Circuit Board Enhances Data Collection, Saves on Cabling

Data Acquisition group

JLab employees pose with the flash ADC board they designed. From left are Fast Electronics Staff Engineers Fernando Barbosa, Benjamin Raydo and Hai Dong; Fast Electronics Group Leader Chris Cuevas, and Data Acquisition Staff Scientist Ed Jastrzembski and Fast Electronics Associate Coordinator Jeff Wilson.

Experiments in Jefferson Lab's experimental halls typically begin with a smash, as millions of electrons from the accelerator crash into an experimental target. Much of the resulting debris is collected and measured by large detectors.

Ideally, scientists would keep all of the information recorded by the detectors, but there's simply too much of it. So they sample portions of the data and use a computer, called the trigger, to process the samples to determine what data to keep and what to throw away. While the trigger is making that determination, the full data set is preserved by sending it through a loop of cable. This process takes just eight millionths of a second – but that's time enough for the data to travel through nearly 1.25 miles of cable!....... more


Detector Group Develops Dual-Headed Cancer Imager

Jefferson Lab and the University of Virginia have redoubled their efforts to catch breast cancer in its earliest stages. Researchers are now developing and testing a two-headed compact gamma camera system.....more

 

In Their Own Words with Kostas Orginos

I spent my first five years on the island of Andros, Greece, in a small village called Vouni. Since the local school had only one teacher for all six elementary grades, my mother took my brother and me to Athens to attend a better school. My father was captain of an oil tanker, so he was away a great deal. My father's choice of profession had followed the traditional path of educated young men on the island......more

 

Ready, Set, Go! to the 2008 JAG Run-A-Round

Break out those running shoes! The 23rd annual Jefferson Activities Group Run-A-Round will be held Wednesday, May 14 from 3-6 p.m. Jefferson Lab staff, users, full-time contractors and immediate family members are invited to participate. Staff and users that participate can receive a free 2008 JLab T-shirt by turning in their Run-A-Round bibs.....more


Below the Fold:

Circuit Board Enhances Data Collection, Saves on Cabling

Data Acquisition group

JLab employees pose with the flash ADC board they designed. From left are Fast Electronics Staff Engineers Fernando Barbosa, Benjamin Raydo and Hai Dong; Fast Electronics Group Leader Chris Cuevas, and Data Acquisition Staff Scientist Ed Jastrzembski and Fast Electronics Associate Coordinator Jeff Wilson.

Experiments in Jefferson Lab's experimental halls typically begin with a smash, as millions of electrons from the accelerator crash into an experimental target. Much of the resulting debris is collected and measured by large detectors.

Ideally, scientists would keep all of the information recorded by the detectors, but there's simply too much of it. So they sample portions of the data and use a computer, called the trigger, to process the samples to determine what data to keep and what to throw away. While the trigger is making that determination, the full data set is preserved by sending it through a loop of cable. This process takes just eight millionths of a second – but that's time enough for the data to travel through nearly 1.25 miles of cable!

Soon, though, all that cable may be replaced by a circuit board designed by Jefferson Lab's Fast Electronics Group in collaboration with the Data Acquisition Group.

"We spent a lot of time doing the simulations and talking to various groups to get the data that is important to them. This is a general-purpose board that anybody can use. And we are excited, because this is the first prototype," says Fernando Barbosa, a staff engineer in the Physics Division’s Fast Electronics group.

The circuit board, called a flash analog-to-digital converter, converts the data into a digital format and stores it while an onboard processor determines which parts to keep. The flash ADC can then send the data to other processors and/or to tape.

flash analog-to-digital converter


Physicists will use the flash ADC to convert and pare experimental data down their essentials.

"You practically don't lose anything for eight microseconds. But the trigger should take two microseconds max to make a decision. So you have plenty of time to make a decision and to start writing to tape what you really need," Barbosa explains. "So, you'll be writing less to tape, but you’ll get the same or more data out."

The group has been working on the project, when time permitted, for several years. According to Hai Dong, staff engineer, all the pieces the group needed to complete the board only came together recently, due to advances in processor technology and in time spent writing and verifying the computer code to make it all work.

"We couldn't have built this board two years ago. The processors were not available at the speed we needed. These are the analog-to-digital converters; these were not available," Dong says. "It's also about a year's worth of time, just for the code."

