Matter will be created from light within a year, claim scientists
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Matter will be created from light within a year, claim scientists
Matter will be created from light within a year, claim scientists
In a neat demonstration of E=mc 2, physicists believe they can create electrons and positrons from colliding photons
http://www.theguardian.com/science/2014/may/18/matter-light-photons-electrons-positrons
Sunday 18 May 2014 18.00 BST Last modified on Saturday 21 June 2014 02.30 BST
Researchers have worked out how to make matter from pure light and are drawing up plans to demonstrate the feat within the next 12 months.
The theory underpinning the idea was first described 80 years ago by two physicists who later worked on the first atomic bomb. At the time they considered the conversion of light into matter impossible in a laboratory.
But in a report published on Sunday, physicists at Imperial College London claim to have cracked the problem using high-powered lasers and other equipment now available to scientists.
"We have shown in principle how you can make matter from light," said Steven Rose at Imperial. "If you do this experiment, you will be taking light and turning it into matter."
The scientists are not on the verge of a machine that can create everyday objects from a sudden blast of laser energy. The kind of matter they aim to make comes in the form of subatomic particles invisible to the naked eye.
The original idea was written down by two US physicists, Gregory Breit and John Wheeler, in 1934.
They worked out that – very rarely – two particles of light, or photons, could combine to produce an electron and its antimatter equivalent, a positron. Electrons are particles of matter that form the outer shells of atoms in the everyday objects around us.
But Breit and Wheeler had no expectations that their theory would be proved any time soon. In their study, the physicists noted that the process was so rare and hard to produce that it would be "hopeless to try to observe the pair formation in laboratory experiments".
Oliver Pike, the lead researcher on the study, said the process was one of the most elegant demonstrations of Einstein's famous relationship that shows matter and energy are interchangeable currencies. "The Breit-Wheeler process is the simplest way matter can be made from light and one of the purest demonstrations of E=mc2," he said.
Writing in the journal Nature Photonics, the scientists describe how they could turn light into matter through a number of separate steps. The first step fires electrons at a slab of gold to produce a beam of high-energy photons. Next, they fire a high-energy laser into a tiny gold capsule called a hohlraum, from the German for "empty room". This produces light as bright as that emitted from stars. In the final stage, they send the first beam of photons into the hohlraum where the two streams of photons collide.
The scientists' calculations show that the setup squeezes enough particles of light with high enough energies into a small enough volume to create around 100,000 electron-positron pairs.
The process is one of the most spectacular predictions of a theory called quantum electrodynamics (QED) that was developed in the run up to the second world war. "You might call it the most dramatic consequence of QED and it clearly shows that light and matter are interchangeable," Rose told the Guardian.
The scientists hope to demonstrate the process in the next 12 months. There are a number of sites around the world that have the technology. One is the huge Omega laser in Rochester, New York. But another is the Orion laser at Aldermaston, the atomic weapons facility in Berkshire.
A successful demonstration will encourage physicists who have been eyeing the prospect of a photon-photon collider as a tool to study how subatomic particles behave. "Such a collider could be used to study fundamental physics with a very clean experimental setup: pure light goes in, matter comes out. The experiment would be the first demonstration of this," Pike said.
(...more at link)
http://www.theguardian.com/science/2014/may/18/matter-light-photons-electrons-positrons
In a neat demonstration of E=mc 2, physicists believe they can create electrons and positrons from colliding photons
http://www.theguardian.com/science/2014/may/18/matter-light-photons-electrons-positrons
Sunday 18 May 2014 18.00 BST Last modified on Saturday 21 June 2014 02.30 BST
Researchers have worked out how to make matter from pure light and are drawing up plans to demonstrate the feat within the next 12 months.
The theory underpinning the idea was first described 80 years ago by two physicists who later worked on the first atomic bomb. At the time they considered the conversion of light into matter impossible in a laboratory.
But in a report published on Sunday, physicists at Imperial College London claim to have cracked the problem using high-powered lasers and other equipment now available to scientists.
"We have shown in principle how you can make matter from light," said Steven Rose at Imperial. "If you do this experiment, you will be taking light and turning it into matter."
The scientists are not on the verge of a machine that can create everyday objects from a sudden blast of laser energy. The kind of matter they aim to make comes in the form of subatomic particles invisible to the naked eye.
The original idea was written down by two US physicists, Gregory Breit and John Wheeler, in 1934.
They worked out that – very rarely – two particles of light, or photons, could combine to produce an electron and its antimatter equivalent, a positron. Electrons are particles of matter that form the outer shells of atoms in the everyday objects around us.
But Breit and Wheeler had no expectations that their theory would be proved any time soon. In their study, the physicists noted that the process was so rare and hard to produce that it would be "hopeless to try to observe the pair formation in laboratory experiments".
Oliver Pike, the lead researcher on the study, said the process was one of the most elegant demonstrations of Einstein's famous relationship that shows matter and energy are interchangeable currencies. "The Breit-Wheeler process is the simplest way matter can be made from light and one of the purest demonstrations of E=mc2," he said.
