Welcome to

FP13

Measurement of Muon Properties in the Advanced Students Laboratory

of the
Universität Heidelberg

 
Feynman diagram of muon decay
Feynman diagram of muon decay.
The muon decays into an electron,an electron antineutrino and a muon neutrino.		 Qustion raised by I.I. Rabi after learning about the lepton muon
When I.I. Rabi learned about the lepton muon
  he asked this still puzzling question.
 		 poster of the STANDARD MODEL from the particle data group
Summary of the STANDARD MODEL in particle physics (particle data group)
The setup of the experiment FP13 was prepared by the Heidelberg muon group.
We are sure, you as a young physicist  will certainly not mind reading this page in English language

 
 SS 2002: Your assistents are in this semester 

 
Introductory Remarks



The muon is an elementary particle which differs according to our present knowledge from the electron only in its mass and its mass dependent properties. The muon and the electron are leptons of two different particle generations. In this experiment we are studying the behaviour of the muon as a heavy leptonic particle and its fundamental interactions. You can learn how this particle differs from the electron and that its existence is still a mystery, despite many years of particle research. It is typical example of a medium energy physics experiment
and the techniques used in this branch of our science.
 This page is supposed to give you additional information in the context of the experiment. Details about the available instrumentation and the necessary background can be found in the script to the  experiment FP13
The muons for this experiment are born in the earth atmosphere when pions are created in the interaction of primary cosmic rays (e.g. protons) with the nuclei of the air up there. Those pions decay into muons and their antineutrinos.

In this FP13 you will become acquainted with 

     
    • particle physics and its relations to other parts of physics, 
    • scintillation particle detectors, 
    • photomultipliers, 
    • elementary data acquisition concepts
    		 A cosmic muon is stopped in a sandwich of metal plates and plastic scintillators

    Principle of the experiment:Cosmic muons are stopped in metal plates, which are sandwiched  between plastic scintillation detectors. The positive muon decays into a positron which can also be detected by the plastic counters.The scintillation light is read by photomultipliers.
    Their electrical signals are transformed into norm pulses and fed into a multihit Time to Digital Converter. The time dependent hit pattern  is recorded by a computer and analyzed. Cosmic muons are polarized; therefore one can observe muon spin precession in an external magnetic field. 
Particularly you will use cosmic muons to
  • determine the lifetime of positve and negative muons in matter (Al and Cu metal)
  • observe the muon spin precession in a magnetic field
  • extract the weak interaction Fermi coupling constant  from your measurements
  • and many things more.
The experiments will extend over a week and in the end you yourself will have set up a system which takes data over a weekend all by its own. This will allow you to collect sufficient events for good result.
At the end of your experiment, you can create your own CD-ROM to store your data and to take the analysis programs home to your own PC or to the University computing center. We will provide you with the necessary software for Linux and in part for Windows 95/98/NT. This is just being set up. Therefore we need your feedback in order to straighten out inevitable problems with soft- and hardware incompatibilities.

PMT tubes sticking out of metal plate stack.
The 'black box' surrounding the scitillators is a 
magnet providing the fiel;d for spin rotation.
Students adjusting electronics.
FP 13 Setup (Computer, Electronics, Target and Scitillators).

Discussion on theory associated with the experiment.
Discussing vectorial quantities.

 
For your amusement, education and pleasure:
 

 
The particle data group offers:  The Particle Adventure
 
x-rays
x-rays
 typical dimensional scales
typical.dimensions 
 an atom
an.atom 
  •  Where and how does the muon fit into these pictures ? Can you explain how muon and electron differ ?
  • In preparation of your diploma exam you maywant to TEST YOURSELF .   If there are any questions about  theses sheets, don't hesitate to ask your assistent.
  • Which one is the particle, which the anti-particle: The positive or the negative muon?

 
Actual Precision  Experiments closely related to FP13


  • Muon g-2(magnatic anomaly of the muon) 
The experiment aims for a determination of the muon magnetic anomaly to a few parts in 10-7. At this level it provides a very sensitive test of the standard model in particle physics.
muon g-2 experiment at Brookhaven

The magnetic storage  ring for muons
of the muon g-2 experiment at Brookhaven.
It uses the worlds largest diameter superconducting magnet.
  • Muon Lifetime (µLan) at PSI
In this experiment the muon lifetime will be measured to 10-6. It will yield the most precise value for the Fermi coupling constant GF.
Principle of Detector

The proposed detector of a high precision muon lifetime experiment uses scintillators and photomultilpiers. It covers the full solid angle. The goal is 1 ppm accuracy for the muon lifetime.
This expriment is competing with µLan.
This setup of a high precision muon lifetime experiment is based on muon detection with wire chambers. Here a few ppm accuracy is aimed for.

 

 
 
 
Some links with relation to Modern Muon Phyics


pion creation ,pion decay, muon decay (from TRIUMF)

muos are produced at accelerators mostly by bombarding carbon nuclei with protons above 500 keV energy. Pions are created which decay into muons and their corresponding neutrinos.


 
Accelerator Centers with Highly Active Muon Work


AGS Accelerator at the Brookhaven National Laboratory (USA)

Alternating Gradient Synchrotron accelerator at the Brookhaven National Laboratory in the USA

 KEK accelerator center in Tsukuba, Japan

KEK accelerator site in Tsukuba, Japan
Some Actual (Muon) Experiments


Apparatus for Laser Spectroscopy of Muonium at RAL
Apparatus for Laser Spectroscopy of Muonium
SINDRUM II Detector at PSI
SINDRUM II Detector searching for
muon - electron conversion at PSI		 Search for Muonium to Antimuonium Conversion at PSI
MACS 
Muonium-Antimuonium-Conversion-Spectrometer
at PSI

 
 

The History:
 
first recording of a muon
The muon was discovered 1932 by Paul Kunze in Rostock. Just the "standard model" of that time didn't forsee any new particles - so his discovery was forgotten and others are now reported to have  found  the muon. As you know, later there was a prediction of a new particle by Yukawa. So when this object, now called the pion, was observed, it made a lot of publicity.Although the latter "discoverers" mistook the particles real nature, they get a lot of credit in citations everywhere still today.

 

The Future:

Muon Colliders -
Machines with an enourmous Physics Potential beyond e+-e- Colliders. 

The 207 times higher mass of the muon compared to the electron makes small ring machines possible, without too much synchrotronradiation losses and therefore one can reach very high energies. In addition many physics processes scale with the muon-electron mass ration squared. Futher, due to their high intensities such facilities will offer possibilities for neutrino physics, low engery muon science, material research and much more. Of particular interest and high actuality  are such machines in connection with the generation of muon neutrino beams.  Those can be generated with high insities from straight sections in muon storage rings. 
 
BNL Muon Collider design


 


 
Some useful links

 
 
 
These Review articles by Heidelberg colleagues may contain more details


"Aspects of Fundamental Muon Physics",
K. Jungmann, Scottish Summer School on Physics 51, St Andrews (1998) (gzipped version)
"Präzisionsmessungen am Myoniumatom",
K. Jungmann, Phys. Bl. 51, 1167 (1995).
"Myonium, ein künstliches Wasserstoffisotop",
G. zu Putlitz, in: Jahrbuch 1995, Leopoldina, (R. 3) 41 (1996).
"The Muonium Atom as a Probe of Physics beyond the Standard Model ",
L. Willmann and K. Jungmann, in: Atomic Physics Methods in Modern Research, Lecture Notes in Physics 499, p.49 (1997).


 
For Heidelberg  Muon Physics see:     Home page of the muon group at the Physikalisches Institut der Universität Heidelberg