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Showing posts with label Gran Sasso. Show all posts
Showing posts with label Gran Sasso. Show all posts

Wednesday, November 20, 2013

Muon Detection


An image of the shadow of the Moon in muons as produced by the 700m subterranean Soudan 2 detector in the Soudan Mine in Minnesota. The shadow is the result of approximately 120 muons missing from a total of 33 million detected in Soudan 2 over its 10 years of operation. The cross denotes the actual location of the Moon. The shadow of the Moon is slightly offset from this location because cosmic rays are electrically charged particles and were slightly deflected by the Earth's magnetic field on their journey to the upper atmosphere. The shadow is produced due to the shielding effect the Moon has on galactic and cosmic rays, which stream in from all directions. The cosmic rays normally strike atoms high in the upper atmosphere, producing showers of muons and other short lived particles.

Just an update here while looking at Sean Carroll's blog post article, entitled," Scientists Confirm Existence of Moon." While we understand the need for confirmation of the existence of things, seeing how our perception is used in order to make such a statement,  is a statement of such a measure then as to what is real.

 We report on the observation of a significant deficit of cosmic rays from the direction of the Moon with the IceCube detector. The study of this "Moon shadow" is used to characterize the angular resolution and absolute pointing capabilities of the detector. The detection is based on data taken in two periods before the completion of the detector: between April 2008 and May 2009, when IceCube operated in a partial configuration with 40 detector strings deployed in the South Pole ice, and between May 2009 and May 2010 when the detector operated with 59 strings. Using two independent analysis methods, the Moon shadow has been observed to high significance (> 6 sigma) in both detector configurations. The observed location of the shadow center is within 0.2 degrees of its expected position when geomagnetic deflection effects are taken into account. This measurement validates the directional reconstruction capabilities of IceCube. See: Observation of the cosmic-ray shadow of the Moon with IceCube,

So I have spent some time here looking at how this measure is used in term sof such clarifications and this to me is an exciting off shoot of what particle research has done for us. The skies the limit then as to our use of such a measure then is seen and understood in the post written by Sean Carroll.

Tuesday, November 22, 2011

first tau-neutrino “appearing” out of several billion of billions muon neutrinos

Layout of the CNGS beam line.
The OPERA neutrino experiment [1] at the underground Gran Sasso Laboratory (LNGS) was designed to perform the first detection of neutrino oscillations in direct appearance mode in the νμ→ντ channel, the signature being the identification of the τ− lepton created by its charged current (CC) interaction [2]. See: Measurement of the neutrino velocity with the OPERA detector in the CNGS beam-

Computer reconstruction of the tau candidate event detected in the OPERA
experiment. The light blue track is the one likely induced by the decay of a tau lepton
produced by a tau-neutrino. See: The OPERA experiment

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See Also:

Proton Collision ->Decay to Muons and Muon Neutrinos ->Tau Neutrino ->

Sunday, November 20, 2011

Energy Boost From Shock Front

Main Components of CNGS
A 400 GeV/c proton beam is extracted from the SPS in 10.5 microsecond short pulses of 2.4x1013 protons per pulse. The proton beam is transported through the transfer line TT41 to the CNGS target T40. The target consists of a series of graphite rods, which are cooled by a recirculated helium flow. Secondary pions and kaons of positive charge produced in the target are focused into a parallel beam by a system of two pulsed magnetic lenses, called horn and reflector. A 1 km long evacuated decay pipe allows the pions and kaons to decay into their daughter particles - of interest here is mainly the decay into muon-neutrinos and muons. The remaining hadrons (protons, pions, kaons) are absorbed in an iron beam dump with a graphite core. The muons are monitored in two sets of detectors downstream of the dump. Further downstream, the muons are absorbed in the rock while the neutrinos continue their travel towards Gran Sasso.microsecond short pulses of 2.4x1013 protons per
 For me it has been an interesting journey in trying to understand the full context of a event in space sending information through out the cosmos in ways that are not limited to the matter configurations that would affect signals of those events.

In astrophysics, the most widely discussed mechanism of particle acceleration is the first-order Fermi process operating at collisionless shocks. It is based on the idea that particles undergo stochastic elastic scatterings both upstream and downstream of the shock front. This causes particles to wander across the shock repeatedly. On each crossing, they receive an energy boost as a result of the relative motion of the upstream and downstream plasmas. At non-relativistic shocks, scattering causes particles to diffuse in space, and the mechanism, termed "diffusive shock acceleration," is widely thought to be responsible for the acceleration of cosmic rays in supernova remnants. At relativistic shocks, the transport process is not spatial diffusion, but the first-order Fermi mechanism operates nevertheless (for reviews, see Kirk & Duffy 1999; Hillas 2005). In fact, the first ab initio demonstrations of this process using particle-in-cell (PIC) simulations have recently been presented for the relativistic case (Spitkovsky 2008b; Martins et al. 2009; Sironi & Spitkovsky 2009).
Several factors, such as the lifetime of the shock front or its spatial extent, can limit the energy to which particles can be accelerated in this process. However, even in the absence of these, acceleration will ultimately cease when the radiative energy losses that are inevitably associated with the scattering process overwhelm the energy gains obtained upon crossing the shock. Exactly when this happens depends on the details of the scattering process. See: RADIATIVE SIGNATURES OF RELATIVISTIC SHOCKS

So in soliton expressions while trying to find such an example here in the blog does not seem to be offering itself in the animations of the boat traveling down the channel we are so familiar with that for me this was the idea of the experimental processes unfolding at LHC. The collision point creates shock waves\particle sprays as Jets?


