Stanley ("Stan") Duane Ecklund died on April 8, 2025, age 86, surrounded by his family after a short battle with pancreatic cancer. Known to family, friends, and colleagues as a solid, steady and reliable presence, Stan will be deeply missed.

Stan was born to Arnold F. Ecklund and Mabel S. (Swenson) Ecklund in Minneapolis, MN on March 18, 1939. He was a 1957 graduate of Roosevelt High School in Minneapolis, MN. Stan attended the University of Minnesota, where he received a Bachelor of Science degree and then California Technical Institute (CalTech), where he received a PhD in high-energy physics in 1967. Stan then did a postdoctoral fellowship at the Stanford Linear Accelerator Center (SLAC).

Stan married Marian Gladys Holmgren (Ecklund) on August 29, 1964, to whom he was married for 60 years.  The couple had three children, Karl Matthew Ecklund, Kreig Timothy Ecklund, and Kier Jonathan Ecklund. They first moved to Pasadena, CA, where Stan received his PhD. Upon graduation, the couple lived in CA (Menlo Park, Redwood City and Los Altos). They also lived in Wheaton, IL. And for the past forty-five years, Stan and Marian lived in California, first in Cupertino, (39 years), and then at The Villages in San Jose (7 years). where he loved to ride his bike and play bocce with friends.

Stan's life was marked by his commitment to Christian faith and his commitment to science, which he never thought were inconsistent. He was known for his keen intellect and sensitive, humble spirit and found great joy in spending time with family and friends. He grew up attending church in Minneapolis MN, continuing to attend Covenant churches throughout his life, and was most recently a member of Foothill Covenant Church for 45 years, where he served as a leader, was active in the choir, men's bible study, and helped with countless maintenance projects.

Stan enjoyed his work as a particle physicist and said he "looked forward to going to work, which is a great gift." Stan began his physics career working on the production of subatomic particles by gamma rays at Caltech, where he measured photoproduction of the pi plus meson, and continued this work as a postdoctoral fellow.  Moving to Fermilab in 1972, Stan helped construct a beamline for related studies using meson beams and conducted experiments at both Fermilab and Brookhaven National Lab on Long Island.  While at Fermilab he contributed to accelerator design for a colliding beam machine, the Tevatron.  Moving back to SLAC in 1979, Stan worked on two accelerator projects, leading the design of the positron source for the Stanford Linear Collider (SLC) in the 1980s and then working on the interaction region for SLAC's B-Factory, PEP-II.  His work on these accelerators enabled precision measurements of the Z boson (SLC) and of B mesons (PEP-II), recognized by co-authorship of seminal papers from experiments at SLAC. Stan's work on experiments and accelerators was in the center of particle physics throughout his career. Stan worked at the Stanford Linear Accelerator Center (SLAC) for 29 years, retiring in 2008.

Stan was predeceased by his wife, Marian, his parents, and an older sister, Audrey Maxine Gustafson. He is survived by his sons Karl (and Elaine), Kreig (and Karen), Kier (and Hung), six grandchildren (Kaitlyn, Kaleb, Keyara, Sonia, Anika, and Erich Ecklund), nieces and nephews Eric Gustafson, Sonia Thomsen, John Peter Gustafson, Karin Walen, Kent Syverson, and Dawn Capp as well as close friends, all of whom feel his loss profoundly. A celebration of life will be held at Foothill Covenant Church, 1555 Oak Ave, Los Altos, CA on May 26th at 2PM. Instead of flowers, the family requests that gifts in memory of Stan be sent to Keyara's Gift, an educational non-profit ( https://www.keyarasgift.org/ ). Please write "in memory of Stan Ecklund" in the check memo, or the "notes" if giving online.