Brookhaven Lab’s oldest and most-trophied workhorse, the Alternating Gradient Synchrotron (AGS), has broke its own world record for producing intense beams of polarized protons – particles that “spin” in the same direction.
Spin, a quantum property that describes a particle’s intrinsic angular momentum, is used in a wide range of fields, from astronomy to medical imaging. But where spin comes from is still unknown.
In this picture of a proton-proton collision, the spin of the particles is shown as arrows circling the spherical particles. The red and green particles represent reaction products from the collision that are "seen" and analyzed by RHIC detectors.
To explore the mystery of spin, Brookhaven’s Relativistic Heavy Ion Collider (RHIC) smashes beams of polarized protons at close to the speed of light. RHIC is the only machine in the world with this capability. But before reaching RHIC’s high-speed collision course, the protons travel about one million miles through a series of linear and circular accelerators, including the AGS, a 41-year old circular accelerator more than a half mile around. Home to three of BNL’s seven Nobel Prize-winning discoveries, the AGS is Brookhaven’s longest-running accelerator.
Now, with a new upgrade, the AGS can keep up to 75 percent of those particles in the beam polarized while they accelerate – a 5 to 8 percent increase over the previous record. This feat was accomplished with custom-built power supplies created from old inventory and two revamped 1960s quadrupole magnets pulled from storage.
The two refurbished quadrupole magnets before being installed at the AGS
As the particles race through the AGS, two of the customized power supplies quickly pulse, hold, and pull back surges of power for each of the quadrupoles in a matter of milliseconds. Forty-two times within half a second, these pulsed currents produce magnetic kicks that keep the particles spinning in the correct direction.
For more details, see this story.
-Kendra Snyder, BNL Media & Communications
Tags: accelerators, Alternating Gradient Synchrotron, Brookhaven National Laboratory, physics, polarized protons, RHIC, spin
