Pressure gradients and annealing effects in solid helium-4

• Author / Creator

  Suhel, Abdul

• The Kim and Chan experiment in 2004 gave the first experimental evidence of a possible supersolid state. Even though the origin of this state is not clear yet, several experimental and theoretical investigations suggest defects are responsible for this curious phase. We have used heat pulses and thermal quenching to study pressure gradients and annealing mechanisms in solid 4He crystals. Large pressure gradients exist in crystals grown at constant volume. These can be enhanced by phase transitions, thermal quenching or by partial melting. Annealing reduces defect densities and hence pressure gradients in crystals. Our measurements show that the pressure at different points in a crystal can behave differently, even if there is little change in the crystal’s average pressure. We measured the activation energy that is associated with the annealing process.

• Subjects / Keywords

  • Helium-4
  • Pressure gradients
  • Annealing
  • Activation energy
  • Defects

• Graduation date

  Spring 2011

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3GS9J

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.