Post on 19-Jan-2016
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Performance Study of Pair-monitorPerformance Study of Pair-monitor
2009/06/30Yutaro Sato
Tohoku Univ.
Pair-monitorPair-monitor2
Pair-monitor is a silicon pixel detector to measure the beam profile at IP.
• The distribution of the pair B.G. is used.– The same charges with respect to the
oncoming beam are scattered with large angle.– The scattered particles have information on beam shape.
• The pair-monitor is required to measure the beam size with 10% accuracy.
e-
e+
IPe+ beam
e- beam
Pair-monitor
Distribution of pair B.G.
X [cm]
Y [
cm]
Y [
cm]
X [cm]
1σx (nominal) 2 σx
Tohoku group has developed
– development of the readout ASIC for the pair-monitor.
– the performance study of pair-monitor.
• The combined analysis with BeamCal was performed.
– Pair-monitor is a silicon pixel detector to measure hit counts.
– BeamCal is a calorimeter to measure energy deposit.
• Beam parameters (σx, σy, Δy/σy ) were reconstructed using the matrix
method (second order).
ContentContent3
Offset Δy [nm]e - bunch
e+ bunch
Simulation setupSimulation setup
Simulation setup• CM energy : 500GeV
• Noinal beam size (σx0, σy
0, σz0, ) = ( 639nm, 5.7nm, 300 μm )
• Tools : CAIN (Pair background generator)
Jupiter (Tracking emulator)
• Magnetic field : 3.5 T + anti-DID
• Pair-monitor is located in front of the BeamCal.
• Scattered e+ was studied.
4
LumiCal
BeamCal
BeamCal
Pair-monitor
IP
The beam parameters are reconstructed by the Taylor expansion.
→ The measurement variables were studied.
yy
y
x
yyyx
yy
y
x
n
BA
m
m
m
M
σΔ
σ
σ
σΔσσ
σΔ
σ
σ
/
/,,
/
2
1
Matrix method for reconstructionMatrix method for reconstruction5
MBXAX T
yy
y
x1
/
σΔ
σ
σ
Matrix of the first order term Matrix of the second order termMeasurement variable
Beam parameter (X)
The beam parameters are reconstructed by the inverse matrix.
The radial distribution changes, due to the difference of Pt’ kick at IP.
( Pt’ is the perpendicular momentum to the e- beam line. )
Measurement variables were defined.
• Rmax : Radius to contain 97.5% of the all hits. ( Pair-monitor )
• Rave : Average radius weighted energy deposit. ( BeamCal )
Radial distributionRadial distribution6
σx = 639 [nm]σx = 958.5 [nm]
Pt’ [MeV]
i
iiave Edep
EdepRR
( Ri is the radius of the i-th cell )
e - bunchz’ axis
Pt’
e+ bunch
e+
Rmax and Rave were obtained with various beam parameters.
Rmax and Rave decrease for larger horizontal beam size (σx).
Variable : RVariable : Rmaxmax and R and Raveave
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σy = 5.7 [nm]σy = 8.55 [nm]σy = 11.4 [nm]σy = 17.1 [nm]
Rmax [cm] v.s. Horizontal beam size (σx) [nm]
Rave [cm] v.s. Horizontal beam size (σx) [nm]
Rm
ax [
cm]
Rav
e [cm
]Horizontal beam size (σx) [nm] Horizontal beam size (σx) [nm]
The azimuthal distribution at IP also changes with the beam parameters.
The measurement variables with the pair-monitor were defined.
→ ND1/Nall for vertical beam size (σy)
NU/ND2 for relative offset (Δy/σy)
e - bunch (z’ axis)
e+ bunch
e+
e+
Azimuthal distributionAzimuthal distribution8
σy = 5.7 [nm]σy = 17.1 [nm]
φ’ [rad]
Hit distribution
ND1/Nall and NU/ND2were obtained with various beam parameters.
ND1/Nall and NU/ND2change as a function of the beam parameters.
Variable : NVariable : ND1D1/N/Nallall, N, NUU/N/ND2D2
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NU/ND2 v.s. Vertical beam size (σy) [nm]
Vertical beam size (σy) [nm]
NU/N
D2
ND1/Nall v.s. Vertical beam size (σy) [nm]
Vertical beam size (σy) [nm]
ND
1/N
all
σx = 639 [nm]σx = 702.9 [nm]σx = 798.75 [nm]σx = 958.5 [nm]
Δy / σy = 0Δy / σy = 0.2Δy / σy = 0.4
The total number of hits (Nall) and total energy deposit (Edepall)
also have information of the beam parameters.
1/Nall and 1/Edepall change as a function of the σx and σy.
