Download - Step IV Studies
Step IV Studies
Timothy CarlisleOxford
Intro.
• CM28 – Step III vs Step IV• Cooling formula & G4MICE disagree on
– Also observed in ICOOL (note #199 – Marco/John Cobb)
Step IV, 63mm LiH + AFC inc. windows
2
2 30
0.014 GeV
2tn nd dE
dz E dX Em X
0
[from CM28]
• Cooling formula assumes Gaussian approximation:
)ln(038.01MeV6.13
00 XxXxzcp
rmsplane
PDG:From Moliere
G4MICEGEANT4:
uses Lewis Theory,
“develops a theory valid for any angle by using Legendre polynomials and then goes over into the small Angle”
...simple then!
xrmsplane
zxx PPa
)/tan(
Px
Pz
58cm LH2
G4MICE:Nm=10,000pencil beam on axis no fields
• Compare PDG with scattering in G4MICE.
Z Xo x [cm]
1 63.04 LH2 57.613 82.78 Li 10.064 65.19 Be 2.296 42.7 C 1.39
14 24.01 Al 0.5822 16.16 Ti 0.2329 12.86 Cu 0.09
2.00 79.62 LiH 6.305.44 44.77 Polyethylene (C2H4) 3.095.69 43.79 Polystyrene (C8H8) 2.68
• Absorbers in Step IV scaled so DE = const.
• Instead fix the scattering angle scaled to 63mm LiH
0Xx = const.
Scattering Angle
0 5 10 15 20 25 300.000
0.002
0.004
0.006
0.008
0.010
0.012
0.014
0.016
0.018
0.020
ElementsCom-poundsPDG
LH2
Li
Carbon CuAlLiH
Atomic Number Z
rmsplane
Energy Loss
0 5 10 15 20 25 3002468
101214161820
Elements
Com-pounds
PDG
MeV
Atomic Number Z
LH2
LiH
Carbon CuAl
• Scattering isn’t so simple to predict it seems.• Energy Loss seems fine however.• MICE acceptance limited to
– i.e. measure up to Carbon (maybe Aluminium)
• Find in G4MICE in different materials, for:
pz = 207 MeV/c
Nm= 10,000
sPz = 1MeV/c
bT = 41cm
0
mminput 100
1
0
2
0 2
)c/MeV14(
dz
dE
XmT
Absorber study
0 1 2 3 4 5 6 7
-0.15
-0.1
-0.05
0
0.05
0.1 BeLiLH2LiHCarbon
Input emittance [mm]
De
LH2
C
Equilibrium Emittance
0 1 2 3 4 5 6 70
1
2
3
4
5
6
7 Elements: G4MICE
Elements: Theory
Compounds: G4MICE
Compounds: Theory
][0 mm
Atomic Number Z
LH2
LiLiH
Be
C
PolyE
15.9cm LH2 Target
MuScat Experiment• Measured muon scattering.• Compared with – GEANT 4.7.0 (10yrs old now)– ELMS
Summary
• Cooling formula/Moliere disagree with G4MICE– 1.5-2x less than predicted– Particularly bad with LH2
• MuScat– Moliere & GEANT 4.7.0 overestimate scattering at low Z– ELMS code much better
• G4MICE uses GEANT 4.9.2 however...– Is this closer to MuScat?– ELMS in MAUS?
0
Scattering Angle (Li fraction)
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10.0000.0020.0040.0060.0080.0100.0120.0140.0160.018
G4MICE
PDB
G4MICE: LiH
rmsplane
Li mass fraction
(mLi/mLi+mLH2)
LH2LiLiH