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BANG polymer gel dosimetry using magnetic resonance imaging (MRI) was applied to an ophthalmologic 68 MeV proton beam. The object was to examine the use of BANG gel for the verification of proton fields in eye tumor therapy and to explore the applicability of polymer gel dosimetry in proton therapy under practical aspects. The gel phantoms were irradiated with monoenergetic and modulated proton beams. MRI analysis was carried out at clinical 1.5 and 3 T MR scanners. At constant LET, results show a linear relationship between spin-spin relaxation rates and dose. However, depth dose curves in BANG gel reveal a quenching of the Bragg maximum due to LET effects. The dose response of the gel for monoenergetic protons and spread-out depth dose distributions can be calculated based on ionization chamber measurements. Experiment and calculations show good agreement and indicate that BANG polymer gels might become a valuable tool in proton therapy quality assurance.

Mean lives and limits of lifetimes have been determined for some ten mostly yrast states in 7~ by means of the recoil distance Doppler shift technique. The states were excited in the reaction 4~ c~2p) at 115 MeV resp. the reaction 58Ni(14N, pn) at 39 MeV beam energy. The systematic decrease of B(E2) values along the the ground band transitions indicates a band crossing consistent with the ))-ray energies. Effects of continuum feeding times in both reactions are being discussed. The lifetimes of the lowest three yrast transitions in 72Se have been remeasured by means of the reactions 4OCa (36Ar ' 4p) and 6~ (14N, pn).