Enhancing Accelerator Science and its Impact on Other Sciences: the Role
of Universities

M. Berz~1~, H. Blosser1, J. Bisognano2, R. Davidson3, K. Gelbke1, S.
Gruner4, C. Joshi5,

J. Kirz6, C. Pellegrini5, J. Rush7, M. Tigner4, R. York1

1\. Michigan State Univ., 2. U. Wisconsin, 3. Princeton U., 4. Cornell
U., 5. Univ. of California Los Angeles, 6. SUNY Stony Brook, 7. NIST

### Abstract

The science of particle beams is rich and challenging. Particle beams
are many body systems with non-isotropic, non-thermal distribution,
exhibiting many collective instabilities and self-organizing phenomena
when interacting with electromagnetic fields and plasmas. Studies of
these transitions from one non-equilibrium state to another, has
progressed rapidly in recent years, but much remains to be done. The
impact of particle beam, or accelerator science is extremely broad.
Indeed, advances in many branches of science such as the materials
sciences, nuclear science, elementary particle science, to name but a
few, are paced by advances in accelerator science and technology. Much
of the work in these areas has come to reside in the DoE National
Laboratories. There is growing realization that universities have a
unique and important role to play and that enhancing the university role
will result in significant advances in accelerator science and
development and in their broad impact on other sciences. The needs and
opportunities are discussed herein.

## Introduction

### Beam Science

The study of particle beams interacting with electromagnetic fields and
plasmas is an exciting part of physics. Beam optics, the transport of
particles using electromagnetic lenses and bending fields is well
developed, and is continuing to evolve to include more complex
non--linear dynamical effects, like the long term stability of particle
orbits over billions of revolutions

The study of high intensity effects, such as collective instabilities
and self organization phenomena, has already achieved important results.
As we move toward the study and utilization of beams with higher phase
space density, and smaller dimensions of the particle bunches for the
next generations of colliders, synchrotron radiation sources, and
free-electron lasers, new phenomena continue to appear that will need
further studies.

The interaction of laser and plasmas provide a rich new range of
possibilities and exciting physics. The interaction of lasers and
plasmas with particle beams provides an entirely new paradigm for
accelerating and focusing dense relativistic beams at unprecedented high
gradients using collective fields. Learning to control these phenomena
could lead to table-top, GeV class, accelerators in the near term, and
to a much more compact high energy machine at the energy frontier in the
future.

Progress in these fields may also make it possible, in the not too
distant future, to simulate certain aspects of particle and plasma
astrophysics phenomena in the laboratory by studying the behavior of co-
and counter-propagating electron and positron beams with or without
external magnetic fields. Examples of these are gamma ray bursts, pulsar
winds and acceleration mechanisms for cosmic rays. In summary, it is
clear that beam physics is a rich area of science, in which we expect
exciting breakthroughs for the foreseeable future.

### The Broader Impact

Accelerators now find essential uses with amazing breadth of purpose
from materials analysis to alteration of materials on an industrial
scale, from medical diagnosis to medical treatment, from age
determination of ancient artifacts to microanalysis of meteorites and,
of course, to the many uses where structure determination is central to
many areas of science from the molecules of life to the elementary
particles that underlie the material world \[1,2,3\]. (See Appendix 1
for an approximate enumeration of the number of the various types of
accelerators now in use.)

Historically, the application of accelerator science has led to rapid
progress in the creation of accelerators as illustrated by the famous
Livingston Chart \[4\]. As the accelerator dependent sciences advance
the needed accelerators become more sophisticated and scientifically and
technologically challenging. This leads to the need for increasing
intellectual input into accelerator science and technology. In many
cases, the frontiers of the scientific and technological activities
based on accelerator usage are set by the current capabilities of the
accelerators being used. The most obvious and well-known cases are the
various branches of nuclear and particle physics and those myriad
sciences using synchrotron radiation as a basic tool. Because of the
breadth of applications and the critical societal impact of advances in
accelerators, it is important that a systematic approach be used in
accelerator development. This approach must range from the proof of
principle and basic accelerator physics studies known as Advanced
Accelerator Research and Development to technological developments
directly relevant to accelerators and to concepts for new facilities
that will serve accelerator based sciences and technologies.

In this White Paper we give specific examples of important scientific
frontiers that will be advanced by new accelerator developments, and
some specific accelerator physics and technical areas from which these
frontier advances will derive. A listing of some of the scientific and
technical advances needed to push forward accelerator science and
technology will be found in Appendix III.

