Below the Fold

Advisory Committee Sets Direction for JLab's Scientific Program

One by one, the dozen scientists filtered back into a conference room at Jefferson Lab, where sheets of paper, coffee cups, blinking laptop computers and thick, three-ringed binders lay scattered across four tables arranged in a square.

To one side of the tables stood Michael Pennington, a nuclear physicist from the University of Durham in England. A member of what is known as the Program Advisory Committee 32, or PAC 32, Pennington waited patiently as the other scientists took their seats so he could announce the future experiments that he and fellow committee members had selected to run at Jefferson Lab.

"I think the Lab is to be complimented for providing interesting physics," Pennington said as he began his presentation. "One of the nice things about this PAC is that ...we were able to concentrate on the science."

The experiments his committee selected were significant not only for the knowledge they will contribute to the understanding of nuclear physics, but also because they will likely be among the first to run at Jefferson Lab after it upgrades its facilities and doubles the energy of its electron beam accelerator to 12 GeV, or 12 billion electron volts.

Twice a year, Jefferson Lab solicits research experiment proposals. The submissions are scrutinized by the Lab’s program advisory committee, which acts as a scientific "jury" and ranks and prioritizes the proposed experiments. The committee is an independent group composed of internationally respected scientists with different areas of expertise. The committee strives to select the very best and most cutting-edge science to run at JLab. Similar review committees exist at other research laboratories in the United States and around the world.

During the review process held at Jefferson Lab Aug. 6-8, 2007, members of the committee listened to presentations and reviewed proposals. Coming from France, Italy, Germany, Poland, England and the United States, the committee members brought a diversity of perspectives to the table. They discussed, debated and, finally, winnowed the proposals based on scientific merit and feasibility of success.

"They’re all central to the 12 GeV Upgrade program," Pennington said of the experiments selected, "in that they study, essentially, the electromagnetic properties of protons, how the features of the proton reflect the properties of their constituents, their flavor, their spin and all the other properties."

Typically, it can take weeks or years to develop and write an experiment proposal, which often are based on ideas that have been around for years but not previously studied, says Ron Gilman, chairman of Jefferson Lab’s Users Group and a physics professor at Rutgers University. The Users Group consists of more than 1,200 scientists, primarily university faculty members, who use the facilities at Jefferson Lab to conduct experiments.

Gilman says that submitting a research proposal to a PAC is like submitting an article to a scientific journal. The comments provided by members of the PAC can help those who have submitted proposals to refine their experiments and produce better science. Typically, the proposals are submitted by international collaborations of scientists and other experts. Often a scientist from Jefferson Lab is among the collaborators, because of his or her familiarity with the Lab’s capabilities and equipment.

"When a proposal is submitted to PAC," Gilman explains, "the committee members can say it’s a great experiment and they approve it. Or they may say it’s a good experiment but we don’t have any beam time to give you; in that case you’re usually deferred with regret. Or they may decide that this proposal wasn't as interesting as some others, so you’re not approved, but you are welcome to return in the future and make your proposal more compelling."

As an advisory group, the committee submits its selections to Jefferson Lab’s director, who makes the final decision. Invariably, the director accepts the PAC’s decisions and the experiments are scheduled.

At Jefferson Lab, about 25 to 30 experiment proposals are submitted each year. The PAC 32 reviewed nine proposals and three letters of intent, with five of the proposals approved and three conditionally approved. These experiments will run after the 12 GeV Upgrade is complete.

PAC approval begins a lengthy process for those that were selected. For researchers, the wait to start an experiment is routine. At Jefferson Lab, the demand for beam time is extremely competitive because it is the world’s leading facility in the experimental study of hadronic matter. The Lab’s typical backlog of approved experiments is about four years, which is considered efficient for scheduling purposes. The Lab will not allow the backlog to become too long, because it can threaten funding for researchers, particularly for college students and professors. Of course, for this particular PAC, which focused on experiments to run after the 12 GeV Upgrade is complete, the wait is likely to be seven to 10 years.

The funding at Jefferson Lab comes primarily from the U.S. Department of Energy’s Office of Science which provides the funds for operating the accelerator and the support for setting up and running experiments including funds to fabricate experimental instrumentation. In conjunction with DOE, the National Science Foundation and other countries provide funds to support university research groups for running experiments at JLab and related experimental equipment.

Particle Physics Goes Nuclear: Detector Tests for MINERvA Experiment

Last summer, scientists tested a set of prototype detectors in Hall C that were built for the MINERvA experiment at Fermilab. MINERvA will measure how neutrinos interact with matter and study the structure of the nucleus and its building blocks, protons and neutrons.

