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Constance Walter

Ben Jasinski, a Ph.D. candidate at the University of South Dakota (USD), joined the Majorana Demonstrator (MJD) team just six months ago. Last week, he helped the collaboration reach a major milestone when the team finished assembling the first enriched germanium (Ge76) string.

?For me it?s exciting because I get to play a big role in the construction of the project and work with researchers from all over,? Jasinski said. ?But it?s more exciting for the collaboration because we?re that much closer to deploying the Demonstrator.?

MJD is searching for a rare form of radioactive decay. Essentially, they hope to determine whether the neutrino is its own antiparticle, or a Majorana particle. Its detection could help explain why matter?planets, stars, humans and everything else in the universe?exists. 

During neutrinoless double-beta decay, two electrons are ejected in the germanium. Those electrons ionize the germanium and create a very specific amount of electric charge that can be measured with special equipment. The experiment is built of ultra-clean materials and located underground to avoid contaminants and cosmic rays that could also create the same amount of charge in the detectors.

For some time, MJD has been collecting data from natural germanium detectors that were installed and tested in a prototype cryostat nearly identical to the ultra-clean cryostats that will eventually be used. This allowed the team of scientists, engineers and machinists to understand different backgrounds, test for any problems and make modifications where needed. 

?We?ve learned a lot in terms of getting everything working the right way,? said John Wilkerson, principal investigator and the John R. and Louise S. Parker Distinguished Professor of Physics and Astronomy at the University of North Carolina.

Ryan Martin, assistant professor of physics at USD, oversees the assembly of the strings, making sure procedures are in place and everything is put together correctly. The assembly of the first string is the beginning of the production phase, and the end of the R&D period, Martin said. 

Over the next few weeks, six more strings containing up to four detectors will be assembled and placed in the cryostat where they will be cooled to liquid nitrogen temperatures (-346F). The cryostat will then be placed inside the shield and begin collecting data. 

?It?s taken many years to get here and a tremendous effort by everyone on the collaboration,? Martin said. ?We can see the light at the end of the tunnel and everyone is very excited.?