Dr. Wim Leemans, a physicist at the Lawrence Berkeley National Laboratory, shows a touch of parental pride for the hulking machine he affectionately calls T-Rex  a high-intensity laser that pushes electrons around. But a new machine called Bella  formally, the Berkeley Lab Laser Accelerator  is uppermost on his mind these days.

Bella will be twice as large and 20 times more powerful, and Dr. Leemans just got the $20.7 million in federal stimulus money that he needs to build it. “Bella is T-Rex on steroids,” said Dr. Leemans, a slight man of 46. Bella has the potential, he said, to help restore the nation’s prowess in particle physics.

Less certain, however, is whether Bella represents smart economics. The cash for the project is a tiny slice of the stimulus package developed by Congress and the Obama administration to jump-start the economy. The stimulus legislation included about $18 billion for nondefense scientific research and development, a significant boost to the estimated $61.6 billion already going to science in the 2009 budget, according to the White House Office of Science and Technology Policy. But experts are divided about whether projects like Bella are compatible with the intent of Congress to create jobs as fast as possible.

“This is the kind of spending that is not really oriented toward jump-starting the economy and ending the recession,” said John Taylor, a professor of economics at Stanford, a senior fellow at the Hoover Institution and an adviser to Senator John McCain’s presidential campaign. “It is longer term, and because of that, I think it shouldn’t be classified as a stimulus.”