In working to improve our programs for accelerator development, it will
be essential to cultivate appropriate intellectual \[5\] and
infrastructure resources. While it is true that we will always need
accelerator physicists and other professionals to design, build and
operate these instruments, it will also be important to educate the
scientists and technologists who use the accelerators and its auxiliary
equipment to better understand their capabilities and limitations. In
this way they will be able to understand where accelerators can be
better used and improved, and where the always necessary compromises can
be made. As much of the strength of the US scientific community lies in
our universities, it follows that any scheme for improving the way in
which we develop accelerator science and technology needs to involve
universities in a fundamental way. Aside from enhancing the numbers of
minds focusing on the challenges, there are two other very important
aspects of university involvements. Many of the scientific uses of
accelerators cross the boundaries of many sciences and technologies,
making interdisciplinary efforts mandatory, both in the apprehension of
the needs and in the capabilities needed for implementation.
Universities have these breadths "in house" if we can learn how to
engage with them. Last but far from least, universities offer a natural
setting for the training of the next generations of accelerator and beam
line scientists while at the same time entraining scientific users in
the process of advancing the accelerators that they need for their
science. The present shortage of expert manpower is made painfully
evident by the many "help wanted" advertisements carried in any journal
dealing with the accelerator-based sciences. Below we attempt to suggest
some ways for enhancing university involvement in accelerator
development.

## Needed Advances in Accelerator Science, Technology and Related Apparatus

### Particle Beam Science

The science of particle beams is rich and challenging. The field of
particle beam optics, the study of the transport of particles using
electromagnetic lenses and bending fields is well developed. It is now
possible to include many effects of non-linear fields, to control and
minimize aberrations, and to include some self --field effects like
space-charge or wakefields. More work will however be needed in the
future when pushing the frontier to beams with extremely high
phase-space density or to the case of very high intensity beams where
even small losses can be very important.

In the case of storage rings there has been a large effort to study the
stability over billions of revolutions, and understand the effects of
resonances on the long-term stability of the beam. Advanced
instrumentation to measure the response of the beam to external
excitations has been developed, and the analysis tools to relate these
results to the short and long-term stability have been the subject of
intense studies. This area of research has offered and will continue to
offer very interesting interdisciplinary opportunities for joint work
with other physicists and mathematicians studying dynamical systems, and
with astronomers studying the stability of the solar system and its
constituents.

Particle beams are many body systems with a non-isotropic, non-thermal
distribution, exhibiting many collective instabilities and
self-organizing phenomena when interacting with electromagnetic fields
and plasmas. Studies of these transitions from one non-equilibrium state
to another, have progressed rapidly in recent years, but much remains to
be done. Particularly important is the question of the limits produced
by collective instabilities on the 6-dimensional phase-space density
achievable in a beam in a given configuration, and, alternatively, what
are the more favorable configurations to reach a very high phase-space
density. These limits are now partially understood in storage rings and
linear accelerators, but questions remain when one pushes the limits
toward beams with very small emittance, high peak current and short
duration bunches.

![](media/image1.jpeg){width="5.995138888888889in"
height="4.580555555555556in"}

Top: Computer generated representation of forces induced by a
high-energy electron beam as it propagates through a plasma. Bottom
(left) The beam contours without the plasma and (right) when propagated
through the plasma. The plasma in turn can tightly focus the electron
beam by partially or fully neutralizing the space charge of the beam

(Courtesy C. Joshi, UCLA)

Also important is the question of understanding self-organization
phenomena -due to the interaction of the beam with the long range
electromagnetic forces it produces- and of using them to achieve
desirable beam configurations not reachable with external control
systems. One example is the free-electron laser instability. In this
case the initial state is a beam produced by an accelerator in a
non-equilibrium state. If the beam phase space density satisfies the
conditions for the free-electron laser instability to take place while
the electron beam traverses an undulator magnet, a transition occurs.
The beam final state has a high degree of order, similar to that of a
1-dimensional crystal, with the electrons contained in slices equally
separated by a distance equal to the radiation wavelength. New
developments, like the X-ray free-electron lasers now under development
in the US and Europe, and to which universities have made essential
contributions, are only possible because we can control the
instabilities in the linac producing the electron beam, and thus
preserve a large beam phase space density, and then create the
conditions for the free-electron laser instability to develop.

The interaction of lasers and plasmas with particle beams provides an
entirely new opportunity for accelerating and focusing dense
relativistic beams at unprecedented high gradients using collective
fields. For instance, the possibility exists of synchronous acceleration
of particles using wakes, produced in a plasma by a short intense laser
pulse or by the beam itself, that have gradients in excess of 100 GeV/m
and focusing beams using effective gradients on the order 10^6^ T/m.
Learning to control these phenomena could lead to table-top, GeV class,
accelerators in the near term and to a much more compact high energy
machine at the energy frontier in the future.

Aside from acceleration and focusing, these fields can be made to
undulate beams resulting in efficient generation of radiation. The beams
can also be modulated on a sub-femtosecond scale using lasers and
plasmas. These bunchlets can be subsequently made to emit radiation in
attosecond range. The measurements of such short bunches, phase-locking
them to micro-scale accelerating structures and focusing of beams to
nanometer spot-sizes are formidable challenges at the forefront of beam
physics.

