Waveform Analysis for a Precision Pion Decay...
Transcript of Waveform Analysis for a Precision Pion Decay...
Waveform Analysis for a Precision Pion DecayMeasurement
Anthony Palladinofor the PEN Collaboration
University of Virginia
APS DNP Meeting; Oakland, California25 October 2008
Anthony Palladino (UVa) Waveform Analysis for a Precision Pion Decay Measurement 25 Oct ’08 1 / 23
Outline
IntroductionOverview of the PEN ExperimentConstraints on pseudoscalar and scalar couplings
PEN ExperimentDetectorExtracting the π+ → e+νµ Tail
Waveform DigitizerDigitizerWaveform Analysis
Conclusion
Anthony Palladino (UVa) Waveform Analysis for a Precision Pion Decay Measurement 25 Oct ’08 2 / 23
Introduction Overview of the PEN Experiment
Physics Motivation / Theory
• Precision Measurement of the π+ → e+ν branching ratio.
B =Γ(π+→e+νµ(γ))Γ(π+→µ+νµ(γ)) =
(ge
gµ
)2 (memµ
)2 (1−m2e/m2
µ)2
(1−m2µ/m2
π)2 (1 + δR)
Bcalc = (1.2352± 0.0001)× 10−4Cirigliano&Rosel, HepPH/07073439v1 (2007)
Bexp = (1.230± 0.004)× 10−4Experiment World Average (Current PDG)
Lepton Universality: W. Loinaz, et. al., Phys. Rev. D 65, 113004 (2004) [hep-ph/0403306](ge
gµ
)π
= 1.0021± 0.0016
Our Goal:∆Bexp
Bexp≤ 5× 10−4
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Introduction Constraints on pseudoscalar and scalar couplings
Mass Limits on Leptoquark and Supersymmetric Particles
We will be able to give lower bounds on the masses of some hypotheticalparticles.
Mass of the Charged Higgs Boson: mH > 6.9 TeVMass of the Pseudoscalar Leptoquark: mp > 3.8 TeVMass of the Vector Leptoquark: MG > 630 TeV
Current limits: mH > 2 TeV, mp > 1.3 TeV, MG > 220 TeV.
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PEN Experiment Detector
Beamline
Anthony Palladino (UVa) Waveform Analysis for a Precision Pion Decay Measurement 25 Oct ’08 5 / 23
PEN Experiment Detector
20 cm
15 cm
75 cm 100 cm
45 cm
37.5 cm
21 cm
70 cm
276 cm
0.5 cm
32 cm~16 cm ~13 cm
PEN Experiment Beamline (Pase II : 2008)Not drawn to scale.
WallLead
O − Ring : 0.6 cm (un−compressed)O − Ring : 0.5 cm (compressed)
4.5 cm
B0
31.5 cm
8.9 cm
10.1 cm
14.2 cm
Thermal HouseWall
Frame
Figure: Beam Counter and Focusing Magnets.
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PEN Experiment Detector
Detector
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PEN Experiment Detector
Detector
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PEN Experiment Extracting the π+ → e+νµ Tail
Tails via Geant4
Positron Energy in CsI (MeV)
Arb
itrar
y N
orm
aliz
atio
n
10-6
10-5
10-4
10-3
10-2
10 20 30 40 50 60 70 80 90 100
Must accurately distinguish the π+ → e+νµ events from the π → µ → eevents.
Suppress the Michel events and recover the π+ → e+νµ tail.
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Waveform Digitizer Digitizer
Acqiris High Speed 10-bit PXI/CompactPCI Digitizer, Model DC2824 Channels, each with 2 GS/s
Digitized PMT waveforms from three beamline detectors:
• Beam Counter
• Degrader (wedge: left,right,top,bottom)
• Target
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Waveform Digitizer Digitizer
0 10 20 30 40 50 60 70 800
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Degrader (Top) pion Waveform
0 10 20 30 40 50 60 70 800
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Target pion Waveform
Figure: System Response Functions (Waveforms).
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Waveform Digitizer Digitizer
Channel Number (ns*2)0 100 200 300 400 500 600 700 800
Tar
get D
SC A
mpl
itude
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DEG LR Waveform
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DEG TB Waveform
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TGT Waveform
Figure: Digitizer Waveforms and Deconvolution Output.
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Waveform Digitizer Digitizer
Channel Number (ns*2)0 100 200 300 400 500 600 700 800
Dig
itize
r A
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itize
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Figure: Fitted Digitizer Waveforms.
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Waveform Digitizer Digitizer
Channel Number (ns*2)0 100 200 300 400 500 600 700 800
Dig
itize
r A
mpl
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Figure: Michel vs. π+ → e+νµ Waveforms.
