Search for dissertations about: "I gamma"

Showing result 1 - 5 of 397 swedish dissertations containing the words I gamma.

2. 1. Seeking the faint extremes : Detection and characterisation of extragalactic soft-spectrum gamma-ray sources and exploring methods to enhance their detection with machine learning in the 50 GeV-50 TeV energy range

   Author : Tomas Bylund; Yvonne Becherini; Gilles Henri; Linnéuniversitetet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; GeV gamma-rays; TeV gamma-rays; AGN; blazar; deep learning; observational high-energy astronomy; Astroparticle Physics; Astropartikelfysik;

   Abstract : This thesis deals with an observational study of Blazars, strong gamma-ray sources with Very High Energies (VHE) located far outside our Galaxy. Blazars are a class of galaxies that contain a supermassive black hole that is actively consuming large quantities of matter, a process that results in the liberation of tremendous amounts of energy that then powers the emission of huge bulks of charged particles that get accelerated almost to the speed of light. READ MORE

4. 2. Photospheric emission in gamma ray bursts : Analysis and interpretation of observations made by the Fermi gamma ray space telescope

   Author : Shabnam Iyyani; Felix Ryde; David Burrows; Stockholms universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; gamma ray bursts; photosphere; radiation mechanism; Theoretical Physics; teoretisk fysik;

   Abstract : The large flashes of radiation that are observed in GRBs are generally believed to arise in a relativistic jetted outflow. This thesis addresses the question of how and where in the jet this radiation is produced. READ MORE

5. 3. On-line Mobile in situ Gamma Spectrometry

   Author : Thomas Hjerpe; Lund Medicinsk strålningsfysik; []
   Keywords : MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; radiobiologi; Kärnfysik; Nuclear physics; radiation protection.; 137Cs; peak-to-valley method; depth distribution; orphan source search; orphan sources; emergency preparedness; mobile gamma spectrometry; nuclear accidents; Nuclear medicine; radiobiology; Nukleärmedicin;

   Abstract : Mobile in situ gamma spectrometry is an important instrument in the emergency preparedness for nuclear accidents. This work contributes through the development of strategies and analysis methods for two applications: an on-line search for gamma-emitting orphan sources and on-line estimation of the depth distribution of 137Cs. READ MORE

6. 4. Multi-messenger emission from gamma-ray bursts

   Author : Filip Samuelsson; Felix Ryde; Peter Mészáros; KTH; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; astrophysics; gamma-ray bursts; cosmic rays; Atomic; Subatomic and Astrophysics; Atomär fysik; subatomär fysik och astrofysik;

   Abstract : Multi-messenger astronomy is a very hot topic in the astrophysical community. A messenger is something that carries information. Different astrophysical messenger types are photons, cosmic rays, neutrinos, and gravitational waves. They all carry unique and complementary information to one another. READ MORE

7. 5. The short, excited life of tellurium : Lifetime analysis of excited states in the Te midshell region

   Author : Ebba Ahlgren Cederlöf; Ayse Nyberg; Torbjörn Bäck; Johan Nyberg; Matthias Weiszflog; KTH; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; gamma spectroscopy; lifetime measurement; lifetime; shell model; RDDS; DDCM; nuclear physics; nuclear structure; gamma spektroskopi; livstidsmätningar; livstid; skalmodellen; RDDS; DDCM; kärnfysik; kärnstruktur; Atomic; Subatomic and Astrophysics; Atomär fysik; subatomär fysik och astrofysik;

   Abstract : In this licentiate thesis, lifetimes of low lying excited states in the midshell region of tellurium isotopes are discussed. The nuclear lifetimes are interesting properties to study, since they are inversely proportional to the transition probabilities, which contain information on the underlying structure of the nucleus. READ MORE