The flash ADC was designed to meet growing data rate needs in the Jefferson Lab experimental program.  It will have particular impact on the Hall D data acquisition systems following the 12 GeV Upgrade.  JLab will need several hundred of these custom-built boards once the design has been finalized.

In the meantime, group members are anxious to see how well the flash ADC performs in experiments. Once testing is complete, it’s likely that prototypes will be installed in one or more of the experimental halls. The group expects that to happen by the end of the year.

Chris Cuevas, Fast Electronics group leader, says researching and developing the flash ADC has been a great project.

"This is a big deal for JLab. There is nothing on the market that could have accomplished exactly what we need for digitizing the detector signals and performing first-level trigger processing. We don't normally design these things in-house, but we’ve shown we can do that."

By Kandice Carter
JLab science writer

 

Detector Group Develops Dual-Headed Cancer Imager

Kent Paschke
Patty Judy, a graduate student at the University of Virginia, shows the two-headed compact gamma camera system, developed by Jefferson Lab's Radiation Detector and Medical Imaging Group, and is being used in clinical trials at the University of Virginia

Jefferson Lab and the University of Virginia have redoubled their efforts to catch breast cancer in its earliest stages. Researchers are now developing and testing a compact gamma camera systemwith two camera heads.

Breast cancer strikes more women in the U.S. than any other cancer, killing more than 40,000 women each year. The first line of defense is to spot it early. While mammography is the primary method of breast cancer screening, the Dilon 6800 Gamma Camera has saved women’s lives by revealing cancers not seen on mammograms.

The Dilon system, built and marketed by Dilon Technologies, is based on technologies originally developed by Jefferson Lab's Radiation Detector and Medical Imaging Group. It uses breast-specific gamma imaging. In this method, a radiopharmaceutical is injected into the body, where it accumulates in cancer cells. The drug contains a radioactive agent that releases gamma rays, which are imaged by the gamma camera, thus revealing the hidden cancer. The system uses one gamma camera.

Now scientists are testing to see if two gamma cameras, each similar to the Dilon 6800's single camera, working in concert with each other can spot cancer better than one.

Patty Judy, a graduate student at the University of Virginia, presented the results of early preclinical tests of the two-camera system at the 2007 IEEE Medical Imaging Conference.

"What we wanted to look at was would we get better detection of lesions, especially small lesions, in all regions of the breast with that setup," she said.

With assistance from Dilon, the researchers imaged breast phantoms, plastic and gel mockups of the breast with an embedded radioactive agent to simulate cancer. They found that the system, which combines information from both cameras, imaged the lesions better than each camera alone.

"The resolution is better than an individual camera's resolution at any depth. So in most cases, you're going to do better with a multiplied image," Judy concludes.

As for its effectiveness in spotting cancer in patients, initial results of clinical trials confirm the conclusions from the phantom tests.

By Kandice Carter
JLab science writer

 

In Their Own Words with Kostas Orginos


Konstantinos "Kostas" Orginos, a joint faculty member with JLab's Theory Center and the College of William and Mary, is a recipient of a DOE Office of Science Outstanding Junior Investigator grant.
I spent my first five years on the island of Andros, Greece, in a small village called Vouni. Since the local school had only one teacher for all six elementary grades, my mother took my brother and me to Athens to attend a better school. My father was captain of an oil tanker, so he was away a great deal. My father's choice of profession had followed the traditional path of educated young men on the island. My mother's father followed the other option – available to the less educated – he had emigrated to America. It seems that, despite all the education I've had, I have followed my grandfather's path, since I too, have come to America.

In Greece, by the time you are in 10th grade you have to select your career path so you can take the appropriate courses and exams for a university education. By the time you're admitted to a university, your decision has long been final and changing your mind is not really an option. In my case that was not a problem, I had known since I was in sixth grade that I wanted to be a physicist. The private school I attended had a wonderful lab where we performed fascinating experiments. Being able to study and understand the physical world seemed the most amazing thing to me.

After graduating from the University of Patras, I came to Brown University in August 1991 to attend graduate school. The day before I arrived in Providence, Hurricane Bob had slammed across New England, so I spent my first day in America barricaded in the house with no electricity. Although I had studied English for years in Greece, I initially struggled with the language and the culture. Living in Providence did not help the situation, since the heavy local accent made it very hard for me to understand the people around me. A fellow grad student from Korea was the only one who had the patience to talk with me and we soon became good friends.