Writing in the journal Nature Photonics, the scientists describe how they could turn light into matter through a number of separate steps. The first step fires electrons at a slab of gold to produce a beam of high-energy photons. Next, they fire a high-energy laser into a tiny gold capsule called a hohlraum, from the German for "empty room". This produces light as bright as that emitted from stars. In the final stage, they send the first beam of photons into the hohlraum where the two streams of photons collide.
The scientists' calculations show that the setup squeezes enough particles of light with high enough energies into a small enough volume to create around 100,000 electron-positron pairs.
The process is one of the most spectacular predictions of a theory called quantum electrodynamics (QED) that was developed in the run up to the second world war. "You might call it the most dramatic consequence of QED and it clearly shows that light and matter are interchangeable," Rose told the Guardian.
The scientists hope to demonstrate the process in the next 12 months. There are a number of sites around the world that have the technology. One is the huge Omega laser in Rochester, New York. But another is the Orion laser at Aldermaston, the atomic weapons facility in Berkshire.
A successful demonstration will encourage physicists who have been eyeing the prospect of a photon-photon collider as a tool to study how subatomic particles behave. "Such a collider could be used to study fundamental physics with a very clean experimental setup: pure light goes in, matter comes out. The experiment would be the first demonstration of this," Pike said.
(...more at link)
http://www.theguardian.com/science/2014/may/18/matter-light-photons-electrons-positrons
Re: Matter will be created from light within a year, claim scientists
With gold and photons, scientists offer way to turn energy into matter
In a study published online Sunday in the journal Nature Photonics, four physicists from Imperial College London and the Max Planck Institute for Nuclear Physics in Heidelberg, Germany, propose a relatively straightforward method for witnessing the conversion of two photons into two particles. The trio came up with the idea and hammered out the key details in a single, coffee-fueled day, according to Imperial.
The experiment the physicists describe requires the construction of a new type of subatomic particle collider. But they insist this would be much less complicated than, say, building the Large Hadron Collider at CERN, where physicists confirmed the existence of the Higgs boson.
“The implementation of this scheme … is possible using existing technology,” physicists Oliver Pike, Felix Mackenroth, Edward Hill and Steve Rose wrote in Nature Photonics.
....
Physicists would shoot high-energy electrons into a gold target, creating a high-energy photon beam. Those photons would be fired through the middle of a specialized tube with other photons inside. After pairs of photons collide and convert into electrons and positrons, a magnetic field would separate the particles as they emerge from the end of the tube.
How do they know it would work? They used math to simulate the photons that would emerge from the gold target and how they’d behave inside the tube (a chamber called a vacuum hohlraum). According to their calculations, their photon-photon collider would work with “a wide variation of experimental parameters.”
Experiments at the Stanford Linear Accelerator Center have already demonstrated that if you mix up a lot of photons at high energies, you can create pairs of electrons and positrons. But the SLAC machines would have needed to be about 4 times more powerful to pull off the same feat with only two photons, according to Pike, Mackenroth and Rose.
Rose, a plasma physicist at Imperial and the study’s senior author, said he and his colleagues are now looking for collaborators to build the collider and give their idea a try. He and Pike, a graduate student in the college’s plasma physics group, told the BBC that the collider could be built in less than a year.
“With a good experimental team, it should be quite doable,” Pike said.
http://www.latimes.com/science/sciencenow/la-sci-sn-creating-matter-from-light-collider-20140519-story.html
In a study published online Sunday in the journal Nature Photonics, four physicists from Imperial College London and the Max Planck Institute for Nuclear Physics in Heidelberg, Germany, propose a relatively straightforward method for witnessing the conversion of two photons into two particles. The trio came up with the idea and hammered out the key details in a single, coffee-fueled day, according to Imperial.
The experiment the physicists describe requires the construction of a new type of subatomic particle collider. But they insist this would be much less complicated than, say, building the Large Hadron Collider at CERN, where physicists confirmed the existence of the Higgs boson.
“The implementation of this scheme … is possible using existing technology,” physicists Oliver Pike, Felix Mackenroth, Edward Hill and Steve Rose wrote in Nature Photonics.
....
Physicists would shoot high-energy electrons into a gold target, creating a high-energy photon beam. Those photons would be fired through the middle of a specialized tube with other photons inside. After pairs of photons collide and convert into electrons and positrons, a magnetic field would separate the particles as they emerge from the end of the tube.
How do they know it would work? They used math to simulate the photons that would emerge from the gold target and how they’d behave inside the tube (a chamber called a vacuum hohlraum). According to their calculations, their photon-photon collider would work with “a wide variation of experimental parameters.”
Experiments at the Stanford Linear Accelerator Center have already demonstrated that if you mix up a lot of photons at high energies, you can create pairs of electrons and positrons. But the SLAC machines would have needed to be about 4 times more powerful to pull off the same feat with only two photons, according to Pike, Mackenroth and Rose.
