Muon lifetime
Stou Sandalski
I've used cosmic ray muons as an example in support of special
relativity... but every time I mention it, I fear the logical question
"Oh but how was the muon lifetime measured at rest"... it hasn't come
up yet... but surely one day it will. So how was the muon lifetime
measured at rest? Or more accurately who/when/where first measured the
muon lifetime at rest.
Although I do not doubt that SR is valid (for now), I want to know if
people just measured muon decay rates at different velocities and
extrapolated (using SR) the lifetime at rest... since that would kind
of make for a circular argument when it comes to SR validity.
Stou
Tom Roberts
> how was the muon lifetime
> measured at rest? Or more accurately who/when/where first measured the
> muon lifetime at rest.
They surely have numerous references giving measurements of muon
lifetimes (and, of course, other particles and other properties).
While I don't have references, I know there are a number of muon
beamlines in the world in which muons are routinely brought to rest, and
a measurement of their lifetime would naturally be part of the analysis
of other things of interest (e.g. muon catalyzed fusion, which requires
stopped muons).
Tom Roberts tjro...@lucent.com
Stou Sandalski
account of some sort. I've asked a couple of experimentalists in my
department and none of them could recall the first experiment...
ironically I got theoretical answers (i.e. just match the muon
production threshold in a collider and they'll be at rest)
=)
dlzc1 D:cox T:net@nospam.com N:dlzc D:aol T:com (dlzc)
"Stou Sandalski" <stou.sa...@gmail.com> wrote in message
news:1142830527.5...@j33g2000cwa.googlegroups.com...
> Thanks for the information but I was looking for
> more of a historic account of some sort.
Google
"discovered the muon"
344 hits like:
http://www.ps.uci.edu/physics/news/nobel.html
... down to "The Physics of Fundamental Particles"
http://www.orau.org/PTP/collection/Miscellaneous/cloudchamber.htm
... Carl Anderson
Other links set its discovery at 1937.
David A. Smith
Hexenmeister
When a muon dies they put it on a gurney and wheel it into the morgue
where it is kept at a low temperature to slow decay. Then later a
pathologist
dissects it to find the cause of death, and usually they take the clock out
and find it has stopped at 2.2 microseconds.
Cosmic ray muons are similar to ghost trains, you can find out
exactly how SR works at
http://www.androcles01.pwp.blueyonder.co.uk/Smart/Smart.htm
As you say, you do not doubt that SR is valid, so you may as well
find out how it works.
Androcles.
Hexenmeister
"Tom Roberts" <tjro...@lucent.com> wrote in message
news:cmqTf.56182$H71....@newssvr13.news.prodigy.com...
"Real has nothing to do with it." -- Tom Roberts.
Androcles.
Bilge
>
>I've used cosmic ray muons as an example in support of special
>relativity... but every time I mention it, I fear the logical question
>"Oh but how was the muon lifetime measured at rest"... it hasn't come
>up yet... but surely one day it will.
It's done all the time.
>So how was the muon lifetime
>measured at rest? Or more accurately who/when/where first measured the
>muon lifetime at rest.
>
>Although I do not doubt that SR is valid (for now), I want to know if
>people just measured muon decay rates at different velocities and
>extrapolated (using SR) the lifetime at rest... since that would kind
>of make for a circular argument when it comes to SR validity.
Accelerators that produce muon beams (as well as pion beams)
rely on relativity to optimize the usable beam that can be extracted
from the system. For exmple, muon beams are usually produced by
from high energy proton beams which react with a target to produce
pions (\pi+). The pions decay in flight to produce muons. To obtain
the greatest beam intensity, one needs the flight path to be long enough
for many of the pions to decay and not too long so that muons reach the
experimental areas.
Stou Sandalski
freshmen level though... nothing Marion and Thornton didn't cover a
year ago... or Griffiths E&M from last quarter... or Griffiths Particle
from this quarter.... but yea I'll bookmark it in case I run out of
textbooks or somehow forgot everything i learned in the past 2 years...
or I drop some acid and feel compelled to watch that psychedelic
Michelson interferometer animation you got going on...
