Michigan Ultra-Cold Polarized Atomic Hydrogen Jet Target

To study spin effects in high energy collisions, we are developing an ultra-cold high-density jet target of proton-spin-polarized hydrogen atoms. The target uses a 12 Tesla magnetic field and a 0.3 K separation cell coated with superfluid helium-4 to produce a slow monochromatic electron-spin-polarized atomic hydrogen beam, which is then focused by a superconducting sextupole into the interaction region. In recent tests, we studied a polarized beam of hydrogen atoms focused by the superconducting sextupole into a compression tube detector, which measured the polarized atoms' intensity. The Jet produced, at the detector, a spin-polarized atomic hydrogen beam with a measured intensity of about 2.8 . 10(15) H s(-1) and a FWHM area of less than 0.13 cm(2). This intensity corresponds to a free jet density of about 1 . 10(12) K cm(-3) with a proton polarization of about 50%. When the transition RF unit is installed, we expect a proton polarization higher than 90%.