The understanding of the complex interaction of particle beams, lasers
and plasmas, and the control of non-linear and multi-particle effects
and collective instabilities in beam transport, such as the electron
cloud instability, requires extensive use of large-scale massively
parallel computing. These requirements will become even more important
in the future as we push the frontier toward beams of ever increasing
phase-space density, or more complex interactions of beams and plasmas.
The continued development of theoretical tools and large-scale
simulations will play an increasingly important role in the development
of beam physics in universities and accelerator centers.

### Particle Beam Physics and Accelerator Development

Particle accelerators have had a broad impact on many areas of science
and technology. Further advances in beam science will lead to
significantly improved capabilities that will open new opportunities for
advancements in physical and life sciences and in medical therapies.

Looking beyond the R&D for the electron-positron and hadron colliders
that are either being built or contemplated at the energy frontier
(discussed in the next section), the accelerator community is already
pursuing other novel machines such as the neutrino factory and even a
muon collider. No accelerator has ever been built using an unstable
particle such as the muon. There are a number of beam physics issues
that are unique to this concept such as \"ionization cooling\" of the
muon beam where energy loss by ionization in matter is alternated with
the re-acceleration of muons in radio-frequency cavities. In fact,
testing of novel ideas for beam cooling is a forefront beam physics
issue irrespective of the type of future machine that is contemplated.

Other beam physics issues that are of pressing concern are a deeper
understanding of: the beam-beam interaction that ultimately sets the
luminosity limit in e+-e- colliders; the propagation of higher current
beams (an order of magnitude) through cavities without instabilities;
the intra-beam scattering, and other beam dynamics issues in damping
rings; the collective effects in proton machines such as the Transverse
Mode-Coupling Instability, Resistive Wall instabilities and space-charge
tune shifts.

Other current topics in beam physics are beam dynamics in energy
recovery linacs, improved operation of polarized electron and positron
sources, efficient production of intense beams of protons, other light
ions and extremely highly stripped heavy ions using ultra-intense
lasers.

Recent progress in the development of efficient infrared lasers and
optics has fueled the possibility of building a proof of concept device
for a future  collider by colliding laser photons with relativistic
electrons. More radical ideas that utilize an ion column to wiggle the
electron beam to copiously produce -rays, albeit with a broader energy
spread, have been proposed.

The beam physics developments described above are both exciting and
essential to extend the capabilities of accelerators, but looking
further ahead new technologies must be invented to make a significant
impact, at the energy frontier on the one hand and making \"desktop\"
accelerators available for myriad applications on the other. This
presents opportunities to do forefront beam physics. We quote from the
2001 Snowmass Accelerator R&D Report from the section on Fundamental
Research in Accelerator Physics and Technology:

\"To make significant future impact, new ideas are needed not only to
accelerate but also to generate, focus, and manipulate charged
particles. Fortunately, there are many possibilities to do just that.
Over the last fifteen years a small but vigorous advanced accelerator
community has been engaged in finding alternatives to radio frequency
acceleration methods. These researchers have proposed and demonstrated
new ways of accelerating, bunching, and phasing particles. Some have
demonstrated the use of laser radiation instead of microwaves to power
plasma structures that can sustain accelerating gradients orders of
magnitude greater than those in a RF linear accelerator. Other
researchers have shown that electron and positron beams from a
conventional accelerator can power plasma structures with promising
results for developing new types of lenses for future machines and
magnet-less wigglers for next generation light sources. Many small
groups are actively pursuing this exciting new work in universities and
national laboratories.

The Advanced Accelerator R&D effort is poised to leap to the next stage.
The initial rounds of experiments demonstrating a factor of 10-100 more
accelerating gradient have been done. A new generation of tightly
bunched, high quality beam sources is under active investigation.
However, it is clear that this field needs scientists and resources if
it is to fulfill its promise. It is time to embark on large-scale
collaborations, which can leverage the intellectual contributions of the
university groups and the infrastructure of the laboratories.

These larger collaborations can address issues that require a
significant investment both in the experimental design and execution.
Large laboratories possess the infrastructure to provide high quality,
stable beams that are critical for the next round of experiments. This
is an outstanding research opportunity, especially for physicists that
expect to perform experiments at accelerator facilities in the future.

As we push the limits of acceleration to achieve high energy and the
limits of beam quality to achieve high luminosity, we must carefully
study fundamental limits and processes that are uncovered. The
transition from metallic structures to plasma acceleration introduces
many new problems and will necessarily involve a deeper understanding of
the instabilities that might appear. Higher quality beams might begin to
approach fundamental limits that have to be explored. Intense beams
interacting with each other push beyond our experience with strong field
electrodynamics. However, the key to this progress is to build a
substantial experimental foundation, which could form the basis for a
new generation of particle accelerators.\"

The authors of this White Paper concur with this assessment of the
opportunities in advanced R&D in Particle Beam Science and accelerators,
and what is needed to accomplish them.

