How To Detect Nuclear Device

How to keep U.S. ports of entry safe and secure by detecting and interdicting illicit radioactive or nuclear materials? A team led by Northeastern’s Swastik Kar and Yung Joon Jung has developed a technology that could go a long way toward achieving that goal.

nuclear radiation

Our detector could dramatically change the manner and accuracy with which we are able to detect nuclear threats at home or abroad,” says Kar, associate professor in the Department of Physics. It could also help streamline radio-medicine, including radiation therapies and scanning diagnostics, boost the effectiveness of unmanned radiation monitoring vehicles in mapping and monitoring contaminated areas following disasters, and revolutionize radiometric imaging in space exploration. Made of graphene and carbon nanotubes, the researchers’ detector far outpaces any existing one in its ultrasensitivity to charged particles, minuscule size, low-power requirements, and low cost.

All radiation, of course, is not harmful, and even the type that may be depends on dosage and length of exposure. The word “radiation” refers simply to the emission and propagation of energy in the form of waves or particles. It has many sources, including the sun, electronic devices such as microwaves and cellphones, visible light, X-rays, gamma waves, cosmic waves, and nuclear fission, which is what produces power in nuclear reactors. Most of the harmful radiations are “ionizing radiations”—they have sufficient energy to remove electrons from the orbits of surrounding atoms, causing them to become charged, or “ionized.” It is those charged particles, or ions, that the detectors pick up and quantify, revealing the intensity of the radiation. Most current detectors, however, are not only bulky, power hungry, and expensive, they also cannot pick up very low levels of ions. Kar and Yung Joon’s detector, on the other hand, is so sensitive it can pick up just a single charged particle.

Our detectors are many orders of magnitude more sensitive in terms of how small a signal they can detect,” says Yung Joon, associate professor in the Department of Mechanical and Industrial Engineering. “Ours can detect one ion, the fundamental limit. If you can detect a single ion, then you can detect everything larger than that.”


The First Satellite Using Quantum Cryptography Is Chinese

Congratulations are in order for China: by launching the world’s first quantum communications satellite, the country has achieved an interesting — if somewhat difficult to explain — milestone in space and cryptography.

quantum dots

Quantum Experiments at Space Scale (QUESS), nicknamed Micius after the philosopher, lifted off from Jiuquan Satellite Launch Center at 1:40 AM local time (late yesterday in the U.S.) and is currently maneuvering itself into a sun-synchronous orbit at 500 km.

So what’s in the package that’s so exciting?

QUESS is an experiment in the deployment of quantum cryptography — specifically, a prototype that will test whether it’s possible to perform this delicate science from space. Inside QUESS is a crystal that can be stimulated into producing two photons that are “entangled” at a subatomic, quantum level. Entangled photons have certain aspects — polarization, for example — that are the same for both regardless of distance; if one changes, the other changes. The trouble is that photons are rather finicky things, and tend to be bounced, absorbed, and otherwise interfered with when traveling through fibers, air, and so on. QUESS will test whether sending them through space is easier, and whether one of a pair of entangled photons can be successfully sent to the surface while the other remains aboard the satellite.

If this is possible, the entangled photons can be manipulated in order to send information; the satellite could, for example, send binary code by inverting its photon’s polarization, one way for 1, the other way for 0. The ground station would see its photon switching back and forth and record the resulting data. This process would be excruciatingly slow, but fast enough for, say, key creation and exchange — after which data can be exchanged securely by more ordinary means. The critical thing about this is that there is no transmission involved, or at least not one we understand and can intercept.


Nanotechnology: The Brillant Future Of CubeSats

To understand why CubeSats could be the next big thing in the study of comets and asteroids, consider the story of Philae, the European Space Agency (ESA) probe that recently made history with the first-ever landing on the surface of a comet. The idea was to get close enough to the comet to analyze its composition in situ—what scientists call “ground truthing.” You can only learn so much about small bodies by studying them from Earth, so scientists built and launched the first spacecraft to sample a comet directly. Trouble is, Philae cost around $240 million, and we almost lost it. Harpoons designed to help the lander grab on to the comet in the low gravity failed to deploy. Another smidgeon of velocity in its bounce, and that $240 million would have been drifting uselessly in the comet’s wake. Philae was lucky; after another bounce it finally came to rest on the surface. But comet landings remain an inherently risky business. That’s where CubeSats—which can cost in the tens of thousands rather than the hundreds of millions of dollars—start to look appealing.
Because CubeSat is low-cost, one can afford to tolerate more risks,” says USC’s Joseph Wang, who has been working on CubeSat engineering for the past several years. In theory, low cost means that scientists can afford to explore more small bodies, more often. The challenge is designing small, light instruments with enough capability to do serious science.