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Waveform Digitizer Waveform Analysis
Target Waveform Fit Parameters
Pulse Position in time (bin) Amplitude
π+ Known (from Degrader) Known (from TOF and EB0 +∑
Edeg )
µ+ Unknown Known
e+ Known (from Plastic Hod.) Known (from tracking)
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Waveform Digitizer Waveform Analysis
π+ PositionDetermined from bin position of π in degrader.σ ∼ 110 ps
Entries 6505
Mean 33.26
Constant 13.5± 871.4
Mean 0.00± 33.25 Sigma 0.002± 0.224
mean in degraderπ mean in tgt - π31.5 32 32.5 33 33.5 34 34.5 35
0
100
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300
400
500
600
700
800
900Entries 6505
Mean 33.26
Constant 13.5± 871.4
Mean 0.00± 33.25 Sigma 0.002± 0.224
Figure: π+ Bin Prediction Accuracy
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Waveform Digitizer Waveform Analysis
π+ Amplitude
Determined from TOF and the energy deposited in beam counter anddegrader.σ ∼ 250 keVee
deg + EB0 E
1600 1800 2000 2200 2400 2600 2800
310×
targ
et
E
500
600
700
800
900
1000
1100
310×Entries 6505
Mean 2.971e+06
Constant 9.8± 593.6
Mean 1054± 2.964e+06
Sigma 886± 7.932e+04
target + Edeg + EB0 E
2000 2200 2400 2600 2800 3000 3200 3400 3600 3800
310×0
100
200
300
400
500
600
Entries 6505
Mean 2.971e+06
Constant 9.8± 593.6
Mean 1054± 2.964e+06
Sigma 886± 7.932e+04
Figure: π+ Energy Prediction Accuracy, σ/mean = 2.6%
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Waveform Digitizer Waveform Analysis
e+ PositionDetermined from the time of the Plastic Hodoscope.σ ∼ 250 ps
position in waveform (ns)+e300 305 310 315 320 325
(ns
)ho
dosc
ope
t
-10
-5
0
5
10
Mean 314.6
Constant 5.4± 211.2
Mean 0.0± 314.6
Sigma 0.0073± 0.4904
(ns)hodoscope
position - t+e310 312 314 316 318 320
0
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40
60
80
100
120
140
160
180
200
220 Mean 314.6
Constant 5.4± 211.2
Mean 0.0± 314.6
Sigma 0.0073± 0.4904
Figure: e+ Timing Prediction Accuracy
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Waveform Digitizer Waveform Analysis
e+ Amplitude
Determined from the distance e+ travels in the target.
Requires knowledge of the positron decay vertex.
• π+ entry position from wedged degraders.
• e+ track from MWPC, Plastic Hodoscope, and CsI Calorimeter.
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Waveform Digitizer Waveform Analysis
µ+ Amplitude
Known precisely since it is a two body decay.σ ∼ 100 keVee
Entries 8924
Constant 2.5± 175.6
Mean 89± 1.779e+05
Sigma 80.5± 7317
muE165 170 175 180 185 190
310×20
40
60
80
100
120
140
160
180
200 Entries 8924
Constant 2.5± 175.6
Mean 89± 1.779e+05
Sigma 80.5± 7317
Figure: µ+ Energy from Waveform, σ/mean = 4.2%
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Conclusion
Conclusion - PRELIMINARY
∆t = tµ - tπ (ns)
Eff
icie
ncy
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
0 10 20 30 40 50 60
(ns)π - t_µt = t_∆0 10 20 30 40 50
Eff
icie
ncy
0
0.5
1
1.5
2
• Currently, only the positions are implemented as initial fit parameters.This results in a reliable π → µ → e event identification with aπ+,µ+ separation as small as ∼ 1 ns.
• Inclusion of π+ and e+ amplitude data will increase speed andaccuracy.
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Conclusion
PEN Experiment collaboration members:
L.P. Alonzi,a V. A. Baranov,c W. Bertl,b M. Bychkov,a Yu.M. Bystritsky,c
E. Frlez,a V. Kalinnikov,c N.V. Khomutov,c A.S. Korenchenko,c
S.M. Korenchenko,c M. Korolija,f T. Kozlowski,d N.P. Kravchuk,c
N.A. Kuchinsky,c D. Mekterovic,f D. Mzhavia,c,e A. Palladino,a,b
D. Pocanic,a P. Robmann,g O.A. Rondon-Aramayo,a
A.M. Rozhdestvensky,c T. Sakhelashvili,b V.V. Sidorkin,c U. Straumann,g
I. Supek,f Z. Tsamalaidze,e A. van der Schaaf,g E.P. Velicheva,c
V.V. Volnykh,c
aDept of Physics, Univ of Virginia, Charlottesville, VA 22904-4714, USAbPaul Scherrer Institut, CH-5232 Villigen PSI, SwitzerlandcJoint Institute for Nuclear Research, RU-141980 Dubna, RussiadInstitute for Nuclear Studies, PL-05-400 Swierk, PolandeIHEP, Tbilisi, State University, GUS-380086 Tbilisi, GeorgiafRudjer Boskovic Institute, HR-10000 Zagreb, CroatiagPhysik Institut der Universitat Zurich, CH-8057 Zurich, Switzerland
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Conclusion
Paul Scherrer Institute
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