Stou Sandalski
measured at rest?" Especially using a cloudchamber... Surely we can do
it now with the digital detectors but back in the day.... how would you
see it, wouldn't there be only one vertex where the muon existed for a
while and subsequently decayed... since its at rest... there wouldn't
be a track so how would you know... how long it lived for?
Stou Sandalski
> Stou Sandalski:
> >Hello,
> >
> >I've used cosmic ray muons as an example in support of special
> >relativity... but every time I mention it, I fear the logical question
> >"Oh but how was the muon lifetime measured at rest"... it hasn't come
> >up yet... but surely one day it will.
>
> It's done all the time.
What is?
> Accelerators that produce muon beams (as well as pion beams)
> rely on relativity to optimize the usable beam that can be extracted
> from the system. For exmple, muon beams are usually produced by
> from high energy proton beams which react with a target to produce
> pions (\pi+). The pions decay in flight to produce muons
Yes like the CMS testbeam... but methinks measuring the lifetime of the
muon in this way requires an extrapolation of its rest lifetime based
on its lifetime at different beam energies...
Sue...
Electrons exist only because a positron or its equivalent, exist
somewhere else. A charge has no definition except in relation
to its polar opposite.
The same applies for the muon. You have to consider what the
polar opposite material is doing to permit it to exist. Tho the
muons existance is related to near luminal motion wrt its
polar opposites, the characterization as some type of
self contained clock is faulty. An automoble tyre has
a long life if the car is moving at a speed appropriate to
its rotation rate. Its lifetime is very short if the car is
chocked in postition but the tyre is spinning.
http://hotrod.com/techarticles/p155371_image_small.jpg
Muons are massive enough we might even identify
some decay products we could consider "muon smoke"
Sue...
Hexenmeister
| Amusing post... but rather useless... cute web-site too... a bit
| freshmen level though...
It was written for high school level.
nothing Marion and Thornton didn't cover a
| year ago... or Griffiths E&M from last quarter... or Griffiths Particle
| from this quarter.... but yea I'll bookmark it in case I run out of
| textbooks or somehow forgot everything i learned in the past 2 years...
| or I drop some acid and feel compelled to watch that psychedelic
| Michelson interferometer animation you got going on...
|
Amusing post. Totally useless though.
Androcles.
Hexenmeister
| thank you... but my original question was "So how was the muon lifetime
| measured at rest?"
It wasn't.
Especially using a cloudchamber... Surely we can do
| it now with the digital detectors but back in the day.... how would you
| see it, wouldn't there be only one vertex where the muon existed for a
| while and subsequently decayed... since its at rest... there wouldn't
| be a track so how would you know... how long it lived for?
Mildly amusing post. Must try harder.
Androcles.
Hexenmeister
| Bilge wrote:
| > Stou Sandalski:
| > >Hello,
| > >
| > >I've used cosmic ray muons as an example in support of special
| > >relativity... but every time I mention it, I fear the logical question
| > >"Oh but how was the muon lifetime measured at rest"... it hasn't come
| > >up yet... but surely one day it will.
| >
| > It's done all the time.
|
| What is?
Fucking with shitheads like Bilge is.
|
| > Accelerators that produce muon beams (as well as pion beams)
| > rely on relativity to optimize the usable beam that can be extracted
| > from the system. For exmple, muon beams are usually produced by
| > from high energy proton beams which react with a target to produce
| > pions (\pi+). The pions decay in flight to produce muons
|
| Yes like the CMS testbeam... but methinks measuring the lifetime of the
| muon in this way requires an extrapolation of its rest lifetime based
| on its lifetime at different beam energies...
Mildly amusing post. Must try harder.
Androcles.
|
Sue...
"Retarded potential"
http://farside.ph.utexas.edu/teaching/em/lectures/node50.html
Sue...
> Androcles.
Randy Poe
The muons wouldn't have been at rest, merely moving
at moderate velocities. If you are measuring something
at a velocity where gamma is .000001% different from 1,
and your lifetime measurement has an error bar of .1%,
it's reasonable to call that a measurement of the rest lifetime.
