LHC performance with low-emittance h=9 beam Focus on emittance preservation
Emittance–momentum matrix1 Demonstrating the emittance-momentum matrix Mark Rayner, MICE Video...
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Transcript of Emittance–momentum matrix1 Demonstrating the emittance-momentum matrix Mark Rayner, MICE Video...
Emittance–momentum matrix 1
Demonstrating the emittance-momentum matrix
Mark Rayner, MICE Video Conference, 21 January 2010
3 6 10
140
200
240
Initial 4D N (mm)
Abs
orbe
r pz (
MeV
/c)
Cooling
channel
Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9DK sol D2D1
TOF1TOF0Target
Diffuser
GVA1 BPM1
,
1 2
Diffuser
t
Emittance–momentum matrix 2
Introduction• Purpose of the beam line:
– Generate the emittance-momentum matrix elements in pion muon decay beam lines
• (3, 6, 10) mm (140, 200, 240) MeV/c
• Data taking in December– 6 mm – 200 MeV/c element
• Runs 1380 – 1393, Kevin Tilley’s optics, 6k target pulses– 6 mm – 140 MeV/c element
• Runs 1409 – 1411, KT’s optics re-scaled to the new momentum, 2k target pulses
– 6 mm, and an intermediate momentum• Runs 1407 – 1408, KT’s optics re-scaled to the new momentum, 1k target
pulses
• Phase space reconstruction by TOF0 and TOF1– Longitudinal momentum resolution O(5 MeV/c)– Transverse position resolution O(2 cm)
– Transverse momentum resolution O(pxmax/70)
• Dependent on pxmax, the maximum un-scraped momentum of the optics in
question
• Comparison with Monte Carlo simulations– The 6-200 element has been simulated using G4BeamLine and G4MICE
Emittance–momentum matrix 3
Selection of the muon peak
6-200
6-140
Intermediate
momentum
Emittance–momentum matrix 4
Reconstruction procedure
Estimate the momentum
p/E = S/t
Calculate the transfer matrix
Deduce (x’, y’) at TOF1 from (x, y) at TOF0
Deduce (x’, y’) at TOF0 from (x, y) at TOF1
Assume the path length S zTOF1 – zTOF0
s leff + F + D
Track through through each quad,
and calculate
Add up the total pathS = s7 + s8 + s9 + drifts
Q5 Q6 Q7 Q8 Q9
TOF1TOF0
zTOF1 – zTOF0 = 8 m
Emittance–momentum matrix 5
Momentum reconstruction: 6-200 simulation
Path length
!
Measuring path length removes the bias on the momentum measurement
Emittance–momentum matrix 6
Simulation/data comparison at TOF1 (6-200 matrix element)
This simulation uses the geometry from before TOF1
was moved z = – 16.7 cm = – 0.56 ns / c
Muon time of flight Muon momentum
Emittance–momentum matrix 7
Horizontal (x,x’) trace space Vertical (y,y’) trace space
Simulation/data comparison at TOF1 (6-200 matrix element)
Simulation (truth)
Data
1, 2, and 3 fits
Emittance–momentum matrix 8
Conclusion• 6-200 element
– Beam properties required at TOF1
• <pz> = 261.8 MeV/c, x = 2.55 mm, y = 1.12 mm, and 4D N = 1.69 mm
• Takes into account binning effects– Beam properties measured at TOF1
• <pz> = 258.6 MeV/c, x = 2.31 mm, y = 0.93 mm, and 4D N = 1.47 mm
– Given the complexity of the beam line, this is not a bad start!
• Next analysis steps– Refinements of the simulation are possible in both G4BeamLine and
G4MICE– Simulate the other matrix elements
• Suggestion for the data taking in February– Observe >40k muons (~6k target pulses?) for each of the nine
elements• Kevin Tilley’s re-scaled 6-200 optics• Optics derived from Marco’s genetic algorithm
– Demonstrating the emittance-momentum matrix would be a nice step forward!