It was at that time that I met my wife, Lily, also from Greece, a Brown grad student in classics. When we got married we knew that it would be extremely difficult to get academic jobs in the same geographical area, let alone the same institution, and that we might have to sacrifice living together while we each pursued our own career paths.

The Sims Side of Protons
Konstantinos Orginos is building a simulated universe. But unlike The Sims, his virtual world won't have nosy neighbors and yappy dogs. It will, however, be populated by the very particles that make up these everyday things. The goal is to understand how these particles, such as protons and neutrons, interact to build matter.

Orginos was named an Outstanding Junior Investigator by the Department of Energy's Office of Nuclear Physics in 2007. Along with the recognition came a $110,000 grant for each of three years to build a cluster computer with 192 processors (24 eight-processor nodes). He plans to combine these processors with others to build a 96-node cluster at The College of William and Mary.

's hoped that the simulations will help physicists understand, for the first time, how a simple nucleus is made in terms of the fundamental theory of QCD.

And that's what we did for almost eight years. She first worked at the University of Virginia, while I was a postdoctoral fellow at the University of Arizona; she then taught at Williams College in Williamstown, Mass., and I served my second stint as a postdoc at Brookhaven National Lab. This was a great improvement, as we were only about five hours apart. A couple of years later she had a sabbatical; during that time we lived together and our son, Nikolas, was born. After Lily returned to Williams, I was able to get a position at MIT, so we were able to reduce further the distance between us.

In 2005, we were happily surprised to have both been offered teaching positions at William & Mary, in my case as a joint faculty member with the Jefferson Lab Theory Center. I cannot tell you how extraordinary it seems to us to have our family united under one roof.

Receiving one of the Department of Energy’s Outstanding Junior Investigator awards last year was a great honor. It's a highly prestigious award and I knew how hard it is to get it, as this was my second try. Having $330,000 to spend over a period of three years mostly means that I'll be able to hire a post-doc to help with my research and set in motion my research agenda for the next few years. This is a very exciting step for my career.

My wife and I now live in Williamsburg. We have since had a second child, our daughter Anna. Lily is up for tenure this year and I split my week between the college and the Jefferson Lab Theory Group. Although I have given up swimming, which was my favorite hobby, I have a new one that I share with my wife: taking care of our two small children. Our weekends are spent chasing them around and doing fun things with them.

As told to Judi Tull
JLab feature writer

 

Ready, Set, Go! to the 2008 JAG Run-A-Round

Timeline Reminders

  • Register online: Now through 5 p.m., Tuesday, May 13
  • Pick up racing bib (number): Wednesday, May 14, 9 a.m. – 2 p.m. in the CEBAF Center Lobby
  • Late registration: 9 a.m. – 2 p.m. in the CEBAF Center Lobby (Not eligible for awards)
  • 3 p.m.: Winning T-shirt announced and designer recognized (CEBAF Center Circle)
  • 3:30 p.m.: Run-A-Round begins (Start line on SURA Road in front of CEBAF Center Circle)
  • 4 p.m.: Food and beverages on Rattley Road – just beyond the finish line. JLab employees and users turn in run/walk bib for JLab T-shirt.
  • 5 p.m.: Awards announced

Break out those running shoes! The 23rd annual Jefferson Activities Group Run-A-Round will be held Wednesday, May 14 from 3-6 p.m. Jefferson Lab staff, users, full-time contractors and immediate family members are invited to participate. Staff and users that participate can receive a free 2008 JLab T-shirt by turning in their Run-A-Round bibs.

The Run-A-Round will begin in front of CEBAF Center at 3 p.m. with the debut of the 2008 T-shirt. The run/walk will start promptly at 3:30 p.m., following the same 1.5 mile course used in previous years. The finish line will be east of CEBAF Center, where the parking lot intersects with Rattley Road. The Peninsula Track Club will collect official times at the finish line.

Food and beverages, music and the awards presentations will follow the race on Rattley Road. Awards will go to the top three male and female finishers in each age group and the overall best male and female finishers.

In addition to the awards for top finishers, JAG will present a Spirit Award to the division or group that has the highest percentage of participation and the best combined times. Only employees with times under 18 minutes for the 1.5 mile course (including the top three finishers in every age group regardless of time) will be tallied for the award. Participants of the winning group will each receive a Spirit Ribbon.

