Download Measurement of lifetime for muons captured inside nuclei

Measurement of lifetime for muons
captured inside nuclei
Advisors: Tsung-Lung Li
Wen-Chen Chang
Student: Shiuan-Hal Shiu
2007/06/27
Content

Introduction

Experimental Apparatus

Analysis and Discussions

Conclusion
Introduction
Flow Chart
Physics motivation
Physics events
Detectors
Electronic devices
DAQ
Data analysis
Physics Results
Standard Model

6 quarks.

6 leptons.

Force carrier
particles.
The Four Interactions
Force
carrier
Action
object
Graviton
Photon
Gluon
Electroweak
interaction
Everything
Charge Quarks,
particles Gluons
W,Z
boson
Quarks,
Leptons
Muon

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 Decay

Muon mean lifetime : 2.197μsec

Muon and antimuon decay:
Lepton Type Conservation

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 GF

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
constant GF :
 free
192 
 2 5 4
GF m c
3
7

The new world average of muon lifetime is:2.197019μsec.

The new GF is:1.166371*10-5 GeV2 .
Muon 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 Distribution
Muon decay is a typical
process of radioactive
decay.
N (t )  N 0 e  t
dN (t )   N (t )dt
Random process
N (t )  N 0 e  t
We call the muon lifetime is  
1

Muon Capture

Muon capture is the capture of a negative muon by a proton.

Ordinary muon capture (OMC):
   p  n  

Radiative muon capture (RMC):
   p  n    

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.
Muon capture Process

Capture process

1. Muon enter the matter

2. Electromagnetic interactions

3. Muonic atom formed

4. μ+p→n+ν
μ
nucleus
μ
Matter

Captured by nuclei: μ+p→n+ν

only occur with negative charged muon

In the order of nano-sec
e
Muon Capture Time Distribution
N (t )  N 0 e  t
y  C freee
y  C freee


t
 free
 C pedistal
t
 free
 C pedistal  Ccapturee

t
 ca pture
Previous Result
Experiment Flow Chart
Experimental apparatus
Detector Physics
1.
Charged particle passing
2.
Slow down
μ
μ
3.
Stop
e
4.
Decay
Scintillation detector
PMT
Measuring Muon Lifetime
μ
e
Scintillation detector
PMT
Detector
start: P1P2P3
μ
stop: P3
PMT3
TARGET
Free decay
Free decay
Capture
decay
Capture decay
μ
μ
Pass through
μ
PMT1
n
e
p
PMT2
n
e
p
Electronic Device Block Diagram
Gate condition
Calibration of Experiment Apparatus

Calibrate the PMT working voltage : Plateau measurement
Calibration of Experiment Apparatus
Calibration of Experiment Apparatus
Calibration of Experiment Apparatus

Calibrate the PMT working voltage :
Coincidence plateau measurement
Calibration of Experiment Apparatus
Calibration of Experiment Apparatus

Calibrate the efficiency of data acquisition system
Data analysis
TDC 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 Procedure
y  C1e

x
 free
 C 2  C3 e

x
 capture
The start point of
background fitting
The end point of
background fitting
Background (change end point)

The 50ns/bin figure
have a comparative
little value with other
figure.
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)
Al (change end point)
Change start point
The start point of
background fitting
Background (change start point)

The 50ns/bin figure still
have a comparative little
value with other figure.
Cu (change start point)

The first serveral
points are less than
world average.

We select the 800ns
to be the 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)

We choose the 1500ns
to be the start point.
Background Fitting Result

Background do not
have any target the
capture lifetime may
come from the
scintillation detector
atom.
Cu Fitting Result
Fe Fitting Result
Al Fitting Result
ADC 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 (TDC>10000)
ADC VS. TDC Profile (TDC>1000)

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

The TDC analysis result is listed on the table
TDC Analysis with Different ADC Cut
All cut in 800