### Elementary Particle Science

The understanding of the basic features of energy, matter, space and
time remain the focus of elementary particle physics. Elucidation of
many of the particular questions under these headings will best be done
using accelerator experiments under tightly controlled laboratory
conditions: what is the origin of mass; what is the mechanism of
electro-weak symmetry breaking; is supersymmetry a feature of our
universe; what are the dark matter and dark energy that seem to dominate
the universe; can the universe be described by four dimensions; is time
one of the fundamental dimensions; is there but one fundamental
interaction and if so at what energy is it completely unified. Answering
some of these questions will require accelerators with energies beyond
our current capabilities. Securing the needed capabilities will require
intellectual effort at a level significantly beyond current engagements.

Over the history of accelerator based science remarkable increases in
accelerator capabilities and cost effectiveness have routinely taken
place. In the last 40 years the frontier has moved from a center of mass
energy (proton collisions) of about 30 GeV to 14,000 GeV and a cost per
center of mass GeV of \$8.3M/GeV to \$0.3M/GeV. Even so the cost per
facility has reached the level of several billion dollars, taxing the
economic capacity of the world scientific enterprise severely. Not only
is the cost a challenge but the technical requirements become extremely
challenging as energies rise. This stems from the fact that the
elementary cross-sections that must be measured are inversely
proportional to the square of the energy. The practical effect of this
is that beam power required for sufficient event rates are very high,
demanding unprecedented beam brightness and efficiencies of acceleration
to be practical. Input power to accelerators now being planned are of
the order of 100 MW. To make practical a further step in accelerator
energies beyond that contemplated today will require another order of
magnitude unit cost reduction and increase in luminosity. Indeed, even
to successfully complete and exploit the proton and electron-positron
colliders being discussed today will require accelerator scientific and
technical accomplishments and cost reduction measures still under
development and needing much further attention. It may well be that the
needed advances in the future can only be achieved with radical
departures from current approaches. For example, to control radiation
effects, it may be necessary in future to utilize muons as the colliding
particles, which will present enormous challenges. This same science and
technology, if realized, can also provide pure neutrino beams of
unprecedented intensity \[6\]. In the future it may also become feasible
to provide large scale electromagnetic acceleration and confinement
based on plasma media with internal fields orders of magnitude larger
than practical today \[7\].

![](media/image2.jpeg){width="3.2909722222222224in"
height="6.2555555555555555in"}

Schematic of a muon collider scheme (courtesy Muon Collider
Collaboration)

Both hadron and electron machines continue to play important roles in
pushing the frontiers of elementary particle science and advances in
both areas and more need to be pursued. Some of the scientific and
technical advances that will be needed if these difficult goals are to
be achieved are brighter and higher current particle sources, higher
gradients and improved higher mode damping in normal and superconducting
cavities, increased efficiency in transfer of AC power to beam power,
faster and higher field beam manipulation devices including normal and
superconducting magnets, more inclusive cradle to grave simulations for
complete accelerator systems including non-linearities and collective
effects, improved manufacturing methods and materials, practical optical
wavelength acceleration and manipulation schemes, improved beam cooling
methods, beam instrumentation with nanometer and femtosecond spatial and
time resolution and improved methods of muon acceleration.

### Nuclear Science

In nuclear science both hadron and lepton probes have proven important
and complementary in putting together a coherent body of knowledge and
will continue to do so, necessitating technical and scientific
developments in both of these directions.

##### Electron Accelerators

Electrons provide precise information about the electromagnetic
structure of the nucleus. Increasingly higher energy electrons have been
required to probe ever-finer structures of the nucleus. Basic research
in Accelerator Physics initially met the increasing Nuclear Science
energy requirement by using room temperature copper structures developed
in support of High Energy Physics programs. Significant information
gains from the Nuclear Science program can be achieved through particle
coincidence experiments most efficiently accomplished with cw
(continuous wave) beams. This requirement was met by taking benefit of
research programs in Superconducting Radio Frequency (SRF) structures.
Fundamental understanding of collective beam phenomena has allowed
cost-saving strategies such as recirculating-linacs with their lower
beam breakup thresholds to be realized through the provision of
appropriate damping mechanisms.

Fundamental insights into the nuclear environment have been achieved
through the use of polarized electrons from photo-cathode guns most
recently achieving after years of basic research very high (\>90%)
polarization. Today, the premier electron facility for doing nuclear
physics with electrons is a recirculating superconducting 6 GeV linear
accelerator \[ref to an article describing the CEBAF facility\]
operating in continuous wave mode and having excellent energy resolution
and stability. Pressing to double the available beam energy is an
important priority for advancing understanding of the strong force and
its manifestation in gluonic matter.

Electron-based Nuclear Science has and will continue to benefit from
basic Accelerator Physics research which has led to cost-effective tools
with cutting-edge performance to advance this field.

