Can Coal Be A Clean Fuel?
Index
Sl. No.
Topic
Page No.
1.
Introduction
3
2.
The LHC
4
3.
Design
5
4.
Cyclotron
7
5.
Mathematics
8
6.
Practical Applications
9
7.
Conclusion
13
8.
Acknowledgement
14
9.
Bibliography
14
“The beauty of living things is the atoms that go into it, but the way those atoms are put together.”
-Carl Sagan
Introduction
If, in some cataclysm, all of scientific knowledge was to be destroyed, and only one sentence passed on to the next generation of creatures, what statement would contain the most information in the fewest words?
To this question, Richard Feynman answered- I believe it is the atomic hypothesis that all things are made of atoms — little particles that move around in perpetual motion, …show more content…
attracting each other when they are a little distance apart, but repelling upon being squeezed into one another. In that one sentence, you will see, there is an enormous amount of information about the world, if just a little imagination and thinking are applied.
The Universe constantly challenges and surprises us. And yet, all this majesty is made up of twelve particles of matter and four forces of nature – The recipe for the Universe, but is there more?
The German physicist Johann Wilhelm Hittorf studied electrical conductivity in rarefied gases: in 1869, he discovered a glow emitted from the cathode that increased in size with decrease in gas pressure. In 1876, the German physicist Eugen Goldstein showed that the rays from this glow cast a shadow, and he dubbed the rays cathode rays. During the 1870s, the English chemist and physicist Sir William Crookes developed the first cathode ray tube to have a high vacuum inside. He then showed that the luminescence rays appearing within the tube carried energy and moved from the cathode to the anode. Furthermore, by applying a magnetic field, he was able to deflect the rays, thereby demonstrating that the beam behaved as though it were negatively charged. In 1879, he proposed that these properties could be explained by what he termed 'radiant matter '. He suggested that this was a fourth state of matter, consisting of negatively charged molecules that were being projected with high velocity from the cathode.
In 1896, the British physicist J. J. Thomson, with his colleagues John S. Townsend and H. A. Wilson, performed experiments indicating that cathode rays really were unique particles, rather than waves, atoms or molecules as was believed earlier. Thomson made good estimates of both the charge e and the mass m, finding that cathode ray particles, which he called "corpuscles," had perhaps one thousandth of the mass of the least massive ion known: hydrogen. He showed that their charge to mass ratio, e/m, was independent of cathode material. He further showed that the negatively charged particles produced by radioactive materials, by heated materials and by illuminated materials were universal. The name electron was again proposed for these particles by the Irish physicist George F. Fitzgerald, and the name has since gained universal acceptance.
The Large Hadron Collider and Atom Smashers
Purpose
Physicists hope that the LHC will help answer some of the fundamental open questions in physics, concerning the basic laws governing the interactions and forces among the elementary objects, the deep structure of space and time, and in particular the interrelation between quantum mechanics and general relativity, where current theories and knowledge are unclear or break down altogether. Data are also needed from high energy particle experiments to suggest which versions of current scientific models are more likely to be correct – in particular to choose between the Standard Model and Higgsless models and to validate their predictions and allow further theoretical development. Many theorists expect new physics beyond the Standard Model to emerge at the TeV energy level, as the Standard Model appears to be unsatisfactory. Issues possibly to be explored by LHC collisions include:
Are the masses of elementary particles actually generated by the Higgs mechanism via electroweak symmetry breaking? It is expected that the collider will either demonstrate or rule out the existence of the elusive Higgs boson, thereby allowing physicists to consider whether the Standard Model or its Higgsless alternatives are more likely to be correct.
Is supersymmetry, an extension of the Standard Model and Poincaré symmetry, realised in nature, implying that all known particles have supersymmetric partners?
Are there extra dimensions, as predicted by various models based on string theory, and can we detect them?
What is the nature of the dark matter that appears to account for 27% of the mass-energy of the universe?
Other open questions that may be explored using high energy particle collisions:
It is already known that electromagnetism and the weak nuclear force are different manifestations of a single force called the electroweak force. The LHC may clarify whether the electroweak force and the strong nuclear force are similarly just different manifestations of one universal unified force, as predicted by various Grand Unification Theories.
Why is the fourth fundamental force (gravity) so many orders of magnitude weaker than the other three fundamental forces? See also Hierarchy problem.
Are there additional sources of quark flavour mixing, beyond those already predicted within the Standard Model?
Why are there apparent violations of the symmetry between matter and antimatter? See also CP violation.
