Linearity Measurement of Photomultiplier Tubes
Open Access
- Author:
- Yin, Zhiyu
- Area of Honors:
- Physics
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Stephane Coutu, Thesis Supervisor
Prof. Richard Wallace Robinett, Thesis Honors Advisor - Keywords:
- Photomultiplier Tubes
Scintillators
Elementary particles
Linearity measurement
Cosmic Rays - Abstract:
- Photomultiplier tubes (PMTs) coupled to scintillators are one of the most commonly used, reliable and popular equipment for particle detection. Cosmic rays are energetic particles, including elementary particles, nuclei and electromagnetic radiation, traveling to Earth from astrophysical sources in the Milky Way Galaxy or even beyond. Research on cosmic rays (radiation and charged particles) in history could be classified in three periods: an early stage (from discovering electrons to neutrons), a middle stage (discovery of antiparticles, neutrinos and mesons), and a modern stage (studies of the standard model and quarks). The scintillators are devices that can emit a small flash of light when hit by a cosmic charged particle or high energy radiation. There are six common types of scintillator in use nowadays. Photomultiplier tubes are electron tube devices which convert light signals into a measurable current pulse. Their design requires careful optimization of a number of criteria to achieve specific performance objectives. In this thesis, we verify the linearity of PMTs, which tracks the relationship between incident photons onto the active from face of the PMT and the resulting anode current output from the tube. We measured the range of linearity of PMTs used in the NASA CREAM (Cosmic Ray Energetic And Mass) experiment, to be deployed on the International Space Station in 2017. The PMTs are mounted on either a tapered trigger base (in which case a linear behavior is observed up to 100,000 photoelectrons), or else on an untapered base (in which case the linear behavior extends up to 10,000 photoelectrons). There remain possibilities to improve the technique used to make the linearity measurements with reduced sources of error.