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Test run results

Kinematics: Beam energy = 5.650 GeV, $\theta_e=45^\circ$
Target: 4 cm LH2 for electron runs, 15 cm LH2 for positron runs

Results of $e^-$, $\pi^-$ and $e^+$ cross sections (nb/GeV-sr) are shown in Table 9.


Table 9: Test run result for E99-117
$p_e$(GeV/c) 1.5 0.9 0.55
$\pi^-$ (epc) 12.01 705.2 5405.3
$\pi^-$ (epcv) 0.00 0.000 0.000
(wiser) 2.98 204.4 1607.1
$\pi^-$(data) 3.2 150 890
$e^-$(qfs) 0.499 1.684 3.844
(Whitlow) 0.305 1.324 2.219
(rosetail) 0.011 0.251 1.521
$e^-$(data) 0.166 1.062 3.924
$e^+$(epc) 0.0022 0.0038 0.0074
(wiser) 0.011 1.001 11.2
$e^+$(data) 0.0006 0.17 2.03


$\star$ The internal radiation length used in wiser's fit is: 2.7%
$\star$ The radiation length used in rosetail is:
for 4cm liquid H$_2$ target
before interaction: 2.8 mil Al + 4 cm/2 LH2 = 0.08% + 0.23%= 0.31%
after interaction: 4 cm/2 LH2 + 7 mil Al/$\sin\theta$ + 16mil Al + 20 cm Air + 7 mil Kapton
= 0.23% + 1.01% = 1.24%

For pion yields we compare data with wiser and epc code for pion, while for $e^-$ we compare data with (whitlow+rosetail) and (qfs+rosetail). From the comparison we can see that wiser gives better result for $\pi$ cross section (thougth there is an overestimation). For $e^-$ cross section whitlow's fit is better. For positron yield, though much better than pos_epc, there is an overestimation in code pos_wiser. We expect that this is because we didn't include the angular distribution of $\pi^0 \rightarrow e^+ + e^-$. This overestimation will be corrected by a reasonable factor (about 6).


next up previous contents
Next: Estimation of electron, pion Up: Simulation for Data Taking Previous: Programs electron scattering, pion   Contents
Xiaochao Zheng 2001-06-09