What are the nature and properties of quark–gluon plasma, believed to have existed in the early universe and in certain compact and strange astronomical objects today? This will be investigated by heavy ion collisions in ALICE.
Design
The LHC is the world 's largest and highest-energy particle accelerator. The collider is contained in a circular tunnel, with a circumference of 27 kilometres (17 mi), at a depth ranging from 50 to 175 metres (164 to 574 ft) underground.
The 3.8-metre (12 ft) wide concrete-lined tunnel, constructed between 1983 and 1988, was formerly used to house the Large Electron–Positron Collider. It crosses the border between Switzerland and France at four points, with most of it in France. Surface buildings hold ancillary equipment such as compressors, ventilation equipment, control electronics and refrigeration plants.
The collider tunnel contains two adjacent parallel beamlines (or beam pipes) that intersect at four points, each containing a proton beam, which travel in opposite directions around the ring. Some 1,232 dipole magnets keep the beams on their circular path (see image), while an additional 392 quadrupole magnets are used to keep the beams focused, in order to maximize the chances of interaction between the particles in the four intersection points, where the two beams will cross. In total, over 1,600 superconducting magnets are installed, with most weighing over 27 tonnes. Approximately 96 tonnes of superfluid helium 4 is needed to keep the magnets, made of copper-clad niobium-titanium, at their operating temperature of 1.9 K (−271.25 °C), making the LHC the largest cryogenic facility in the world at liquid helium temperature.
When running at full design power of 7 TeV per beam, once or twice a day, as the protons are accelerated from 450 GeV to 7 TeV, the field of the superconducting dipole magnets will be increased from 0.54 to 8.3 teslas (T). The protons will each have an energy of 7 TeV, giving a total collision energy of 14 TeV. At this energy the protons have a Lorentz factor of about 7,500 and move at about 0.999999991 c, or about 3 metres per second slower than the speed of light (c). It will take less than 90 microseconds (μs) for a proton to travel once around the main ring – a speed of about 11,000 revolutions per second. Rather than continuous beams, the protons will be bunched together, into 2,808 bunches, 115 billion protons in each bunch so that interactions between the two beams will take place at discrete intervals never shorter than 25 nanoseconds (ns) apart. However it will be operated with fewer bunches when it is first commissioned, giving it a bunch crossing interval of 75 ns. The design luminosity of the LHC is 1034 cm−2s−1, providing a bunch collision rate of 40 MHz.
Prior to being injected into the main accelerator, the particles are prepared by a series of systems that successively increase their energy. The first system is the linear particle accelerator LINAC 2 generating 50-MeV protons, which feeds the Proton Synchrotron Booster (PSB). There the protons are accelerated to 1.4 GeV and injected into the Proton Synchrotron (PS), where they are accelerated to 26 GeV. Finally the Super Proton Synchrotron (SPS) is used to further increase their energy to 450 GeV before they are at last injected (over a period of 4 minutes 20 seconds) into the main ring. Here the proton bunches are accumulated, accelerated (over a period of 20 minutes) to their peak 4-TeV energy, and finally circulated for 10 to 24 hours while collisions occur at the four intersection points.
The LHC physics program is mainly based on proton–proton collisions. However, shorter running periods, typically one month per year, with heavy-ion collisions are included in the program. While lighter ions are considered as well, the baseline scheme deals with lead ions (see A Large Ion Collider Experiment). The lead ions will be first accelerated by the linear accelerator LINAC 3, and the Low-Energy Ion Ring (LEIR) will be used as an ion storage and cooler unit. The ions will then be further accelerated by the PS and SPS before being injected into LHC ring, where they will reach an energy of 2.76 TeV per nucleon (or 575 TeV per ion), higher than the energies reached by the Relativistic Heavy Ion Collider. The aim of the heavy-ion program is to investigate quark–gluon plasma, which existed in the early universe.
Cyclotron
Principle of operation
Cyclotrons accelerate charged particle beams using a high frequency alternating voltage, which is applied between two "D"-shaped electrodes (also called "dees"). An additional static magnetic field is applied in perpendicular direction to the electrode plane, enabling particles to re-encounter the accelerating voltage many times at the same phase. To achieve this, the voltage frequency must match the particle 's cyclotron resonance frequency
,
with the relativistic mass m and its charge q. This frequency is given by equality of centripetal force and magnetic Lorentz force. The particles, injected near the centre of the magnetic field, increase their kinetic energy only when recirculating through the gap between the electrodes; thus they travel outwards along a spiral path. Their radius will increase until the particles hit a target at the perimeter of the vacuum chamber, or leave the cyclotron using a beam tube, enabling their use e.g. for particle therapy. Various materials may be used for a target, and the collisions will create secondary particles which may be guided outside of the cyclotron and into instruments for analysis.