Soliton


Solitary wave in a laboratory wave channel.
In mathematics and physics, a soliton is a self-reinforcing solitary wave (a wave packet or pulse) that maintains its shape while it travels at constant speed. Solitons are caused by a cancellation of nonlinear and dispersive effects in the medium. (The term "dispersive effects" refers to a property of certain systems where the speed of the waves varies according to frequency.) Solitons arise as the solutions of a widespread class of weakly nonlinear dispersive partial differential equations describing physical systems. The soliton phenomenon was first described by John Scott Russell (1808–1882) who observed a solitary wave in the Union Canal in Scotland. He reproduced the phenomenon in a wave tank and named it the "Wave of Translation".

So in a sense the shock front\horn for me in respect of Gran Sasso is the idea that such a front becomes a dispersive element in medium expression of earth to know that such densities in earth have a means by which we can measure relativist interpretations as assign toward density determinations in the earth.  Yet,  there are things not held to this distinction so know that they move on past such targets so as to show cosmological considerations are just as relevant today as they are while we set up the experimental avenues toward identifying this relationship here on earth.

 For more than a decade, scientists have seen evidence that the three known types of neutrinos can morph into each other. Experiments have found that muon neutrinos disappear, with some of the best measurements provided by the MINOS experiment. Scientists think that a large fraction of these muon neutrinos transform into tau neutrinos, which so far have been very hard to detect, and they suspect that a tiny fraction transform into electron neutrinos. See: Fermilab experiment weighs in on neutrino mystery

When looking out at the universe such perspective do not hold relevant for those not looking past the real toward the abstract? To understand the distance measure of binary star of Taylor and Hulse,  such signals need to be understood in relation to what is transmitted out into the cosmos? How are we measuring that distance? For some who are even more abstractedly gifted they may see the waves generated in gravitational expression. So this becomes a means which which to ask if the binary stars are getting closer then how is this distance measured? You see?


Measurement of the neutrino velocity with the OPERA detectorin the CNGS beam 





Monday, October 31, 2011

Gran Sasso and Fermilab

Gran Sasso

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deconstruction: soudan mural
The Soudan mural is next to the 6000-ton MINOS detector. Mural artists: Joseph Giannetti, Leila Giannetti, Mick Pulsifer. Funded by a grant from the University of Minnesota. (Credit: Fermilab Visual Media Services)
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Fermilab experiment weighs in on neutrino mystery
Scientists of the MINOS experiment at the Department of Energy’s Fermi National Accelerator Laboratory announced today (June 24) the results from a search for a rare phenomenon, the transformation of muon neutrinos into electron neutrinos. The result is consistent with and significantly constrains a measurement reported 10 days ago by the Japanese T2K experiment, which announced an indication of this type of transformation.

The results of these two experiments could have implications for our understanding of the role that neutrinos may have played in the evolution of the universe. If muon neutrinos transform into electron neutrinos, neutrinos could be the reason that the big bang produced more matter than antimatter, leading to the universe as it exists today.

The Main Injector Neutrino Oscillation Search (MINOS) at Fermilab recorded a total of 62 electron neutrino-like events. If muon neutrinos do not transform into electron neutrinos, then MINOS should have seen only 49 events. The experiment should have seen 71 events if neutrinos transform as often as suggested by recent results from the Tokai-to-Kamioka (T2K) experiment in Japan. The two experiments use different methods and analysis techniques to look for this rare transformation.
To measure the transformation of muon neutrinos into other neutrinos, the MINOS experiment sends a muon neutrino beam 450 miles (735 kilometers) through the earth from the Main Injector accelerator at Fermilab to a 5,000-ton neutrino detector, located half a mile underground in the Soudan Underground Laboratory in northern Minnesota. The experiment uses two almost identical detectors: the detector at Fermilab is used to check the purity of the muon neutrino beam, and the detector at Soudan looks for electron and muon neutrinos. The neutrinos’ trip from Fermilab to Soudan takes about one four hundredths of a second, giving the neutrinos enough time to change their identities.

For more than a decade, scientists have seen evidence that the three known types of neutrinos can morph into each other. Experiments have found that muon neutrinos disappear, with some of the best measurements provided by the MINOS experiment. Scientists think that a large fraction of these muon neutrinos transform into tau neutrinos, which so far have been very hard to detect, and they suspect that a tiny fraction transform into electron neutrinos.