- Randy
Hexenmeister
"Sue..." <suzyse...@yahoo.com.au> wrote in message
news:1142870113....@j33g2000cwa.googlegroups.com...
http://tinyurl.com/kcbjq
Androcles.
Sue...
http://www.androcles01.pwp.blueyonder.co.uk/RP/Zauberlehrling%20Jahn.htm
601KB 11 files
That's a considerable improvement over eleventeen megga flopers
that takes 3 broadband connections to get in a week.
Mathemagics and arithmancy?
Let's see now... Space time continuum is real.
Euclidean geometry is all an illusion.
So if the campfire is too warm, move closer (north).
If the wine bottle is draining too fast, move east.
If your watch needs a battery move south.
To signal rescurers with photons move west.
If ya just want to take a walk... don't dare move
all the axes are used up so something else will happen.
;o)
Sue...
> Androcles.
G=EMC^2 Glazier
properties are very similar,but it weighs 207 times more. The muon is
sometime seen in cosmic rays,and yet it is not a component of ordinary
matter(tricky stuff) Best to keep in mind that a muon can be heavier
because it is moving very fast(more energy or inertia) TreBert
Hexenmeister
And you couldn't interrupt :-)
Admittedly gifs are expensive, but you get quality. I never met a woman
yet that didn't like extravagance.
| Mathemagics and arithmancy?
Mathema?ics ... t stands time, g stands for 1/sqrt(1-v²/c²) .
Muggles attempt mathemagics.
Arithmancy you need to see J K Rowling about. She's a woman,
you know, and a fine witch. She conjures movies as well as that
other important magic, m.o.n.e.y. Not too hot on physics, perhaps,
witch is why I opened hogwarts.physics school for zauberlehrlings.
|
| Let's see now... Space time continuum is real.
"Real has nothing to do with it" -- Humpty Roberts.
news:hG3Sf.54263$H71....@newssvr13.news.prodigy.com...
`And how many birthdays have you?'
`One.'
`And if you take one from three hundred and sixty-five what remains?'
`Three hundred and sixty-four, of course.'
Humpty Roberts looked doubtful. `I'd rather see that done on paper,' he
said.
Alice couldn't help smiling as she took out her memorandum book, and worked
the sum for him:
365
1
----
364
----
Humpty Roberts took the book and looked at it carefully. `That seems to be
done right --' he began.
`You're holding it upside down!' Alice interrupted.
`To be sure I was!' Humpty Roberts said gaily as she turned it round for
him. `I thought it looked a little queer. As I was saying, that seems to be
done right -- though I haven't time to look it over thoroughly just now --
and that shows that there are three hundred and sixty-four days when you
might get un-birthday presents --'
`Certainly,' said Alice.
`And only one for birthday presents, you know. There's speed for you!'
`I don't know what you mean by "speed",' Alice said.
Humpty Roberts smiled contemptuously. `Of course you don't -- till I tell
you. I meant "there's a nice knock-down argument for you!"'
`But "speed" doesn't mean "a nice knock-down argument",' Alice objected.
`When I use a word,' Humpty Roberts said, in rather a scornful tone, `it
means just what I choose it to mean -- neither more nor less.'
`The question is,' said Alice, `whether you can make words mean so many
different things.'
`The question is,' said Humpty Roberts, `which is to be master -- that's
all.'
Alice was too much puzzled to say anything; so after a minute Humpty Roberts
began again. `They've a temper, some of them -- particularly verbs: they're
the proudest -- adjectives you can do anything with, but not verbs --
however, I can manage the whole lot of them! Impenetrability! That's what I
say!'
And of course relativity is as impenetrable as his thick shell-like skull.
| Euclidean geometry is all an illusion.
| So if the campfire is too warm, move closer (north).
| If the wine bottle is draining too fast, move east.
| If your watch needs a battery move south.
| To signal rescurers with photons move west.
|
| If ya just want to take a walk... don't dare move
| all the axes are used up so something else will happen.
|
| ;o)
| Sue...
