SUMMER OPPORTUNITIES

STUDENTS RESEARCHERS
3 AVAILABLE POSITIONS at Queen’s University, Kingston, ON, Canada

Project overview:  Observations and measurements obtained since the 1930’s give evidence for the existence of Dark Matter. This invisible matter constitutes approximately six times the total mass of all known matter in the Universe.  Using a spherical detector first invented by I. Giomataris, the NEWS-G collaboration led by Gilles Gerbier and his research team at Queen’s University will search for very low mass Weakly Interacting Massive Particles (WIMPS), a likely candidate for Dark Matter, at a level of sensitivity beyond the capability of any current research. The main characteristics of this detector are its sub-keV energy threshold, fiducialisation, background rejection by pulse shape analysis, and ability to operate at pressures up to 10 bar, allowing the vessel to be filled with  kilograms of low mass target gas, such as H, He, and Ne.  This detector will be placed 2 km underground at the SNOLAB facility in Sudbury, ON. Currently, R&D for this project is performed at Queen’s University.


POSITION 1 – Simulation and modelling of the response of Spherical Proportional Counters (SPCs)

The experiment uses gaseous detectors called Spherical Proportional Counters (SPCs) in order to measure the low-energy deposits expected from the interaction of dark matter particles with target gas nuclei. This detector technology consists of a grounded spherical metallic vessel that is filled with gas, and a small sensor at a high voltage to collect ionization signals. The analysis of the detected pulses not only  allows for a measurement of the deposited energy but also provides information on the radial location of the event based on the shape of pulses. The sensitivity of the experiment to sub-GeV WIMPs relies on its capability to detect very small energy depositions of a few 10’s of eV. Therefore, it is critical to properly characterize the detector response to single electrons. The SPC technology also allows for the discrimination of background surface-events from signal bulk-events, which requires a good understanding of the detector response. In order to accomplish this, detailed simulations and models of the physics of the detector are needed. This is also a crucial aspect of extending the knowledge gained here at Queen’s to the operation of the future full-scale experiment at SNOLAB.

The successful candidate will participate in the design and creation of a Monte Carlo simulation code. They will familiarize themselves with finite-element software to compute electric field maps, and MAGBOLTZ simulation package to derive drift properties of electrons in different gases. Simulation results will be compared to calibration data collected by another student researcher. Together these two efforts will result in a verified model of the detector that will greatly enhance our understanding of the experiment.


POSITION 2: Precision calibration measurements of a Spherical Proportional Counter (SPC) with laser and radioactive sources

The experiment uses gaseous detectors called Spherical Proportional Counters (SPCs) in order to measure the low-energy deposits expected from the interaction of dark matter particles with target gas nuclei. This detector technology consists of a grounded spherical metallic vessel that is filled with gas, and a small sensor at a high voltage to collect ionization signals. The analysis of the detected pulses not only  allows for a measurement of the deposited energy but also provides information on the radial location of the event based on the shape of pulses. The sensitivity of the experiment to sub-GeV WIMPs relies on its capability to detect very small energy depositions of a few 10’s of eV. Therefore, it is critical to properly characterize the detector response to single electrons. The SPC technology also allows for the discrimination of background surface-events from signal bulk-events, which requires a good understanding of the detector response.

The successful candidate will be in charge of performing precision calibration measurements with a SPC prototype at Queen’s University to refine our understanding of the detector response. They will make use of radioactive sources (Am-Be, 37Ar) as well as a recently acquired 213 nm laser which will allow for the extraction of single electrons from the inner surface of the vessel. While they will be mainly focusing on data collection and analysis, they will also collaborate with another student researcher to compare their measurements to simulations.


POSITION 3: Monitoring, control and improvement of the gas quality in Spherical Proportional Counters (SPCs)

The experiment uses gaseous detectors called Spherical Proportional Counters (SPCs) in order to measure the low-energy deposits expected from the interaction of dark matter particles with target gas nuclei. This detector technology consists of a grounded spherical metallic vessel that is filled with gas, and a small sensor at a high voltage to collect ionization signals. Because the detector response is strongly correlated with the purity of the gas, it is critical to ensure at all times a strict control of contaminants such as H20 or O2  that are responsible for electron attachment, and thereby a loss of signal.

The successful candidate will be mainly in charge of controlling the gas quality, monitoring the stability of the detector response over time, and identifying correlations between them. Ultimately, they will make use of a “getter” filter to trap contaminants to improve the gas quality and thereby the performance of the detector. They will familiarize themselves with the use of a Residual Gas Analyzer (RGA), an instrument based on mass spectrometer technology, in order to measure the concentration of different contaminants. They will also use a Helium leak checker to locate potential leaks in the set-up that may be responsible for a reduction in the gas quality.


Required skills, background:

  • Completion of 2 or 3 years of undergraduate degree in physics or engineering physics
  • Strong research skills
  • Ability to work as part of a team. We are a diverse group with many different backgrounds.
  • Ability to work well with others and take direction is very important
  • Ability to work independently, while managing time in order to meet deadlines
  • An interest in particle physics and instrumentation
  • Familiar with at least one programing language (e.g. C++,python,etc.)

Application:

If you are interested in any of these positions, please send your application to Julie McDonald (NEWS-G Research Administrator) at jmm27@queensu.ca.

Your application must contains:
– CV
– Cover letter
– Last transcript
– References (optional)

Please indicate the number of the position you apply in the email subject.

DEADLINE: February 9, 2018 – CLOSED