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University of Hawaii

Electrical Engineering

Enhanced Scintillating Tracker for Evaluating the 2ND Generation Borehole Muon Detector at the Hawaii Muon Beamline

Date: 2018-04-03           Add to Google Calendar
Time: 2:00pm - 3:00pm
Location: Holmes Hall 389
Speaker: Khanh Le, candidate for MS, advisor Dr. Gary Varner

Muon tomography generates three-dimensional, volume images using Coulomb scattering cosmic ray muons [1]. When comparing the imaging capability to X-rays, muons can penetrate much thicker materials. The muons ability to penetrate deep into materials, like rock and metal, makes muon detectors ideal for subsurface geological feature reconstruction. In the past, muon detectors have been used by Luis Alvarez in an attempt to discover hidden chambers in the Second Pyramid of Chep-hren in Giza and successfully image the displacement of magma in active volcanoes [2-4]. In the early days of muon tomography, detectors were very large and had very low resolution. Early detectors used large drift tubes and Photo-Multiplier Tubes to measure muon flux attenuation. With advancements in readout electronics and Silicon Photo Multipliers, modem detectors are much smaller in size, have higher resolution, and come at a lower cost.

The Borehole Muon Detector (BMD) project intends to greatly reduce the size, power expenditure, and operational cost of current muon detection technology [5]. Muon detection starts when a muon passes through the detector's scintillating planes, exciting scintillating materials, and resulting in a flash of light. The flash of light, measured in units of photoelectrons, is then converted to an electrical pulse by photosensors and saved in the TARGETX ASIC. Information from the TARGETX is read out using a Spartan 6 FPGA and sent back to the PC via standard fiber optic Ethernet link for analysis and reconstruction. When fully realized, the BMD will be approximately 1 m long with a diameter of 15.24 cm (6 in). The full detector encloses all readout electronics, scintillating planes, and an integrated Thermo-Electric Cooler. The design is intended for deployment in subsurface boreholes with diameters greater than 17.78 cm (7 in), up to a depth of 914 m (3000 ft) [5], and has the capability to collect data for long periods of time.

This talk focuses on the design of the 2nd generation center daughter cards, development of the readout firmware and software, and construction of the tracker planes to be used the Hawai’i Muon Beamline. The initial results from calibration, pedestal subtraction, sine wave reconstruction, LED pulsar test, and RC gain circuit evaluation of the 2nd generation BMD center daughter cards are also included.