Hans Burkal Jensen

Our beloved Hans Burkal Jensen passed away peacefully on January 12, 2026, a sunny winter afternoon at home, surrounded by his immediate family.

Born on April 26, 1944, in Lyngby, Denmark, Hans was the middle child of Aage and Inge Jensen, growing up alongside his older sister Birgitte and younger sister Charlotte. Growing up in post-WWII Denmark, he developed an early love for science and math, curiosity that would guide his life's work. Outside of school, Hans spent much of his youth in the countryside outside Copenhagen, visiting family farms and enjoying time with his parents and sisters at their summer house in Humlebæk. He also loved adventure from a young age, taking biking trips across continental Europe with friends, experiences he always remembered with joy.

Hans earned his PhD in physics from the Niels Bohr Institute. After graduation, in the mid-1970s, with strong encouragement from his thesis advisor, he accepted a postdoctoral position at Caltech's Kellogg Laboratory in nuclear physics. During his time there, he met one of his closest friends and collaborators, Alvin Tollestrup. After several years at Caltech, Alvin encouraged him to pivot toward high-energy physics. That guidance shaped the rest of his career. Hans spent the following two years at Caltech working on a SLAC experiment, and he often spoke of his years in California in the 1970s as some of his happiest, both professionally and personally.

His next chapter took him back to Europe for a position at CERN in Switzerland, where he worked on proton-proton collision experiments at the Intersecting Storage Rings (ISR). On his journey back however, Hans decided to see more of the world and detoured through South America, a decision that changed his life forever.

In Cusco, Peru, Hans met the love of his life, Estela "Tita". It was truly love at first sight. Family legend says Hans was walking down a small street with a friend, while Tita was walking the same street in the opposite direction with a friend. Their friends happened to recognize each other, leaving Hans and Tita standing face-to-face, and the rest, as they say, was history.

Hans and Tita were married on June 12, 1976, in Flushing, New York. On February 1, 1979, they settled in Wheaton, Illinois, where they raised their two children, Katrina and Erik. They also both began their long careers at Fermilab National Accelerator Laboratory. Hans dedicated his professional life to Fermilab, focusing primarily on the Collider Detector at Fermilab (CDF), where he made lasting contributions and formed deep friendships. Tita also became a beloved part of the Fermilab community, running her French-inspired restaurant, Chez Léon, which for more than two decades nourished not only the lab's scientists and staff, but the spirit of the place itself.

Hans had a passion for history, especially Ancient Greece and Rome, the Napoleonic Wars, and Winston Churchill; classical music, including many evening events at the Lyric Opera of Chicago; 60s music, such as the Beatles, Joan Baez, and Bob Dylan; walking along the Chicago lakefront; watching British tv shows, such as Fawlty Towers; eating Danish cuisine, including pickled herring and Akvavit; and celebrating festive holidays with his family and friends. One of his favorite sayings was, "Variety is the spice of life."

Hans and Tita retired in May 2008 and devoted themselves to traveling the world together, something both had always loved deeply. Travel was also a cornerstone of family life, and the four of us shared countless adventures and memories that we will treasure forever.

Hans is survived by his wife of 49 years, Tita; his children, Katrina and Erik (Angie); and his two grandchildren Henry and Juliet, who knew him as the grandfather who always had time for one more story. He is also survived by his sisters, Birgitte and Charlotte (Poul); his sister-in-laws Julia (Bill) and Ana (Steve); and their families. He was preceded in death by his sister-in-law Maury and his parents, whom he missed deeply throughout his life.

The family is incredibly grateful for the devoted and attentive care that Hans received in his final years. Thank you to Hector, Martin & Joy, Mar, Raquel and Michelle. You treated Hans with respect and dignity and we are forever grateful.

Like his children, many of us affectionately also knew him as "Far", Danish for "Father". We will miss his voice, his steady presence, and his remarkable gift for storytelling. We will carry him with us in the work we do, the love we give, and the way we show up for one another, just as he always did.

A celebration of Hans' life will be held at a later date. In lieu of flowers, the family asks that you make a donation in his name to one of the following: The Nature Conservancy, Doctors Without Borders, Geneseo Food Pantry.