The observation of electron neutrino-like events in the detector in Soudan allows MINOS scientists to extract information about a quantity called sin213 (pronounced sine squared two theta one three). If muon neutrinos don’t transform into electron neutrinos, this quantity is zero. The range allowed by the latest MINOS measurement overlaps with but is narrower than the T2K range. MINOS constrains this quantity to a range between 0 and 0.12, improving on results it obtained with smaller data sets in 2009 and 2010. The T2K range for sin213 is between 0.03 and 0.28.
“MINOS is expected to be more sensitive to the transformation with the amount of data that both experiments have,” said Fermilab physicist Robert Plunkett, co-spokesperson for the MINOS experiment. “It seems that nature has chosen a value for sin213 that likely is in the lower part of the T2K allowed range. More work and more data are really needed to confirm both these measurements.”
The MINOS measurement is the latest step in a worldwide effort to learn more about neutrinos. MINOS will continue to collect data until February 2012. The T2K experiment was interrupted in March when the severe earth quake in Japan damaged the muon neutrino source for T2K. Scientists expect to resume operations of the experiment at the end of the year. Three nuclear-reactor based neutrino experiments, which use different techniques to measure sin213, are in the process of starting up.
“Science usually proceeds in small steps rather than sudden, big discoveries, and this certainly has been true for neutrino research,” said Jenny Thomas from University College London, co-spokesperson for the MINOS experiment. “If the transformation from muon neutrinos to electron neutrinos occurs at a large enough rate, future experiments should find out whether nature has given us two light neutrinos and one heavy neutrino, or vice versa. This is really the next big thing in neutrino physics.”
The MINOS experiment involves more than 140 scientists, engineers, technical specialists and students from 30 institutions, including universities and national laboratories, in five countries: Brazil, Greece, Poland, the United Kingdom and the United States. Funding comes from: the Department of Energy Office of Science and the National Science Foundation in the U.S., the Science and Technology Facilities Council in the U.K; the University of Minnesota in the U.S.; the University of Athens in Greece; and Brazil's Foundation for Research Support of the State of São Paulo (FAPESP) and National Council of Scientific and Technological Development (CNPq).

Fermilab is a national laboratory supported by the Office of Science of the U.S. Department of Energy, operated under contract by Fermi Research Alliance, LLC.
For more information about MINOS and related experiments, visit the Fermilab neutrino website: http://www.fnal.gov/pub/science/experiments/intensity/

See: 

Intensity Frontier


See Also: The Reference Frame: CMS: a very large excess of diphotons

Thursday, October 27, 2011

XKCD Significant-Speed of Light Issue?

You got to love it when correlations can be made, and a thank you to the ICECUBE Blog
If the histograms and data are exactly right, the paper quotes a one-in-ten-thousand (0.0001) chance that this bump is a fluke. That's pretty small; although bear in mind that lots of distributions like this get plotted. If you plot 100 different distributions, the chances become about one in a hundred (0.01) that you'll see something odd in one of them. The Tevatron goes bump

http://imgs.xkcd.com/comics/significant.png

ICECUBE Blogging Research Material and more

In regards to Cherenkov Light

Thinking outside the box See: A physicist inthe cancer lab

Ackerman became interested in physics in middle school, reading popular science books about quantum mechanics and string theory. As an undergraduate at the Massachusetts Institute of Technology, she traveled to CERN, the European particle physics laboratory near Geneva, to work on one of the detectors at the Large Hadron Collider, the most powerful particle collider in the world. Then she spent a summer at SLAC working on BaBar, an experiment investigating the universe’s puzzling shortage of antimatter, before starting her graduate studies there in 2007.

 Linking Experiments(Majorana, EXO); How do stars create the heavy elements? (DIANA); What role did neutrinos play in the evolution of the universe? (LBNE). In addition, scientists propose to build a generic underground facility (FAARM) ...

 Dialogos of Eide: Neutrinoless Double Beta DecayCOBRA · CUORICINO and CUORE · EXO · GERDA · MAJORANA · MOON · NEMO-3 and SuperNEMO · SNO+. See Also:Direct Dark Matter Detection.

Also From my research:

  1. Neutrinoless Double Beta Decay
  2. A first look at the Earth interior from the Gran Sasso underground laboratory
  3. Mysterious Behavior of Neutrinos sent Straight through the Earth
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ICECUBE Blog put up some links that I wanted to go through to see what is happening there. Their links provided at bottom of blog post here. Each link of theirs I have provided additional information in concert while I explore above.

Tuesday, October 04, 2011

P.I. Chats: Faster-than-light neutrinos?

Measurements by GPS confirm that the neutrinos identified by the Super-Kamiokande detector were indeed produced on the east coast of Japan. The physicists therefore estimate that the results obtained point to a 99.3% probability that electron neutrino appearance was detected.Neutrino Oscillations Caught in the Act



The Gran Sasso National Laboratory (LNGS) is one of four INFN national laboratories.




PERIMETER INSTITUTE RECORDED SEMINAR ARCHIVE



PIRSA:11090135  ( Flash Presentation , MP3 , PDF ) Which Format?
P.I. Chats: Faster-than-light neutrinos?
Abstract: Can neutrinos really travel faster than light? Recently released experimental data from CERN suggests that they can. Join host Dr. Richard Epp and a panel of Perimeter Institute scientists in a live webinar to discuss this unexpected and puzzling experimental result, and some theoretical questions it might raise.
Date: 28/09/2011 - 12:15 pm
Thanks Phil 

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Using the NuMI beam to search for electron neutrino appearance.

The NOνA Experiment (Fermilab E929) will construct a detector optimized for electron neutrino detection in the existing NuMI neutrino beam. The primary goal of the experiment is to search for evidence of muon to electron neutrino oscillations. This oscillation, if it occurs, holds the key to many of the unanswered questions in neutrino oscillation physics. In addition to providing a measurement of the last unknown mixing angle, θ13, this oscillation channel opens the possibility of seeing matter/anti-matter asymmetries in neutrinos and determination of the ordering of the neutrino mass states.See:The NOνA Experiment at Fermilab (E929)

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Image from a neutrino detection experiment. (Credit: Image courtesy of Southern Methodist University)

Hunting Oscillation of Muon to Electron: Neutrino Data to Flow in 2010; NOvA Scientists Tune Design


Bee:And for all I know you need a charge for Cherenkov radiation and neutrinos don't have one.

