Search for dissertations about: "liquid helium"

Showing result 1 - 5 of 25 swedish dissertations containing the words liquid helium.

  1. 1. High-Resolution Measurement of the 4He(g,n) Reaction in the Giant Resonance Region

    Author : Björn Nilsson; Kärnfysik; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; tagged photons; photonuclear reactions; liquid helium; neutron detectors; liquid scintillators; giant resonances; angular distributions; differential cross sections; total cross sections; Nuclear physics; Kärnfysik; Fysicumarkivet A:2003:Nilsson;

    Abstract : A comprehensive near-threshold 4He(g,n) absolute cross section measurement has been performed at the high-resolution tagged-photon facility MAX-lab located in Lund, Sweden. The 20 < Eg < 45 MeV tagged photons (covering the Giant Dipole Resonance energy region) were directed towards a liquid 4He target, and knocked-out neutrons were detected in a pair of 60 cm x 60 cm vetoed NE213A liquid scintillator arrays. READ MORE

  2. 2. Novel RF MEMS Switch and Packaging Concepts

    Author : Joachim Oberhammer; KTH; []
    Keywords : 0-level packaging; adhesive bonding; BCB; benzocyclobutene; bond strength; contact printing; film actuator; glass lid encapsulation; glass lid packaging; helium leak test; hermetic packaging; hermeticity; high isolation switch; low stress silicon nitride; low volt; TECHNOLOGY; TEKNIKVETENSKAP;

    Abstract : Radio-frequency microelectromechanical systems (RF~MEMS) are highly miniaturized devices intended to switch, modulate, filter or tune electrical signals from DC to microwave frequencies. The micromachining techniques used to fabricate these components are based on the standard clean-room manufacturing processes for high-volume integrated semiconductor circuits. READ MORE

  3. 3. Development of high-Tc SQUID magnetometers for on-scalp MEG

    Author : Minshu Xie; Chalmers University of Technology; []
    Keywords : MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; nanowire junctions; on-scalp MEG; Bicrystal grain boundary; magnetoencephalography; YBCO; magnetometers; high-Tc SQUIDs;

    Abstract : This thesis describes the development of high critical temperature superconducting quantum interference device (high-Tc SQUID) magnetometers based on bicrystal grain boundary and nanowire junctions for the potential use in on-scalp magnetoencephalography (MEG), which is a new generation MEG technique with reduced sensor-to-subject standoff distances.MEG is a method of mapping neural dynamics in the human brain by recording the magnetic fields produced by neural currents. READ MORE

  4. 4. Applications of Soft X-Ray Spectroscopy

    Author : Conny Såthe; Jan-Erik Rubensson; Joseph Nordgren; Marcus Agåker; Raimund Feifel; Marc Simon; Uppsala universitet; []
    Keywords : NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

    Abstract : Soft X-ray emission spectroscopy is an old experimental technique that has seen a strong revival since the advent of new high brilliance soft X-ray sources in the shape of synchrotrons.  This thesis covers a range of applications where soft x-ray techniques have been applied. READ MORE

  5. 5. On-scalp MEG using high-Tc SQUIDs: Measuring brain activity with superconducting magnetometers

    Author : Christoph Pfeiffer; Chalmers University of Technology; []
    Keywords : NATURVETENSKAP; MEDICIN OCH HÄLSOVETENSKAP; NATURAL SCIENCES; MEDICAL AND HEALTH SCIENCES; high-Tc SQUID; neuroimaging; magnetoencephalography; localization; on-scalp MEG; sensor array; magnetometer;

    Abstract : This thesis describes work done towards realizing on-scalp magnetoencephalography (MEG) based on high critical temperature (high- T c) superconducting quantum interference device (SQUID) sensors. MEG is a non-invasive neuroimaging modality that records the magnetic fields produced by neural currents with good spatial and high temporal resolution. READ MORE