USA, Russia, China Lead The Nanotechnology Race

It is this breadth of nanotechnology’s potential that makes it vital to America’s future competitiveness. Congressman Lamar Smith, chairman of the House Committee on Science, Space, and Technology, believes that American dominance in the field has enormous economic potential and the ability to create new jobs: “it’s a game-changer that could transform and improve Americans’ daily lives in ways we can’t foresee,” he says. On any measure — patents, private and government-sector investment, academic activity — America has so far been a leader in nanotechnology research and, to a lesser extent, development. Federal funding has helped. From 2000-2013 Congress appropriated some $US18 billion for nanotechnology R&D (although the $US1.7 billion budgeted for 2014 is 8% lower than two years ago). Numbers for private-sector investment are harder to come by, but estimates by Lux Research, a firm of analysts, suggest that by 2010, America’s private sector was investing at least $US3.5 billion a year in nanotechnology-related ventures — far more than its closest global competitors.
So why is the United States Government Accountability Office (GAO), an independent agency that works for Congress and scrutinises how the federal government spends taxpayer dollars, now fretting that America may lose the nanotechnology race? In a new report on nanotechnology manufacturing (or nanomanufacturing) released today and prepared for Congressman Smith’s committee, the GAO finds flaws in America’s approach to many things nano.
The main concern is “the missing middle”. Government, universities and start-ups focus their investment on basic research, proofs of concepts and production at laboratory scale. But to win the global nanotechnology race, says the GAO, America must bridge the gap between such activities and being able to produce the technologies at scale.
RusnanoThe GAO’s experts chide the government for lacking a “grand strategy” and to fall behind China and Russia in annual spending on nanotechnology. Russia in particular, is taking advantage of America’s missing-middle mortality rate. Rusnano, a government-owned fund, is picking up the intellectual property of failed American nanotechnology firms

(The GAO report also comes hot on the heels of a National Science Board study showing that China’s global share of overall high-tech manufacturing rose from 8% to 24% from 2003-2012, close to America’s 27%.)

Miniature Rockets For NanoSatellites

For the last few years, researchers around the world have been trying to build mini rockets using microscopic hollow needles to electrically spray thin jets of fluid, which push the spacecraft in the opposite direction. The fluid propellant is a special chemical known as an ionic liquid. A single thruster needle is finer than a human hair, less than one millimeter long and produces a thrust force equivalent to the weight of a few grains of sand. A few hundred of these needles fit in a postage-stamp-size package and produce enough thrust to maneuver a nanosatellite.
Miniature rockets aren’t needed to launch a nanosatellite from Earth. The small vehicles can hitchhike with a regular rocket that is going that way anyway. But because they are hitchhikers, these nanosats don’t always get dropped off in their preferred location. Once in space, a nanosatellite might need some type of propulsion to move it from its drop-off point into its desired orbit. This is where the micro rocket engine comes in. These new electrospray thrusters face some design challenges, however. “Because they are so small and intricate, they are expensive to make, and the needles are fragile,” says King, the Ron and Elaine Starr Professor of Mechanical Engineering-Engineering Mechanics at Michigan Technical University. “They are easily destroyed either by a careless bump or an electrical arc when they’re running.

Nanosatellites are smartphone-sized spacecraft that can perform simple, yet valuable, space missions. Dozens of these little vehicles are now tirelessly orbiting the earth performing valuable functions for NASA, the Department of Defense and even private companies.
nanosat Nanosatellites borrow many of their components from terrestrial gadgets: miniaturized cameras, wireless radios and GPS receivers that have been perfected for hand-held devices.
However, according to Michigan Tech’s L. Brad King, there is at least one technology need that is unique to space: “Even the best smartphones don’t have miniaturized rocket engines, so we need to develop them from scratch.”


Solar Cells at the Price of Pocketbooks

Engineers at the University of California, Berkeley, have developed an inexpensive new way to grow thin films of a material prized in the semiconductor and photovoltaic industries, an achievement that could bring high-end solar cells within reach of consumer pocketbooks.

solar-satelliteUC Berkeley engineers could help make high-end solar cells, currently used in satellites and other space and military applications, affordable for consumer markets.
Performance is everything in the solar cell industry, but performance at a reasonable cost is key,” said Javey, who is also a faculty scientist at the Lawrence Berkeley National Laboratory. “The techniques we are reporting here should be a game-changer for III-V solar cells, as well as for LEDs.”

Top of the line photovoltaics are made from a class of material known as III-V (pronounced “three-five”) compounds, known for their superior efficiency at converting light into power. However, the complex manufacturing requirements for III-V materials make them up to 10 times more expensive than silicon, limiting their use to military applications and NASA satellites, the researchers said.

The work, led by Ali Javey, UC Berkeley associate professor of electrical engineering and computer sciences, is described in a paper published in Scientific Reports, Nature’s open access journal.

A Computer Chip That Can Assemble Itself

Eric Furst is intent on advancing the science of the super-small, and not even Earth’s gravity can hold him back. From his office in University of Delaware’s Department of Chemical and Biomolecular Engineering, Furst has directed astronauts aboard the International Space Station (ISS) in some of the first nanoscience experiments in space. Furst’s focus is colloids — otherwise known as emulsions or suspensions — materials that are part solid and part liquid. You know them as paint, glue, egg whites, gels, milk, even blood. He is exploring colloids at the nanoscale to reveal their physics. Ultimately, his goal is to identify how nano-“building blocks” of various shapes and chemistries can be directed to “self-assemble” into specific structures with desired functions. Such “smart materials” could endow a robot, for example, with the dexterity to be able to pick up an item as fragile as an egg.

With the basic principles of directed self-assembly decoded on the ISS, his team is creating materials from more complex nano-building blocks — doublets he calls “smashed spheres,” and titania ellipsoids, shaped like rice, but 10,000 times smaller. With these infinitesimal components, Furst’s lab already has created novel functional nanomaterials for use in optical communication systems and as thermal coatings, with the support of the Department of Energy and the National Science Foundation.
The sky’s the limit!” Furst says.