Variable : 1/NVariable : 1/Nallall, 1/Edep, 1/Edepallall 10
σx = 639 [nm]σx = 702.9 [nm]σx = 798.75 [nm]σx = 958.5 [nm]
Δy / σy = 0Δy / σy = 0.2Δy / σy = 0.4
1/Nall v.s.Vertical beam size (σy) [nm]
Vertical beam size (σy) [nm] Vertical beam size (σy) [nm]
1/N
all
1/N
all
Measurement variables • Pair-monitor … Rmax, ND1 / Nall, NU / ND2, 1 / Nall
• BeamCal … Rave, ND / Nall, NU / ND, 1 / Edepall
Matrix components were determined by the fitting with the second polynomials.
yy
y
x
yyyx
yy
y
x
n
BA
m
m
m
M
σΔ
σ
σ
σΔσσ
σΔ
σ
σ
/
/,,
/
2
1
Reconstruction of beam sizeReconstruction of beam size11
MBXAX T
yy
y
x1
/
σΔ
σ
σ
Matrix of the first order term
Matrix of the second order termMeasurement variableBeam parameter (X)
Beam parameter can be reconstructed.
Results (σResults (σyy))
Beam sizes were reconstructed using the matrix.
The combined analysis provides more precise measurement.
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Acc
urac
y [%
]
Vertical beam size (σy) [nm]
Pair-monitor
BeamCal
Pair-monitor +
BeamCalAcc
urac
y [%
]
Acc
urac
y [%
]
Vertical beam size (σy) [nm]
Measurement of σy
Results (σResults (σxx, σ, σyy, Δ, Δyy/σ/σyy))
The accuracy of measurements is as follows.
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Pair-monitor BeamCal Pair-monitor + BeamCal
σx 3.2 % 4.1 % 2.8 %
σy 10.1% 15.6 % 8.6 %
Δy/σy 8.6 % 9.4 % 7.4 %
SummarySummary• Pair-monitor and BeamCal measures the beam profile at IP.
– Pair-monitor is a silicon pixel detector to measure the hit count.
– BeamCal is a calorimeter to measure the energy deposit.
• The combined analysis with BeamCal was performed.
• Beam parameters (σx, σy, Δy/σy ) are reconstructed using the matrix
method (second order).
• The combined analysis can provide more precise measurement.
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Pair-monitor BeamCal Pair-monitor + BeamCal
σx 3.2 % 4.1 % 2.8 %
σy 10.1% 15.6 % 8.6 %
Δy/σy 8.6 % 9.4 % 7.4 %
BackupBackup
15
• Inverse matrix of a non-square matrix A is defined as follows.
Matrix method for reconstructionMatrix method for reconstruction16
1
11
11
AAAAAA
AAAATT
TT
2
/
2
1
OA
m
m
m
M
yy
y
x
n
σΔ
σ
σ
Matrix of the first order term
Measurement variable Beam parameter (X)
yyyx
yy
all
y
all
x
all
RRR
NNN
AσΔσσ
σΔσσ
/
/
/1/1/1
maxmaxmax
RRmaxmax and R and Raveave
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Δy / σy = 0Δy / σy = 0.2Δy / σy = 0.4
Rmax [cm] v.s. Horizontal beam size (σx) [nm]
Rave [cm] v.s. Horizontal beam size (σx) [nm]
Rm
ax [
cm]
Rav
e [cm
]
Horizontal beam size (σx) [nm] Horizontal beam size (σx) [nm]
i
iiave Edep
EdepRR
( Ri is the radius of the i-th cell )
Azimuthal distributionAzimuthal distribution18
Δy / σy = 0Δy / σy = 1.0
φ’ [rad]
The measurement variable was defined.→ NU/ND2
e - bunch (z’ axis)
e+ bunch
e+
e+
Variable : NVariable : ND1D1/N/Nallall, N, NUU/N/ND2D2
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Δy / σy = 0Δy / σy = 0.2Δy / σy = 0.4
NU/ND2 v.s. Vertical beam size (σy) [nm]
ND1/Nall v.s. Vertical beam size (σy) [nm]
Vertical beam size (σy) [nm]
ND
1/N
all
NU/N
D2
Vertical beam size (σy) [nm]
σx = 639 [nm]σx = 702.9 [nm]σx = 798.75 [nm]σx = 958.5 [nm]
Variable : 1/NVariable : 1/Nallall, 1/Edep, 1/Edepallall 20
Δy / σy = 0Δy / σy = 0.2Δy / σy = 0.4
σx = 639 [nm]σx = 702.9 [nm]σx = 798.75 [nm]σx = 958.5 [nm]
Vertical beam size (σy) [nm] Vertical beam size (σy) [nm]
1/Edepall v.s. Vertical beam size (σy) [nm]
Result (σResult (σxx))21
BeamCal
Pair-monitor Pair-monitor+ BeamCal
Result (ΔResult (Δyy/σ/σyy))22
BeamCal
Pair-monitor Pair-monitor+ BeamCal