Thursday, September 29, 2011

Cassiopeia A

In conclusion, we have a rich panorama of experiments that all make use of neutrinos as probes of exotic phenomena as well as processes which we have to measure better to gain understanding of fundamental physics as well as gather information about the universe. See:Vernon Barger: perspectives on neutrino physics May 22, 2008


This image presents a beautiful composite of X-rays from Chandra (red, green, and blue) and optical data from Hubble (gold) of Cassiopeia A, the remains of a massive star that exploded in a supernova. Evidence for a bizarre state of matter has been found in the dense core of the star left behind, a so-called neutron star, based on cooling observed over a decade of Chandra observations. The artist's illustration in the inset shows a cut-out of the interior of the neutron star where densities increase from the crust (orange) to the core (red) and finally to the region where the "superfluid" exists (inner red ball). X-ray: NASA/CXC/UNAM/Ioffe/D. Page, P. Shternin et al.; Optical: NASA/STScI; Illustration: NASA/CXC/M. WeissSee Also:Superfluid and superconductor discovered in star's core

Illustration of Cassiopeia A Neutron Star
This is an artist's impression of the neutron star at the center of the Cassiopeia A supernova remnant. The different colored layers in the cutout region show the crust (orange), the higher density core (red) and the part of the core where the neutrons are thought to be in a superfluid state (inner red ball). The blue rays emanating from the center of the star represent the copious numbers of neutrinos that are created as the core temperature falls below a critical level and a superfluid is formed.
(Credit: Illustration: NASA/CXC/M.Weiss)


X-ray and Optical Images of Cassiopeia A
Two independent research teams studied the supernova remnant Cassiopeia A, the remains of a massive star, 11,000 light years away that would have appeared to explode about 330 years as observed from Earth. Chandra data are shown in red, green and blue along with optical data from Hubble in gold. The Chandra data revealed a rapid decline in the temperature of the ultra-dense neutron star that remained after the supernova. The data showed that it had cooled by about 4% over a ten-year period, indicating that a superfluid is forming in its core.
(Credit: X-ray: NASA/CXC/UNAM/Ioffe/D.Page,P.Shternin et al; Optical: NASA/STScI)
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See: Galactic Neutrino Communications

Monday, September 26, 2011

Measurement of the neutrino velocity with the OPERA detector in the CNGS beam

We know already why the neutrinos could go faster and what new experiments this suggests, why it does not imply time travel or violates causality, and why it is somewhat expected for neutrinos. Now let us focus on what kind of superluminal velocity is indicated.See:A Million Times The Speed Of Light



Measurement of the neutrino velocity with the OPERA detectorin the CNGS beam
The OPERA neutrino experiment at the underground Gran Sasso Laboratory has measured the velocity of neutrinos from the CERN CNGS beam over a baseline of about 730 km with much higher accuracy than previous studies conducted with accelerator neutrinos. The measurement is based on highstatistics data taken by OPERA in the years 2009, 2010 and 2011. Dedicated upgrades of the CNGS timing system and of the OPERA detector, as well as a high precision geodesy campaign for the measurement of the neutrino baseline, allowed reaching comparable systematic and statistical accuracies.

An early arrival time of CNGS muon neutrinos with respect to the one computed assuming the speed of light in vacuum of (60.7 ± 6.9 (stat.) ± 7.4 (sys.)) ns was measured. This anomaly corresponds to a relative difference of the muon neutrino velocity with respect to the speed of light (v-c)/c = (2.48 ± 0.28 (stat.) ± 0.30 (sys.)) ×10-5. See:
Measurement of the neutrino velocity with the OPERA detectorin the CNGS beam


Measurement of the neutrino velocity with the OPERA detectorin the CNGS beam

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See:  

See Also:

Sunday, September 25, 2011

Relativistic Time Dilation in Muon Decay

See: Relativistic Time Dilation in Muon Decay

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Muons reveal the interior of volcanoes

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It has been recently shown that puzzling excess events observed by the LSND and MiniBooNE neutrino experiments could be interpreted as a signal from the radiative decay of a heavy sterile neutrino (nu_h) of the mass from 40 to 80 MeV with a muonic mixing strength ~ 10^{-3} - 10^{-2}. If such nu_h exists its admixture in the ordinary muon decay would result in the decay chain mu -> e nu_e nu_h -> e nu_e gamma nu. We proposed a new experiment for a sensitive search for this process in muon decay at rest allowing to definitively confirm or exclude the existence of the nu_h. To our knowledge, no experiment has specifically searched for the signature of radiative decay of massive neutrinos from muon decays as proposed in this work. The search is complementary to the current experimental efforts to clarify the origin of the LSND and MiniBooNE anomalies. Bounds on the muonic mixing strength from precision measurements with muons are discussed. See: New muon decay experiment to search for heavy sterile neutrino and also The LSND/MiniBooNe excess events and heavy neutrino from muon and kaon decays

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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. 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. They found the ratio of the muon flux was 1.4, whereas the ratio should have been about 22 even if the muons were traveling at the speed of light, using the muon half-life of 1.56 microseconds. When the time dilation relationship was applied, the result could be explained if the muons were traveling at 0.994 c.

