Working groups and group leaders
Working Group 1:
Karl Krushelnick (Lead, Univ. of Michigan)
Anthony Gonsalves (Co-Lead, LBNL)
Dmitri Kaganovich (Co-Lead, NRL)
The laser plasma acceleration group will focus its work on the acceleration of electrons using laser-driven plasma based structures. In recent years, laser accelerators have demonstrated that intense electron beams with percent level energy spread, and normalized emittance on the order of 1 mm-mrad can be produced at the 1 GeV level. At the present time experiments are under way to increase the beam energy beyond 1 GeV and to increase the repetition rate.
The working group will look at issues associated with the acceleration of electrons beyond the 1 GeV level while continuing to improve emittance and energy spread, with the secondary aim of developing a roadmap for the community to reach beam energies on the TeV-scale. A challenge of such magnitude will have to engage the entire international community of accelerator, laser-plasma and laser physicists. Methods to improve efficiency, average current, and reliability of laser-plasma accelerators, and to develop the required diagnostic and simulation capabilities, will be fundamental components of this discussion.
The structure of the working group sessions will be to first have an oral session that includes opening invited talks from major experimental groups summarizing latest results, status and plans. These will be augmented with a limited number of additional oral presentations selected from submitted abstracts, and short student talks. Most remaining submitted work will be presented in poster sessions so that the group can focus on workshop-style discussions of the major laser-plasma accelerator issues. The group will organize itself to identify the key questions and address them through a combination of sub-group and whole-group discussions.
Examples of key questions are:
(1) Linear, Quasi-linear, Bubble? Is there a clear "best" intensity regime? Will we use different regimes for different applications?
(2) Acceleration and self-injection during guiding? External injection into a guiding structure?
(3) Injection: In quasi-linear or linear regime, what seems to be the best method of injection?
(4) Staging: How do we couple in laser energy in consecutive stages? Avoiding self-trapping in consecutive stages. What is the optimum stage design or will consecutive stages be different?
(5) Stability: Will external injection be required for the stability and beam quality required for most applications
(6) Diagnostics: What diagnostics are required - both during and after interaction?
(7) Simulations: Do we have the necessary simulations to help the designs?
(8) Scaling up lasers: new concepts? What is a possible R&D path for laser development in near, medium and long term?
Participants of the working group will be encouraged to come prepared to address a list of outstanding questions that will initially be provided by the working group conveners with input from all participants. Emphasis will be on interactive, creative work during the workshop.
Working Group 2: Computation
Peter Stolz (Lead, Tech-X Corp.)
Frank Tsung (Co-Lead, UCLA)
In the past few years there have been great advances in advanced accelerators, and simulations have played an important role in helping to understand and to optimize current experiments, as well as to design future ones. With the recent arrival of the 100 teraflop Franklin computer at NERSC and the emergence of several promising technologies such as simulation on multicore processors and graphics processing units, the next few years are filled with promises and challenges for the computational accelerator community.
The goals of the computational working group (WG2) of the 13th Advanced Concepts Workshop are to share results from recent simulations and to discuss new algorithms which: (i) add realism to current simulations and facilitate quantitative comparison between simulations and experiments, (ii) are tailored for future hardware such as multicore CPU's or GPU's, and (iii) facilitate longer timescale calculations through the use of reduced models.
This working group will feature sessions held jointly with the other working groups and focused on physics issues related to laser-driven and beam-driven plasma wakefield acceleration, high energy density physics, high-gradient structures and breakdown, and high-brightness electron guns. In addition, it will also feature sessions focused on computational issues such as: new algorithms, programming strategies for new hardware, benchmarking of codes, and new techniques in visualization.
Working Group 3: High gradient & EM structure based accelerators
Vyacheslav P. Yakovlev (Lead, FNAL)
Evgenya I. Smirnova (Co-Lead, LANL)
WG3 talks, (some withheld)
The purpose of this Working Group is to survey technologies for high-gradient electromagnetic structures. We need to discuss past and ongoing research efforts in high gradient acceleration and high power generation, and identify the highest practical accelerating gradient and establish a working accelerator frequency for a multi-TeV linear collider. While the primary application for these developments is a technology for a multi-TeV linear collider, broader benefits are foreseen.
For future collider applications gradients of 100 MV/m and higher are desired. However, for most nowadays structures even relatively simple laws, such as the scaling of gradient with frequency, are not known or understood well. We will try to advance the development of a systematic R&D program which addresses the issues of high gradient accelerating structures and components, high power sources, and understanding the breakdown phenomena.
The charge of the Working Group is five-fold:
1. Survey the state-of-the-art electromagnetic structures to include:
a. superconducting structures;
b. room-temperature copper structures;
c. dielectric-loaded slow-wave structures.
