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