Advanced Undergraduate Laboratory

Department of Physics

University of Toronto

HEP: High Energy Physics

Photographs of 10 GeV bubble chamber events are studied in which strange particle creation and decay are evident. Careful measurement of vector momentum makes it possible to set upper limits on the unobservable missing tracks. Donald Glaser won the Nobel Prize in Physics in 1960 for his invention of the bubble chamber.

Specialized bubble chambers are currently used to search for hypothetical Weakly Interacting Massive Particles (WIMPs) that may be the primary constituents of Dark Matter

Although bubble chambers are no longer used in experiments at the high energy frontier at CERN and elsewhere, the the analysis principles are very similar to those used at experiments such as ATLAS: Charged particles are detected by their ionization and their momentum determined from their curvature in a magnetic field, neutral particles are detected through their interactions, and conservation laws play a key role in the analysis.

Write-Up in PDF Format. or Microsoft Word Format

(This experiment is currently done at home by students on their own computer. Students must download Traxis code and bubble chamber pictures below. Last write-up revision: October 2020.)

Additional resources:

• Python code and instructions for analyzing bubble chamber pictures, originally written by Engineering Science Physics students Syed Haider Abidi, Nooruddin Ahmed and Christopher Dydula (Fall 2014).
  APL Demo John Ladan has converted this so that it can be installed with "pip install traxis"; the package is available at https://pypi.org/project/traxis/.
• Selection of high resolution bubble chamber pictures (including 2 strange particle events), also available as a single 2 GB compressed file.
  Low resolution (2400 dpi) images of the same pictures are also available, if desired for preliminary studies.
• Appendix I: 1972 Tables of Particle Properties from the Particle Data Group, where the best current values for subatomic particle properties can be found.
• Ballam et al, Phys. Rev. D 5, 545–589 (1972), an article which mentions the SLAC 82-inch bubble chamber properties
• M. Goddard's University of Toronto M.Sc. thesis which analyzed data from this same beam and bubble chamber under the supervision of Prof. A.W. Key.
• If you are planning to use WinPython, here is a version from August 2015: WinPython-64bit-3.4.3.5Qt5.exe. The current version can be found at https://winpython.github.io.
• Previous version of the experiment write-up, when actual scanning tables were used.

A portion of a bubble chamber image used in this experiment, showing the paths of many particles. The tight spirals are due to electrons.

Last updated on 20 September 2021