Arielle (Bartlett High School), Antony (Adlai E. Stevenson High School)

Mentors: Bradford Benson, Donna Kubik, Adam Anderson, Sasha Rahlin

Approximately 13.8 billion years ago, the universe began from a hot, dense state through an explosion of matter and energy, known as the Big Bang. During the primordial stages of the universe, light was emitted during the recombination of particles; this thermal radiation — a near perfect blackbody — is known as the Cosmic Microwave Background (CMB). The South Pole Telescope uses a polarization sensitive focal plane and superconducting Transition-Edge Sensor (TES) bolometers to interpret these ~3K (2.725K) microwave signals from the early universe. To characterize the response of these detectors on the South Pole Telescope, calibration is performed with an optical chopper and polarization setup. The purpose of the research conducted through the QuarkNet summer program with the South Pole Telescope is to assist in the development, construction, and testing of this setup which sends modulated light to detectors. Testing of these detectors — known as bolometers — for the South Pole Telescope is necessary to measure whether or not the polarized pixels are orthogonal.

Specific wavelengths of electromagnetic radiation which hit these bolometers originate from an infrared emitter source which simulates a 4K blackbody. From the IR source and through an aluminum tunnel, these wavelengths are sent through a rotating optical chopper which chops light flow at a specific frequency. The light continues onwards to a wire grid that polarizes the IR emission and then to the detectors. Information on the operation of both the optical chopper and the stage holding the polarization grid can be received via scripting through a serial port. The reason to use an optical chopper lies with its ability to reduce noise in the system as the detectors will only be looking for a specific reference frequency. Currently, the optical chopper and polarization setup is installed below a cryostat where the detector orientation lies. Further work will utilize the setup to receive specific readings on the detector's operation.

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