Relativistic considerations
In the nonrelativistic approximation, the frequency does not depend upon the radius of the particle 's orbit, since the particle 's mass is constant. As the beam spirals out, its frequency does not decrease, and it must continue to accelerate, as it is travelling a greater distance in the same time period. In contrast to this approximation, as particles approach the speed of light, their relativistic mass increases, requiring either modifications to the frequency, leading to the synchrocyclotron, or modifications to the magnetic field during the acceleration, which leads to the isochronous cyclotron. The relativistic mass can be rewritten as
,
where is the particle rest mass, is the relative velocity, and is the Lorentz factor.
The relativistic cyclotron frequency and angular frequency can be rewritten as
, and
,
where would be the cyclotron frequency in classical approximation, would be the cyclotron angular frequency in classical approximation.
The gyroradius for a particle moving in a static magnetic field is then given by
,
because
where v would be the (linear) velocity.
10 Reasons Why You Can’t Live Without A Particle Accelerator
Physicists use particle accelerators to answer questions of fundamental physics—how our universe was created, why objects have mass, and so on. Accelerators are huge—Fermilab’s Tevatron, near Chicago, is four miles in circumference, while the Large Hadron Collider in Geneva is more than four times that size—and extremely expensive. In some ways, they’re the epitome of the pure research instrument. But if you think these machines have no use outside of research, you’re in for a surprise.
Particle accelerators have been winding their way out of research labs and into industry for decades, and new applications continue to be dreamt up. When federal money for fundamental research dwindled, scientists started to invent new funding methods. Robert Kephart, director of the Illinois Accelerator Research Center (IARC) at Fermilab, partnered with the Illinois State Department of Commerce and Economic Opportunity to fund science research and applied applications of accelerators. In its 2009 capital bill, the state allocated $20 million toward research at Fermilab, which will be raised the same way states raise money to build roads and bridges—by selling state bonds.
Here are 10 applications of accelerators you probably haven’t heard of.
1. Is your milk carton sealed? An accelerator did it.
Accelerators use electromagnetic force to accelerate charged particles. The resulting particle beams can be directed along the desired path, including to the outside of the accelerator walls. When a charged particle moves past an atom, it can interact with the electrons in that atom, knocking them out of their orbits and breaking bonds. That can cause some chemical compounds to fall apart and others to polymerize. The latter ability has been used in one of the earliest industrial applications of accelerators, stretching back at least to the 1980s: sealing potato chip bags and milk cartons. The potato bag is made from two layers of aluminum foil held together by glue. That glue would take too long to dry on industrial conveyor belts. “It would be sticky forever,” says Kephart—but electron beams can make it happen instantly. “With an accelerator you can polymerize that glue and it’s set.”
2. A lot of natural gas is wasted. Accelerators can fix that problem.
Natural gas is harder to harness than oil and requires a pipeline to transport. That’s why millions of cubic feet of natural gas are flared or vented every year instead of being delivered to the market—a wasteful and polluting practice.
3. Want your spinach E. coli free? Accelerators may have cleaned it.
The more complicated a molecule is, the easier it is for the beam to break it—bacterial DNA is more complex than that of a plant, so it would fall apart first. Unlike the radioactive isotopes of accidental nuclear fallout, electron beams are fully under human control, and, unlike protons or neutrons, they don’t break the atomic nuclei. “The radiation we’re talking about comes out of an accelerator, so when you turn the switch off, all radiation stops,” Kephart says. In a similar way, electron beams are used in rhodotrons, machines used for sterilization of medical devices.
4.
Can coal be a clean fuel? Yes, if you attach an accelerator to the smokestack.
Burning coal produces flue gases like nitrogen and sulfur oxides: NO2, NO3, SO2, and SO3. When these gases react with atmospheric water, they turn into sulfuric and nitric acids such as H2SO4 or HNO3, eventually spilling back to earth as toxic acid rains. But when these oxides are mixed with ammonia (NH3) and exposed to electron beams, they can be turned into ammonium sulfate and ammonium nitrate, common fertilizers. The reaction creates dust-like particles that could be gathered with an electrostatic or centrifugal particle separator and put on the field.
Kephart sees the idea as an opportunity to make coal a cleaner fuel. “Even with the most optimistic projection of renewable energy sources and nuclear power, coal is likely to be providing 20 percent of our energy 20 years from now,” he says. “This is a way to make it more environmentally acceptable.” PAVAC, a company in British Columbia, Canada started by Ralf Edinger, is working on its first installation of this technology.
