MICROSCOPE TAKES IMAGES USING PROTONS

FROM:  LOS ALAMOS NATIONAL LABORATORY 

Taking pictures with protons

U.S., German, Russian collaboration conducts first experiments in Germany

LOS ALAMOS, N.M., June 17, 2014—A new facility for using protons to take microscopic images has been commissioned at the ring accelerator of the GSI Helmholtzzentrum für Schwerionenforschung GmbH (Helmholtz Centre for Heavy Ion Research) in Darmstadt, Germany.

The proton microscope was developed by an international collaboration consisting of Los Alamos National Laboratory, GSI, the Technical University Darmstadt, and the Institute for Theoretical and Experimental Physics, Russia.

Protons, like neutrons, are the building blocks of atomic nuclei. Similar to x-rays, they can be used to radiograph objects, generating images of them. Protons are able to penetrate hot dense matter that can't be examined with light or x-rays. This technology, also known as "proton radiography," was originally invented at Los Alamos National Laboratory in the 1990s, but has been adopted around the world. In the future, the technique will be used at an accelerator currently under construction in Darmstadt called the Facility for Antiproton and Ion Research (FAIR) and at the proposed Matter and Radiation In Extremes (MaRIE) facility at Los Alamos.

In their first experiments, researchers used a proton beam accelerated to an energy of 4.5 gigaelectronvolts (more than 98 percent of the speed of light) by the GSI accelerator facility. A special setup of four quadrupole magnets served as optics to magnify objects with the beam. Initially, they radiographed different items like sets of wires with varying sizes and a wristwatch.

Scientists have succeeded in resolving objects and structures down to a size of 30 micrometers or one thousandth of an inch. The GSI facility, called the Proton Microscope for FAIR, or PRIOR, achieved resolutions comparable to existing facilities in the U.S. or Russia. Scientists plan to improve this to a value of up to 10 micrometers in experiments this year. Another goal is the recording of image sequences of moving objects. In experiments scheduled for July 2014 thin wires will be explosively evaporated by a strong electrical discharge, and this "plasma explosion" will be examined with the proton beam.

The study of plasma is of particular interest to scientists because plasma is found in stars or gas planets like Jupiter. This state of matter can be generated in the laboratory with lasers or strong electrical discharges for short intervals of time. Because protons can penetrate plasmas, they offer unique possibilities to measure the properties of plasma with instruments like PRIOR.

"Combining the experience of this international collaboration has proven to be very productive," said Frank Merrill of the Laboratory's Neutron Science and Technology group and a collaborator on the project. "By joining the enhancements gained from increased proton energy with the gains from proton microscope imaging lenses, a new and remarkable proton radiography capability has been developed."

"Next to the research on events in space, the technique also has very practical applications", said Dmitry Varentsov from GSI's department Plasma Physics and Detectors. "For example one could radiograph running engines or diagnose and treat tumors with it. We want to explore all these opportunities."

The proton microscope will also play an important role at the FAIR accelerator facility. GSI will serve as injector for FAIR. The new FAIR accelerators will provide protons with even higher energies improving the possibilities for experiments. After the completion of FAIR the PRIOR setup will be moved to the new facility. The development of this technique is being extended to the use of electrons and will be utilized for applications at MaRIE.

NASA STUDIES THE BIRTH OF STAR CLUSTERS

FROM:  NASA 

Stars are often born in clusters, in giant clouds of gas and dust. Astronomers have studied two star clusters using NASA's Chandra X-ray Observatory and infrared telescopes and the results show that the simplest ideas for the birth of these clusters cannot work, as described in our latest press release.

This composite image shows one of the clusters, NGC 2024, which is found in the center of the so-called Flame Nebula about 1,400 light years from Earth. In this image, X-rays from Chandra are seen as purple, while infrared data from NASA's Spitzer Space Telescope are colored red, green, and blue. A study of NGC 2024 and the Orion Nebula Cluster, another region where many stars are forming, suggest that the stars on the outskirts of these clusters are older than those in the central regions. This is different from what the simplest idea of star formation predicts, where stars are born first in the center of a collapsing cloud of gas and dust when the density is large enough. The research team developed a two-step process to make this discovery. First, they used Chandra data on the brightness of the stars in X-rays to determine their masses. Next, they found out how bright these stars were in infrared light using data from Spitzer, the 2MASS telescope, and the United Kingdom Infrared Telescope. By combining this information with theoretical models, the ages of the stars throughout the two clusters could be estimated. According to the new results, the stars at the center of NGC 2024 were about 200,000 years old while those on the outskirts were about 1.5 million years in age. In Orion, the age spread went from 1.2 million years in the middle of the cluster to nearly 2 million years for the stars toward the edges. Explanations for the new findings can be grouped into three broad categories. The first is that star formation is continuing to occur in the inner regions. This could have happened because the gas in the outer regions of a star-forming cloud is thinner and more diffuse than in the inner regions. Over time, if the density falls below a threshold value where it can no longer collapse to form stars, star formation will cease in the outer regions, whereas stars will continue to form in the inner regions, leading to a concentration of younger stars there. Another suggestion is that old stars have had more time to drift away from the center of the cluster, or be kicked outward by interactions with other stars. Finally, the observations could be explained if young stars are formed in massive filaments of gas that fall toward the center of the cluster.