*Hadron Accelerators*

The proton through heavy-ion based Nuclear Science programs owe their
research productivity to steady progress in Accelerator Physics
disciplines. The forefront accelerator today for Nuclear Science
investigations of matter as it existed fractions of a second after the
birth of the universe is the Relativistic Heavy Ion Collider. The
Accelerator Physics technology base including superconducting magnets,
fast cycling cascaded synchrotrons, and colliding beam storage rings
developed in support of High Energy Physics programs allowed the
effective realization of the required facility parameters. Future
upgrade plans for the RHIC facility call for colliding electron-ion
interaction regions effectively requiring both superconducting electron
and hadron technologies. Another upgrade plan requires the use of an
electron energy recovery linac for electron cooling of the heavy ion
beam.

Accelerator physics has brought the invention of the Radio Frequency
Quadrupole (RFQ) providing efficient early acceleration for ions of all
types and permitting cost-effective and in some cases otherwise
unachievable performance parameters. Decades of basic research on
Electron Cyclotron Resonance (ECR) ion sources have provided the Nuclear
Science program with beams of virtually all stable isotopes at ever
increasing intensities. Proton and heavy-ion based accelerators have
increasingly taken advantage of SRF technology to provide high
performance at modest cost.

The most recent example of Accelerator Physics research and design in
support of Nuclear Science is the Rare Isotope Accelerator (RIA). Among
other fundamental questions, RIA will provide basic insight into the
origin of the elements. RIA received the highest priority for a major
new facility in the recent Nuclear Science Advisory Committee Long Range
Plan. RIA will accelerate any of the stable isotopes to \~400
MeV/nucleon, and using these stable beams produce beams of radioactive
isotopes by any of several methods. Electron Cyclotron Resonance (ECR)
ion sources feeding an RFQ will be used as input to a stable beam linac
with the ECR performance providing one of the facilities intensity
limitations. The SRF-based linac will use superconducting structures
suitable for particle velocities ranging from a few percent to about 70%
the speed of light. A primary technical challenge will be the
achievement of high gradient superconducting structures at high Q. The
higher beta (v/c) structures are primarily foreshortened speed-of-light
structures and take benefit of the significant advances made from basic
research on the superconducting beta =1 designs. The lower beta (\<0.5)
structures will utilize quite different geometries (l/4 or l/2) where
the research maturity is less evident. Understanding the basic physics
issues and developing approaches likely following those of the high beta
community has the potential of providing breakthrough performance gains.
In addition, RIA will require magnetic elements in radiation
environments that exceed the dose resistance of normal organic-based
insulating systems in an impractically short time. These magnets would
benefit from the utilization of superconducting technology. As a
consequence the development of radiation resistant superconducting
magnet technology would provide a significant cost and performance
advantage. (Similar problems have arisen in the muon collider design.)
One of the radioactive beam production mechanisms used at RIA utilizes a
magnetic chicane to filter the desired radioactive isotopes from the
background of other isotopes. Because of the large radioactive beam
phase space, the requirements of large bore and relatively high magnetic
field designs are most efficiently met by superconducting magnet
technology. Advances in superconducting magnets will clearly benefit the
performance and reduce the cost of these systems.

![](media/image3.pct){width="6.0in" height="5.113194444444445in"}
Through understanding the r process, RIA will allow understanding of the
origin of the heavy elements and through data on neutron rich weakly
bound nuclei promote further understanding of nuclear many body science
(courtesy R. York, Michigan State U.)

#### Key Research Areas

Superconducting radiofrequency structures are needed to provide cw
operation. As heavy particles need to be accelerated from low energy to
high, structures appropriate to the various velocities are needed. To
date, elliptical structures have been used for v/c \~ 0.5 to 1 and are
based on decades of R&D which has brought performance to a high level
although further improvements can be expected. Non-elliptical structures
have received less attention. Using the knowledge base provided by the
elliptical structure work, one may expect large advances in the
capabilities of non-elliptical structures for low velocity acceleration.

Beam intensity increases can move the Nuclear Science program frontier
into uncharted and fruitful arenas by enabling previously unachievable
experiments. As a consequence, fundamental research in the areas of
intense electron and high intensity heavy ion sources will support
advances in Nuclear Science.

Concomitant to increasing beam intensities are increased radiation
fields. To achieve appropriate performance often demands the reliable
operation of high field magnetic elements a high radiation environment.
Basic research into the radiation resistance of materials and magnetic
element designs appropriate for their application will support advances
in Nuclear Science.

### Particle Accelerators for Cancer Therapy

*Introduction*

In the United States, some 550,000 deaths were caused by cancer in the
year 2001, (exceeded only by heart disease as a cause of death).
Worldwide, more than 7,500 electron linear accelerators are installed in
Radiation Therapy departments and used heavily in the treatment of most
forms of life threatening cancer. Most frequently radiation treatments
are given in combination with chemotherapy or surgery, the other two
major cancer therapy modalities. (The overall effect is that more than
50% of patients with life threatening internal cancers, receive
radiation therapy as a part of their treatment protocol.)