Carry three watches if you walk anywhere.
tau = (t-vx/c²)/sqrt(1-v²/c²) Einstein
tau = (t-uy/c²)/sqrt(1-u²/c²) Androcles
tau = (t-wz/c²)/sqrt(1-w²/c²) Androcles
xi = (x-vt)/sqrt(1-v²/c²) Einstein
eta = (y-ut)/sqrt(1-u²/c²) Androcles
zeta= (z-wt)/sqrt(1-w²/c²) Androcles
I prefer to stay in bed with three witches.
| > Androcles.
Dirk Van de moortel
"Stou Sandalski" <stou.sa...@gmail.com> wrote in message news:1142846539.9...@e56g2000cwe.googlegroups.com...
You haven't seen this one yet?
http://users.telenet.be/vdmoortel/dirk/Physics/Fumbles/AndroMMX.html
Dirk Vdm
Henry Haapalainen
another muon in rest. It's between those two, and the third, outward
observer cannot see difference in their ageing. Using muon to prove time
dilation is a serious misunderstanding.
Henry Haapalainen
Bilge
>> Stou Sandalski:
>> >Hello,
>> >
>> >I've used cosmic ray muons as an example in support of special
>> >relativity... but every time I mention it, I fear the logical question
>> >"Oh but how was the muon lifetime measured at rest"... it hasn't come
>> >up yet... but surely one day it will.
>>
>> It's done all the time.
>
>What is?
Measurements of the muon lifetime with the muon at rest.
>
>> Accelerators that produce muon beams (as well as pion beams)
>> rely on relativity to optimize the usable beam that can be extracted
>> from the system. For exmple, muon beams are usually produced by
>> from high energy proton beams which react with a target to produce
>> pions (\pi+). The pions decay in flight to produce muons
>
>Yes like the CMS testbeam... but methinks measuring the lifetime of the
>muon in this way requires an extrapolation of its rest lifetime based
>on its lifetime at different beam energies...
Since there exist accelerators which produce muon beams and
since the muons can be stopped in a target, the lifetime of the
muon in the laboratory rest frame is easy to measure simply by
stopping the muons in the target and counting the decays over
some time interval. A straight forward way to do that (possibly
limited by technical details) is to use the muon beam to irradiate
a solid state detector that is thick enough to stop the muons,
then chop the beam so that the target is irradiated for some
time interval, T_1 and the beam is turned off for some time interval
T_2. So, in principle, one counts the numer of muons which stop
in the detector over a short time interval, then turns off the
beam for a long time interval while counting the decays in small
fixed steps \delta t to get the lifetime. This direct approach is
limited by some practical considerations, but there are more
complex ways to acheive the same result.
Dirk Van de moortel
"Henry Haapalainen" <kir...@kolumbus.fi> wrote in message news:dvna6a$8v7$1...@phys-news4.kolumbus.fi...
Trying to talk sense into an imbecile is a serious waste of time.
Dirk Vdm
Stou Sandalski
> Since there exist accelerators which produce muon beams and
> since the muons can be stopped in a target, the lifetime of the
> muon in the laboratory rest frame is easy to measure simply by
> stopping the muons in the target and counting the decays over
> some time interval. A straight forward way to do that (possibly
> limited by technical details) is to use the muon beam to irradiate
> a solid state detector that is thick enough to stop the muons,
> then chop the beam so that the target is irradiated for some
> time interval, T_1 and the beam is turned off for some time interval
> T_2. So, in principle, one counts the numer of muons which stop
> in the detector over a short time interval, then turns off the
> beam for a long time interval while counting the decays in small
> fixed steps \delta t to get the lifetime. This direct approach is
> limited by some practical considerations, but there are more
> complex ways to acheive the same result.
That explains it perfectly. thank you =)
Hexenmeister
"Dirk Van de moortel" <dirkvand...@ThankS-NO-SperM.hotmail.com> wrote
in message news:ldHTf.328040$WS4.10...@phobos.telenet-ops.be...
You've proven that many a time, senseless turkey.
However, time can be spent frivolously as you've also proven.
Androcles.
