Vacuum ultraviolet excitation of the 4.4 eV emission band in neutron irradiated KU1 and KS-4Vquartz glasses

The photoluminescence emission around 4.4 eV, induced by UV and vacuum ultraviolet excitation, in neutron irradiated silica, was investigated at temperature from 300 to 10 K. High purity silica grades with different OH content: KU1, KS-4V and for comparison commercial silica Infrasil I301 were studied. The neutron fluences were 1021 and 1022 n/m2. Irradiated samples showed similar excitation spectra shape provided that fluence and measuring temperature were the same. Neutron irradiated samples showed intense excitation bands related to ODC(II) defect, around 4.95 and 6.8 eV. Relative intensity of 7.3 eV band, associated to ODC(I) defect, was greater at lower temperature. Band intensities were different depending on silica grade. KU1 grade showed the lowest photoluminescence so it is the best candidate for radiation applications.