1. Measurement of the Muon’s Lifetime & Cosmic Ray Flux J.C.Xu13307110206 Q.Y.Tang13307110168

2. Content 1 、 Introduction 2 、 Measurement &Result 3 、 Discussion & Improvement

3. 3 、 The muon is an unstable subatomic particle with a mean lifetime of 2.2 µs. 1 、 Introduction——What’s Muon? 2 、 Muons are produced in copious amounts in high-energy interactions in normal matter. These interactions usually produce pi mesons initially, which most often decay to muons. 1 、 The muon is an elementary particle similar to the electron, but with a much greater mass. it is not thought to be composed of any simpler particles.

4. Is made of these: The Universe’s fundamental building blocks. 1 、 Introduction—— What’s Muon?

5. But if we consider the Einstein's theory of relativity: So it could reach the ground surface. 1 、 Introduction——What’s Muon? Muon travels at a speed slightly below that of light, if we observe muon in static reference frames ， muon could travel 600m （ far below the thickness of the atmosphere within its lifetime.

6. Can we at least measure one of those fundamental particle parameters in a classroom? At ground level, we have mostly muons from these cosmic showers. The questions is what can we measure and how do we measure. Muons decay and its lifetime is a fundamental particle parameter. So let’s measure muon lifetime.

7. Our Detector  e By measuring the time difference muon entrance and the electron production, we can calculate the muon lifetime . So we need a detector to count a double pulse. 1 、 Introduction—How to Measure Muon Lifetime?

8. 1 、 Introduction—How to Measure Muon Lifetime?

9. X(-4) X5 Disc V thrd TDC (FPGA) 1 、 Introduction—How to Measure Muon Lifetime?

10. 1 、 Introduction—How to Measure Muon Lifetime?

11. Threshold:400mV Time:10min HV649607551499448431415401 muon count 1115133732535193098450614328 2 、 Measurement &Results——Explore

12. HV: 400V Time: 10min thres hold 101149200250299326349401 muon count 287517658864801631066931 2 、 Measurement &Results——Explore

13. CH1CH2Effect 11 Coincidence Counting 10Muon Lifetme 01Muon Lifetime 00 Anti-coincidence Counting Coincidence Counting: The entangled particles are vastly outnumbered by non-entangled particles which are also detected; patternless noise that drowns out the entangled signal. In a two detector system, a coincidence counter alleviates this problem by only recording detection signals that strike both detectors simultaneously. This ensures that the data represents only entangled particles. 2 、 Measurement &Results——Flux

14. sigma+sigma-measured E30383.1344.9364 E15413.8374.2394 Vertical455.9414.1435 W15543.8498.2521 W30335.8300.2318 sigma+sigma-measured N30391.3352.7372 N15466.1423.9445 Vertical347.1310.9329 S15308.1273.9291 S30221.4192.6207 2 、 Measurement &Results——Flux

15. sigma+sigma-measured E3013.192.9103 E15117.396.7107 Vertical118.497.6108 W15147.7124.3136 W30135.1112.9124 sigma+sigma-measured N30165.4140.6153 N15210.0182.0196 Vertical183.0157.0170 S15147.7124.3136 S30145.6122.4134 2 、 Measurement &Results——Flux

18. For data analyses ， plot muon decay times and fit to 1 ） elapsed time: 16h40m 2 、 Measurement &Results—Muon Lifetime

19. 2 ） elapsed time: 7d23h33m 2 、 Measurement &Results—Muon Lifetime

20. Data format: 40010 1047328747  10 muons during this time 40005 1047328748 40010 1047328749 40004 1047328750 900 1047328750  one muon decay, 900*20 ns 40005 1047328751 40007 1047328752 40008 1047329027 40006 1047329028 40006 1047329029 17280 1047329029  one muon decay,17280*20 ns 40013 1047329030 40007 1047329031 2 、 Measurement &Results——Data Analysis

21. --Lengthen the time duration for the experiment --Increase the size of the muon detector to collect more data --Deploy multiple detectors in different locations to form a controlled experiment --Better ways to analyse the data --...... Improvement 3 、 Discussion & Improment

22. In a medium with an index of refraction of n the light velocity is c/n. When a charged particle traverses the medium with velocity larger than the light velocity, so called Cherenkov light is emitted. The minimum energy of the particle with this velocity (called "Cherenkov threshold energy'') is 0.768 MeV for electrons and 158.7 MeV for muons. Cherenkov light is emitted in a cone of half angle  from the direction of the particle track. In water this angle is about 42 o. 3 、 Discussion & Improment Another way to detect muons and lectrons:cherenkov light

23. A suggested muon detector based on water water muon electron 3 、 Discussion & Improment

24. Check out the eCube website!

26. Reference 1.“A compact apparatus for muon lifetime measurement and time dilation demonstration in the undergraduate labrotory.” T.Conan, T.Liu and J.YE.J.Ye Am.J.Phys.74,161(2006) 2.“Studies of the performance of the ATLAS detector using cosmic-ray muons.” The ATLAS Collaboration, Nov 2010. Published in Eur.Phys.J.C71:1593, 2011. 3.“Cosmic Ray Muons an the Muon Lifetime.”University of Florida- department of Physics,Published in Advanced Physics Laboratory, October 14, 2013