Suffolk Reporter

Scientists at the U.S. Department of Energy's Brookhaven National Laboratory have successfully designed and tested the highest voltage polarized electron gun globally. This development is a significant step towards constructing the world's first fully polarized Electron-Ion Collider (EIC). The EIC, in collaboration with DOE’s Thomas Jefferson National Accelerator Facility, aims to accelerate and collide polarized electrons with protons and ions to explore the fundamental components of visible matter.

"This gun not only exceeds the EIC requirements, but we also get world-leading results," stated Erdong Wang, a physicist at Brookhaven Lab who led the project's design and implementation.

The project commenced as a research proposal by Wang in 2017 and involved extensive work at Stony Brook University (SBU), which is part of Brookhaven Science Associates. It drew expertise from various institutions including Jefferson Lab and Old Dominion University.

"Our team includes experts in beam dynamics, high voltage, materials science, lasers, engineering, and beam diagnostics," Wang added.

EIC Science Director Abhay Deshpande highlighted the collaborative efforts between Brookhaven Lab and SBU. "This project is a great example of the strong collaboration between Brookhaven Lab and Stony Brook," he said.

The new electron gun will serve as an essential component for one of EIC's particle streams. John Skaritka from Brookhaven Lab emphasized its role: "We put the 'e' in the EIC."

Wang explained that this technology accelerates electrons to 80% of light speed over just two inches inside the gun within two ten-billionths of a second. The polarization of these electrons is crucial for understanding proton spin origins through collisions with polarized protons.

"For the EIC, we need polarized electron bunches with spins oriented forward and backward simultaneously," Wang noted.

The photoelectric effect underpins this advancement. Despite historical progress since Albert Einstein's Nobel-winning explanation in 1921, no existing guns could meet EIC's needs until now. Collaborators developed a unique photocathode structure using gallium arsenide crystals arranged periodically for optimal performance.

"We discovered a small wavelength zone that can get both high polarization and long cathode lifetime," said Wang regarding laser-driven actions facilitating efficient electron generation.

Protecting delicate materials like gallium arsenide photocathodes necessitated innovative solutions such as placing systems within ultra-high vacuum environments—more so than on Earth's moon—to prevent damage while maintaining high voltages necessary for intense beams production without greenhouse gases usage or safety risks associated therewith due largely because Bob Lambiase contributed significantly toward designing safer setups devoid such gases altogether: "Our connector is derived from standard X-ray machines...but jazzed up."

Success was achieved during commissioning tests conducted at SBU where stable operations were maintained over extended periods showcasing required characteristics needed probing protons/ions via upcoming experiments planned utilizing facilities once completed future developments already underway include higher-voltage/current guns cooling ions beams among other tasks being pursued actively ensuring continued progress towards achieving goals set forth initially when embarking upon journey embarked upon years ago ultimately culminating fruition seen today marking milestone momentous occasion indeed worthy recognition acknowledgment given deservedly so here now present day context ongoing efforts remain steadfast unwavering commitment excellence demonstrated consistently throughout process undertaken thus far...