Rose, a plasma physicist at Imperial and the study’s senior author, said he and his colleagues are now looking for collaborators to build the collider and give their idea a try. He and Pike, a graduate student in the college’s plasma physics group, told the BBC that the collider could be built in less than a year.
“With a good experimental team, it should be quite doable,” Pike said.
http://www.latimes.com/science/sciencenow/la-sci-sn-creating-matter-from-light-collider-20140519-story.html
Re: Matter will be created from light within a year, claim scientists
Shape-Dependent Two-Photon Photoluminescence of Single Gold Nanoparticles
Nengyue Gao , Yang Chen , Lin Li , Zhenping Guan , Tingting Zhao , Na Zhou , Peiyan Yuan , Shao Q. Yao , and Qing-Hua Xu *
Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
J. Phys. Chem. C, 2014, 118 (25), pp 13904–13911
DOI: 10.1021/jp502038v
Publication Date (Web): May 30, 2014
Copyright © 2014 American Chemical Society
*E-mail: chmxqh@nus.edu.sg.
Gold (Au) nanoparticles that display strong two-photon photoluminescence (TPPL) are attractive contrast agents for noninvasive live cell/tissue imaging with deep penetration because of their excellent biocompatibility and low cytotoxicity. The TPPL properties of Au nanoparticles are strongly dependent on the particle shape. As chemically prepared nanoparticles are generally inhomogeneous, conventional ensemble-based TPPL measurements can only give averaged results of particles of different morphologies. Single-particle spectroscopy can avoid the complication induced by the sample inhomogeneity in ensemble measurements and help to establish the morphology–property relationship. Here we have investigated the scattering spectra and TPPL properties of Au nanoparticles of different shapes on the single particle level and explored their potential applications in cancer cell imaging. Au nanoparticles of five different shapes (nanospheres, nanocubes, nanotriangles, nanorods, and nanobranches) with similar dimensions have been chosen for the study. The TPPL spectra of these Au nanoparticles were found to be strongly modulated by plasmon resonance. TPPL intensity increases in the order of nanospheres, nanocubes, nanotriangles, nanorods, and nanobranches. The averaged TPPL intensity of a single Au nanobranch is 47750 times that of a single Au nanosphere. Two-photon action cross sections of single Au NSs, Au NCs, Au NTs, Au NRs, and Au NBs were estimated to be ∼83, ∼500, ∼1.5 × 103, ∼4.2 × 104, and ∼4.0 × 106 GM, respectively. Laser-induced melting experiments on single Au nanobranches demonstrate that the tips played an important role in the observed strong TPPL. Application of these Au nanobranches as excellent two-photon imaging contrast agents has been demonstrated on HepG2 cancer cells.
http://pubs.acs.org/doi/abs/10.1021/jp502038v
Nengyue Gao , Yang Chen , Lin Li , Zhenping Guan , Tingting Zhao , Na Zhou , Peiyan Yuan , Shao Q. Yao , and Qing-Hua Xu *
Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
J. Phys. Chem. C, 2014, 118 (25), pp 13904–13911
DOI: 10.1021/jp502038v
Publication Date (Web): May 30, 2014
Copyright © 2014 American Chemical Society
*E-mail: chmxqh@nus.edu.sg.
Abstract
Gold (Au) nanoparticles that display strong two-photon photoluminescence (TPPL) are attractive contrast agents for noninvasive live cell/tissue imaging with deep penetration because of their excellent biocompatibility and low cytotoxicity. The TPPL properties of Au nanoparticles are strongly dependent on the particle shape. As chemically prepared nanoparticles are generally inhomogeneous, conventional ensemble-based TPPL measurements can only give averaged results of particles of different morphologies. Single-particle spectroscopy can avoid the complication induced by the sample inhomogeneity in ensemble measurements and help to establish the morphology–property relationship. Here we have investigated the scattering spectra and TPPL properties of Au nanoparticles of different shapes on the single particle level and explored their potential applications in cancer cell imaging. Au nanoparticles of five different shapes (nanospheres, nanocubes, nanotriangles, nanorods, and nanobranches) with similar dimensions have been chosen for the study. The TPPL spectra of these Au nanoparticles were found to be strongly modulated by plasmon resonance. TPPL intensity increases in the order of nanospheres, nanocubes, nanotriangles, nanorods, and nanobranches. The averaged TPPL intensity of a single Au nanobranch is 47750 times that of a single Au nanosphere. Two-photon action cross sections of single Au NSs, Au NCs, Au NTs, Au NRs, and Au NBs were estimated to be ∼83, ∼500, ∼1.5 × 103, ∼4.2 × 104, and ∼4.0 × 106 GM, respectively. Laser-induced melting experiments on single Au nanobranches demonstrate that the tips played an important role in the observed strong TPPL. Application of these Au nanobranches as excellent two-photon imaging contrast agents has been demonstrated on HepG2 cancer cells.
http://pubs.acs.org/doi/abs/10.1021/jp502038v
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