Manufacture of radiation therapy linacs is at this time a relatively
mature technology but with a large economic impact (roughly estimating:
7,500 linacs @ \$2,000,000 with a 10 year useful life implies \$1.5
billion/year and approximately half of these devices are manufactured in
the USA). In addition to electron linac therapy systems, three other
radiation therapy systems are at present in trial use in the world, with
the goal of further improving patient survival and/or reducing overall
costs. These three systems (referred to as neutron therapy, proton
therapy, and heavy-ion therapy) are at the present time heavily
developmental in nature and provide many challenging opportunities for
major societal benefit from cutting edge accelerator physics research.

*Biological Basis for Radiation Therapy*

Ionizing radiations injure or kill cells, depending on the ionization
density received by a particular cell. (The ionization density is
usually expressed as the Linear Energy Transfer or LET of the particular
ionizing radiation.) Death of a cell due to low LET radiations depends
heavily on the amount of Oxygen in the cell (the "Oxygen effect"),
whereas the cell killing capability of high LET radiations is virtually
independent of the Oxygen level. The rapid growth of advanced tumors is
thought to result in a blood (i.e. Oxygen) deficiency in the tumor since
the network of arteries and veins remains the same or is actually
constricted by the tumor growth and so the tumor becomes Oxygen
deficient, allowing the tumor to "hide" from the radiation injury by a
factor of two, relative to the level of radiation required to kill a
normal cell. High LET radiations such as heavy-ions or neutrons (recoil
nuclei) are then said to have a "biological advantage".

Charged particle beams such as protons and heavy ions are in contrast
said to have a "Physical Advantage" in that they can be aimed to hit the
tumor with 5 to 10 mm accuracy. Heavy ions have both the biological
advantage and the physical advantage and then would be the clear
radiation of choice except for a major cost disadvantage. Thus
accelerator physics research at various centers at present focuses on
improving one or another of the treatment modalities depending on the
experience and facility capabilities at the particular center. With each
treatment modality in a reasonably optimum configuration, the nation
would have a sound basis for choosing the modality best matched to
overall national goals (this decision obviously needing to consider both
medical effectiveness and cost containment).

*Neutron Therapy Research Issues*

Goal -- design a facility where physical characteristics match those
achieved by electron linacs so that therapeutic comparison between
neutrons and electron/photons can be made on even handed basis.
(Incentives \-- Results for advanced Prostate cancer are better than any
other technique, facility costs are comparable to linacs, and advanced
prostate is second highest cause of cancer death in males.)

1\) Increase cyclotron energy to match attenuation length of modern
linacs.

2\) Incorporate dynamic collimation.

3\) Reduce operator radiation exposure (time in vault and radioactivity
in patient alignment area).

*Proton Therapy Research Issues*

World Status -- Operating cyclotron facilities have extraction
efficiencies of less than 30% caused by extreme non-linearity of edge
field in the region of a tiny (9 mm) magnet gap at edge. Synchrotron
facilities are complicated and costly. A German company expects to
complete prototype superconducting cyclotron facility in April 2005 --
calculations of extraction efficiency involve frontier numerical
techniques for shaping main magnet B field, and extraction element
fields.

*Heavy Ion Facilities*

World status -- expensive (400 MeV/nucleon needed to achieve 35 cm
range)/much higher rigidity than present largest cyclotrons \--
synchrotron seems design of choice. The first hospital-based facility
(Chiba, Japan) cost 350 million (\$US). Second facility designed by GSI
has funding approval for installation at major medical center in
Heidelberg (costs are said to be much lower than Chiba but accounting
differs from US conventions). Beam rigidity makes gantries very costly
-- superconducting gantry magnets clearly need to be developed.

### The Materials Sciences Including Biology

*Synchrotron Radiation*

Accelerators are having an enormous impact on materials and biological
science, largely due to their use as radiation sources. World-wide
growth in storage-ring based synchrotron radiation (SR) sources has been
phenomenal, from just a few machines in the late 1960's to roughly 70
machines now either built or in advanced stages of development. The
capital invested in this activity is in the \$10B -- 20B range, with
yearly operating expenses exceeding \$1B and supporting a continuing
user base of well over 10,000 scientists and engineers. Synchrotron
sources are used throughout the materials and biological sciences for
materials and molecular structure determination, elemental analysis,
imaging and microtomography, determination of electronic structure, etc.
-- the list is long and continually growing. An indication of both the
rate of growth and present trends in synchrotron radiation usage is
given in the figure below. Note that the growth of utilization continues
to increase. As opposed to high energy physics experiments, where
accelerators serve a small number of very large, long-lived experiments,
SR facilities ![](media/image4.pct){width="4.625in"
height="2.25in"}serve a very large number of small, short-lived
experiments.

All of this activity is, of course, based on accelerators. Further, the
demands of synchrotron radiation have provided an impetus for ever more
sophisticated storage rings, actively soaking up available
accelerator-skilled research personnel. As the community becomes more
and more aware of the possibilities of SR, it increasingly demands
enhanced SR source capabilities, specifically, increased photon beam
brightness and flux, smaller focused beam sizes, and faster photon
pulses. It is now recognized that the limits of storage ring based
sources are within sight. In the last decade this has led to a flowering
of new ideas for SR sources based on free electron lasers (FELs) and
energy recovery linac (ERL) machines.

