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The 12 GeV CEBAF Upgrade is a $338 million, multi-year project to triple CEBAF's original operational energy for investigating the quark structure of the atom's nucleus. The majority of the upgrade is complete and will be finishing up in 2017. Scientists have been rigorously commissioning the experimental equipment to prepare for a new era of nuclear physics experiments. These activities have already led to the first scientific result, which comes from the Gluonic Excitations Experiment. GlueX conducts studies of the strong force, which glues matter together, through searches for hybrid mesons. According to Curtis Meyer, a professor of physics at Carnegie Mellon University and spokesperson for the GlueX experiment at Jefferson Lab, these hybrid mesons are built of the same stuff as ordinary protons and neutrons, which are quarks bound together by the "glue" of the strong force. But unlike ordinary mesons, the glue in hybrid mesons behaves differently. "The basic idea is that a meson is a quark and antiquark bound together, and our understanding is that the glue holds those together. And that glue manifests itself as a field between the quarks. A hybrid meson is one with that strong gluonic field being excited," Meyer explains. He says that producing these hybrid mesons allows nuclear physicists to study particles in which the strong gluonic field is contributing directly to their properties. The hybrid mesons may ultimately provide a window into how subatomic particles are built by the strong force, as well as "quark confinement" - why no quark has ever been found alone. "We hope to show that this "excited" gluonic field is an important constituent of matter. That's something that has not been observed in anything that we've seen so far. So, in some sense, it's a new type of hadronic matter that has not been observed," he says. In this first result, data were collected over a two-week period following equipment commissioning in the spring of 2016. The experiment produced two ordinary mesons called the neutral pion and the eta, and the production mechanisms of these two particles were carefully studied. The experiment takes advantage of the full-energy, 12 GeV electron beam produced by the CEBAF accelerator and delivered into the new Experimental Hall D complex. There, the 12 GeV beam is converted into a first-of-its-kind 9 GeV photon beam. "The photons go through our liquid hydrogen target. Some of them will interact with a proton in that target, something is exchanged between the photon and the proton, and something is kicked out - a meson," Meyer explains. "This publication looked at some of the simplest mesons you could kick out. But it's the same, basic production mechanism that most of our reactions will follow." The result was published as a Rapid Communication in the April issue of Physical Review C. It demonstrated that the linear polarization of the photon beam provides important information by ruling out possible meson production mechanisms. "It's not so much that the particles we created were interesting, but how they were produced: Learning what reactions were important in making them," Meyer says. The next step for the collaboration is further analysis of data already collected and preparations for the next experimental run in the fall. "I'm sure that we've produced hybrid mesons already, we just don't have enough data to start looking for them yet," Meyer says. "There are a number of steps that we're going through in terms of understanding the detector and our analysis. We're doing the groundwork now, so that we'll have confidence that we understand things well enough that we can validate results we'll be getting in the future." "This new experimental facility - Hall D - was built by dedicated efforts of the Jefferson Lab staff and the GlueX collaboration," says Eugene Chudakov, Hall D group leader. "It is nice to see that all of the equipment, including complex particle detectors, is operating as planned, and the exciting scientific program has successfully begun." The 12 GeV CEBAF Upgrade project is in its last phase of work and is scheduled for completion in September. Other major experimental thrusts for the upgraded CEBAF include research that will enable the first snapshots of the 3D structure of protons and neutrons, detailed explorations of the internal dynamics and quark-gluon structure of nuclei, and tests of fundamental theories of matter. Explore further: Jefferson Lab accomplishes critical milestones toward completion of 12 GeV upgrade More information: H. Al Ghoul et al, Measurement of the beam asymmetryforandphotoproduction on the proton atGeV, Physical Review C (2017). DOI: 10.1103/PhysRevC.95.042201


Simmons-Duffin D.,Jefferson Lab
Journal of High Energy Physics | Year: 2014

We introduce a method for computing conformal blocks of operators in arbitrary Lorentz representations in any spacetime dimension, making it possible to apply bootstrap techniques to operators with spin. The key idea is to implement the shadow formalism of Ferrara, Gatto, Grillo, and Parisi in a setting where conformal invariance is manifest. Conformal blocks in d-dimensions can be expressed as integrals over the projective null-cone in the embedding space Rd+1,1. Taking care with their analytic structure, these integrals can be evaluated in great generality, reducing the computation of conformal blocks to a bookkeeping exercise. To facilitate calculations in four-dimensional CFTs, we introduce techniques for writing down conformally-invariant correlators using auxiliary twistor variables, and demonstrate their use in some simple examples. © The Authors.