In case of inclement weather on May 14, the event will take place at the same time on the following day, May 15.

JAG Remembers Young Engineer at this Year's Event

During this year's Run-A-Round, the JAG is remembering Ravi Anumagalla, a JLab Physics Division engineer who died last May 27. Ravi, who was engaged in many JLab activities, first as a student and later as an employee, had been training in hopes of earning an award in last year's Run-A-Round before his tragic death. Anyone participating in the Run-A-Round who wishes to remember Ravi will be able to pick up a ribbon to wear during the race. The ribbons will be available when participants get their bib numbers in CEBAF Center the day of the race.

Run-A-Round Registration
Online registration is open on the JAG webpage. All runners/walkers must be registered to be eligible for prizes. Online registration is open through 5 p.m. on Tuesday, May 13. All participants can pick up their race bibs on Wednesday, May 14 between 9 a.m. and 2 p.m. in the CEBAF Center lobby. Late registration will be accepted 9 a.m. to 2 p.m. on Wednesday, May 14 in the CEBAF Center lobby. Individuals registering the day of the race won't be eligible for awards.

Volunteers Needed

Volunteers are needed in various capacities. Sign-up online; help is needed before, during and after the event. Volunteers are needed for:

  • Early food preparation
  • Staff the late registration and bib distribution tables the day of the event
  • Help with water stations, course set up and monitoring the finish line
  • Help with T-shirt distribution
  • Food and beverage tents before and during event
  • Clean-up

Event Closes JLab Roads

Please be aware that Rattley Road will be closed all day, Wednesday, May 14, and Thursday morning, May 15, to accommodate set up and tear down for the event. During the event, the following streets will be closed to traffic: JLab’s main entrance (Onnes Drive), SURA Road, Lawrence Drive, Hofstadter Road and Rutherford Road (the parking lot between the VARC and CEBAF Center).

 

Below the Fold

Jefferson Lab Hall A User Honored for Teaching

Adam Sarty, a physics professor with Saint Mary's University, Nova Scotia, recently received the Canadian Association of Physicists Medal for Excellence in Teaching. He is a member of JLab's users community – scientists representing more than 200 institutions that come to JLab to conduct experiments.

Saint Mary’s University physics professor and Hall A user Adam Sarty has captured this year's Canadian Association of Physicists (CAP) Medal for Excellence in Teaching. The CAP Medal honors university faculty members who have a comprehensive knowledge and deep understanding of their subject and who possess an exceptional ability to communicate their knowledge and understanding in ways that help students achieve academic success in physics.

"I am humbled and honored to receive this medal, and would like to share the recognition with my team – my wife and children, my department and dean, and the Saint Mary's Centre for Academic and Instructional Development. All have taught me, guided me and supported me in my physics teaching," said Sarty.

Merit for the medal is based on all forms of undergraduate teaching, from classroom lecturing and consultation with individual students, to the introduction of innovative teaching methods and the production of educational materials. Sarty takes particular pride in getting people excited about physics.

"Removing people's fear of science in general, and physics in particular, is a passion I have," said Sarty. "This is what drives me to implement as many resources as possible in my introductory classes, to remove barriers to understanding, and to take my physics shows on the road to schools and community groups."

Saint Mary's University is located in Halifax, Nova Scotia. This information is provided courtesy of the Saint Mary's University Public Affairs office. For the complete news release, please visit the St. Mary's University webpage.

 

 

 


California High School Wins Science Bowl; Virginia team takes 3rd

Finishing in third place at the DOE Science Bowl Nationals, held May 1-6 in Washington, D.C., was the team from Thomas Jefferson High School for Science & Technology from Alexandria, Va. Here they are pictured after winning the Virginia Regional High School Science Bowl held Feb. 2 at Jefferson Lab. The winning team includes, from left to right: Huanqi Deng, Bruce Sun, Jack Wang, Meng-Yang Chen and Evan Warner and Coach Sharon Webb.

On May 5, the U.S. Department of Energy announced Santa Monica High School from Santa Monica, Calif., winner of the 2008 DOE National Science Bowl.  Santa Monica beat Mira Loma High School from Sacramento, Calif., in the championship match held in Washington, D.C. Teams representing 67 high schools from across the United States competed in the national finals.

Members of the winning team won a trip to the International Youth Science Forum in London in addition to $1,000 for their school’s science department.

