As the most precise balance in the world, KATRIN is to determine the exact mass of the smallest particle of matter, the neutrino, a subject area that was awarded the Nobel Prize in Physics last year. An important step on the way to measurement operation is the "First Light", i.e. when the detector "sees" electrons for the first time, which were guided through the entire 70-meter-long system.
The final preparations for the KATRIN plant began at 3:30 p.m., surrounded by numerous representatives of the press, with introductory words by project manager Professor Guido Drexlin, Professor Oliver Kraft, Vice President of the KIT for Research, Professor Ernst Otten, founding father of the experiment, Professor Blümer, Head of the Department of Physics and Mathematics at KIT, and Professor Hamish Robertson from the University of Washington.
Finally, at 3.50 p.m., the festive joint press on the "red button" started the electron source and delivered the hoped-for screen signal of the "First Light" to great applause.
Neutrinos play an important role in the investigation of the origin of matter and in the design of visible structures in the cosmos. Their mass, which must be more than a billion times smaller than that of a hydrogen atom, is an important but still imprecise parameter. The international experiment KATRIN will limit the neutrino mass with an accuracy that will be more than an entire order of magnitude better than before. Starting in autumn 2017, electrons from the beta decay of tritium, in which neutrinos play a major role, will be measured exactly.
Even if the instrument does not yet perform at its best with the "First Light", this moment is an important functional test for scientists and engineers. The numerous system parts and components of KATRIN will interact for the first time. The 70-meter-long path of an electron through the entire experiment includes superconducting magnets and cold traps, gas-filled areas and vacuum, zones with temperatures below 4 Kelvin and with room temperature, whose operation must be optimally matched to one another. For the "First Light", a switchable electron source is used that uses a UV light source to strike suitable electrons from a gold-plated stainless steel plate, which hit the detector after a flight time of a few millionths of a second. The detector made of silicon semiconductor material has a diameter of about 125 millimeters and contains 148 pixels, which are arranged similar to a dart board and thus allow a spatial "view" into the world of KATRIN.
In recent years, KATRIN researchers have solved numerous scientific challenges and entered uncharted technological territory in order to master the century-long task of "measuring the neutrino mass". For example, to keep a high voltage of 18 600 volts stable with an accuracy of 0.01 volts. Or the generation of an ultra-high vacuum, which corresponds to that on the moon's surface, in a gymnasium-sized world record volume of 1240 cubic metres. Around 150 scientists from 6 countries and 18 renowned institutions are involved in the KATRINE experiment, which has a budget of 60 million euros.
The measurement of the neutrino mass in tritium operation is scheduled to begin in autumn 2017. The first interesting results on neutrino mass are expected as early as mid-2018. Then the measurement sensitivity of KATRIN will already be significantly better than that of all other tritium decay experiments of the last 3 decades combined. However, KATRIN only achieves the final, planned sensitivity after 5 calendar years of measurement time.
"First Light" in the press:
SWR, ka-news, Baden-TV, KIT, Deutsche Welle, Zeit online, Physik Journal,
Fox News, The New York Times, The China Post