Rudelius T.,Jefferson Lab
Journal of Cosmology and Astroparticle Physics | Year: 2015

We study the diameters of axion moduli spaces, focusing primarily on type IIB compactifications on Calabi-Yau three-folds. In this case, we derive a stringent bound on the diameter in the large volume region of parameter space for Calabi-Yaus with simplicial Kähler cone. This bound can be violated by Calabi-Yaus with non-simplicial Kähler cones, but additional contributions are introduced to the effective action which can restrict the field range accessible to the axions. We perform a statistical analysis of simulated moduli spaces, finding in all cases that these additional contributions restrict the diameter so that these moduli spaces are no more likely to yield successful inflation than those with simplicial Kähler cone or with far fewer axions. Further heuristic arguments for axions in other corners of the duality web suggest that the difficulty observed in [1] of finding an axion decay constant parametrically larger than Mp applies not only to individual axions, but to the diagonals of axion moduli space as well. This observation is shown to follow from the weak gravity conjecture of [2], so it likely applies not only to axions in string theory, but also to axions in any consistent theory of quantum gravity. © 2015, IOP. All rights reserved.


Rudelius T.,Jefferson Lab
Journal of Cosmology and Astroparticle Physics | Year: 2015

We derive constraints facing models of axion inflation based on decay constant alignment from a string-theoretic and quantum gravitational perspective. In particular, we investigate the prospects for alignment and 'anti-alignment' of C4 axion decay constants in type IIB string theory, deriving a strict no-go result in the latter case. We discuss the relationship of axion decay constants to the weak gravity conjecture and demonstrate agreement between our string-theoretic constraints and those coming from the 'generalized' weak gravity conjecture. Finally, we consider a particular model of decay constant alignment in which the potential of C4 axions in type IIB compactifications on a Calabi-Yau three-fold is dominated by contributions from D7-branes, pointing out that this model evades some of the challenges derived earlier in our paper but is highly constrained by other geometric considerations.


Briceno R.A.,Jefferson Lab
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

The quantization condition for two-particle systems with an arbitrary number of two-body open coupled channels, spin, momentum, and masses in a finite volume with either periodic or twisted boundary conditions is presented. Although emphasis is placed in cubic volumes, the result holds for asymmetric volumes. The result is relativistic, holds for all momenta below the three- and four-particle thresholds, and is exact up to exponential volume corrections that are governed by L/r, where L is the spatial extent of the volume and r is the range of the interactions between the particles. For hadronic systems the range of the interaction is set by the inverse of the pion mass, mπ, and as a result the formalism presented is suitable for mπL1. The condition presented is in agreement with all previous studies of two-body systems in a finite volume. Implications of the formalism for the studies of multichannel baryon-baryon systems are discussed. © 2014 American Physical Society.


Grant
Agency: Department of Energy | Branch: | Program: STTR | Phase: Phase I | Award Amount: 150.00K | Year: 2015

Most radioisotopes are produced by nuclear reactors or positive ion accelerators, which are expensive to construct and to operate. Photonuclear reactions using bremsstrahlung photon beams from less-expensive electron linacs can generate isotopes of critical interest, but much of the beam energy in a conventional electron linac is dumped, making unwanted radioactivation. GENERAL STATEMENT OF HOW THIS PROBLEM OR SITUATION IS BEING ADDRESSED. A Superconducting Radio Frequency (SRF) Energy Recovery Linac (ERL) is a path to a more diverse and reliable domestic supply of short-lived, high-value, high-demand isotopes at a cost lower than that of isotopes produced by reactors or positive-ion accelerators. A Jefferson Lab approach to this problem involves a thin photon production target, which allows the electron beam to recirculate through rf cavities so the beam energy can be recovered while the spent electrons are extracted and absorbed at a low enough energy to minimize unwanted radioactivation. MuPlus, in partnership with Jefferson Lab and Niowave, proposes to extend this ERL technology to the commercial world of radioisotope production for medical diagnostics and therapy. WHAT WILL BE DONE IN PHASE I. MuPlus will use our own codes, MuSim for MCNP6 and G4beamline for GEANT4, and others to optimize beam parameters of an ERL-based radioisotope production facility. Components include the radiator with photon and electron beam parameters, absorbers for scattered electrons, target cooling, beam-radiator interactions, radiator optimization, thermal distributions and power handling, management of energy spread and angular acceptance for the recirculation arc, and optimization of isotope production versus energy recovery requirements. Particular isotopes to be first examples of this new technology will be chosen based on market analysis for an engineering design to be done in Phase II. COMMERCIAL APPLICATIONS AND OTHER BENEFITS ERLs are increasingly the technology of choice for highly demanding applications. In energy recovery, more than 90% of the beam power is recycled and not deposited in a beam dump. Our first application will be for nuclear medicine, which has humanitarian and commercial benefits. Of the 30 million people who are hospitalized each year in the United States, a third are treated with nuclear medicine. More than 10 million nuclear-medicine procedures are performed on patients and more than 100 million nuclear- medicine tests are performed each year in the United States alone. There are nearly one hundred radioisotopes whose beta and/or gamma radiation is used in diagnosis, therapy, or investigations in nuclear medicine. We are interested in the commonly used isotopes as well as developing techniques for isotopes for new applications, both medical and industrial. KEY WORDS: energy-recovery, superconducting RF, linac, commercial, radioisotope, production SUMMARY FOR MEMBERS OF CONGRESS: An energy recovery technique for superconducting linear accelerators developed at Jefferson Lab is being applied to the production of radioisotopes used for medical diagnostics and therapy. This Energy Recovery Linac will reduce operating costs for isotope production facilities by being more efficient and by producing fewer unwanted radiation byproducts.


