B.Azmoun, S.StollBrookhaven 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) (1 week of flow thru cells)

About the same levels of absorbance persist a few weeks later.

5

(2.5hrs. of flow thru cells)

(2.5hrs. of flow thru cells)(2.5hrs. of flow thru cells)(2.5hrs. of flow thru cells)

(2.5hrs. of flow thru cells) (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