Credit: Brookhaven National Laboratory
When spin-aligned (polarized) protons collide with another beam of protons, particles called neutrons come out with a slight rightward preference. But when polarized protons collide with much larger gold nuclei, the neutrons’ directional preference becomes larger and switches to the left. These surprising results imply that the mechanisms producing particles along the proton projectile’s path may be very different in these two types of collisions.