2. Survey the high-power components (such as pulse compressors, phase shifters, etc.).
3. Survey the state-of-the-art high power sources and their applicability for high-gradient
collider applications. 4. Discuss current developments in understanding of the rf breakdown phenomenon (frequency scaling, materials, geometric issues, etc.).
5. Discuss other (different from rf breakdown) limitations of the acceleration gradient for room-temperature and superconducting structures (pulse heating, quench, thermal breakdown, etc.).
Working Group 4: HEDP & exotic accelerator schemes
Tomas Plettner (Lead, Stanford Univ.)
Manuel Hegelich (Co-Lead, LANL)
The research and development efforts covered by this working group encompass a fairly wide range of "unconventional" acceleration schemes that can be grouped into two distinct categories:
1) Visible and infra-red laser acceleration schemes, where the laser drives an accelerator structure of some form. Those include, for example, photonic-structure architectures, semi-free-space optical geometries, or magnetic-structure vacuum laser acceleration configurations such as IFEL or LACARA. Other electron acceleration schemes with visible or infrared laser beams fall into this group. (Far infrared, millimeter-wave or RF acceleration schemes will be discussed in WG3).
2) Short pulse laser-driven ion acceleration schemes like Target Normal Sheath Acceleration (TNSA), Break-Out Afterburner (BOA), Radiation Pressure Acceleration (RPA) or Phase-Stable Acceleration (PSA), etc., where the laser does not drive an accelerator structure but directly accelerates ions from gas or solid targets to multi-MeV to GeV energies.
Our mission is to review recent progress in these R&D disciplines, to identify application opportunities and limitations that are specific to each technology, and finally, to define near-term and long term R&D objectives that are necessary to materialize these.
For group (1) the activities include:
i) review significant experimental advances that occurred since AAC2006
ii) review important theoretical advances and new proposed concepts
iii) identify the present limitations and advantages for these technologies, and explore an R&D pathway for a future high-energy collider based on these technology iv) identify other applications for these technologies
For group 2) the relevant questions are:
i) What beam parameters have been reached experimentally and in simulations?
ii) What driver and target technology is necessary to confirm the simulations experimentally and how can it be realized?
iii) Can GeV schemes possibly be staged to reach high-energy physics (TeV) regimes in an economically feasible fashion?
iv) How do those parameters match possible applications like medical, fast ignition, high-energy colliders, etc? Where are technology gaps that need to be addressed?
Working Group 5: Electron beam driven plasma accelerators
Mark Hogan (Lead, SLAC)
Manoel Conde (Co-Lead, ANL)
This working group will identify and explore ideas for creating a plasma wakefield accelerator based linear collider. After a brief review of the current state of experiments, theory and simulations, the working group will identify a candidate format to reach a TeV CM energy using (1) a single stage plasma afterburner at the end of a conventional linac and (2) a staged plasma wakefield accelerator linear collider (single or multi-bunch). The working group sessions will examine specific issues in detail and recommend solutions or areas requiring further investigation.
Possible session topics include:
1. Energy deposition and removal with multi-MW beam power and finite efficiencies and corresponding implications for minimum bunch separation
2. Beam loading: optimum pulse format and beam shaping for high transformer ratio and efficiencies
3. Staging: beam combination & separation at early (25/25) and late (25/475)
4. Positron acceleration: electron or positron drivers, linear or non-linear regime, loading, hollow-channels
5. Final Focus & IP issues: energy spread, collimation and plasma lenses
6. Emittance preservation: collisions, scattering, aberrations
7. Polarization: production, measurement and preservation
Working Group 6: Beam & radiation generation, monitoring & control
Daniel Gordon (Lead, NRL)
John Power (Co-Lead, ANL)
Advanced accelerator concepts often require injection sources with exceptional characteristics such as ultrashort bunch length, low emittance, high charge, and precise control over timing. Working group 6 will focus on the generation of such beams, as well as techniques for manipulating their phase space distributions, diagnosing their properties, and synchronizing them to external systems. Radiation generation will also be discussed, particularly as it pertains to beam diagnostics.
The class of sources considered is broadly defined to include: photoinjectors, field-emitters, thermionic cathode, plasma-based generation, phase space manipulation techniques (such as 3D ellipsoidal distributions and emittance exchange), innovative bunch train production methods, etc. We will discuss both the practical and fundamental (e.g. space charge) issues related to high quality bunch generation from both the theoretical and experimental view points.
We consider recent developments in beam monitoring (diagnostics) and control techniques that advance the state of the art. Similar to sources, we define advances broadly to include: high-resolution measurements of the beam's phase space, non-disruptive diagnostics, innovative ideas, laser-based and rf-based techniques, synchronization techniques, etc.
Throughout the workshop, we will schedule discussion sessions in order to make a general assessment for sources, diagnostics, and control techniques regarding: (i) the state of the art in what is currently available and (ii) the future needs of the advanced accelerating community. Results of this assessment will be presented during the close out session of the workshop and in the written working group summary.