Cryostat Chills Detectors at Heart of MAJORANA DEMONSTRATOR (IMAGE)
Caption
Researchers work on the delicate wiring of a cryostat, which is like a thermos under vacuum that chills the detectors that are the heart of the MAJORANA DEMONSTRATOR. The experiment's 2 cryostats each house 29 germanium detectors -- diodes that are reverse biased, meaning no current flows because the crystal has no free electrons or "holes" (positive charges created when electrons vacate) to allow charge movement. When a high-energy electron (a beta particle) is created during a double-beta decay, that electron will scatter off other electrons and create electron-hole pairs that move inside the germanium and create a pulse of charge inside the detector. Coaxial cables connect detectors to sensitive electronics that can measure the arrival of this tiny pulse. "Researchers amplify the pulse and measure its height and from that figure out how much energy created the electron-hole pairs," ORNL's David Radford said. "The number of electron-hole pairs that are created is proportional to the energy that was released." This energy is used to distinguish if the original electrons were generated via a process that releases two neutrinos or no neutrinos.
Credit
Sanford Underground Research Facility; photographer Matthew Kapust
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