Grant
Agency: Department of Energy | Branch: | Program: STTR | Phase: Phase I | Award Amount: 150.00K | Year: 2015

Thomas Jefferson National Accelerator Facility (JLab) uses low efficiency klystrons in the CEBAF machine. In the older portion they operate at 30% efficiency with a tube mean time between failure (MTBF) of five to six years. A highly efficient replacement source (>55-60%) must provide a high degree of backwards compatibility, both in size and voltage requirements, to allow its use as a replacement for the klystron (model VKL7811) presently used at Thomas Jefferson Laboratory, while providing significant energy savings. GENERAL STATEMENT OF HOW THIS PROBLEM OR SITUATION IS BEING ADDRESSED. We will develop a highly reliable, highly efficient RF source based upon a novel injection- locked amplitude-modulated (AM) magnetron with a lower total cost of ownership, operating above 80% efficiency with an MTBF of six to seven years. The design of the RF source will be based upon a single injection-locked magnetron system at 8 kW capable of operating up to 13 kW, using the magnetrons magnetic field to achieve the AM which is required for backwards compatibility to compensate for microphonics and beam loads. WHAT WILL BE DONE IN PHASE I. The novel injection-locked 1497 MHz 8 kW AM magnetron will be designed during Phase I. The low-level RF system, required to maintain injection locking during the AM of the magnetron with the magnetic field controlled, will also be designed. A prototype magnetic assembly for the varying magnetic field will be built and tested to assure operation at the modulation frequencies of the microphonics. COMMERCIAL APPLICATIONS AND OTHER BENEFITS Future applications of the novel injection-locked AM magnetron include, commercial magnetron heating applications for more precise material processing in the chemical industry such as microwave driven particle synthesis. Phased array radar systems will also benefit from the injection locked AM magnetron, whether in ground penetrating radar or microwave power transmission. And, of course, it has accelerator applications worldwide. KEY WORDS: magnetron, injection-locking, amplitude-modulation SUMMARY FOR MEMBERS OF CONGRESS: A backward compatible highly efficient microwave source will be developed to replace the low efficiency, costly klystrons currently used at JLAB. The novel injection-locked AM magnetron has commercial applications in accelerator applications, microwave heating in the chemical industry and applications in phased array radar systems.


Grant
Agency: Department of Energy | Branch: | Program: STTR | Phase: Phase II | Award Amount: 1.00M | Year: 2013

