Undergraduate Research Laboratory Assistant

In modern particle accelerators, like Cornell's energy recovery linac, superconducting radio frequency resonators are used to accelerate charged particles. Special materials have to be used to absorb unwanted E&M fields that are exited in these resonators by the charged particles. We are looking for an undergraduate student who would like to participate in this research by measuring the absorption properties of several materials over a large radio frequency range at cryogenic temperatures.

Prerequisites: basic understanding of E&M, especially waves.

Pictured: looking down the Wilson Synchrotron Tunnel.

Undergraduate Research Position: Ion Detection in Particle Accelerators

If you are an undergraduate student interested in experimental physics with some computer experience, please read on!

Electron beams produce positively charged ions either by scattering on the dilute gas in an accelerator's vacuum chamber, or by irradiating gas particles with electromagnetic radiation. The positively charged ions are subsequently attracted to the negative electron beam and accumulate in the vicinity of that beam.

The accumulated ions in turn have a high probability to be further ionized to higher and higher charge states. The increasing ion density close to the electron beam can produce strong fields that perturb the motion of electrons detrimentally, substantial increasing of the electron beam's cross-section.

The Energy Recovery Linac, a novel accelerator that Cornell plans to build, is designed to produce beams of unprecedented small cross-section. Ion accumulation is therefore especially undesired in that accelerator, and has to be investigated in detail.

The student who will take up this research opportunity will join a graduate student in completing the construction of a time of flight spectrometer that extracts ions from the vicinity of the electron beam, accelerates them to a well specified energy, and then measures their velocity. The velocity characterizes the type and charge state of the ions. With this device it will be possible to identify which species of ions accumulate around the electron beam and which charge states of each species is produces.

The student will help to install the ion detector at an accelerator at Cornell, and help measure ion accumulation. This will require gauging the detector to understand what ion densities in the vacuum chamber correspond to the measured voltages. The student will then compare these measurements with an analytical model and with numerical simulations of the ion density in the vicinity of an electron beam.