Emilio Segrè Visual Archives

More than 30,000 photos of scientists and their work

Attention ESVA patrons:

The Emilio Segrè Visual Archives’ site is moving soon and adopting an open access approach to digital image sharing. Once we have transitioned to the new site in 2021, we will no longer charge for our high-resolution digital images or usage fees (note that we do not hold copyright to all the images in our collections and you will still need to obtain permission for those which we do not own).

If you are working on a long-term project, we advise you to wait until the migration is complete so that you may obtain our copies for free. If you cannot wait, email us at nbl [at] aip.org and we will do what we can to assist you. We will not be offering refunds for past purchases.

For more information, please visit our FAQ page on the Ex Libris Universum blog. 

Lawrence Berkeley National Laboratory H19

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Lawrence Berkeley National Laboratory H19

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We charge a usage fee per photo if the photo is published, reproduced in a product or publicly exhibited. This is not a license in the legal sense. As a non-profit institution, we do not make any money providing these photographs. It is only by assessing usage fees that we are able to cover the cost of providing publication quality copies of our photos, preserving the photograph collection according to archival standards, and providing access to the collection by maintaining an online image database. The copyright holder may charge a fee in addition to our service fee.

Images are for use in educational projects only and must be used in a respectful manner.

Image title: 
Two antiprotons (bottom of the photograph) entering the 72-inch hydrogen bubble chamber at the University of California's Lawrence Radiation Laboratory
Credit line: 
Lawrence Berkeley National Laboratory, courtesy of AIP Emilio Segrè Visual Archives

Two antiprotons (bottom of the photograph) entering the 72-inch hydrogen bubble chamber at the University of California's Lawrence Radiation Laboratory, Berkeley. The two four-pronged 'stars' are formed when the antiprotons, generated by the Bevatron, come close to protons, the nuclei of ordinary hydrogen atoms, in the chamber. The process is called annihilation, and is visualized by the profusion of tracks forming the stars. The tracks forming the 'stars' are made of pions, particles of lower mass into which the primary particles disintegrate. Not all of the particles are seen - the neutral ones (those with no electrical charge) make no tracks. It had been theoretically postulated that the Omega meson is composed of three pi mesons (pions), and is neutrally charged.

Original format: 
1 photographic print (black and white; 10 x 8 inches)
Lawrence Berkeley National Laboratory