It is with immense sadness that we inform you of the loss of our dear friend and esteemed colleague Usha Mallik, who died in a car accident on the evening of August 4th in Iowa, USA.

Usha was known to all of us as a distinguished experimental physicist, a dedicated mentor to students and postdocs, and a tireless advocate for equal opportunities in education and research. Born and raised in Calcutta (now Kolkata), she was grateful for what she described as a privileged life, yet she never forgot her roots.

Usha earned her Ph.D. in 1978 from the City College of New York, where she conducted spectroscopy studies at BNL’s Multiparticle Spectrometer (MPS) experiment, utilizing partially separated kaon beams from the AGS. From 1981 to 1982, as a postdoc at LAL-Orsay in France, she measured tau-lepton properties at the CELLO experiment on the DESY e+e– storage ring PETRA. In the mid-1980s she joined the MARK-III collaboration at SLAC’s e+e– storage ring SPEAR, where she performed charmonium studies. 

In 1989, Usha joined the University of Iowa as an Assistant Professor and became a member of the ZEUS collaboration at the HERA deep-inelastic ep collider at DESY. She and her group developed online software and calibration for the uranium scintillator calorimeter’s readout electronics. They measured the gluon momentum density at low-x by studying elastic and inelastic charmonium production.

In the 1990s, Usha and her Iowa team joined the BABAR collaboration at the asymmetric-energy B-factory PEP-II at SLAC, which began operation in 1999 (Usha already co-authored the 1994 letter of intent). Usha played a pivotal role in the BABAR trigger and data acquisition system, where she held several coordination roles. She also served as the BABAR run coordinator. Her research focused on studies of charmed baryons.

Usha was also involved in the ILC project, leading her group in R&D studies in the late 2000s that focused on developing particle flow algorithms.

Towards the end of 2006, Usha joined the ATLAS experiment, initially through SLAC, and, in 2009, her University of Iowa group became a full ATLAS member institution. She and her team first engaged in digital signal processing for the Pixel detector and, in Run 2, became a member of the Liquid-Argon Calorimeter system, to which many Iowa group members have made significant operations contributions over the years.

Under Usha’s guidance, the Iowa University group made strong contributions in particular to Higgs-boson physics and high-profile measurements of other processes as well as new physics searches. The group has also been at the forefront of performance developments and it contributed to the ITk Strip production facility at BNL.

Throughout her career, Usha Mallik was a member of numerous panels and committees, with emphasis on education, the promotion of science, and international development. She has been a Fellow of the American Physical Society since 1996.

Usha’s tragic passing is great loss to the ATLAS experiment and to the high energy physics community as a whole. Her passion and dedication to the pursuit of science, and her devotion to her students and postdocs, were truly remarkable

Misha Borodin and Weitao Wang (for the University of Iowa ATLAS group)
Srini Rajagopalan and Chris Bee (for US ATLAS) 
Emmanuel Monnier, Arnulf Quadt, and Petra Riedler (for the LAr and ITk systems)
Andreas Hoecker (for the ATLAS Collaboration)