Considerable progress has been made in developing promising subsystems for muon beam cooling channels to provide the great reduction of emittances required for an Energy-Frontier Muon Collider; but an end-to-end design is lacking. Meanwhile, the recent discovery of a Higgs-like boson has created interest in the high-energy physics community for a Higgs Factory to investigate whether its properties verify Standard Model predictions or represent new physics. This project is developing principles and tools to match beam phase space distributions between and within muon beam cooling subsystems that may have different characteristics. The Helical Cooling Channel (HCC), with combined helical dipole and solenoid fields, allows a general analytic approach to guide designs of transitions from one set of cooling channel parameters to another. These principles and tools are being applied to design complete cooling channels for a Higgs Factory and an Energy Frontier Muon Collider. Transverse and longitudinal phase space matching techniques were developed in Phase I and applied to previously designed segments that presented the greatest matching challenge. Simulation results demonstrated even better performance in half the length of the original! Theoretical considerations of space charge effects started. Improvements in the G4beamline simulation program and its use on FermiGrid facilitated the computations and associated successes. Studies of early segments in a particular promising cooling channel indicate a need to optimize its design further in Phase II. Armed with the demonstrated matching techniques and further enabled by the computing power of NERSC, where G4beamline will be installed, the entire cooling channel will be revisited and designed, considering space charge effects. Analytic fields used in the Phase I design work will be replaced by realistic fields generated by coil elements. Commercial Applications and Other Benefits: Our ulterior motive is to enable the DOE to hire US companies to construct Muon Colliders, the next multi-billion dollar scientific instruments to investigate the smallest things in the universe. The cold muon beams developed in the project also have important potential applications for homeland security, medicine, and other basic and applied scientific research.


Grant
Agency: Department of Energy | Branch: | Program: STTR | Phase: Phase II | Award Amount: 999.20K | Year: 2013

Current state-of-the-art SRF accelerating cavities require the use of many complex and expensive techniques throughout their fabrication/performance cycle. This project will utilize a novel Additive Manufacturing (AM) process to produce nearly monolithic SRF niobium cavities of arbitrary shape with features such as optimized wall thickness and/or integrated stiffeners, greatly reducing the cost and technical variability of conventional cavity construction. EBM AM niobium material samples have been successfully fabricated and characterized in Phase I. Conceptual designs exploiting EBM AM have been created. Hardware improvements to AM platform have been studied and proposed. Hardware upgrades to the AM platform will be carried out and characterized in Phase II. A prototype EBM Cavity suitable for high power testing will be fully cost-performance optimized through multi-physics simulationsto take advantage of AM technologyand fabricated. High power testing will be carried out at JLab to characterize EBM Cavity performance. Commercial Applications and Other Benefits: The AM manufacturing approach developed in this project can be applied to SRF cavities and other SRF components used in SRF accelerators in: energy recovery linacs (ERLs), linear colliders (ILC), neutrino factories, spallation neutron sources, and rare isotope accelerators used in medicine, as well as imaging/analysis applications to homeland security.


Grant
Agency: Department of Energy | Branch: | Program: STTR | Phase: Phase II | Award Amount: 1.00M | Year: 2016

Thomas Jefferson National Accelerator Facility (JLab) uses low efficiency klystrons in the CEBAF machine. In the older portion they operate at 30% efficiency with a tube mean time between failure (MTBF) of five to six years. A highly efficient source (>55-60%) must provide a high degree of backwards compatibility, both in size and voltage requirements, to replace the klystron presently used at JLab, while providing energy savings. GENERAL STATEMENT OF HOW THIS PROBLEM OR SITUATION IS BEING ADDRESSED. We will develop a highly reliable, highly efficient RF source based upon a novel injection-locked amplitude-modulated (AM) magnetron with a lower total cost of ownership, >80% efficiency, and MTBF of six to seven years. The design of the RF source will be based upon a single injection-locked magnetron system at 8 kW capable of operating up to 13 kW, using the magnetron magnetic field to achieve the AM required for backwards compatibility to compensate for microphonics and beam loads. WHAT WAS DONE IN PHASE I. A novel injection-locked 1497 MHz 8 kW AM magnetron with a trim magnetic coil was designed and its operation numerically simulated during Phase I. The low-level RF system to control the trim field and magnetron anode voltage was designed and modeled for operation at the modulation frequencies of the microphonics. A plan for constructing a prototype magnetron and control system was developed. WHAT IS PLANNED FOR THE PHASE II PROJECT Prototype 1497 magnetrons with a trim magnetic coil will be built. A system to control the magnetron will be built and tested to vary the trim coil current and the anode voltage as required to suppress beam emittance growth due to microphonics and changing beam loads. COMMERCIAL APPLICATIONS AND OTHER BENEFITS The immediate outcome of this project is a high efficiency, low cost replacement for the CEBAF accelerator klystrons at JLab with an energy savings payback time of 5 years. Future applications of the novel injection-locked AM magnetron include, commercial magnetron heating applications for more precise material processing in the chemical industry such as microwave driven particle synthesis. Phased array radar systems will also benefit from the injection locked AM magnetron in ground penetrating radar and microwave power transmission.

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