In an experiment at CERN by Bailey et al., muons of velocity 0.9994c were found to have a lifetime 29.3 times the laboratory lifetime.

Friday, September 23, 2011

Measurement of the neutrino velocity with the OPERA detector

New results from OPERA on neutrino propertieslive from Main Amphitheatre.

“This result comes as a complete surprise,” said OPERA spokesperson, Antonio Ereditato of the University of Bern. “After many months of studies and cross checks we have not found any instrumental effect that could explain the result of the measurement. While OPERA researchers will continue their studies, we are also looking forward to independent measurements to fully assess the nature of this observation.” 


 “When an experiment finds an apparently unbelievable result and can find no artefact of the measurement to account for it, it’s normal procedure to invite broader scrutiny, and this is exactly what the OPERA collaboration is doing, it’s good scientific practice,” said CERN Research Director Sergio Bertolucci. “If this measurement is confirmed, it might change our view of physics, but we need to be sure that there are no other, more mundane, explanations. That will require independent measurements.”See:OPERA experiment reports anomaly in flight time of neutrinos from CERN to Gran Sasso




Have we considered their mediums of expression to know that we have witnessed Cerenkov radiation as a process in the faster than light, to know the circumstances of such expressions to have been understood as backdrop measures of processes we are familiar with. Explain the history of particulate expressions from vast distances across our universe?

The OPERA Detector


This is something very different though and it will be very interesting the dialogue and thoughts shared so as to look at the evidence in a way that helps us to consider what is sound in it's understanding, as speed of light.

See Also:

Friday, April 22, 2011

Geo-neutrinos



The main geophysical and geochemical processes that have driven the evolution of the Earth are strictly bound by the planet̓s energy budget. The current flux of energy entering the Earth’s atmosphere is well known: the main contribution comes from solar radiation (1.4 × 103 W m–2), while the energy deposited by cosmic rays is significantly smaller (10–8 W m–2). The uncertainties on terrestrial thermal power are larger – although the most quoted models estimate a global heat loss in the range of 40–47 TW, a global power of 30 TW is not excluded. The measurements of the temperature gradient taken from some 4 × 104 drill holes distributed around the world provide a constraint on the Earth’s heat production. Nevertheless, these direct investigations fail near the oceanic ridge, where the mantle content emerges: here hydrothermal circulation is a highly efficient heat-transport mechanism.

The generation of the Earth’s magnetic field, its mantle circulation, plate tectonics and secular (i.e. long lasting) cooling are processes that depend on terrestrial heat production and distribution, and on the separate contributions to Earth’s energy supply (radiogenic, gravitational, chemical etc.). An unambiguous and observationally based determination of radiogenic heat production is therefore necessary for understanding the Earth’s energetics. Such an observation requires determining the quantity of long-lived radioactive elements in the Earth. However, the direct geochemical investigations only go as far as the upper portion of the mantle, so all of the geochemical estimates of the global abundances of heat-generating elements depend on the assumption that the composition of meteorites reflects that of the Earth.
See:Looking into the Earth’s interior with geo-neutrinos

Wednesday, March 09, 2011

ICECUBE

 For me, the idea of a backdrop measure, as if Thomas Young experimentally fires his photon gun, the collision points at the LHC provide dimensional references(flight paths) to events that are measured  by comparison of LHC too,  muon detection facilitations as if,  Cosmic Rays collisions in faster then light medium of ice, resulting in ICECUBE data. Cerenkov. Muon detection scenarios are useful tools to speeds through earth and matters for  consideration anyway. Think of Volcano here or looking through pyramids.

That's the plan anyway right?
 
“IceCube: An instrument for neutrino astronomy,” by Francis Halzen and Spencer R. Klein
IceCube completed, University of Wisconsin press release
Ice Cube completed, Berkeley Lab press release
IceCube website

Sunday, December 12, 2010

Muons reveal the interior of volcanoes

The location of the muon detector on the slopes of the Vesuvius volcano.

Like X-ray scans of the human body, muon radiography allows researchers to obtain an image of the internal structures of the upper levels of volcanoes. Although such an image cannot help to predict ‘when’ an eruption might occur, it can, if combined with other observations, help to foresee ‘how’ it could develop and serves as a powerful tool for the study of geological structures.

Muons come from the interaction of cosmic rays with the Earth's atmosphere. They are able to traverse layers of rock as thick as one kilometre or more. During their trip, they are partially absorbed by the material they go through, very much like X-rays are partially absorbed by bones or other internal structures in our body. At the end of the chain, instead of the classic X-ray plate, is the so-called 'muon telescope', a special detector placed on the slopes of the volcano.

See: Muons reveal the interior of volcanoes

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MU-RAY project 
MUon RAdiographY

A. Kircher (1601-1680), “The interior of Vesuvius”  
A. Kircher (1601-1680): “The interior of Vesuvius” (1638)
Read more about Athanasius Kircher on Wikipedia.

Cosmic ray muon radiography is a technique capable of imaging variations of density inside a hundreds of meters of rock. With resolutions up to tens of meters in optimal detection conditions, muon radiography can give us images of the top region of a volcano edifice with a resolution that is significantly better than the one typically achieved with conventional gravity methods and in this way can give us information on anomalies in the density distribution, such as expected from dense lava conduits, low density magma supply paths or the compression with depth of the overlying soil.

