In Memory of Lewis Keller

Lewis Keller, who worked at SLAC for more than 40 years, died March 4 at the age of 81. Below is a tribute written by his colleagues Tom Markiewicz and Ted Fieguth.

Lew was born in 1938 in Valparaiso, Indiana. He and his wife Beatrice and their daughters, Kathryn and Laura, moved to California in 1970 to work at the Stanford Linear Accelerator Center. He had attended Valparaiso University, where he and Beatrice had met, and had gone on to earn his PhD for work in high energy physics at Argonne National Laboratory.

Lew came to SLAC as a particle physicist, but soon after he became head of the Experimental Facilities Department in the Technical Division, where he thrived for the next 20 years.

His steady, respectful and composed personality was highly regarded by his team of engineers, physicists, technicians, sub-group leaders and administrators. His responsibilities included analyzing all new experimental proposals for compatibility with SLAC’s resources, budget and radiation safety. Wolfgang “Pief” Panofsky, SLAC’s director at the time, took Lew’s analysis into account when deciding which experiments to approve. It then became Lew’s responsibility to provide all necessary resources, from construction, fast electronics and data acquisition, and extra manpower support for the successful operation of each and every approved experiment in the Research Yard.

Many experiments were successfully completed, and valuable physics results were published due to his stewardship. During that time Lew was invited to participate as a collaborator and contributed to many of SLAC’s published results. In the 1970s and 1980s, SLAC’s physics program became focused on colliding electrons and positrons. SPEAR and PEP were followed by construction of the SLAC Linear Collider (SLC). For SLC, in the 1980s, the linac was modified to produce very low emittance electrons and positrons to be transported to a single pass collision point at the termini of two buried arcing beamlines. Lew provided EFD resources in support of these projects.

In 1992 Lew took early retirement to work at the Superconducting Super Collider, but returned to SLAC in 1993 after Congress cancelled the project. Retired or not, Lew contributed continuously to projects that benefitted from his expertise. This began with E-158, a 1997 proposal to use high-intensity polarized electrons to measure the weak mixing angle via Møller scattering. Lew also spent a great deal of time helping to design the radiation safety shielding and calculating the radiation dose rates of muons behind End Station A (ESA), and was an author on the 2005 publication. This was followed by Lew’s recruitment into SLAC’s Next Linear Collider (NLC) group, where he designed the accelerator’s muon spoiler system and participated in Snowmass 2001. After the 2004 technology choice for a superconducting linac, Lew became the muon background reduction expert for the International Linear Collider (ILC).

Lew was also adept at using the FLUKA simulation program and contributed to the design of the collimation system and beam dumps of the ILC, focusing on device survivability. When SLAC took on a role in developing a prototype low resistivity high power collimator for the Large Hadron Collider as part of the US LHC Accelerator Research Program, Lew worked closely with the mechanical engineering staff to choose materials and understand their response to possible accidental beam aborts. After SLAC was asked to contribute to the Muon Accelerator Program, Lew again used his favorite transport and energy deposition codes to help SLAC develop an independent analysis of the viability of a muon collider. In an offshoot of this work, he developed a design for a low emittance muon source based on positron annihilation. A week before his death, in the context of a newly approved project to send LCLS-II dark current beam bunches to ESA for a dark matter experimental program, he submitted a design to produce muons for detector calibration purposes.

Lew’s even temper, physics insight and practical knowledge made him invaluable to his colleagues and a pleasure to work with.

Lew’s obituary was published in The Mercury News, and it offers a convenient way to provide messages to Lew’s two daughters, Laura and Kathy, and their families and relatives. Please visit the messages section provided.

A memorial service will be held at the Stanford Golf Course on Saturday, March 21, at 2:30 p.m. All are invited and written and spoken tributes are welcomed.