Every second, 100 billion neutrinos from the sun pass through your thumbnail. Despite the ubiquitousness of these tiny particles, very little is known about them. An experiment set to start at Fermilab in 2009 aims to change that. Last summer, scientists tested a set of prototype detectors in JLab’s Hall C that were built for the Fermilab experiment.

Neutrinos are born of the process that lights up stars. Deep in the sun, protons in the sun's vast store of hydrogen atoms are squished together to make helium. Each time this happens, two neutrinos pop out and cruise through the sun and into the wide universe. In fact, about 100 billion neutrinos from the sun stream through each square centimeter on Earth every second.

Neutrinos are all around us, but they're very difficult to study. The average neutrino will pass through matter with no hesitation. Very rarely, however, a neutrino may pass close enough to the nucleus of an atom to interact with it, creating a signature that physicists can study. These signatures are so rare that there aren't enough to put together a good description of how neutrinos from the sun interact with matter. So rather than rely on the sun, scientists working on the Main Injector Neutrino ExpeRiment v-A, or MINERvA, will study how machine-made neutrinos interact with the nucleus of the atom.

M. Eric Christy, a JLab User and Hampton University professor (left), pauses in Hall C with Hall Leader Stephen Wood. The Hall C Short Orbit Spectrometer was used to test the prototype of a detector that will be used for an experiment to run at Fermilab.

M. Eric Christy, a JLab User and Hampton University professor, is working on the project. He says the experiments at Fermilab will brun similarly to those at Jefferson Lab, where a beam of electrons is hurtled into the nuclei of atoms to study the structure of protons and neutrons. Sophisticated detectors will record information about the particles that emerge from these collisions. Instead of electrons, for the MINERvA experiment, a beam of neutrinos will be directed at various nuclei.

By comparing how neutrinos and the better-understood electrons interact with the nucleus, physicists may garner new information about the mysterious neutrino and perhaps even more insights into the nucleus, as well.

"My interest is mainly in trying to understand these same quantities that we do here with a different interaction," Christy says.

Christy and his colleagues recently built and tested a prototype of one of the types of detectors, a scintillator array, that will be installed in MINERvA. The test run at JLab was actually the result of a bit of serendipity. It turned out that the Short Orbit Spectrometer wasn't needed in the last experiment run in Hall C before the accelerator maintenance period. Christy, who was working on one of the Hall C experiments at the time, jumped at the rare chance to take data for two completely separate experiments at once. He and his colleagues outfitted the SOS with prototypes of the MINERvA detectors.

"We had this nice spectrometer with a set of tracking and trigger detectors and electronics already set up. So all we needed to do is stick the detectors in the spectrometer. This gave us data with fairly low effort that we could get almost immediately," he explains.

Fiber-optic cables extend from the triangular plastic scintillators. The overlapping triangular scintillator design allows scientists to get better information on the position of charged particles that stream through the detector plane and to better measure the particles’ energies.

The full-size MINERvA scintillator assemblies will consist of 196 planes of scintillator material, each plane measuring about two meters on the side and about 4 centimeters thick. A plane will contain 127 triangular strips of plastic scintillator material. At the center of each triangular strip is a fiber-optic cable. During the experiment, as a particle strikes a scintillator, it will produce light inside the scintillator material. The light is collected by the fiber-optic cable and is sent into a photomultiplier tube, which converts the light into an electronic signal.

The prototype detectors used in the recent test at JLab consisted of three planes, each outfitted with 27 triangular scintillator strips. Of those, 12 scintillators in the center of the block were connected to a photomultiplier tube. The prototype was built by Hampton University and The College of William & Mary. Christy and his colleague Jeff Nelson at W&M led the effort.

These detectors were installed in Hall C's Short Orbit Spectrometer, which was moved so that it would only be exposed to particles that were knocked out of the target backwards to the incoming electron beam. Particles coming out of the target at these angles are mostly pions, which are one of the types of particles that Christy and his colleagues expect to get from the neutrino-nucleus collisions in MINERvA. "About all you get off the target at these backward angles are pions; and that's fine, because we were interested in the response of our detector to pions." He adds.

The test had two goals: To measure how well the detector tracks particles expected from the neutrino-nucleus collisions and to provide data for testing the procedures that will later be used to interpret data from MINERvA's complicated detector design, the overlapping triangle scintillators.

"We got tens of millions of events in 10 days of running at the end, when we really got to focus on this experiment. As we analyze the data from these tests, we'll learn a lot about the efficiency of the detectors," Christy comments. "It really gives us a jump start on learning how to analyze data for the later test runs."

Christy says graduate students are currently analyzing the data collected in the run. The next detector test is planned for a full-scale set of MINERvA detectors at Fermilab next winter. In the meantime, he's looking forward to the data he's expecting from MINERvA. "It's complementary to the sort of things that we're doing here," he says.

