Niowave 9-2015

Progress Report, September 2015

Simulations were performed to predict the efficiency of producing positrons using a Lead-Bismuth target and a 10 MeV incident electron. MCNPX and GEANT4 were used to predict this efficiency in an effort to benchmark the results. Niowave performed a simulation using MCNPX and ISU used GEANT4. A comparison of the positron production efficiency predictions made by MCNPX and G4beamline (GEANT4) is shown in the table below. The two simulation packages appear to be consistent with each other for some thicknesses.

PbBi Thickness (mm)	#positrons/million electrons (G4Beamline)	#positrons/million electrons (MCNPX)
1	1138,1154,1097,1159,1125 =1135[math]\pm[/math]25	1091
1.5	1668,1701,1639, 1644, 1628=1656[math]\pm[/math]29	1728
2	1937,1930,1851,1874,1945=1907[math]\pm[/math]42	1984
3	1889,1821,1852,1809,1859=1846[math]\pm[/math]32	1986
4	1726,1696,1673,1693,1681=1694[math]\pm[/math] 20	1858
5	1566,1543,1546,1625,1566=1569[math]\pm[/math]33	1646
6	1549, 1486,1564,1545,1452=1520[math]\pm[/math] 50	1541
7	1462,1327, 1407,1489 ,1477=1432[math]\pm[/math] 67	1541
8	1289, 1335,1280, 1271, 1280 = 1291[math]\pm[/math] 25
10	1141,1241, 1199, 1202, 1148 =1186[math]\pm[/math]42	1216

Below are the momentum distributions observed for both electrons and electrons using MCNPX. Electrons:

Positrons: