| Alabama Tester | Eric and Tester |
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| Tester Top | Tester Bottom |
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This page is a partial description of the Alabama Tester. Additional information can be found in Geoff's Tech Note 31.
| Alabama Tester | Eric and Tester |
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| Tester Top | Tester Bottom |
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The last measurement made before the new sighting system was installed was of distilled water. The water was drained into the reservoir and then returned into the measuring tube. Oil was pushed back into the measuring as the water re-entered. Thus, only the data in the emptying process are plotted in the attached plot. This data has an attenuation length of 34.24 +/- .60 meters when fit with an exponential (solid line in the figure). If the data is fit to a second order polynomial, then the current divided by the slope at 0 cm is 17.47 m and the same ratio at 90 cm is 94.45. This ratio is the equivalent of the attenuation length for an exponential fit in the region of these two points.
The water data were taken very early in the testing process. The PMT needs about 1/2 hour to settle down after the lights have been turned off. These data were probably taken too soon after the HV was turned on as shown by the increasing current on the last three points. If only the third through eighth points are used in the exponential fit, then the attenuation length is 15.79 +/- .51 m.
A number of measurements were made with Witco Oil. The following table summarizes the results:
| Run Number | Att. Length (m) At Zero | Att. Length (m) Fit | Att. Length (m) At 90 cm |
Date Tested |
|---|---|---|---|---|
| 1 | 7.03 | 11.63 +/- .17 | 26.83 | 8/24/01 |
| 2 | 9.63 | 13.85 +/- .24 | 22.17 | 9/6/01 |
| 3 | 9.19 | 13.23 +/- .21 | 20.26 | 9/6/01 |
| 4 | 9.83 | 13.20 +/- .21 | 18.08 | 9/7/01 |
| 5 | 9.18 | 13.48 +/- .23 | 21.32 | 9/7/01 |
The data and the fits of these data are shown in the attached figure. The "fit attenuation length" in the above tables is the attenuation length in an exponential fit (the solid lines in the figures). The dotted lines in the figure are second order polynomial fits to the data. The attenuation length at 0 and 90 cm in the table is the value of the polynomial fit at 0 and 90 divided by the slope.
The oil data seem to have more curvature than a pure exponential. Rex has studied this problem and has written a note on it.
Page last updated: 9/14/01