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    User name A. Deur

    Log entry time 00:54:24 on July22,2003

    Entry number 106018

    keyword=Nice He3 pressure curve

    Here the He3 pressure curve (fig 2). I plot the curve from the espace analysis with elastic peak cut and from scalers (scaler yield is divided by 5 to be on the same plot). The non-linearity problem that happened with the N2 pressure curve is not visible here (rates are much lower than for the Nitrogen). The data have been coorected for contamination) (see below) but not for radiative corrections arising from the difference between the ref. cell wall and the polarized He3 wall. These RC are negligible.
    On fig 1, one see the W spectrum of a ref cell He3 run (red) and N2 run (black). Clearly there is very little contamination from N2 in the ref cell. However, there is contamination from something heavier so it can only be the glass window (Be is lighter than N). One possibility is window events multi-scattering to go around the collimators. Another possibility is beam halo or/and misalignment.
    This background is subtracted using an empty cell run.
    For the scaller analysis the "glass" contamination varies from 15% (34 psig run) to 4% (139 psig run).
    For the elastic peak analysis, the "glass" contamination vary from 2.0% (34 psig run) to 0.9% (139 psig run).
    The contamination for the He3 ref cell is different since it includes also N2. It is 2.1% for the espace elastic peak analysis and 10.0% for scaler analysis.
    The cell pressure expectation from the elastic peak analysis agrees with Vince's temperature test (11.8 atm in both case ! First time it happens) and is off by 4 % in the scaller analysis. So things are looking pretty good. We should also notice that the curves goes to the zero,zero point.


    FIGURE 1

    FIGURE 2