5. Antibiotics harm fish? Accelerators can turn pharmaceuticals into
fertilizer.
Accelerators can clean up sewage sludge by removing nitrogen and phosphorus, which cause algal blooms, and also hormones and antibiotics, which harm fish. Exposing sewage waste to electron beams breaks pharmaceuticals into harmless compounds. The beams ionize the water, producing H3O+ and OH radicals and creating a highly reactive environment in which oxidation and reduction reactions happen. This solution can break complex pharmaceutical compounds into basic elements, and kill pathogens as well. “Irradiated sludge can become a material that you could put on a lettuce field,” Kephart says.
A pilot accelerator plant that cleaned municipal waste was built in Miami, Florida in the early ’90s. Although the plant worked, it wasn’t a turn-key solution, Kephart says, so the idea was never commercialized. “An organization buying a municipal waste plant needs a fully developed system,” he explains, but “it was too soon for the industry to fund it.”
6. Your new computer has arrived. Thank an accelerator for building it.
Breaking down molecules and destroying pathogens’ DNA are not the only tricks accelerators can do—they also help build new materials. The computer chip industry relies on a technique called doping, in which boron and phosphorus ions are implanted into layers of silicon using accelerators. Ions are positively charged, so accelerators can direct ion beams with electromagnetic fields. The ions penetrate the surface of the silicon wafer and are deposited at precise locations inside it. That changes the conductivity of the material.
7. Accelerators make us live longer. They kill cancer.
Electron beams aren’t the only charged particles capable of killing unwanted life. Protons can destroy tumors, and are a good match for radiation therapy because they have stronger penetrating power than electrons. They can pass through tissues causing little damage, but killing cells where they stop.
8. Can nuclear reactors be accident-proof? Yes, if particle accelerators control them.
Traditional nuclear reactors are critical reactors—they produce excess neutrons that must be absorbed by control rods to regulate the reaction. The problem is the rods are susceptible to mechanical issues, which can cause the reaction to spiral out of control. Accelerator-driven subcritical systems control the amount of neutrons that are supplied instead of consuming the excess neutrons.
In accelerator-driven atomic reactors a proton beam would hit a heavy metal target such as mercury or lead, producing a “spray of neutrons,” which then drive the nuclear fission, says Kephart. That is a safer design, he points out, because “when you switch off the accelerator the nuclear reaction stops.” Accelerator-driven reactors would also be able to break the already existing nuclear waste into short-lived isotopes. No such reactors have been built yet, but Europe, India, and China are pursuing the idea, Kephart says.
9. The world still runs on oil. Accelerators can find it.
Portable Neutron Generators (or neutron tubes) help detect oil, gas, or water deposits using a technique called neutron logging. During the discovery process, neutron generators are placed into exploratory boreholes. As the neutrons produced by the accelerator pass through the ground surrounding the borehole, they interact with the atomic nuclei of various materials. That produces gamma rays which can be picked up by gamma-ray detectors. The strength of these signals reflect the type of materials buried underground. “Usually people look at the signatures of reactions,” says Shiltsev. “If there is a pore, less gammas will come out.” Oil and water will produce different amount of gamma rays, too.
10. Accelerators keep watch for weapons of mass destruction.
Muon accelerators enable us to literally see through walls. Muons—subatomic particles similar to electrons but with a greater mass—can easily pass through thick and heavy steel walls and containers, but will react with nuclear material. If a truck, perhaps driving by a border patrol, is carrying concealed fissile materials, muons sent through the truck will produce high energy gamma-rays which can be detected.
This makes muon accelerators invaluable in identifying nuclear threats. For example, helicopters could fly muon accelerators over water, beaming muons down onto cargo ships. “You can remotely send the beams of radiation which selectively interact with the materials and can tell you whether a particular material is present on the boat or not,” Shiltsev says. “You can figure out whether this boat carries nuclear bomb parts.”
Conclusion
Particle accelerators have changed the way we look at our world. To think that such a humble little device like the Cathode Ray Tube, which is found in old Televisions, inspired something as magnificient and powerful as the Large Hadron Collider.
We know so much more of the Universe and it makes us feel significant in such a vast and mysterious place.
Acknowledgement
I would like to take this opportunity to thank all those who have and continue to strive for understanding the Universe. My teacher, Mr. Karthik Chand Karise played a big role in the support, my Parents for their support.
Bibliography
Wikipedia
Scientific American
CERN
CERNLOVE
BrainPickings
Nautil
Sl. No.