Placing second was the Mira Loma High School from Sacramento. The team won a trip to a nuclear science facility in France, sponsored by AREVA, Inc., in addition to $1,000 for their school’s science department.

The third place team was Thomas Jefferson High School for Science & Technology from Alexandria, Va. The team won $1,000 for their school’s science department and a trip to Jefferson Lab which they donated to the fourth place team. TJHSST won the Virginia Regional High School Science Bowl held at Jefferson Lab in early February.

The fourth place team was Fairview High School from Boulder, Colo.

More than 300 high school students competed in the national finals of the 18th annual DOE National Science Bowl. Earlier this spring, more than 12,000 students from across the country participated in regional Science Bowls for high school students. The winners of the regional high school Science Bowls received all-expense paid trips to compete in the national finals in Washington. DOE recognizes all the students who competed as true mathematics and science stars, representing the nation’s next generation of scientists and engineers.

The DOE Office of Science manages the DOE National Science Bowl. The Office of Science is the principal supporter of DOE’s world-class national laboratory system leading the way in innovations including high-end computing, nanotechnology, biotechnology, energy sources, and other material science research.

For more information about the Science Bowl, check out the DOE news release.


New Things are Happening in Quark Cafe

Quark Cafe staff members invite the JLab community to stop in for breakfast and lunch. From left are Sandra Graham, Dan Plummer, Food Services Director Gaye Davenport, Executive Chef Chris Thornhill and Dianne Greene.

Things are bustling backstage at Jefferson Lab's Quark Cafe between the breakfast rush and lunchtime. Dan Plummer is building pannini sandwiches filled with meat and cheese, getting them ready for the brand new pannini press to make them hot and delicious. Dianne Greene is cleaning up after a busy morning of serving up her popular French toast platter breakfast special. Executive Chef Chris Thornhill is preparing hot entrees with the help of Sandra Graham; and Food Services Director Gaye Davenport is orchestrating and overseeing everything.

The crew has been at work since 6 a.m. and will carry through until 3 p.m. "Every day is a busy day," Davenport says with a smile.

Since last fall, she has been with Eurest Dining Services, the Charlotte, N.C.–based company that has the contract to provide food services at JLab. Prior to coming here she had been the Director of Catering at The College of William & Mary for six years.

Davenport and her team have made some exciting changes and beefed up – no pun intended – Quark Cafe's fare. There’s a full line of organic snacks now – everything from chocolate to tea cakes, fruit bars, chips and even Newman's Own peppermint cups. For folks in a hurry, there's a display by the doorway of tropical snacks.

Quark Cafe is located on the first floor at the north end of the CEBAF Center lobby. It is open Monday through Friday (except holidays when JLab is closed). Breakfast is available from 7-10 a.m. and lunch is served from 11:30 a.m. to 1:30 p.m. Snacks and beverages may be purchased through 2 p.m. Breakfast and lunch selections include combo specials (entre, side and drink). However, all items may be purchased ala carte. See the menu for daily selections. Catering requests may be made through Noel Vermeire, Staff Services, ext. 6930, email vermeire@jlab.org.

"These are perfect for people who want to grab a quick bite and go," she says.

In working to meet customers' requests, the team has enlarged – and continues to expand – the beverage selection.

"We have high energy drinks, a variety of iced teas, Starbucks products and even vitamin waters," she says with pride. "We just got the new low-cal Gatorade called G2; and we are keeping our eyes on new products coming to the marketplace."

Nearby, the coffee station sports some new additions as well: powdered cinnamon, nutmeg and cocoa powder for sprinkling on that java. These are an example of the Quark Cafe staff’s responsiveness to customer requests.

"We listen to what people want," Davenport notes. "There's a comment card on the Quark Cafe menu webpage, and soon we'll be adding a suggestion board near the cafe's entrance. We want people to tell us what they want – that we don't have and we'll do our best to accommodate them. For me, my job has always been about customer service. That's what I always like to bring to the table."

The menu for the coming week is posted on the webpage by 2 p.m. on Fridays and there's also a copy of the menu posted in the CEBAF Center lobby, near the cafe's entrance.

When a customer survey was taken last fall, people clamored for healthy options. As a result, there are boxes of Kashi and Smart Start cereals and vegetarian entrees and salads available.

Food Service Director Gaye Davenport pauses in front of some new snack items available in Quark Cafe.

