The antiparticles and the positron are similarly related. Mar 07, 2011 the decay of muons has provided verification of einsteins formula to a high degree of accuracy. They measured the flux of muons at a location on mt washington in new hampshire at about 2000 m altitude and also at the base of the mountain. I am a bit confused about the implications of length contractions. How to escape poverty is your thinking keeping you poor. This is a good example of the application of relativistic time dilation to explain the increased particle range for highspeed particles. In finer detail, these weakinteraction processes involve bosons as intermediates.
May 11, 2015 physics special relativity 39 of 43 relativistic sample problem muon michel van biezen. The muon particle meets these requirements as it has a very short lifetime. The muon is a fundamental particle that is part of the standard model of particle physics. In addition, the collected data is used for several other calculations. Simulation software allows the creation of decay time distributions with a useradjustable muon lifetime. Tot ais the total number of muons received by the detector in a set amount of time at a particular altitude a.
The time dilation formula is, where t 0 is the proper time of a clock comoving with the muon, corresponding with the mean decay time of the muon in its proper frame. To measure the speed, lifetime, and distance we must take in to counter special relativity. If we are sure the muon has s topped inside the liquid scintillator box, one just has to wait a few microsecond and a second pulseof light in left and right detectors will indicate the decay of the muon. Reid, department of physics, university of aberdeen. Muon decay muons were the first elementary particles to be found unstable, i. Muon software ltd develop virtual instrument plugins for use with music recording software such as steinberg cubase or apple logic studio.
Muon decay koos kortland translated and adapted by k. There is also software to simulate muon decay data. The available energy of the reaction is the factor which dictates its lifetime. Time dilation of muons and a paradox physics forums. Why we believe in special relativity spacetime centre. As with the decay of the nonelementary neutron with a lifetime around 15 minutes, muon decay is slow by subatomic standards because the decay is mediated by the weak interaction exclusively rather than the more powerful strong interaction or electromagnetic interaction, and because the mass difference between the muon and the set of its. This experiment is used to detect the speed of a muon and the distance it will travel. A low cost coincidental circuit was designed to select the signals of muon decay events detected by a plastic scintillator detector. A muon is a type of subatomic particle that is created in particle collisions. Einsteins principle of relativity and cosmicray muon decay. However, at relativistic speeds, the lifetime of the muon, as we perceive it, is much longer. Also, because this particule is very small, it very easy to be accelerated to very high speeds. When you take all these effects into account, observers disagree over how much time it takes for a muon to travel along the accelerator, but they all agree over how many muons reach the end. Tuggle ph 255001, group 4 3 may 2010 abstract we describe a procedure for detecting and timing muon decays in a scintillation detector, calculating a value for the muons mean lifetime.
Raw data are written to disk files in a compact format so that students can export them to their own software package and not rely on the one provided. Since the muon is heavier than the electron and is in the same family, the muon will decay into an electron. Muon physics the muon is an elementary particle and one of the fundamental constituents of matter. Some history of the muon experiment the historical experiment upon which the model muon experiment is based was performed by rossi and hall in 1941. Special relativity fails to resolve cosmic muon decay. Pmt coupled plastic scintillator for cosmic muons detection. In the earth frame the muon proper time runs slower, but the distance it covers is not lengthcontracted. An excellent reference on special relativity can be found in french 19682. But what is the thickness of the atmosphere that the muon sees. Note that the central value for the muons lifetime is less than the free space value t 2. Muons time dilation is what one would propose in the given scenario if the theory of relativity was correct.
Muons are very similar to electrons, apart from the fact that a muon has about 200 times more mass than an electron. It is a type of lepton particle, similar to the electron but with a heavier mass. The muon, instead, can turn into an electron indeed i discuss the process in more detail below. Suppose muons decay into other particles with halflife of about 0. Einsteins theory of special relativity is sometimes presented as if it were a piece of philosophy or mathematics that arose purely from abstract thinking about space and time. Physics special relativity 39 of 43 relativistic sample.
These cosmic rays have enough energy to create new particles. How can the decay of muons produced in the earths upper atmosphere provide evidence for the special theory of relativity. The decay time histogram is automatically updated with data from the readout electronics. Aug 30, 2019 with respect to the muon, this distance is therefore 9000m15 600m. An alternative calculation, with approximate numbers. It triggered a digital oscilloscope to record the signals of muon decay events for measuring the muon lifetime and electron energy spectrum. It also possesses a negative charge and a spin of 12. Muon experiment in relativity hyperphysics concepts. Measuring muon lifetime and speed based off special. All software is contained on the cd that accompanies the instrument and can also be freely downloaded from.
Knowing the shape of the distribution of muon energy allows us to take an integral sum. The aim of this project is to detect the muon decay events and to measure the muon mean lifetime. Since the production of muons requires an available com frame energy of over 105 mev, neither ordinary radioactive decay events nor nuclear fission and fusion events such as those occurring in nuclear reactors and nuclear weapons are energetic enough to produce muons. Jan 25, 2011 how to escape poverty is your thinking keeping you poor. Special relativity would be proved in two instances. May 17, 2012 the velocity of the muon relative to the observer isnt obtained just by addingsubtracting the velocities of the muon and observer relative to the lab. Consider, for example, two events think of two ash bombs, or the creation and decay of a muon that occur on the common xaxes of two mutually aligned inertial coordinate systems a and b in uniform motion relative to one another in the direction of their x. I know this misconception is very common for special relativity but i havent found a question that talks a. One type of particles which is created in large numbers is the muon. The time dilation formula is, where t0 is the proper time of a clock comoving with the muon, corresponding with the mean decay time of the muon in its proper frame. Cosmic ray muons and the muon lifetime crm 3 solid angles are expressed in the dimensionless units of steradian, abbreviated sr. At the time of rossis pioneering experiments on muon decay, the only other fundamental particles known. Confusion about length contraction ex in muon decay.
If the rate of muons on ground level suggested a probable number of muons in the earths atmosphere according to special relativity. Due to their mass muons are unstable and decay by the weak force almost exclusively into an. With respect to the muon, this distance is therefore 9000m15 600m. May 29, 2016 homework statement heres a standard example of special relativity in action. For example, in the muon decay problem, we assume that the distance between the muon and the earth is contracted only in the fra. For this purpose we will use the scintillation detector described in the following post. Muon experiment the measurement of the flux of muons at the earths surface produced an early dilemma because many more are detected than would be expected, based on their short halflife of 1. The length contraction refers to the muon itself, in principle the muon dimension in the direction of motion is contracted, but that is irrelevant in this experiment. The figure below is a screen capture from the included software and shows a fit to actual student data. More properly called a mumeson, it has a charge equal to that of an electron and a mass 206 times heavier. A simple setup to measure muon lifetime and electron energy.