Verification of Tracking in G4MICE

1. Verification of Tracking in G4MICE Chris Rogers MICE VC, 15th Dec 2004 MICE Simulation Meeting 19th Jan 05

2. Position - comparison with ICOOL <x> = [x(ICOOL) + x(G4MICE)]/2 at z = 5711 dx = [x(G4MICE) - x(ICOOL)] at z = 5711 1 mm step size Initially, x = (0,0,-5711); p = (px, 0, 200) Initial px plotted on y-axis • Downstream x against upstream px • Absolute value goes linearly, as we would expect • Difference between ICOOL and G4MICE also linear up to px(z = -5711) = 30 MeV

3. Position - comparison with ICOOL (redux) <x> = [x(ICOOL) + x(G4MICE)]/2 at z = 5711 dx = [x(G4MICE) - x(ICOOL)] at z = 5711 1 mm step size Initially, x = (0,0,-5711); p = (px, 0, 200) Initial px plotted on y-axis • Downstream x against upstream px • Absolute value goes linearly, as we would expect • Difference between ICOOL and G4MICE also linear up to px(z = -5711) = 30 MeV

4. Position - along z • Again we have mean x-position and Dx between ICOOL and G4MICE • Note these are the absolute values • Initial px = 30 MeV (left), 100 MeV (right) • where particle crosses axis, relative difference • “Typical” difference ~1% - 10% (grows along channel) • Implications for emittance? - significant

5. Position - along z (redux) • Again we have mean x-position and Dx between ICOOL and G4MICE • Note these are the absolute values • Initial px = 30 MeV (left), 100 MeV (right) • where particle crosses axis, relative difference • “Typical” difference ~0.1% at downstream end of the channel • Implications for emittance? - significant

6. Momentum - comparison with ICOOL <px> = [px(ICOOL) + px(G4MICE)]/ 2 at z = 5711 dpx = [px(G4MICE) - px(ICOOL)] at z = 5711 1 mm step size Initially, x = (0,0,-5711); p = (px, 0, 200) px plotted on y-axis • Downstream px against upstream px • Absolute value again looks quite linear • Difference between ICOOL and G4MICE also linear up to px (z = -5711) = 30 MeV

7. Momentum - comparison with ICOOL (redux) <px> = [px(ICOOL) + px(G4MICE)]/ 2 at z = 5711 dpx = [px(G4MICE) - px(ICOOL)] at z = 5711 1 mm step size Initially, x = (0,0,-5711); p = (px, 0, 200) px plotted on y-axis • Downstream px against upstream px • Absolute value again looks quite linear • Difference between ICOOL and G4MICE also linear up to px (z = -5711) = 30 MeV

8. Momentum - along z • Here we have mean x-position and Dx between ICOOL and G4MICE • Again relative difference when the muon crosses the axis • “Typical” difference ~ 1% at 30 MeV, 10% at 100 MeV • High transverse momentum particles are of interest for physics analysis • Should seek to understand the discrepancy

9. Momentum - along z (redux) • Here we have mean x-position and Dx between ICOOL and G4MICE • Again relative difference when the muon crosses the axis • “Typical” difference ~ 0.1% • High transverse momentum particles are of interest for physics analysis • Should seek to understand the discrepancy

10. Emittance Performance - magnets only (1 mm) 1 mm step size, ~ 1000 events ICOOL G4MICE • Systematic difference ~ 0.2 % • Not yet good enough; we would like this to be << 0.1 % • 1 mm step size = processor heavy

11. Emittance Offset - a bug in ecalc9? • G4MICE emittance plots come out offset from ecalc9 plots by a small amount. • Calculate emittance in ecalc9 for some small set of particles • Calculate emittance in G4MICE for the same set of particles • They are different • Take out the reference particle and the first event from the G4MICE calculation then the emittance is the same in ecalc9 and G4MICE • I think this has to be a bug in ecalc9

12. Proposed Fixes/Improvements • Fix B-field interpolation algorithm plot • Plot decent contours • Use the same field map • Check emittance offset • Fix/improve VirtualPlanes interpolation algorithm • Plot error(step size) • Absorbers/RF/Cooling plots