measurement of lifetime for muons captured inside nuclei advisors: tsung-lung li wen-chen chang...
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Measurement of lifetimMeasurement of lifetime for muons captured ine for muons captured inside nucleiside nuclei
Advisors: Tsung-Lung Li Wen-Chen Chang
Student: Shiuan-Hal Shiu
2007/06/27
ContentContent
Introduction
Experimental Apparatus
Analysis and Discussions
Conclusion
IntroductionIntroduction
Flow ChartFlow ChartPhysics motivationPhysics motivation
Physics eventsPhysics events
DetectorsDetectors
Electronic devicesElectronic devices
DAQDAQ
Data analysisData analysis
Physics ResultsPhysics Results
Standard ModelStandard Model 6 quarks.
6 leptons.
Force carrier particles.
The Four InteractionsThe Four Interactions
Force Force carriercarrier
GravitonGraviton PhotonPhoton GluonGluon W,Z bosoW,Z bosonn
Action oAction objectbject EverythingEverything
Charge Charge particlesparticles
Quarks,Quarks,
GluonsGluonsQuarks,Quarks,
LeptonsLeptons
ElectroweakElectroweakinteractioninteraction
MuonMuon
Muons were observed by Carl D. Anderson in 1936.
Muons are denoted by μ− and antimuons by μ+.
About 207 times mass as electron. (105.65Mev)
Muon mean lifetime : 2.197μsec
Muon have 1 negative electric charge.
Muon is a fermion with ½ spin.
Muon DecayMuon Decay
Muon mean lifetime : 2.197μsec
Muon and antimuon decay:
Lepton Type Lepton Type ConservationConservation
Leptons are divided into three lepton families: 1. electron and electron neutrino 2. muon and muon neutrino 3. tau and tau neutrino
Fermi Coupling Constant Fermi Coupling Constant GGFF
The muon decay is purely leptonic. Its directly related to the strength of the weak interaction. Fermi coupling constant GF is a measurement of the strength of the weak force.
The relationship between the muon lifetime τfree and fermi coupling c
onstant GF :
The new world average of muon lifetime is:2.197019μsec.
The new GF is:1.166371*10-5 GeV2 .
452
73192
cmGFfree
Muon SourceMuon Source
The muon is produced in the upper atmosphere by the decay of pions produced by cosmic rays
The flux of sea-level muons is approximately 1 per minute per cm2
The muon production height in the atmosphere is approximately 15km. If the muon traveling at the speed of light its still need 50μsec.
Muon Decay Time DistributionMuon Decay Time Distribution
dttNtdN )()(
teNtN 0)(
Muon decay is a typical process of radioactive decay.
We call the muon lifetime is
1
teNtN 0)(
Random process
Muon CaptureMuon Capture Muon capture is the capture of a negative muon by a proton.
Ordinary muon capture (OMC):
Radiative muon capture (RMC):
In the past, one motivation for the study of muon capture on the proton is its connection to the proton's induced pseudoscalar form factor gP.
np
np
Capture process 1. Muon enter the matter 2. Electromagnetic interactions 3. Muonic atom formed 4. μ+p→n+ν
Captured by nuclei: μ+p→n+ν only occur with negative charged muon In the order of nano-sec
Muon capture ProcessMuon capture Process
e
nucleus
μ
Matter
μ
pedistal
t
free CeCy free
capturefree
t
capturepedistal
t
free eCCeCy
teNtN 0)(
Muon Capture Time DistributiMuon Capture Time Distributionon
Previous Result
Experiment Flow ChartExperiment Flow Chart
Experimental apparatusExperimental apparatus
Detector PhysicsDetector Physics
1. Charged particle passing
2. Slow down
3. Stop
4. Decay Scintillation detector
PMT
μ
e
μ
Measuring Muon LifetimeMeasuring Muon Lifetime
Scintillation detector
PMT
μ
e
start: P1 P2 P3
stop: P3
PMT1PMT3
TARGET
PMT2
n
pe
μμ
Capture decay
Free decay
Pass through
DetectorDetector
Free decay
n
p
e
μμ
Capture decay
Electronic Device Block Electronic Device Block DiagramDiagram
Gate Gate conditioncondition
Calibration of Experiment Calibration of Experiment ApparatusApparatus
Calibrate the PMT working voltage : Plateau measurement
Calibration of Experiment Calibration of Experiment ApparatusApparatus
Calibration of Experiment Calibration of Experiment ApparatusApparatus
Calibrate the PMT working voltage : Coincidence plateau measurement
Calibration of Experiment Calibration of Experiment ApparatusApparatus
Calibration of Experiment Calibration of Experiment ApparatusApparatus
Calibrate the efficiency of data acquisition system
Calibration of Experiment Calibration of Experiment ApparatusApparatus
Data analysisData analysis
TDC Data AnalysisTDC Data Analysis
In this experiment we use the TDC to save the pulse's timing information and try to fit the lifetime for free decay and capture decay.
TDC Data Analysis TDC Data Analysis ProcedureProcedure
capturefree
xx
eCCeCy
321
The end point of background fitting
The start point of background fitting
Background (change end poinBackground (change end point)t) The 50ns/bin figure ha
ve a comparative little value with other figure.
Cu (change end point)Cu (change end point) The results are all
less than world average.
The 50ns/bin figure have a comparative little value with other figure.
Fe (change end point)Fe (change end point)
Al (change end point)Al (change end point)
Change start pointChange start point
The start point of background fitting
Background (change start poiBackground (change start point)nt)
The 50ns/bin figure still have a comparative little value with other figure.
Cu (change start point)Cu (change start point) The first serveral point
s are less than world average.
We select the 800ns to be the start point.
Fe (change start point)Fe (change start point) Fe data are all too
less.
We choose the 1000ns to be the start point.
Al (change start point)Al (change start point) We choose the 1500ns to
be the start point.
Background Fitting ResultBackground Fitting Result Background do not
have any target the capture lifetime may come from the scintillation detector atom.
Cu Fitting ResultCu Fitting Result
Fe Fitting ResultFe Fitting Result
Al Fitting ResultAl Fitting Result
ADC Data Analysis ProcedureADC Data Analysis Procedure
In this experiment we want to use the ADC to save the pulse's charge information and try to differentiate the free decay events and capture decay events by the information from ADC.
1. Analyze the ADC VS. TDC profile. 2. Comparing the probability of compatibility
between two ADC distribution. 3. Making different ADC cut and analyze the TDC
data for each ADC cut.
ADC VS. TDC Profile (TDCADC VS. TDC Profile (TDC>>10010000)00)
ADC VS. TDC Profile (TDCADC VS. TDC Profile (TDC>>1001000)0) From the figures we
can find there are no obvious evidence to differentiate the capture events
Probability of Compatibility between two ADC Histogram (TDC<1000)
Thistest is a statistical test of compatibility in shape between two histograms.
The background ADC shape is the comparing base line
Probability of Compatibility between two ADC Histogram (TDC>1000)
Conclusion Conclusion
ConclusionConclusion The TDC analysis result is listed on the table
All cut in 800
TDC Analysis with TDC Analysis with Different ADC CutDifferent ADC Cut