The combination of X-rays from Chandra and infrared data is very powerful for studying populations of young stars in this way. With telescopes that detect visible light, many stars are obscured by dust and gas in these star-forming regions, as shown in this optical image of the region. NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Mass., controls Chandra's science and flight operations. Image credit: X-ray: NASA/CXC/PSU/K.Getman, E.Feigelson, M.Kuhn & the MYStIX team; Infrared:NASA/JPL-Caltech.

SUPERCOMPUTER SIMULATIONS RECREATE X-RAYS FROM AREA OF A BLACK HOLE

FROM:  NATIONAL SCIENCE FOUNDATION 
Let there be light
Simulations on NSF-supported supercomputer re-create X-rays emerging from the neighborhood of black holes
February 18, 2014

Black holes may be dark, but the areas around them definitely are not. These dense, spinning behemoths twist up gas and matter just outside their event horizon, and generate heat and energy that gets radiated, in part, as light. And when black holes merge, they produce a bright intergalactic burst that may act as a beacon for their collision.

Astrophysicists became deeply interested in black holes in the 1960s, but the idea of their event horizon was first intimated in a paper by Karl Schwarzschild published after Einstein introduced general relativity in 1915.

Knowledge about black holes--these still-unseen objects--has grown tremendously in recent years. Part of this growth comes from researchers' ability to use detailed numerical models and powerful supercomputers to simulate the complex dynamics near a black hole. This is no trivial matter. Warped spacetime, gas pressure, ionizing radiation, magnetized plasma--the list of phenomena that must be included in an accurate simulation goes on and on.

"It's not something that you want to do with a paper and pencil," said Scott Noble, an astrophysicist at the Rochester Institute of Technology (RIT).

Working with Jeremy Schnittman of Goddard Space Flight Center and Julian Krolik of Johns Hopkins University, Noble and his colleagues created a new tool that predicts the light that an accreting black hole would produce. They did so by modeling how photons hit gas particles in the disk around the black hole (also known as an accretion disk), generating light--specifically light in the X-ray spectrum--and producing signals detected with today's most powerful telescopes.

In their June 2013 paper in the Astrophysical Journal, the researchers presented the results of a new global radiation transport code coupled to a relativistic simulation of an accreting, non-rotating black hole. For the first time, they were able to re-create and explain nearly all the components seen in the X-ray spectra of stellar-mass black holes.

The ability to generate realistic light signals from a black hole simulation is a first and brings with it the possibility of explaining a whole host of observations taken with multiple X-ray satellites during the past 40 years.

"We felt excited and also incredibly lucky, like we'd turned up ten heads in a row," Noble said. "The simulations are very challenging and if you don't get it just right, it won't give you an accurate answer. This was the first time that people have put all of the pieces together from first principles in such a thorough way."

The simulations are the combined results of two computational codes. One, Harm3d, re-creates the three-dimensional dynamics of a black hole accreting gas, including its magnetohydrodynamics (MHD), which charts the interplay of electrically conducting fluids like plasmas and a powerful magnetic field.

"The magnetic field is important in the area outside the black hole because it whips the gas around and can dictate its dynamics," Noble said. "Also, the movement of the field can lead to it kinking and trigger a reconnection event that produces an explosive burst of energy, turning magnetic field energy into heat."

Though the MHD forces are critical near the black hole, it is the X-rays these forces generate that can be observed. The second component, a radiative transport code called Pandurata, simulates what real photons do.

"They bounce around inside the gas, they reflect off the disk's surface, and their wavelengths change along the way," he explained. "Eventually, they reach some distant light collector--a numerically approximated observer--which provides the predicted light output of our simulation."

The researchers' simulations were run on the Ranger supercomputer at the Texas Advanced Computing Center, built with support from the National Science Foundation, which also funded the group's research.

The simulations were the highest resolution thin disk simulations ever performed, with the most points and the smallest length-scales for numerical cells, allowing the researchers to resolve very small features. Varying only the rate at which the black holes accrete gas, they were able to reproduce the wide range of X-ray states seen in observations of most galactic black hole sources.