Keeping meals interesting for a continuing group of customers is a challenge, and Davenport and her staff work to bring new choices to the menu along with the popular staples. Themed meals range from "Silver Diner Classics," including long-time favorites such as meat loaf and chicken pot pie, to spotlighting cultural cuisine, such as Asian, Italian, Mexican and Caribbean dishes. New breakfast specials include a Denver breakfast fold, French toast and a flatbread breakfast fold, which is a sister to the new Mediterranean flatbreads at lunchtime. Freshly made wraps have also been introduced for the lunch crowd.

There's hardly an event to celebrate that the Quark Cafe crowd lets slip by. They've celebrated baseball season with hot dogs and Cracker Jacks, Mardi Gras with a Cajun menu, St. Patrick's Day, the coming of spring and of course, feasts at marking the holidays.

Thornhill agrees with Davenport that the challenge of his job is keeping the food interesting. A graduate of the prestigious Culinary Institute of America in Hyde Park, N.Y., Thornhill's passion for preparing food began during his youth. By age 13 he had bought his first cookbook.

"One of the things I like most about working with Eurest is that the focus is on fresh ingredients, with a minimal amount of frozen food," he notes. "I make it a point to ask our guests how they enjoyed their meal and what we could do to make it better. If they don't see something they want, we stand ready to take their suggestions and see what we can do to make their meal or event more pleasurable."

The cafe staff also performs catering duties for groups ranging in size from five people to 300. The catering menu has been static for a number of years; but a new one is about to be presented. "We're very excited about this," Davenport says. "It was time for a complete rejuvenation of the catering menu and we've done that." Look for the new menu within the next month or so.

"We're very excited about sharing all of the changes we've made with the JLab community, and getting feedback," Davenport concludes. "If you haven’t been in Quark Cafe for some time, it’s time to come back and take a look at – and a taste of – what’s new."


JLab Recognizes Top Small Business Subcontractor for 2007

Mechanical Resources Inc. earned JLab's Small Business of the Year award for 2007. Recognized during a recent reception are, from left: Mike Leveille, Scott Weiss, Robbie Rutherford, John Mancil, Dave Clark, Tim Grencewicz and Todd Hedge. MRI is co-owned by Grencewicz and Mancil.

Mechanical Resources Inc., a Newport News-based business that provides mechanical systems support, was recently recognized as Jefferson Lab's Outstanding Small Business Subcontractor of the Year for 2007.

MRI, co-owned by Tim Grencewicz and John Mancil, received the Jefferson Science Associates/JLab Outstanding Small Business Subcontractor award at a reception held at the Lab in late April. Department of Energy officials, senior Jefferson Lab management, Procurement and Facilities Management & Logistics staff gathered to congratulate Grencewicz and Mancil and several of their employees as they received an award plaque from JLab Director Christoph Leemann.

"This is a tough competition," noted Danny Lloyd, JLab's small business program manager. "Jefferson Lab subcontracts a broad range of services and MRI was one of several hundred small businesses that worked with JLab during 2007. Using the Lab's established criteria, a judging committee rated the top 59 small business and MRI finished at the top. The company is consistently responsive and provides a wide array of mechanical systems support to Jefferson Lab. MRI is a valued member of the JLab team."

MRI's working relationship with Jefferson Lab goes back nearly 14 years and includes 5000 task orders. The company has tackled problems as diverse as dampening the sound from heat pump fans in office buildings, relocating kitchen equipment and installing water treatment equipment to identifying and reducing air conditioning compressor noise, fixing an underground chilled-water pipe and helping to determine the best way to keep hurricane water from flooding JLab's underground experimental halls. Since 1999 when Jefferson Lab started recording subcontractor hours, MRI has recorded more than 135,114 work hours at the research facility. The company has worked late nights and holidays to complete its work.


JLab Scientist Develops Portrait of a Gremlin

Rongli Geng, SRF Institute staff scientist, zeros in on a defect inside an accelerator cavity with a long-distance microscope.

When an expensive accelerator component designed for the International Linear Collider failed to perform as expected, Jefferson Lab scientists set out to find the root of the problem. What they discovered and the tool they used to make their discovery could have widespread applications in accelerator science.

"You can see the cavity is about a meter long, with nine cells. Any defects on the metal surface, inclusions or even particulate contamination, will become a potential source of field-quenching or electron-emitting sites," said Rongli Geng as he stood alongside the shiny niobium component.

