Radiation effects on magnetic bubble domain devices

The effect of nuclear radiation on garnet film material parameters and bubble domain devices has been studied both during and after irradiation. The materials investigated include CVD grown Y
3
(FeGa)
5
O
12
, Er
3
(FeGa)
5
O
12
and LPE grown (YGdTm)
3
(FeGa)
5
O
12
films. The devices were different shift registers fabricated on ion implanted, non implanted and double layer YGdTmGaIG LPE films and GaErIG CVD films. Permanent damage on the material parameters caused by the irradiation were determined by measuring the
4\piM_{s}, \sigma_{w}, l, \mu_{w}, H_{c}, V_{s}
and defect density before and after each irradiation, while the device performances were studied by comparing the propagation and annihilation margin and the detector signal. The irradiation sources included neutrons from a nuclear reactor and gamma rays from a Co
⁶⁰
source. No significant Variation due to irradiation was found in any of the measurements for neutron irradiation up to 10
¹⁵
n/cm
²
1 MeV equivalent and gamma irradiation up to 50 Mrads. Transient stability of information stored in a bubble memory was tested by writing information into different shift registers and then bombarding these registers with a high energy (∼1.5 McV) pulsed electron beam. The results indicate there is no loss of data for a dose rate of 10
⁴
rads in a 30 ns pulse.