Tom Roberts
> I like to think of the muon as being a heavy electron.
That's only a very gross approximation. Muons have their own lepton
number that is conserved, just like but independent of the electron
lepton number.
> Its
> properties are very similar,but it weighs 207 times more.
Hmmm. But the differences can be colossal -- for instance there is no
"electron catalyzed fusion", but there is for negative muons. And, of
course, muons are unstable but electrons are not.
> The muon is
> sometime seen in cosmic rays,and yet it is not a component of ordinary
> matter(tricky stuff)
Actually, on earth muons are the vast majority of cosmic ray particles.
At higher altitudes their prevalence diminishes until they are
essentially absent in outer space.
Tom Roberts tjro...@lucent.com
Dr Ivan D. Reid
Actually the normal way is to adjust your incoming rate so that
you rarely have more than one muon in the sample at a time, and electronic
vetos to remove events where this wasn't true. For all valid events you
(conceptually) start a clock when the muon enters the sample and read it
out when the decay positron is detected[1]. Note that I said positron;
when you use negative muons you find a shorter lifetime, dependent on
the target's atomic number, due essentially to nuclear capture of the
muon from a low-lying atomic orbit -- so one typically uses positive
muons.
There's a whole field of physics and chemistry based on the above,
called muon-spin rotation/relaxation/resonance (µSR); experiments are carried
out principally at TRIUMF in Vancouver, PSI in Switzerland, RAL in the UK
and KEK in Japan.
e.g. http://www.psi.ch/forschung/forschung_myonen_e.shtml
or http://lmu.web.psi.ch/
Muon-spin resonance spectroscopy. ID Reid and E Roduner,
in Encyclopedia of Spectroscopy and Spectrometry, J Lindon, G Tranter
and J Holmes, eds., Academic Press, London (1999).
[1] Some time-to-digital converters have been built specifically for this
application, e.g. the LeCrot TD4204.
--
Ivan Reid, Electronic & Computer Engineering, ___ CMS Collaboration,
Brunel University. Ivan.Reid@[brunel.ac.uk|cern.ch] Room 40-1-B12, CERN
KotPT -- "for stupidity above and beyond the call of duty".
Hexenmeister
"Dr Ivan D. Reid" <Ivan...@brunel.ac.uk> wrote in message
news:slrne1vnds.3...@loki.brunel.ac.uk...
|
| Actually the normal way is to adjust your incoming rate so that
| you rarely have more than one muon in the sample at a time, and electronic
| vetos to remove events where this wasn't true.
Remove any data that does not agree with theory.
| For all valid events you
| (conceptually) start a clock when the muon enters the sample and read it
| out when the decay positron is detected[1]. Note that I said positron;
| when you use negative muons you find a shorter lifetime, dependent on
| the target's atomic number, due essentially to nuclear capture of the
| muon from a low-lying atomic orbit -- so one typically uses positive
| muons.
If the facts don't fit the theory, change the facts.
Androcles.
PD
Henri Wilson and Androcles both figure that the apparatus is rigged to
be blind to superluminal muons. Of course, in this case, the muons are
at low speed, but Androcles figures the apparatus has to be rigged
anyway. He thinks there's something to be gained by doing that.
PD
G=EMC^2 Glazier
explodes in two millionths of a second age. Exploded into electrons
and neutrinos.(that has to tell you something) Accelerated to 99.5
of 'c' it can last 10 time longer than at rest,but best to keep in mind
it can't accomplish anything more than in those two millionths of a
second when at rest, At 99.999999999 of 'c' its 70,000 times heavier
than at rest. It can never reach the speed of light. TreBert
Hexenmeister
"PD" <TheDrap...@gmail.com> wrote in message
news:1142949755....@i39g2000cwa.googlegroups.com...
| "Real" has nothing to do with it.
|
| To obtain a speed, you must divide the distance traveled by the travel
| time, and _all_ quantities _must_ be measured in a single coordinate
| system.
| _Nothing_ else is speed. Because that is what we mean by the word. <shrug>
|
|
| Tom Roberts tjro...@lucent.com
Humpty Roberts in Wonderland:-
`I don't know what you mean by "speed",' Alice said.
