A COMBINED POLARIZED TARGET IONIZATION CHAMBER FOR MEASURING THE SPINDEPENDENCE OF NUCLEAR MUON-CAPTURE IN LASER POLARIZED MUONIC HE-3/

We describe a device used in experiment 1231 at LAMPF and in e683 at T RIUMF to study the spin dependence of the reaction mu(-) + He-3 --> H- 3 + nu(mu). In order to study the spin dependence, we needed to form a nd polarize muonic He-3 and in the same volume detect the 1.9 MeV trit ons created in the reaction. Furthermore, the recoil direction of the tritons had to be determined. The apparatus served both as a polarized target and as a detector. The detector, a gridded ion chamber, was in corporated inside a 51 polarized target that was filled with 8 atm of He-3 and 100 Torr of N-2 and rubidium metal. At the operating temperat ure of the device (205-230 degrees C), the rubidium number density was approximately 10(15) atoms/cm(3). Muons that stopped in the target fo rmed muonic helium atoms, which were then polarized by collisions with optically pumped Rb vapor. Two high-powered GaAlAs diode laser arrays were used to polarize the Rb in the 100 cm(3) fiducial volume located inside the ion chamber. The ion chamber produced clean signals from t he reaction tritons despite having to operate under the extreme condit ions required for efficient optical pumping. The direction of the trit ons was determined by analyzing the shapes of the ionization pulses. T he muon polarization was measured using the decay electron asymmetry.