Fruition of these new developments requires advances in linac, low
emittance electron injector, insertion device, and superconducting
accelerator technology. It is now generally acknowledged that the
rate-limiting step in development of these technologies will be a
world-wide shortage of accelerator scientists and engineers.

*VUV/Soft X-ray and hard X-ray SR Sources*

Broadly speaking, SR sources tend to fall into two categories, depending
on the energy of the SR: VUV/soft x-ray machines and hard X-ray sources.
At present, storage rings are the predominant sources for both
categories. Because low energy radiations may be generated with lower
energy particles, VUV/soft X-ray sources are generally smaller than
their hard x-ray counterparts. Other distinctions of the radiations
(e.g., soft radiation does not readily penetrate windows, necessitating
UHV beamlines and experiments) and the applications (e.g., soft
radiations are more suitable for many spectroscopic experiments whereas
hard X-rays are more suitable for diffraction analysis of molecular
structure) distinguish the beamlines of the two categories.

These distinctions carry over into next-generation SR sources, mainly
free-electron lasers (FELs) and Energy Recirculating Linacs. The scaling
laws for FELs and ERLs are more forgiving at lower photon energies, with
the consequence that sources at these energies are in a more advanced
stage of development, and the first FEL & ERL user facilities have been
constructed. By contrast, hard X-ray FELs and ERLs are more ambitious
undertakings.

Two programs for X-ray FELs with the capability of reaching the 1 Å
wavelength range have been recently approved, one, LCLS, in the US --a
SLAC-ANL-LLNL-BNL-UCLA collaboration- and one in Europe based at DESY.
LCLS is now in the design and construction phase and will be completed
by 2007. The DESY system will follow a few years later. These two X-ray
FELs require electron beams with unprecedented characteristics, in
particular a very large 6-dimensional phase space density, and high peak
current. The X-ray pulses they will produce will have a pulse duration
in the range of 10 to a few hundred femtosecond, and a peak power of
tens of GW.

This new generation of light sources, with order-of-magnitude
improvements in brightness, flux, spot size and pulse duration, can
enable qualitative advances in research capabilities. For example,
improvements in brightness will feed new science related to microscopy,
either by providing microprobes with tighter focus (zone plates,
KB-mirrors) or more intense field illumination in imaging microscopes
(PEEM). These sources offer unique advantages due to the penetrating
power, spectral features and polarization capabilities of the radiation.
Resolution 10 nm and below will be the key to nanoscience and
technology. The basic idea is to look at an individual nanotube, quantum
dot, etc. as opposed to averaging over an inhomogeneous array. The
particular strength of microscopy with synchrotron radiation is chemical
specificity. There is a wide range of applications from the chemistry of
cells and microbes, geology, and magnetic nanostructures for data
storage. The development of spintronic memories will require the
nanoscale characterization of electron spin distributions of magnetic
clusters.

Discussions about next-generation FEL light sources also revolve around
fast timing, coherence, and the large number of photons in a single
pulse. In this context, fast means \<100 femtoseconds. With this
temporal resolution, one can take snapshots of molecules, proteins,
cells, and nanostructures during less than a vibrational period and see
what happens while the atoms in the molecule are still moving around
(Zewail\'s Nobel-winning work popularized this idea of following a
chemical reaction while it is on-going). Coherence opens all kinds of
new imaging (and possible microscopy) methods. An essential idea is
transforming the diffraction pattern (speckles) of a single
molecule/nanocluster/object back into real space without knowing the
phase. Iterative methods reconstruct the phase with the help of the
knowledge that the object is finite. Coherence properties of various
X-ray sources are shown in the figure below.

What enhanced application capabilities might be anticipated for the
future? The possibilities would impact, literally, the full span of the
materials and biological sciences.

![](media/image5.jpeg){width="6.190277777777778in"
height="8.084722222222222in"}

Coherence fraction for various sources of synchrotron radiation
(courtesy Q. Shen Cornell U)

These include, to mention a few examples, the ability to determine the
structure of non-periodic, complex materials down to nanometer
dimensions; extension of analytic capabilities in high-pressure science
into new realms of pressure and temperature; structural analysis of
non-crystalline proteins, viruses, and macromolecular clusters; wide
ranging spectroscopic studies from the microvolt to the eV regime which
are key to the properties of new materials and molecules; exploration of
non-equilibrium, sub-picosecond electronic excitations; definition of
chemical transition states in gases, liquids and enzymes; analysis of
the magnetic thin films; coherent phase sensitive imaging of cellular
organelles; microtomography of nanoscopic metals and composites;
nondestructive 3-dimensional elemental analysis of art works; advanced
microfabrication and patterning methods; and submicron imaging of
elemental and oxidation states of soils, and biological and
environmental materials. The X-ray FEL also opens new capabilities for
High Energy Density physics.