The MU-RAY project is aimed toward the study of the internal structure of Stromboli and Vesuvius volcanoes using this technique.

Thursday, December 09, 2010

Muon










The Moon's cosmic ray shadow, as seen in secondary muons generated by cosmic rays in the atmosphere, and detected 700 meters below ground, at the Soudan II detector.
Composition: Elementary particle
Particle statistics: Fermionic
Group: Lepton
Generation: Second
Interaction: Gravity, Electromagnetic,
Weak
Symbol(s): μ
Antiparticle: Antimuon (μ+)
Theorized:
Discovered: Carl D. Anderson (1936)
Mass: 105.65836668(38) MeV/c2
Mean lifetime: 2.197034(21)×10−6 s[1]
Electric charge: −1 e
Color charge: None
Spin: 12


The muon (from the Greek letter mu (μ) used to represent it) is an elementary particle similar to the electron, with a negative electric charge and a spin of ½. Together with the electron, the tau, and the three neutrinos, it is classified as a lepton. It is an unstable subatomic particle with the second longest mean lifetime (2.2 µs), exceeded only by that of the free neutron (~15 minutes). Like all elementary particles, the muon has a corresponding antiparticle of opposite charge but equal mass and spin: the antimuon (also called a positive muon). Muons are denoted by μ and antimuons by μ+. Muons were previously called mu mesons, but are not classified as mesons by modern particle physicists (see History).

Muons have a mass of 105.7 MeV/c2, which is about 200 times the mass of an electron. Since the muon's interactions are very similar to those of the electron, a muon can be thought of as a much heavier version of the electron. Due to their greater mass, muons are not as sharply accelerated when they encounter electromagnetic fields, and do not emit as much bremsstrahlung radiation. Thus muons of a given energy penetrate matter far more deeply than electrons, since the deceleration of electrons and muons is primarily due to energy loss by this mechanism. So-called "secondary muons", generated by cosmic rays hitting the atmosphere, can penetrate to the Earth's surface and into deep mines.

As with the case of the other charged leptons, the muon has an associated muon neutrino. Muon neutrinos are denoted by νμ.

Contents

History

Muons were discovered by Carl D. Anderson and Seth Neddermeyer at Caltech in 1936, while studying cosmic radiation. Anderson had noticed particles that curved differently from electrons and other known particles when passed through a magnetic field. They were negatively charged but curved less sharply than electrons, but more sharply than protons, for particles of the same velocity. It was assumed that the magnitude of their negative electric charge was equal to that of the electron, and so to account for the difference in curvature, it was supposed that their mass was greater than an electron but smaller than a proton. Thus Anderson initially called the new particle a mesotron, adopting the prefix meso- from the Greek word for "mid-". Shortly thereafter, additional particles of intermediate mass were discovered, and the more general term meson was adopted to refer to any such particle. To differentiate between different types of mesons, the mesotron was in 1947 renamed the mu meson (the Greek letter μ (mu) corresponds to m).
It was soon found that the mu meson significantly differed from other mesons: for example, its decay products included a neutrino and an antineutrino, rather than just one or the other, as was observed with other mesons. Other mesons were eventually understood to be hadrons—that is, particles made of quarks—and thus subject to the residual strong force. In the quark model, a meson is composed of exactly two quarks (a quark and antiquark) unlike baryons, which are composed of three quarks. Mu mesons, however, were found to be fundamental particles (leptons) like electrons, with no quark structure. Thus, mu mesons were not mesons at all (in the new sense and use of the term meson), and so the term mu meson was abandoned, and replaced with the modern term muon.

Another particle (the pion, with which the muon was initially confused) had been predicted by theorist Hideki Yukawa:[2]

"It seems natural to modify the theory of Heisenberg and Fermi in the following way. The transition of a heavy particle from neutron state to proton state is not always accompanied by the mission of light particles. The transition is sometimes taken up by another heavy particle."

The existence of the muon was confirmed in 1937 by J. C. Street and E. C. Stevenson's cloud chamber experiment.[3] The discovery of the muon seemed so incongruous and surprising at the time that Nobel laureate I. I. Rabi famously quipped, "Who ordered that?"

In a 1941 experiment on Mount Washington in New Hampshire, muons were used to observe the time dilation predicted by special relativity for the first time.[4]

Muon sources

Since the production of muons requires an available center of momentum frame energy of 105.7 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. Only nuclear fission produces single-nuclear-event energies in this range, but do not produce muons as the production of a single muon would violate the conservation of quantum numbers (see under "muon decay" below).

On Earth, most naturally occurring muons are created by cosmic rays, which consist mostly of protons, many arriving from deep space at very high energy[5]

About 10,000 muons reach every square meter of the earth's surface a minute; these charged particles form as by-products of cosmic rays colliding with molecules in the upper atmosphere. Travelling at relativistic speeds, muons can penetrate tens of meters into rocks and other matter before attenuating as a result of absorption or deflection by other atoms.