He hopes to use the data from the MINERvA experiment to study the structure of protons and neutrons. In particular, it may be possible to determine the contributions of the permanent resident "valence" quarks in the proton from the "sea" quarks – those that visit from time to time.

SURA Deeds Land for Major Jefferson Lab Upgrade

Land needed for the $310 million upgrade of Jefferson Lab was deeded to the U.S. Department of Energy on Oct. 5.

Key Jefferson Lab, SURA and Department of Energy Site Office leaders visited the site where Hall D will be constructed – to mark the land transfer for the new experimental hall – from SURA to the DOE. Event participants included (l. to r.) Elton Smith, Hall D staff scientist; Roy Holt, chair of JLab’s Program Advisory Committee; Allison Lung, 12 GeV deputy project manager; Jim Turi, manager of JLab’s DOE Site Office; Jerry P. Draayer, SURA president & CEO; Christoph Leemann, JLab director; Anthony Thomas, JLab chief scientist; and Joe May, DOE Accelerator Operations & Projects program manager at JLab.

Jefferson Lab, one of the national research facilities funded by DOE's Office of Science, plans to double the energy of its electron beam accelerator (from 6 GeV to 12 GeV), enhance the capabilities in the three existing experimental halls (Hall A, Hall B, Hall C), and construct a new experimental hall (Hall D). But before going forward with the upgrade, the DOE first needed to acquire 7 acres adjacent to its existing 162-acre parcel.

DOE took ownership of the additional land from the Southeastern Universities Research Association. SURA is the majority owner of Jefferson Science Associates, LLC, the management and operating contractor of Jefferson Lab for DOE.

"When the City of Newport News deeded to SURA a 44-acre plot at the beginning of construction of the research laboratory in the 1980s, few would have imagined the growth of this world-class facility and the world-class science it has accomplished," said Jerry P. Draayer, SURA President & CEO. "SURA is honored to return a portion of that land now for the construction of Hall D, from which we’ll see an even greater return on our investment in science and education."

The city’s contribution also included the primary support for SURA to construct the Residence Facility, which has been used over the past decade to house thousands of researchers who have conducted experiments at Jefferson Lab.

SURA was originally awarded the contract to design the laboratory in 1983 and operated the Lab following its completion until Jefferson Science Associates was awarded the management and operations contract in April 2006. (Information courtesy of SURA news release.)

JLab Science, Math Outreach Program Needs Your Help

BEAMS – Becoming Enthusiastic About Math and Science – Jefferson Lab's long-running math and science enrichment program needs volunteers to assist with classroom-setting, student activities conducted at the Lab during normal business hours.

BEAMS supports Newport News inner-city public school students as they progress from sixth through eighth grade. Nearly 1,500 students and their teachers visit JLab between two and five days each school year to participate in science and math activities conducted by JLab scientists, engineers, technicians and administrators. Volunteers spend about 75 minutes in a BEAMS classroom (VARC 72A & 72B), either leading an activity or assisting the students as they carry out an activity.

The next round of BEAMS visits begin in February. Usually two classes of students attend at a time and participate in two to four separate activities during each day-long visit. Volunteers lead or assist with the following activities:

• Go-Far Cars: Determine how the height of an inclined ramp (potential energy) impacts the distance a model car travels.
• Hot Stuff: Study how heat (energy) transfer works and test materials for their heat absorption or reflecting capabilities.
• Ultra-Violet Detectives: Learn about ultra-violet light and make your own UV detector key chain.
• Is it Getting Hot in Here?: Learn how to measure temperature changes and build a thermometer.
• Hurricanes: Learn how hurricane strength is measured and use longitude and latitude readings to track a storm's path on a grid map.
• Cold Stuff: Study how heat (energy) transfer works and test materials for their insulation capabilities.
• Solar System: Learn about the solar system and build a scale model of the solar system.

"JLab staff, students and users are critical to the success of all of the Lab's science education programs, especially BEAMS," says Christine Wheeler, Science Education administrator. "Our BEAMS volunteers have been exposing young students to the applications, importance, and excitement of mathematics and scientific principles for more than 16 years. Students get to learn about you and your job and you get to have fun working with lots of smiling faces. Everybody wins!"

"We'd love to have you join us: for the first time, the hundredth time, or for the first time in a long time," she adds.

"Want to help, but not sure how? That's what we're here for," Wheeler explains. "Science Education staff will provide the training you need. If you want to observe a classroom activity to learn more, we can schedule that."

For additional information, contact Wheeler at ext. 7560 or email wheelerc@jlab.org.