Burst Shocks

   Författare :Jacob Trier Frederiksen; Claes Fransson; Åke Nordlund; Mikhail V. Medvedev; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; magnetic fields; particle acceleration; plasma instabilities; gamma-ray bursts; collisionless shocks; relativistic outflows; Astronomy and astrophysics; Astronomi och astrofysik; Astronomy; astronomi;

   Sammanfattning : Gamma-Ray Bursts (GRBs) are believed to be connected with either collapse of massive stars or – in some cases – coalescing neutron stars, both of which cause extreme relativistic explosions observable from the entire Universe. GRBs produce rapid flashes of high energy radiation, extending up to 2MeV in photon energies: as much energy per photon as the rest mass of 4 electrons. LÄS MER

3. 17. Monte Carlo particle transport codes for ion beam therapy treatment planning : Validation, development and applications

   Författare :Till Tobias Böhlen; Irena Gudowska; Oliver Jäkel; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Monte Carlo; ion beam therapy; treatment planning; cancer therapy; microdosimetry; Medical Radiation Physics; medicinsk strålningsfysik;

   Sammanfattning : External radiotherapy with proton and ion beams needs accurate tools for the dosimetric characterization of treatment fields. Monte Carlo (MC) particle transport codes, such as FLUKA and GEANT4, can be a valuable method to increase accuracy of dose calculations and to support various aspects of ion beam therapy (IBT), such as treatment planning and monitoring. LÄS MER

4. 18. Pre-Flight Development of the PoGOLite Pathfinder

   Författare :Mózsi Kiss; Mark Pearce; Gottfried Kanbach; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astroparticle physics; Astropartikelfysik;

   Sammanfattning : The Polarized Gamma-ray Observer (PoGOLite) is a balloon-borne instrument that will measure gamma-ray polarization in the energy range 25-80 keV from astronomical sources such as pulsars, accretion discs and jets from active galacticnuclei. The two additional parameters provided by such observations, polarizationangle and degree, will allow these objects to be studied in a new way, providing information about their emission mechanisms and geometries. LÄS MER

5. 19. Performance Studies and Star Tracking for PoGOLite

   Författare :Cecilia Marini Bettolo; Mark Pearce; Nicolas Produit; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; polarization; pulsars; x-ray; PoGOLite; Astroparticle physics; Astropartikelfysik;

   Sammanfattning : PoGOLite is a balloon-borne experiment, which will study polarized soft γ-ray emissionfrom astrophysical targets in the 25-80 keV energy range by applying well-typephoswich detector technology. Polarized γ-rays are expected from a wide variety of sources including rotation-powered pulsars, accreting black holes and neutron stars,and jet-dominated active galaxies. LÄS MER

7. 20. Image Processing for Quantitative Scintillation-Camera Imaging. Application to Radionuclide Therapy

   Författare :Katarina Sjögreen Gleisner; Lund Medicinsk strålningsfysik; []
   Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; tomografi; radiologi; Klinisk fysiologi; medical instrumentation; tomography; radiology; 131-I; Clinical physics; SPECT; conjugate-view; volume quantification; activity quantification; image registration; image segmentation; medicinsk instrumentering; Nuclear medicine; radiobiology; Nukleärmedicin; radiobiologi; Radiopharmaceutical technology; Radiofarmaceutisk teknik;

   Sammanfattning : Individual-based determinations of the absorbed dose in radionuclide therapy largely rely on absolute measurement of the activity distribution and its redistribution over time. Scintillation-camera imaging is the most commonly employed measuring technique, applied in planar or SPECT mode, sometimes in combination with structural images from CT. LÄS MER