When a cosmic ray proton impacts atomic nuclei of air atoms in the upper atmosphere, pions are created. These decay within a relatively short distance (meters) into muons (the pion's preferred decay product), and neutrinos. The muons from these high energy cosmic rays generally continue in about the same direction as the original proton, at a very high velocity. Although their lifetime without relativistic effects would allow a half-survival distance of only about 0.66 km (660 meters) at most (as seen from Earth) the time dilation effect of special relativity (from the viewpoint of the Earth) allows cosmic ray secondary muons to survive the flight to the Earth's surface, since in the Earth frame, the muons have a longer half-life due to their velocity. From the viewpoint (inertial frame) of the muon, on the other hand, it is the length contraction effect of special relativity which allows this penetration, since in the muon frame, its lifetime is unaffected, but the distance through the atmosphere and earth appears far shorter than these distances in the Earth rest-frame. Both are equally valid ways of explaining the fast muon's unusual survival over distances.

Since muons are unusually penetrative of ordinary matter, like neutrinos, they are also detectable deep underground (700 meters at the Soudan II detector) and underwater, where they form a major part of the natural background ionizing radiation. Like cosmic rays, as noted, this secondary muon radiation is also directional.

The same nuclear reaction described above (i.e. hadron-hadron impacts to produce pion beams, which then quickly decay to muon beams over short distances) is used by particle physicists to produce muon beams, such as the beam used for the muon g − 2 experiment.[6]

Muon decay


The most common decay of the muon
Muons are unstable elementary particles and are heavier than electrons and neutrinos but lighter than all other matter particles. They decay via the weak interaction. Because lepton numbers must be conserved, one of the product neutrinos of muon decay must be a muon-type neutrino and the other an electron-type antineutrino (antimuon decay produces the corresponding antiparticles, as detailed below). Because charge must be conserved, one of the products of muon decay is always an electron of the same charge as the muon (a positron if it is a positive muon). Thus all muons decay to at least an electron, and two neutrinos. Sometimes, besides these necessary products, additional other particles that have a net charge and spin of zero (i.e. a pair of photons, or an electron-positron pair), are produced.

The dominant muon decay mode (sometimes called the Michel decay after Louis Michel) is the simplest possible: the muon decays to an electron, an electron-antineutrino, and a muon-neutrino. Antimuons, in mirror fashion, most often decay to the corresponding antiparticles: a positron, an electron-neutrino, and a muon-antineutrino. In formulaic terms, these two decays are:
\mu^-\to e^- + \bar\nu_e + \nu_\mu,~~~\mu^+\to e^+ + \nu_e + \bar\nu_\mu.
The mean lifetime of the (positive) muon is 2.197 019 ± 0.000 021 μs[7]. The equality of the muon and anti-muon lifetimes has been established to better than one part in 104.

The tree-level muon decay width is
\Gamma=\frac{G_F^2 m_\mu^5}{192\pi^3}I\left(\frac{m_e^2}{m_\mu^2}\right),
where I(x) = 1 − 8x − 12x2lnx + 8x3x4;  G_F^2 is the Fermi coupling constant.
The decay distributions of the electron in muon decays have been parameterised using the so-called Michel parameters. The values of these four parameters are predicted unambiguously in the Standard Model of particle physics, thus muon decays represent a good test of the space-time structure of the weak interaction. No deviation from the Standard Model predictions has yet been found.

Certain neutrino-less decay modes are kinematically allowed but forbidden in the Standard Model. Examples forbidden by lepton flavour conservation are
\mu^-\to e^- + \gamma and \mu^-\to e^- + e^+ + e^-.
Observation of such decay modes would constitute clear evidence for physics beyond the Standard Model (BSM). Current experimental upper limits for the branching fractions of such decay modes are in the range 10−11 to 10−12.

Muonic atoms

The muon was the first elementary particle discovered that does not appear in ordinary atoms. Negative muons can, however, form muonic atoms (also called mu-mesic atoms), by replacing an electron in ordinary atoms. Muonic hydrogen atoms are much smaller than typical hydrogen atoms because the much larger mass of the muon gives it a much smaller ground-state wavefunction than is observed for the electron. In multi-electron atoms, when only one of the electrons is replaced by a muon, the size of the atom continues to be determined by the other electrons, and the atomic size is nearly unchanged. However, in such cases the orbital of the muon continues to be smaller and far closer to the nucleus than the atomic orbitals of the electrons.

A positive muon, when stopped in ordinary matter, can also bind an electron and form an exotic atom known as muonium (Mu) atom, in which the muon acts as the nucleus. The positive muon, in this context, can be considered a pseudo-isotope of hydrogen with one ninth of the mass of the proton. Because the reduced mass of muonium, and hence its Bohr radius, is very close to that of hydrogen[clarification needed], this short-lived "atom" behaves chemically — to a first approximation — like hydrogen, deuterium and tritium.

Use in measurement of the proton charge radius

The recent culmination of a twelve year experiment investigating the proton's charge radius involved the use of muonic hydrogen. This form of hydrogen is composed of a muon orbiting a proton[8]. The Lamb shift in muonic hydrogen was measured by driving the muon from the from its 2s state up to an excited 2p state using a laser. The frequency of the photon required to induce this transition was revealed to be 50 terahertz which, according to present theories of quantum electrodynamics, yields a value of 0.84184 ± 0.00067 femtometres for the charge radius of the proton.[9]

Anomalous magnetic dipole moment

The anomalous magnetic dipole moment is the difference between the experimentally observed value of the magnetic dipole moment and the theoretical value predicted by the Dirac equation. The measurement and prediction of this value is very important in the precision tests of QED (quantum electrodynamics). The E821 experiment at Brookhaven National Laboratory (BNL) studied the precession of muon and anti-muon in a constant external magnetic field as they circulated in a confining storage ring. The E821 Experiment reported the following average value (from the July 2007 review by Particle Data Group)
a = \frac{g-2}{2} = 0.00116592080(54)(33)
where the first errors are statistical and the second systematic.