Topic
Page No.
1.
Introduction
3
2.
The LHC
4
3.
Design
5
4.
Cyclotron
7
5.
Mathematics
8
6.
Practical Applications
9
7.
Conclusion
13
8.
Acknowledgement
14
9.
Bibliography
14
“The beauty of living things is the atoms that go into it, but the way those atoms are put together.”
-Carl Sagan
Introduction
If, in some cataclysm, all of scientific knowledge was to be destroyed, and only one sentence passed on to the next generation of creatures, what statement would contain the most information in the fewest words?
To this question, Richard Feynman answered- I believe it is the atomic hypothesis that all things are made of atoms — little particles that move around in perpetual motion, …show more content…
attracting each other when they are a little distance apart, but repelling upon being squeezed into one another. In that one sentence, you will see, there is an enormous amount of information about the world, if just a little imagination and thinking are applied.
The Universe constantly challenges and surprises us. And yet, all this majesty is made up of twelve particles of matter and four forces of nature – The recipe for the Universe, but is there more?
The German physicist Johann Wilhelm Hittorf studied electrical conductivity in rarefied gases: in 1869, he discovered a glow emitted from the cathode that increased in size with decrease in gas pressure. In 1876, the German physicist Eugen Goldstein showed that the rays from this glow cast a shadow, and he dubbed the rays cathode rays. During the 1870s, the English chemist and physicist Sir William Crookes developed the first cathode ray tube to have a high vacuum inside. He then showed that the luminescence rays appearing within the tube carried energy and moved from the cathode to the anode. Furthermore, by applying a magnetic field, he was able to deflect the rays, thereby demonstrating that the beam behaved as though it were negatively charged. In 1879, he proposed that these properties could be explained by what he termed 'radiant matter '. He suggested that this was a fourth state of matter, consisting of negatively charged molecules that were being projected with high velocity from the cathode.
In 1896, the British physicist J. J. Thomson, with his colleagues John S. Townsend and H. A. Wilson, performed experiments indicating that cathode rays really were unique particles, rather than waves, atoms or molecules as was believed earlier. Thomson made good estimates of both the charge e and the mass m, finding that cathode ray particles, which he called "corpuscles," had perhaps one thousandth of the mass of the least massive ion known: hydrogen. He showed that their charge to mass ratio, e/m, was independent of cathode material. He further showed that the negatively charged particles produced by radioactive materials, by heated materials and by illuminated materials were universal. The name electron was again proposed for these particles by the Irish physicist George F. Fitzgerald, and the name has since gained universal acceptance.
The Large Hadron Collider and Atom Smashers
Purpose
Physicists hope that the LHC will help answer some of the fundamental open questions in physics, concerning the basic laws governing the interactions and forces among the elementary objects, the deep structure of space and time, and in particular the interrelation between quantum mechanics and general relativity, where current theories and knowledge are unclear or break down altogether. Data are also needed from high energy particle experiments to suggest which versions of current scientific models are more likely to be correct – in particular to choose between the Standard Model and Higgsless models and to validate their predictions and allow further theoretical development. Many theorists expect new physics beyond the Standard Model to emerge at the TeV energy level, as the Standard Model appears to be unsatisfactory. Issues possibly to be explored by LHC collisions include:
Are the masses of elementary particles actually generated by the Higgs mechanism via electroweak symmetry breaking? It is expected that the collider will either demonstrate or rule out the existence of the elusive Higgs boson, thereby allowing physicists to consider whether the Standard Model or its Higgsless alternatives are more likely to be correct.
Is supersymmetry, an extension of the Standard Model and Poincaré symmetry, realised in nature, implying that all known particles have supersymmetric partners?
Are there extra dimensions, as predicted by various models based on string theory, and can we detect them?
What is the nature of the dark matter that appears to account for 27% of the mass-energy of the universe?
Other open questions that may be explored using high energy particle collisions:
It is already known that electromagnetism and the weak nuclear force are different manifestations of a single force called the electroweak force. The LHC may clarify whether the electroweak force and the strong nuclear force are similarly just different manifestations of one universal unified force, as predicted by various Grand Unification Theories.
Why is the fourth fundamental force (gravity) so many orders of magnitude weaker than the other three fundamental forces? See also Hierarchy problem.
Are there additional sources of quark flavour mixing, beyond those already predicted within the Standard Model?
Why are there apparent violations of the symmetry between matter and antimatter? See also CP violation.
What are the nature and properties of quark–gluon plasma, believed to have existed in the early universe and in certain compact and strange astronomical objects today? This will be investigated by heavy ion collisions in ALICE.
