(CBS SF) — If you see a low-flying helicopter buzzing above the Bay Area this week, don’t freak out. It’s just the U.S. Department of Energy National Nuclear Security Administration (NNSA) testing for radiation.

The government helicopter may seen flying in a grid pattern at 300 feet or higher above Berkeley, San Francisco, Pacifica and Oakland between Tuesday, Sept. 1 and Sunday, Sept. 6.

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According to a statement by the City of Berkeley, the federal government is partnering with the Lawrence Berkeley National Lab on a program “to improve the U.S. government’s ability to detect nuclear and radiological material.”

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The city posted a notice about the flyover, along with the Bay Area flight schedule for this week.

A similar test measuring for naturally-occurring background radiation was done in August 2012.

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NNSA was established by Congress in 2000 as a semi-autonomous agency within the U.S. Department of Energy “responsible for enhancing national security through the military application of nuclear science,” according to a press release.