The TOF measurements with
(Series B) had a good background run
(BG7) with high statistics, comparable to that of the production
run. Neither of the runs had a H2 substrate under the DS D2. The
yields with different energy cuts are given in
Table 8.6.
In the 3 T
run with
there is some 10% increase in the
yield when the cut lower limit is extended from 3.1 MeV to 2.5 MeV (Method
3-nr and Method 3-wd). This is due to an increase in the Si2
counts (Si1 remains constant).
Again, we test different background subtractions. In Method 3-b, the high
energy (>4 MeV) part of the background subtracted spectra (bottom of
Fig. 8.12) were fitted with a constant line as in Method 1-b
above. These gave the results consistent with zero base line, indicating
there is no normalization problem. The spectra was then fitted with either
exponential or linear functions in the region excluding the signal
(
1500<E<2400 ch and
3800<E<6000 ch) to look for a potential residual
background (Method 3-c). While the Si1 fit was consistent with zero
background, the Si2 fit found
/GMU background in the
signal region (
2500<E<3700). The results are summarized in
Table 8.8. The shift between Method 3-wd and Method
3-c is due to the yield B (the area under the fitted curve in the signal
region), which is well determined from the fit. Taking into account both
possibilities that B is due to the background or due to the real signal, we
take an average of two values and accept half the difference as our
systematic uncertainty. Adding the statistical error in quadrature, we
obtain the yield for Series B,
/GMU.