UMass Amherst astrophysicist Andrea Pocar and his colleagues have detected for the first time neutrinos from the main nuclear reaction powering the sun–a top ten breakthrough discovery of 2014 by Physics World. The image above shows an inside detail of the 13.7 meter diameter stainless steel sphere of the Borexino experiment (located deep within Italy’s Apennine Mountains to shield the experiment from cosmic rays) before nylon vessel installation and fluid filling. The tightly packed photo-multiplier tubes (PMTs) and optical fibers used for PMT timing calibration can be seen. The 2,212 installed tubes–most of which are equipped with aluminum light concentrators to focus their view on the central volume of the detector–are designed to detect flashes of light from neutrinos and other ionizing radiation interacting with the liquid scintillator target. In detecting the neutrinos, researchers were looking directly into the sun’s core. Learn more.
Image credit: Borexino Collaboration