Systematic T1 improvement for hyperpolarized 129xenon

The spin-lattice relaxation time T1 of hyperpolarized (HP)-(129)Xe was improved at typical storage conditions (i.e. low and homogeneous magnetic fields). Very long wall relaxation times T(1)(wall) of about 18 h were observed in uncoated, spherical GE180 glass cells of ∅=10 cm which were free of rubidium and not permanently sealed but attached to a standard glass stopcock. An "aging" process of the wall relaxation was identified by repeating measurements on the same cell. This effect could be easily removed by repeating the initial cleaning procedure. In this way, a constant wall relaxation was ensured. The Xe nuclear spin-relaxation rate 1/T1(Xe-Xe) due to van der Waals molecules was invest…