1. 0801 Group meeting
Shiuan-Hal

2. Content 1. How to measure the muon lifetime?
2. The previous measurements.
3. The MuLan experiment.
4. What is muon capture?
5. The MuCap experiment.

3. How to measure the muon lifetime?
The muon lifetime is :

4. How is the muon lifetime measured?

5. How is the muon lifetime measured?

6. How is the muon lifetime measured?

7. How is the muon lifetime measured?

8. How is the muon lifetime measured?

9. How is the muon lifetime measured?

10. How is the muon lifetime measured?

11. How long will it take? Source Muon rate Time to 1012 Cosmic rays
1 / 50 cm2 s
1 / hand s
~104 years e+
Scint.
PMT p+
Continuous beam
20 kHz
~1.6 years
beam time m+
PMT
PMT
Water e+
Pulsed beam
(usable)
~ 3 weeks beam time

12. Why use m+
Muon capture

13. Previous Measurements of the Muon Lifetime
Measured Lifetime
Year
PDG Average
 Bardin*
1984
Bardin
Giovanetti*
1981
Balandin
1974
Duclos
1973
Williams and Williams
 1972
Meyer
1963
Eckhause
Lundy
1962
Farley
The
previous measurements

14. Experiment by G. Bardin 1 1. Incidence 140MeV/C beam
stopped in the sulphur target and provide an unplarized
3. The decay position was detected by scintillator(Sc) p+ p+ m+

15. Experiment by K. L. Giovanetti
Start: S1 S2
Stop: L R
1. Incidence beam
stopped in the water
3. The decay position was detected by
PMT L and R m+ m+

16. The MuLan Experiment
BEAM m+
DETECTORS
DIGITIZERS
DAQ #4

18. The MuLan result

19. What is muon capture? μ
nucleus
Matter e μ

20. The previous measurements
Trigger condition:
Stopped muon:1 2
Gamma ray:3 X

21. The MuCap experiment e m

22. The MuCap experiment

23. ultra-pure hydrogen
The muon will capture by P E m- e- p

24. The MuCap result The muon disappearance rate in pure hydrogen is:
Because the lifetime is :