Design
The LHC is the world 's largest and highest-energy particle accelerator. The collider is contained in a circular tunnel, with a circumference of 27 kilometres (17 mi), at a depth ranging from 50 to 175 metres (164 to 574 ft) underground.
The 3.8-metre (12 ft) wide concrete-lined tunnel, constructed between 1983 and 1988, was formerly used to house the Large Electron–Positron Collider. It crosses the border between Switzerland and France at four points, with most of it in France. Surface buildings hold ancillary equipment such as compressors, ventilation equipment, control electronics and refrigeration plants.
The collider tunnel contains two adjacent parallel beamlines (or beam pipes) that intersect at four points, each containing a proton beam, which travel in opposite directions around the ring. Some 1,232 dipole magnets keep the beams on their circular path (see image), while an additional 392 quadrupole magnets are used to keep the beams focused, in order to maximize the chances of interaction between the particles in the four intersection points, where the two beams will cross. In total, over 1,600 superconducting magnets are installed, with most weighing over 27 tonnes. Approximately 96 tonnes of superfluid helium 4 is needed to keep the magnets, made of copper-clad niobium-titanium, at their operating temperature of 1.9 K (−271.25 °C), making the LHC the largest cryogenic facility in the world at liquid helium temperature.
When running at full design power of 7 TeV per beam, once or twice a day, as the protons are accelerated from 450 GeV to 7 TeV, the field of the superconducting dipole magnets will be increased from 0.54 to 8.3 teslas (T). The protons will each have an energy of 7 TeV, giving a total collision energy of 14 TeV. At this energy the protons have a Lorentz factor of about 7,500 and move at about 0.999999991 c, or about 3 metres per second slower than the speed of light (c). It will take less than 90 microseconds (μs) for a proton to travel once around the main ring – a speed of about 11,000 revolutions per second. Rather than continuous beams, the protons will be bunched together, into 2,808 bunches, 115 billion protons in each bunch so that interactions between the two beams will take place at discrete intervals never shorter than 25 nanoseconds (ns) apart. However it will be operated with fewer bunches when it is first commissioned, giving it a bunch crossing interval of 75 ns. The design luminosity of the LHC is 1034 cm−2s−1, providing a bunch collision rate of 40 MHz.
Prior to being injected into the main accelerator, the particles are prepared by a series of systems that successively increase their energy. The first system is the linear particle accelerator LINAC 2 generating 50-MeV protons, which feeds the Proton Synchrotron Booster (PSB). There the protons are accelerated to 1.4 GeV and injected into the Proton Synchrotron (PS), where they are accelerated to 26 GeV. Finally the Super Proton Synchrotron (SPS) is used to further increase their energy to 450 GeV before they are at last injected (over a period of 4 minutes 20 seconds) into the main ring. Here the proton bunches are accumulated, accelerated (over a period of 20 minutes) to their peak 4-TeV energy, and finally circulated for 10 to 24 hours while collisions occur at the four intersection points.
The LHC physics program is mainly based on proton–proton collisions. However, shorter running periods, typically one month per year, with heavy-ion collisions are included in the program. While lighter ions are considered as well, the baseline scheme deals with lead ions (see A Large Ion Collider Experiment). The lead ions will be first accelerated by the linear accelerator LINAC 3, and the Low-Energy Ion Ring (LEIR) will be used as an ion storage and cooler unit. The ions will then be further accelerated by the PS and SPS before being injected into LHC ring, where they will reach an energy of 2.76 TeV per nucleon (or 575 TeV per ion), higher than the energies reached by the Relativistic Heavy Ion Collider. The aim of the heavy-ion program is to investigate quark–gluon plasma, which existed in the early universe.
Cyclotron
Principle of operation
Cyclotrons accelerate charged particle beams using a high frequency alternating voltage, which is applied between two "D"-shaped electrodes (also called "dees"). An additional static magnetic field is applied in perpendicular direction to the electrode plane, enabling particles to re-encounter the accelerating voltage many times at the same phase. To achieve this, the voltage frequency must match the particle 's cyclotron resonance frequency
,
with the relativistic mass m and its charge q. This frequency is given by equality of centripetal force and magnetic Lorentz force. The particles, injected near the centre of the magnetic field, increase their kinetic energy only when recirculating through the gap between the electrodes; thus they travel outwards along a spiral path. Their radius will increase until the particles hit a target at the perimeter of the vacuum chamber, or leave the cyclotron using a beam tube, enabling their use e.g. for particle therapy. Various materials may be used for a target, and the collisions will create secondary particles which may be guided outside of the cyclotron and into instruments for analysis.
