Fluorescence and Transmittance Spectrophotometer Measurements Donna Kubik 02/04/04
Measurements • The goal was to measure and compare the emission spectra and transmittance of the three types of scintillators tested for the DHC plus the MINOS scintillator • All samples were machined to the same thickness • BC 408 • Cast scintillator • EJ 200 • Cast scintillator • FNAL/NICADD • Extruded scintillator • MINOS • Extruded scintillator
Fluorescence • Used an Hitachi F-4500 fluorescence spectrophotometer (at Lab 6, FNAL) • 1nm resolution • 200nm-730nm range • Xenon lamp Hitachi F-4500
Fluorescence spectrophotometer: modes of operation Frontside illumination Backside illumination ~300 nm ~300 nm mirror scintillator scintillator
Absorption/transmission • Used an HP UV-Vis Diode-Array Spectrophotometer (at Lab 6, FNAL) • 2nm resolution • 190nm-820nm range • Deuterium lamp • Covers UV and Vis HP 8452A Diode Array Spectrophotometer
Absorption/transmissionspectrophotometer: operation Deuterium lamp Dispersion device Slit Scintillator Diode array
Fluors • Instead of using the same fluors as used in the cast scintillators, different (less costly) fluors were used to fabricate the MINOS and FNAL extruded scintillators • The MINOS and FNAL scintillators were designed so that the final emission peak is similar to that of BC408 and EJ200, all of which must be compatible with WSF.
Fluors • The following slides show: • The emission peaks for the cast scintillators • PT 350nm • Bis-MSB 420nm • The emission peaks for the extruded scintillators • PPO 365nm • POPOP 420nm
1st harmonic of the Excitation wavelength Excitation wavelength
Fluors • The 365nm and 420nm (for PPO and POPOP) are the emission maxima for each compound. The remaining bands are part of the PPO and POPOP spectrum. • For PPO and POPOP there are roughly 3 peaks for each, one at each side of the maximum, but it’s difficult to see, because there is a lot of overlap in the middle. • It is easier to see in the PT and bis-MSB samples, because the two spectra do not overlap as in the case of PPO and POPOP.
Superimpose frontside and backside emission • Note that, for each sample, the peaks from the backside illumination are at the same wavelength as the longest- wavelength peaks from frontside illumination, ~420nm. • Zoom on next slide
Emission spectra • The emission for BC408 and EJ200 are the same, ~422nm • Although the chemistry of the FNAL and MINOS scintillators is the same, there is a small difference in the wavelength of maximum emission, 417.6nm vs. 419.8nm • Zoom on next slide
Transmittance spectra • The difference in emission peaks between the FNAL and MINOS scintillator may be explained by the difference in absorption/transmittance • To remove the surface effects due to the different finish quality of each sample, the transmittance spectra were corrected to 100% transmittance at 820nm (because we know that there isno absorption at long wavelengths)
Peaks may be due to D2 Halpha= 656.3nm Absorbed by polystyrene
Emission and transmittance spectra • The next 3 slides show the emission spectra superimposed on the transmittance spectra • The first shows all of the measured spectra • The next 2 slides zoom in on the onset of transmission, revealing that transmission for the FNAL scintillator begins at a slightly shorter wavelength than the other scintillators
Emission spectra • The measurements are consistent with the BC408 and EJ200 data sheets