TOF series B

The TOF measurements with $c_t=0.2\%$ (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$\cdot l$ run with $c_t=0.2\%$ 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.

  

Figure: Si energy spectra for the TOF yield measurement with 3 T$\cdot l$ DS D₂ in Series B ($c_t=0.2\%$), with the time cut of 1<t<6 $\mu$s. Top figures show the fusion signal (filled circles ) and a background run BG 6 (open circles), while bottom figures give background subtracted spectra.

 

Table 8.8: The detector averaged Si yield for Series B ($c_t=0.2\%$) 3 T$\cdot l$ TOF measurement with different energy cuts, with and without a residual background fit. The energy cut dependent corrections (cut efficiency and dd proton contamination) are included. Taking into account the systematic effect in the background we obtain /GMU.

Method	3-nr	3-wd	3-c
BG run	BG7	BG7	BG7
SG cut (MeV)	3.1; 3.7	2.5; 3.7	2.5; 3.7
SG yield (10-6/GMU)	2.89(16)	3.25(21)	3.25(21)
B-LO cut (MeV)	-	-	1.5; 2.4
B-HI cut (MeV)	-	-	3.8; 6.0
B yield (10-6/GMU)	-	-	0.28(9)
TOF yield (10-6/GMU)	2.89(16)	3.25(21)	2.97(23)
dd proton	0	2.4(9)%	2.4(9)%
E cut efficiency	0.980(3)	1.0	1.0
TOFcorr (10-6/GMU)	2.95(16)	3.17(21)	2.90(23)