With each passing year, the significance of black holes--and their role in shaping the cosmos--grows.

Nearly every good-sized galaxy has a supermassive black hole at its center, said Julian Krolik, a professor of physics and astronomy at Johns Hopkins University. For periods of a few to tens of million years at a time, black holes accrete incredible amounts of gas ultimately released as huge amounts of energy--as much as a hundred times the power output of all the stars in a black hole host galaxy put together.

"Some of that energy can travel out into their surrounding galaxies as ionizing light or fast-moving jets of ionized gas," Krolik continued. "As a result, so much heat can be deposited in the gas orbiting around in those galaxies that it dramatically alters the way they make new stars. It's widely thought that processes like this are largely responsible for regulating how many stars big galaxies hold."

In this way black holes may act as cosmic regulators--all the more reason to use numerical simulations to uncover further clues about how black holes interact with gas, stars and other supermassive black holes.

Said Noble: "To see that it works and reproduces the observational data when the observational data is so complicated...it's really remarkable."

-- Aaron Dubrow, NSF
Investigators
Scott Noble
Julian Krolik
Jeremy Schnittman
John Boisseau
Karl Schulz
Omar Ghattas
Tommy Minyard
Yosef Zlochower
Manuela Campanelli
Related Institutions/Organizations
Rochester Institute of Tech
Johns Hopkins University
Goddard Space Flight Center
University of Texas at Austin

HUBBLE CELEBRATES 22 YEARS IN ORBIT

FROM:  NASA
To celebrate its 22nd anniversary in orbit, the Hubble Space Telescope released a dramatic new image of the star-forming region 30 Doradus, also known as the Tarantula Nebula because its glowing filaments resemble spider legs. A new image from all three of NASA's Great Observatories--Chandra, Hubble, and Spitzer--has also been created to mark the event. The nebula is located in the neighboring galaxy called the Large Magellanic Cloud, and is one of the largest star-forming regions located close to the Milky Way. At the center of 30 Doradus, thousands of massive stars are blowing off material and producing intense radiation along with powerful winds. The Chandra X-ray Observatory detects gas that has been heated to millions of degrees by these stellar winds and also by supernova explosions. These X-rays, colored blue in this composite image, come from shock fronts--similar to sonic booms--formed by this high-energy stellar activity. The Hubble data in the composite image, colored green, reveals the light from these massive stars along with different stages of star birth, including embryonic stars a few thousand years old still wrapped in cocoons of dark gas. Infrared emission data from Spitzer, seen in red, shows cooler gas and dust that have giant bubbles carved into them. These bubbles are sculpted by the same searing radiation and strong winds that comes from the massive stars at the center of 30 Doradus. Image Credits: X-ray: NASA/CXC/PSU/L.Townsley et al.; Optical: NASA/STScI; Infrared: NASA/JPL/PSU/L.Townsley et al.

FDA'S RECOMMENDATIONS FOR HAND HELD X-RAY DEVICES

FROM:  U.S. FOOD AND DRUG ADMINISTRATION
Hand-held Dental X-Ray Units: FDA Safety Communication - Unreviewed Products May Not Be Safe or Effective
[Posted 02/10/2012]
AUDIENCE: Dentistry

ISSUE: FDA notified healthcare professionals, including dentists, dental care professionals and veterinarians, about the illegal sale of hand-held dental X-ray units that have not been reviewed by the FDA. The FDA is aware of hand-held dental X-ray units being sold online by manufacturers outside the U.S. and directly shipped to customers in the U.S. These devices may not be safe or effective and could potentially expose the user and the patient to unnecessary and potentially harmful X-rays.

BACKGROUND: All hand-held dental X-ray units that have been certified by the manufacturer to meet the FDA’s radiation safety standards bear a certification label/tag, a warning label, and an identification (ID) label/tag on the unit's housing. All labels/tags should be in the English language and permanently affixed or inscribed on each product so that they are legible and readily accessible when the X-ray unit is fully assembled for use.

RECOMMENDATION: Healthcare professionals should:
Verify that your device bears certification, warning and ID labels as described in the FDA Safety Communication.
Ask your vendor whether the device has been reviewed and cleared by the FDA.
Access the FDA Medical Device Approvals and Clearances searchable database to verify that the X-ray unit you are using has been reviewed by the FDA.
If you become aware of a device that you think is hazardous or does not meet FDA’s radiation safety or premarket clearance requirements, contact your state regulatory agency, which will then notify the FDA. The Conference of Radiation Control Program Directors (CRCPD)   website has a list of contacts for each state