Humpty Roberts smiled contemptuously. `Of course you don't -- till I tell
you. I meant "there's a nice knock-down argument for you!"'
`But "speed" doesn't mean "a nice knock-down argument",' Alice objected.
`When I use a word,' Humpty Roberts said, in rather a scornful tone, `it
means just what I choose it to mean -- neither more nor less.'
`The question is,' said Alice, `whether you can make words mean so many
different things.'
`The question is,' said Humpty Roberts, `which is to be master -- that's
all.'
Alice was too much puzzled to say anything; so after a minute Humpty Roberts
began again. `They've a temper, some of them -- particularly verbs: they're
the proudest -- adjectives you can do anything with, but not verbs --
however, I can manage the whole lot of them! Impenetrability! That's what I
say!'
With thanks to Lewis Carroll.
Professor Androcles.
Henry Haapalainen
the only one using that alt.morons "newsgroup" when somebody is trying to
answer you. Why several names, if you expose yourself anyway?
Henry Haapalainen
Peri of Pera
cosmic ray muons created? They are created on impact with other
particles in the earth's atmosphere and that can be from 1mm to 100km
above the surface of the earth. Lifetime is not really significant in
this context. The earth's atmosphere is like a sieve and the assumption
that all muons come into being immediately 100km above the earth is not
a valid assumption.
Peter Riedt
Peri of Pera
Andy, but do the three witches prefer to stay in bed with you?
Hexenmeister
"Peri of Pera" <rie...@yahoo.co.uk> wrote in message
news:1143270095.6...@g10g2000cwb.googlegroups.com...
> Mathema?ics ... t stands time, g stands for 1/sqrt(1-v2/c2) .
> tau = (t-vx/c2)/sqrt(1-v2/c2) Einstein
> tau = (t-uy/c2)/sqrt(1-u2/c2) Androcles
> tau = (t-wz/c2)/sqrt(1-w2/c2) Androcles
> xi = (x-vt)/sqrt(1-v2/c2) Einstein
> eta = (y-ut)/sqrt(1-u2/c2) Androcles
> zeta= (z-wt)/sqrt(1-w2/c2) Androcles
>
> I prefer to stay in bed with three witches.
>
> | > Androcles.
Andy, but do the three witches prefer to stay in bed with you?
Let me tell you the nine facts of life.
A- young witch
B - middle aged witch
C - old witch
1 - young wizard
2 - middle aged sorcerer
3 - old hexenmeister
A B C
1 A1 B1 C1
2 A2 B2 C2
3 A3 B3 C3
1A -- "I lovey dovey you, darling, let's make babies."
A1 -- "I lovey dovey you, darling, can I have a white wedding?"
2B -- "I orgy porgy you, sorry about the premature ejaculation last week".
B2 -- "I have a headache and the kids might hear".
1B -- "What if your old man finds out?"
B1 -- "He doesn't understand a witches needs."
3B -- "Can I take you for a drive?"
B3 -- "Ah jest lurve yer red shiny stickshift!" (Translation: I love
your money.)
C1 -- see 1C.
1C -- http://www.androcles01.pwp.blueyonder.co.uk/Show_me_your_tits.jpg
C2 -- "Such a nice young wizard." (Translation: Sigh...If only I were
younger)
2C -- "Hmm...possible, I suppose... nah."
C3 -- "Did you forget to take your Viagra?"
3C -- (snore)
2A -- "May I take you to dinner?"
A2 -- "Ah jest lurve yer accent!" (Translation: I love your money.)
3A -- "Can I take you and your friend to bed?"
A3 -- "Ah jest lurve yer intelligence!" (Translation: I love your money.)
Androcles.
Peri of Pera
Peter Riedt
Hexenmeister
| Andy, a very good approximation of reality. Better than your physics.
|
| Peter Riedt
|
What are you babbling about?
Peri of Pera
Andy, you should be a comedian.
Peter Riedt
Hexenmeister
I am.
What were you babbling about?
Androcles.