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AMDG. Demonstrating the emittance – momentum matrix A second look at December’s beam line data. Mark Rayner 12 January 2009. Introduction – The MICE beam line. Initial 4D e N (mm). 3. 6. 10. Absorber P z (MeV/c). 140. Data. 200. 240. D1. D2. Cooling channel - PowerPoint PPT Presentation
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MICE analysis meeting – BL analysis12 January 2010 1
Demonstrating the emittance – momentum
matrixA second look at
December’s beam line data
Mark Rayner
12 January 2009
AMDG
MICE analysis meeting – BL analysis12 January 2010 2
Introduction – The MICE beam line• Purpose: generate the elements of the “emittance-momentum matrix”
Study performance at every portion of a full cooling channel
• Can we use the TOFs to demonstrate the matrix elements?
Q1Q1 Q2Q2 Q3Q3 Q4Q4 Q5Q5 Q6Q6 Q7Q7 Q8Q8 Q9Q9DK solDK sol D2D2D1D1
TOF1TOF1TOF0TOF0TargetTarget
DiffuserDiffuser
Cooling channel Cooling channel and spectrometersand spectrometers
33 66 1010
140140
200200
240240
Initial Initial 4D 4D NN (mm) (mm)
Abso
rber
Abso
rber
PPzz (
MeV
/c)
(M
eV
/c)
DataData
MICE note 176 Apollonio, Cobb
MICE analysis meeting – BL analysis12 January 2010 3
Timing detectors TOF0 and TOF1
Tof-0
0.48 m
10 x 4cm scintillator barsx = 1.15 cmt = 50 ps
Tof-1
0.48 m
7 x 6cm scintillator barsx = 1.73 cmt = 50 ps
MICE analysis meeting – BL analysis12 January 2010 4
Beam characterization using the TOFs
PID
at the diffuserat the diffuser
emittance
phase ellipse orientation
beam size at TOF1at TOF1
emittance
phase ellipse orientation
longitudinalmomentum
path lengthtrans mom
z
g0
0
10
20
30
40
50
60
70
80
0 100 200 300 400 500
Momentum / MeV/c
Tim
e o
f fl
igh
t /
ns
e+
mu
pi
p
pi - mu
MICE analysis meeting – BL analysis12 January 2010 5
PID on December’s scaled decay beam line data
Kevin’s optics6-200
Runs 1380-1397 and 1391-1393
6-140(rescaled currents)Runs 1409-1411
Intermediate momentum beam line with scaled quad currents
Runs 1407-1408
MICE analysis meeting – BL analysis12 January 2010 6
Reconstruction procedure• Iterative calculation of increasingly good s=z+ and P
– Begin with P from P/E=z/t• 1 Calculate a linear transfer map at P from TOF0 to TOF1 (top hat
quadrupoles)
• 2 Deduce x0’ and y0’ from x1 and y1
• 3 Integrate ds while tracking the initial trace space vector through the beam line
• 4 Make a better estimate of P from P/E=s/t• 5 Make a small Bethe-Bloch correction for the energy loss in air between
the TOFs
Marco’s=6mm pabsorber=200 MeV/c centre of the -p matrix beam
MICE analysis meeting – BL analysis12 January 2010 7
6-200 momentum reconstructionMC truth (and hence the reconstructed detector response of the truth) and data have slightly different geometries and optics, but both have been designed by Marco to generate the 6-200 element of the -p matrix
Momentum is reconstructed just before TOF1The simulation contains only muonsSlide 5 shows show the data cut on t to select muons
Old geometry (May 2009, simulation) z = 796.61 cmNew geometry (December 2009, data) z = 779.91 cmDifference = 16.7 cm = 0.557 ns / c
Det. resp. t (blue) looks surprisingly good compared to the truth (light blue), but there is indeed a 70 ps error
MICE analysis meeting – BL analysis12 January 2010 8
x and y trace space
Truth Recon’d det. sim. Data
MICE analysis meeting – BL analysis12 January 2010 9
(Raw) RMS trace emittances from the 2D histograms
Binned truthx RMS trace emittance = 2.367800 mmy RMS trace emittance = 1.453120 mmTransverse 4d RMS trace emittance = 1.854912 mm
Reconstruction of detector response simulationx RMS trace emittance = 2.552532 mmy RMS trace emittance = 1.123380 mmTransverse 4d RMS trace emittance = 1.693359 mm
Datax RMS trace emittance = 2.309358 mmy RMS trace emittance = 0.933133 mmTransverse 4d RMS trace emittance = 1.467971 mm
MICE analysis meeting – BL analysis12 January 2010 10
Extra slides
MICE analysis meeting – BL analysis12 January 2010 11
Momentum measurement by the TOFs• Muon energy approximately constant
between TOFs– p/E = s/t– s = path length between TOF0 and
TOF1 (~8m)– t = time of flight (~29ns at 250
MeV/c)
• Predicted resolution
– 4.7 MeV/c at 250 MeV/c
• Bias on the measurement
– Time of flight mis-calibration by 10 ps: 0.57 MeV/c bias
– Path length over/underestimation by 10 mm: 2.1 MeV/c bias
• Positron calibration is necessary
x (mm)
y (mm)
s - L (mm)
s - L (mm)
py (
MeV
/c)
px (
MeV
/c)
MICE analysis meeting – BL analysis12 January 2010 12
Monte Carlo simulation• P/E=s/t where s=true path length
– Measures true p before TOF1 with RMS error 0.65 MeV/c– See right histogram– Width and bias due to dE/dx in the air between TOF0 and TOF1
Marco’s=6mm pabsorber=200 MeV/c centre of the e-p matrix beam
MICE analysis meeting – BL analysis12 January 2010 13
Should we simply approximate s=z?• P/E=z/t
– RMS error 3.38 MeV/c– Bias -4.06 MeV/c– Due to the width of the =s-z distribution
Marco’s=6mm pabsorber=200 MeV/c centre of the e-p matrix beam