It was Geng, a staff scientist at Jefferson Lab's Institute of Superconducting Radiofrequency Science and Technology, who found the problem with the cavity: a tiny metallic speck just a bit wider than a human hair on the cavity's internal surface. The cavity is one of eight ILC cavities processed and evaluated by Jefferson Lab staff thus far. The problematic cavity, which is the fourth manufactured by Advanced Energy Systems, has been dubbed AES4.

While conducting performance tests on AES4, Geng found that the cavity did not meet target specifications, likely due to two electron-emitting sites caused by surface defects. These sites leach away energy that would ordinarily go into accelerating subatomic particles, the accelerator cavity's main purpose. Emitted electrons heat up the cavity wall as they gain energy from the field stored in the cavity, giving scientists a method for locating emitting sites.

"We have a set of temperature sensors built by our JLab colleague Gigi Ciovati, which we attach to the outer surface of the cavity. They will tell which part of the cavity wall is hotter than the surrounding area, even very small temperature rises," Geng explains.

Once the sensors confirm which of AES4's doughnut-shaped cells have developed electron-emitting sites, Geng can scour the area for defects. To conduct his search, Geng turned to a favorite tool of birders and backyard astronomers – a telescope.

"This is the Questar. The technical name is long-distance microscope," he said, pointing to the small telescope he had mounted on a stand. "The theoretical resolution of this tool is three microns. That is enough for our purposes."

This novel way of looking inside accelerator components has given scientists their first clear snapshot of a performance-killing defect (arrow pointing to imperfection on inside of cavity wall). Researchers suspect that the tiny spot (about the width of a human hair) on this otherwise smooth surface is preventing the component being tested at Jefferson Lab from reaching its design specifications

Aiming the device at the inside surface of one of the suspect cells, Geng managed to quickly find a microscopic defect.

"There was a trick to this, and that was finding the correct source of illumination," Geng said. "We have successfully identified the defects in the cavity without actually inserting a camera into the cavity."

Scientists may not know exactly how the defect is formed, but Geng explained that the "defect can be introduced in the beginning. For instance, when you are forming the cups, you can have a defect embedded into the material and afterward, when you do the chemistry and remove the defect, you could leave a damaged site there. You could also have inclusions from the original material."

Geng and his colleagues are still deciding how they will remove the defect they found in AES4.

"A typical fix would be just to mechanically remove it. It's not easy, though, because you are talking about the size of a human hair. You need to precisely go to that spot and remove it." The next step is to develop countermeasures to prevent or remove these defects.

Currently, the electron-emitting problem limits the performance of the cavity to roughly 28 Megavolts per meter, but Geng hopes that removing the defect will allow the cavity to eventually reach its 35 MV/m goal, making this cavity eligible for further testing.

JLab is working with other labs to develop the capability for realizing this ambitious project (ILC). Past experience in working with niobium accelerator components, used in JLab's CEBAF accelerator and in the Free-Electron Laser, allow Lab staff to successfully tackle technical challenges in applications of superconducting radiofrequency technology. Further developments in the field, in return, pay dividends in reliability and performance of the CEBAF 12 GeV Upgrade and energy-recovering linear accelerators.

Some funding for this work was also provided by Japanese colleagues via the U.S.-Japan Agreement.

By Kandice Carter
JLab science writer


Milestones for April 2008

Hello
Kai Tian, Superconducting Radiofrequency Postdoctoral Fellow (Structures & Simulations), Accelerator Operations, Research & Development Division

Goodbye
William Hicks, Mechanical Project Engineer, Engineering Division
Alex Dizerba, Distinguished Fellow, Directorate, retired
Carter Ficklen, ESH&Q Reporting Manager, Environment, Safety, Health & Quality Division, retired

These Milestone entries, listed alphabetically, are actions posted by Human Resources from February through early April 2008. Current JLab career opportunities are posted at: http://www1.jlab.org/mis/jobline/

The On Target newsletter is published monthly by the Thomas Jefferson National Accelerator Facility (Jefferson Lab), a nuclear physics research laboratory in Newport News, Virginia, operated by Jefferson Science Associates, LLC, for the U.S. Department of Energy's Office of Science. Possible news items and ideas for future stories may be emailed to jlabinfo@jlab.org, or sent to the Jefferson Lab Public Affairs Office, Suite 15, 12000 Jefferson Avenue, Newport News, VA 23606