The difference between the g-factors of the muon and the electron is due to their difference in mass. Because of the muon's larger mass, contributions to the theoretical calculation of its anomalous magnetic dipole moment from Standard Model weak interactions and from contributions involving hadrons are important at the current level of precision, whereas these effects are not important for the electron. The muon's anomalous magnetic dipole moment is also sensitive to contributions from new physics beyond the Standard Model, such as supersymmetry. For this reason, the muon's anomalous magnetic moment is normally used as a probe for new physics beyond the Standard Model rather than as a test of QED (Phys.Lett. B649, 173 (2007)).

See also

References

  1. ^ K. Nakamura et al. (Particle Data Group), J. Phys. G 37, 075021 (2010), URL: http://pdg.lbl.gov
  2. ^ Yukaya Hideka, On the Interaction of Elementary Particles 1, Proceedings of the Physico-Mathematical Society of Japan (3) 17, 48, pp 139-148 (1935). (Read 17 November 1934)
  3. ^ New Evidence for the Existence of a Particle Intermediate Between the Proton and Electron", Phys. Rev. 52, 1003 (1937).
  4. ^ David H. Frisch and James A. Smith, "Measurement of the Relativistic Time Dilation Using Muons", American Journal of Physics, 31, 342, 1963, cited by Michael Fowler, "Special Relativity: What Time is it?"
  5. ^ S. Carroll (2004). Spacetime and Geometry: An Introduction to General Relativity. Addison Wesly. p. 204
  6. ^ Brookhaven National Laboratory (30 July 2002). "Physicists Announce Latest Muon g-2 Measurement". Press release. http://www.bnl.gov/bnlweb/pubaf/pr/2002/bnlpr073002.htm. Retrieved 2009-11-14. 
  7. ^ [1]
  8. ^ TRIUMF Muonic Hydrogen collaboration. "A brief description of Muonic Hydrogen research". Retrieved 2010-11-7
  9. ^ Pohl, Randolf et al. "The Size of the Proton" Nature 466, 213-216 (8 July 2010)

External links


***
Comment on Backreaction made to Steven

Hi Steven

Would we not be correct to say that unification with the small would be most apropos indeed with the large?

Pushing through that veil.

My interest with the QGP is well documented, as it presented itself "with an interesting location" with which to look at during the collision process.

Natural Microscopic blackhole creations? Are such conditions possible in the natural way of things? Although quickly dissipative, they leave their mark as Cerenkov effects.

As one looks toward the cosmos this reductionist process is how one might look at the cosmos at large, as to some of it's "motivations displayed" in the cosmos?

What conditions allow such reductionism at play to consider the end result of geometrical propensity as a message across the vast distance of space, so as to "count these effects" here on earth?

Let's say cosmos particle collisions and LHC are hand in hand "as to decay of the original particles in space" as they leave their imprint noticeably in the measures of SNO or Icecube, but help us discern further effects of that decay chain as to the constitutions of LHC energy progressions of particles in examination?

Emulating the conditions in LHC progression, adaptability seen then from such progressions, working to produce future understandings. Muon detections through the earth?

So "modeled experiments" in which "distillation of thought" are helped to be reduced too, in kind, lead to matter forming ideas with which to progress? Measure. Self evident.

You see the view has to be on two levels, maybe as a poet using words to describe, or as a artist, trying to explain the natural world. The natural consequence, of understanding of our humanity and it's continuations expressed as abstract thought of our interactions with the world at large, unseen, and miscomprehended?

Do you think Superstringy has anything to do with what I just told you here?:)

Best,

    Hi Steven,

    Maybe the following will help, and then I will lead up to a modern version for consideration, so you understand the relation.

    Keep Gran Sasso in your mind as you look at what I am giving you.

    The underground laboratory, which opened in 1989, with its low background radiation is used for experiments in particle and nuclear physics,including the study of neutrinos, high-energy cosmic rays, dark matter, nuclear decay, as well as geology, and biology-wiki


    Neutrinos, get set, go!

    This summer, CERN gave the starting signal for the long-distance neutrino race to Italy. The CNGS facility (CERN Neutrinos to Gran Sasso), embedded in the laboratory's accelerator complex, produced its first neutrino beam. For the first time, billions of neutrinos were sent through the Earth's crust to the Gran Sasso laboratory, 732 kilometres away in Italy, a journey at almost the speed of light which they completed in less than 2.5 milliseconds. The OPERA experiment at the Gran Sasso laboratory was then commissioned, recording the first neutrino tracks.

    Because I am a layman, does not reduce the understanding that I can have, that a scientist may have.

    Now for the esoteric :)

    Secrets of the Pyramids In a boon for archaeology, particle physicists plan to probe ancient structures for tombs and other hidden chambers. The key to the technology is the muon, a cousin of the electron that rains harmlessly from the sky.

    What kind of result would they get from using the muon. What will it tell them?:)

    Best,