Niowave 1-2016

Niowave Positron Project Progress for January 2016

Question: Will a thicker downstream exit window increase the positron production efficiency by providing more material for a brehm photon to pair produce in?

Positrons were counted exiting a ideal 0.2 Tesla solenoid that was 15 cm long. A ten MeV electron beam with a 0.5 cm cylindrical radius impinged a 2mm thick PbBi liquid target that had a surface area of 2.54 cm x 2.54 cm. A 0.25 mm thick stainless steel entrance window was used.

Target is at -106 mm, entrance SS window is at -108.25 mm , exit SS window is at -103.75 mm, A sensitive detector for positron is placed at Z= +44mm. The sensitive detector is a cylinder of radius 11.74 cm.

SS Exit WIndow Thickness (mm)	Positrons/Million electrons
0.0	1142,1096,1149,1073,1083 = 1109 +/- 35
0.25	774,836,800,785,798 = 798 +/- 23
0.5	693,704,713,697,715 = 704 +/- 10
1.0	587,606,548,592,550 =577 +/- 26

Conclusion 1

Positron production efficiency improves when the exit window is made thinner

Conclusion 2

You loose about 28 +/- 4 % of the positrons in the 0.25 mm thick SS exit window.