TRAP MUTATION IN HE-DOPED ION-IMPLANTED TUNGSTEN

In this work, we report on an investigation of the defect complexes In Ve(2)He(n) in tungsten by means of PAC. The release steps InVe(2)He(n) , --> InV2Hen-1 + He were identified for n = 1-5. The dissociation ene rgies, in the range of 2.9-4.5 eV, agree perfectly with the values tha t have been previously determined by means of THDS. The quadrupole fre quency is about 122 Mrad/s for n = 1,2 and about 101 Mrad/s for n = 3, 4. These values are smaller than the frequency of the undecorated vaca ncy (n = 0). The vacancy mutates into a divacancy if it is filled with about 10 He atoms, giving rise to a quadrupole frequency of about 218 Mrad/s. This so-called ''trap mutation'' ultimately leads to bubble i nformation. We observed at least three different bubble-associated qua drupole interactions.