B.Azmoun, S.Stoll Brookhaven National Lab HBD Meeting 1/6/09

2 The East is not installed yet at this point; gas is flowing through a bypass in the East circuit and interestingly there is less absorbance here than in the West  looks like contaminants are coming from the HBD itself (needs further testing).

3 Here the East is now installed and we see about the same level of absorbance in both arms of the HBD.

4 (1 week of flow thru cells) About the same levels of absorbance persist a few weeks later.

5 (2.5hrs. of flow thru cells)

 All back to back Vac scans show that the system is stable and reliable.  All gas transmittance scans are more or less consistent and show [H2O]=30-35ppm and [O2]=5- 7ppm on the East and West outputs, whereas the input is quite clean  this consistency may be another sign that we are measuring something real.  Although all three O2 analyzers agree quite well with the transmittance calculated ppm’s, the H2O sensor reading and the transmittance calculation remain discrepant.  The most compelling theory that reconciles this discrepancy is that both the analyzers and the transmittance calc.s are simply correct; that there is an unknown substance in the gas that is not detected by the analyzers.  The shape of the trans. Spectrum is not very distinctive so as to rule out the possibility of the presence of a significant amount of an unknown contaminant.  Whatever is outgassing, it does not show signs of letting up, ie, the transmittance has remained fairly constant for two months.  We’ve learned that flowing gas through the transmittance cells for 1 week results in the same levels of transmittance compared to flowing gas through the cells for an hour or two.  We’ve also learned that bracketing a gas scan with two Vac scan before and after the gas scan is more or less equivalent to doing a single gas scan either before or after. That is, the Vac scans before and after do not change enough to significant ly impact the transmittance results. 6

 Scan in bypass mode to rule out the possibility that the trans. cells and lines themselves are contaminating the gas.  Since the input is so clean, this is unlikely  CF4 Scan: while the detector had CF4 flowing through it a few weeks ago we attempted a scan, but were unsuccessful.  Install O2 fuel cell and calibrate Sensor on HBD gas Input.  Since the O2 levels are so low to begin with on the input, it is unlikely we’ll see any differences in O2 levels once this operation is complete.  Perform Scan during high gas flow through HBD  this is promising! 7