Fluorescence and Transmittance Spectrophotometer Measurements - PowerPoint PPT Presentation

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Fluorescence and Transmittance Spectrophotometer Measurements

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  1. Fluorescence and Transmittance Spectrophotometer Measurements Donna Kubik 02/04/04

  2. 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

  3. Fluorescence • Used an Hitachi F-4500 fluorescence spectrophotometer (at Lab 6, FNAL) • 1nm resolution • 200nm-730nm range • Xenon lamp Hitachi F-4500

  4. Fluorescence spectrophotometer: modes of operation Frontside illumination Backside illumination ~300 nm ~300 nm mirror scintillator scintillator

  5. 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

  6. Absorption/transmissionspectrophotometer: operation Deuterium lamp Dispersion device Slit Scintillator Diode array

  7. 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.

  8. 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

  9. 1st harmonic of the Excitation wavelength Excitation wavelength

  10. 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.

  11. 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

  12. ~420nm ~420nm

  13. 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

  14. 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)

  15. Peaks may be due to D2 Halpha= 656.3nm Absorbed by polystyrene

  16. 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

  17. Emission spectra • The measurements are consistent with the BC408 and EJ200 data sheets