Relativistic considerations
In the nonrelativistic approximation, the frequency does not depend upon the radius of the particle 's orbit, since the particle 's mass is constant. As the beam spirals out, its frequency does not decrease, and it must continue to accelerate, as it is travelling a greater distance in the same time period. In contrast to this approximation, as particles approach the speed of light, their relativistic mass increases, requiring either modifications to the frequency, leading to the synchrocyclotron, or modifications to the magnetic field during the acceleration, which leads to the isochronous cyclotron. The relativistic mass can be rewritten as
,
where is the particle rest mass, is the relative velocity, and is the Lorentz factor.
The relativistic cyclotron frequency and angular frequency can be rewritten as
, and
,
where would be the cyclotron frequency in classical approximation, would be the cyclotron angular frequency in classical approximation.
The gyroradius for a particle moving in a static magnetic field is then given by
,
because
where v would be the (linear) velocity.
10 Reasons Why You Can’t Live Without A Particle Accelerator
Physicists use particle accelerators to answer questions of fundamental physics—how our universe was created, why objects have mass, and so on. Accelerators are huge—Fermilab’s Tevatron, near Chicago, is four miles in circumference, while the Large Hadron Collider in Geneva is more than four times that size—and extremely expensive. In some ways, they’re the epitome of the pure research instrument. But if you think these machines have no use outside of research, you’re in for a surprise.
Particle accelerators have been winding their way out of research labs and into industry for decades, and new applications continue to be dreamt up. When federal money for fundamental research dwindled, scientists started to invent new funding methods. Robert Kephart, director of the Illinois Accelerator Research Center (IARC) at Fermilab, partnered with the Illinois State Department of Commerce and Economic Opportunity to fund science research and applied applications of accelerators. In its 2009 capital bill, the state allocated $20 million toward research at Fermilab, which will be raised the same way states raise money to build roads and bridges—by selling state bonds.
Here are 10 applications of accelerators you probably haven’t heard of.
1. Is your milk carton sealed? An accelerator did it.
Accelerators use electromagnetic force to accelerate charged particles. The resulting particle beams can be directed along the desired path, including to the outside of the accelerator walls. When a charged particle moves past an atom, it can interact with the electrons in that atom, knocking them out of their orbits and breaking bonds. That can cause some chemical compounds to fall apart and others to polymerize. The latter ability has been used in one of the earliest industrial applications of accelerators, stretching back at least to the 1980s: sealing potato chip bags and milk cartons. The potato bag is made from two layers of aluminum foil held together by glue. That glue would take too long to dry on industrial conveyor belts. “It would be sticky forever,” says Kephart—but electron beams can make it happen instantly. “With an accelerator you can polymerize that glue and it’s set.”
2. A lot of natural gas is wasted. Accelerators can fix that problem.
Natural gas is harder to harness than oil and requires a pipeline to transport. That’s why millions of cubic feet of natural gas are flared or vented every year instead of being delivered to the market—a wasteful and polluting practice.
3. Want your spinach E. coli free? Accelerators may have cleaned it.
The more complicated a molecule is, the easier it is for the beam to break it—bacterial DNA is more complex than that of a plant, so it would fall apart first. Unlike the radioactive isotopes of accidental nuclear fallout, electron beams are fully under human control, and, unlike protons or neutrons, they don’t break the atomic nuclei. “The radiation we’re talking about comes out of an accelerator, so when you turn the switch off, all radiation stops,” Kephart says. In a similar way, electron beams are used in rhodotrons, machines used for sterilization of medical devices.
4.
Can coal be a clean fuel? Yes, if you attach an accelerator to the smokestack.
Burning coal produces flue gases like nitrogen and sulfur oxides: NO2, NO3, SO2, and SO3. When these gases react with atmospheric water, they turn into sulfuric and nitric acids such as H2SO4 or HNO3, eventually spilling back to earth as toxic acid rains. But when these oxides are mixed with ammonia (NH3) and exposed to electron beams, they can be turned into ammonium sulfate and ammonium nitrate, common fertilizers. The reaction creates dust-like particles that could be gathered with an electrostatic or centrifugal particle separator and put on the field.
Kephart sees the idea as an opportunity to make coal a cleaner fuel. “Even with the most optimistic projection of renewable energy sources and nuclear power, coal is likely to be providing 20 percent of our energy 20 years from now,” he says. “This is a way to make it more environmentally acceptable.” PAVAC, a company in British Columbia, Canada started by Ralf Edinger, is working on its first installation of this technology.
