Estimation of $\pi$ and $e^+$ background for E99-117

Kinematics: Beam energy = 6.0 GeV, $\theta_e=45^O$, 40cm $^3He$ target

Kin: $p_e$(GeV/c)	1.5	1.31	1.10	0.90
$\pi^-$ (epc)	0.260	0.293	0.334	0.394
$\pi^-$(Wiser)	16.908	81.934	315.380	1144.040
$e^-$(qfs)	1.289	2.170	3.150	4.488
$e^-$(Whitlow)	0.783	1.530	2.540	3.800
$e^+$(epc)	0.00547	0.00625	0.00812	0.00998
$e^+$(Wiser)	0.06606	0.34462	1.58369	6.40059
$\pi^-/e^-$(Wiser/qfs)	13.117	37.764	100.114	254.909
$\pi^-/e^-$(Wiser/Whitlow)	21.581	53.541	124.183	301.082
$\pi^-/e^-$(epc/qfs)	0.201	0.135	0.106	0.088
$\pi^-$ decay ratio	41.67%	39.31%	36.57%	33.33%
$\pi^-/e^-$ (detected)	$\sim$30	$<$50	$<$50	$<$50
$e^+/e^-$(epc/qfs)	0.425%	0.288%	0.258%	0.222%
$e^+/e^-$(epc/Whitlow)	0.699%	0.408%	0.320%	0.263%
$e^+/e^-$(Wiser/qfs)	5.125%	15.884%	50.273%	142.615%
$e^+/e^-$(Wiser/Whitlow)	8.432%	22.520%	62.359%	168.447%
$e^+/e^-$(Wiser/Born)	0.087%	0.292%	0.375%	1.965%
$e^+/e^-$(conservative)	$\sim<$2%	$\sim$4%	$\sim$10%	$\sim$20%

$\bigstar$ The radiation length for 40cm $^3$He target is:
10 mil Be + 10 mil Al + 0.012 mm Pyrex + 20 cm Air + 40 cm/2 $^3$He (10atm)=0.3574%
$\bigstar$ No Wiser code for D2 or He3 is available, so use 3 times Wiser for proton as He3 result;
$\bigstar$ Final result (the last row) of pion and positron background is the code result corrected by over/under-estimation factor obtained from test run.