5. Antibiotics harm fish? Accelerators can turn pharmaceuticals into
fertilizer.
Accelerators can clean up sewage sludge by removing nitrogen and phosphorus, which cause algal blooms, and also hormones and antibiotics, which harm fish. Exposing sewage waste to electron beams breaks pharmaceuticals into harmless compounds. The beams ionize the water, producing H3O+ and OH radicals and creating a highly reactive environment in which oxidation and reduction reactions happen. This solution can break complex pharmaceutical compounds into basic elements, and kill pathogens as well. “Irradiated sludge can become a material that you could put on a lettuce field,” Kephart says.
A pilot accelerator plant that cleaned municipal waste was built in Miami, Florida in the early ’90s. Although the plant worked, it wasn’t a turn-key solution, Kephart says, so the idea was never commercialized. “An organization buying a municipal waste plant needs a fully developed system,” he explains, but “it was too soon for the industry to fund it.”
6. Your new computer has arrived. Thank an accelerator for building it.
Breaking down molecules and destroying pathogens’ DNA are not the only tricks accelerators can do—they also help build new materials. The computer chip industry relies on a technique called doping, in which boron and phosphorus ions are implanted into layers of silicon using accelerators. Ions are positively charged, so accelerators can direct ion beams with electromagnetic fields. The ions penetrate the surface of the silicon wafer and are deposited at precise locations inside it. That changes the conductivity of the material.
7. Accelerators make us live longer. They kill cancer.
Electron beams aren’t the only charged particles capable of killing unwanted life. Protons can destroy tumors, and are a good match for radiation therapy because they have stronger penetrating power than electrons. They can pass through tissues causing little damage, but killing cells where they stop.
8. Can nuclear reactors be accident-proof? Yes, if particle accelerators control them.
Traditional nuclear reactors are critical reactors—they produce excess neutrons that must be absorbed by control rods to regulate the reaction. The problem is the rods are susceptible to mechanical issues, which can cause the reaction to spiral out of control. Accelerator-driven subcritical systems control the amount of neutrons that are supplied instead of consuming the excess neutrons.
In accelerator-driven atomic reactors a proton beam would hit a heavy metal target such as mercury or lead, producing a “spray of neutrons,” which then drive the nuclear fission, says Kephart. That is a safer design, he points out, because “when you switch off the accelerator the nuclear reaction stops.” Accelerator-driven reactors would also be able to break the already existing nuclear waste into short-lived isotopes. No such reactors have been built yet, but Europe, India, and China are pursuing the idea, Kephart says.
9. The world still runs on oil. Accelerators can find it.
Portable Neutron Generators (or neutron tubes) help detect oil, gas, or water deposits using a technique called neutron logging. During the discovery process, neutron generators are placed into exploratory boreholes. As the neutrons produced by the accelerator pass through the ground surrounding the borehole, they interact with the atomic nuclei of various materials. That produces gamma rays which can be picked up by gamma-ray detectors. The strength of these signals reflect the type of materials buried underground. “Usually people look at the signatures of reactions,” says Shiltsev. “If there is a pore, less gammas will come out.” Oil and water will produce different amount of gamma rays, too.
10. Accelerators keep watch for weapons of mass destruction.
Muon accelerators enable us to literally see through walls. Muons—subatomic particles similar to electrons but with a greater mass—can easily pass through thick and heavy steel walls and containers, but will react with nuclear material. If a truck, perhaps driving by a border patrol, is carrying concealed fissile materials, muons sent through the truck will produce high energy gamma-rays which can be detected.
This makes muon accelerators invaluable in identifying nuclear threats. For example, helicopters could fly muon accelerators over water, beaming muons down onto cargo ships. “You can remotely send the beams of radiation which selectively interact with the materials and can tell you whether a particular material is present on the boat or not,” Shiltsev says. “You can figure out whether this boat carries nuclear bomb parts.”
Conclusion
Particle accelerators have changed the way we look at our world. To think that such a humble little device like the Cathode Ray Tube, which is found in old Televisions, inspired something as magnificient and powerful as the Large Hadron Collider.
We know so much more of the Universe and it makes us feel significant in such a vast and mysterious place.
Acknowledgement
I would like to take this opportunity to thank all those who have and continue to strive for understanding the Universe. My teacher, Mr. Karthik Chand Karise played a big role in the support, my Parents for their support.
Bibliography
Wikipedia
Scientific American
CERN
CERNLOVE
BrainPickings
Nautil