*Needed Developments*

The underlying accelerator research and development necessary to ensure
the success of next-generation light sources spans a broad range of
physics and engineering. For the storage ring approach, the low energy
storage rings that are optimal for producing low energy photons will be
limited, much as next-generation B-factories, by the Touschek lifetime.
This is especially true as one attempts to store currents of several
amperes or short, femtosecond long, bunches. Work to improve nonlinear
behavior and coupling in relatively compact, low emittance storage rings
will be a high priority in dealing with this effect.

For both FEL and ERL light sources, one of the most crucial areas is the
electron-source development. For ERL the issue is achieving storage-ring
levels of average current (\>100 mA) with normalized emittances of 1
nm-rad or less. For FELs the issue is to reduce the beam emittance while
keeping constant or increasing the peak current. Additionally, the
understanding of recirculation and energy recovery at these high
currents is in its infancy and will require experimental studies to
confirm present theoretical models. Issues of halo formation and beam
loss are also of importance.

Increased efforts in the development of stabilization schemes and
hardware for both the accelerators and their associated photon beam
lines are required to take full advantage of the potential offered by
the low emittance light sources that will be coming online in the
next-decade. This is driven by the smaller beam sizes and by the
stringent requirements of experiments using, for example, magnetic
dichroism (0.01 % intensity constancy during polarization switching), IR
Fourier transform spectroscopy, and monochromators with 10^-5^
resolution. Scanning and modulating insertion device fields have added
to the scale of problems that must be addressed, and improvements of an
order of magnitude or more have become essential.

Extensive cross-cutting efforts are needed between groups in accelerator
physics, diagnostics/instrumentation, optics, signal processing, and
researchers to define stability requirements and to solve the
fundamental problems presented. Developments in beam-based diagnostics
(electrical and optical), component stabilization, active machine
feedback, dynamical compensation systems for variable insertion devices,
and beam-line feedback on both the photon beam and electron beam will be
necessary.

Synchrotron radiation facilities generally want maximum flexibility and
range of the radiation provided to users. Advances in shorter-period,
variable period, higher field insertion devices would provide this
flexibility and enable lower-energy, lower-cost accelerators (both
storage ring and ERLs) to provide higher photon energy and increased
flux without excessive higher harmonic power. This work would
necessitate development of higher remnant field permanent magnets,
migration to superconducting devices with exotic coil arrays, or
possibly microwave devices.

*Neutron Sources*

Accelerators are the heart of spallation neutron sources, again with a
heavy emphasis on developments in proton linac and superconducting
accelerator technologies. There is an emphasis here on improving
accelerator technology to provide higher power pulses at low repetition
rates with high reliability and constant current to allow long periods
of continuous operation. Advanced high power proton accelerators are
also a key to very important applications in proton radiography for
materials imaging in the stock pile stewardship program.

*Other Materials and Biological Accelerator Applications*

On a much more modest scale, accelerator technology forms the basis for
smaller-scale industries that produce thousands of machines for specific
analytical and processing purposes in the materials and biological and
medical sciences and for therapeutic applications. These include
Rutherford back-scattering instruments, very high-current electron
sources, machines for elemental activation and identification,
implantation devices, microtron-based UV SR sources for lithography,
etc. There is increasing research on developing relatively low-flux, but
high brilliance and short-pulse table-top SR devices based on Compton
back-scattering of laser light by electron beams. Each of these
technologies requires research personnel skilled in accelerator
methodologies and a search for higher efficiency in the machines
themselves.

### Fusion and High Energy Density Sciences

*Impact of Accelerator Science on High Energy Density Physics*

A fundamental understanding of the influence of nonlinear effects and
collective processes on the propagation, acceleration and compression of
intense, high-brightness, charged particle beams is essential to the
identification of optimal operating regimes in which emittance growth
and beam losses are minimized in periodic focusing accelerators and
transport systems. This is particularly true at the high beam currents
and charge densities envisioned in present and next-generation
accelerators for high energy and nuclear physics research, in coherent
radiation sources using high-intensity electron beams, in high-current
linear ion accelerators, and in the space-charge-dominated beams used in
heavy ion fusion.

High-intensity particle beams, like high-intensity lasers, are playing
an increasingly important role in the rapidly developing field of high
energy density physics, which explores the properties of matter under
conditions of extreme energy density (exceeding 10^11^ J/m^3^ ), or
equivalently, at very high pressures (exceeding 1 Mbar). Chapters 1, 2
and 4 of the recent National Research Council report entitled *Frontiers
in High Energy Density Physics **--** the X-Games of Contemporary
Science* (National Academy Press, 2003
http://www.nationalacademies.org/bpa) provides a summary of
particle-beam-related research activities and opportunities in high
energy density physics. A few illustrative examples include:

1.  The creation of quark-gluon plasmas, simulating conditions in the
    early universe, using colliding beams of relativistic heavy ions.
    (See illustration below)

2.  The installation of dedicated beam-lines on high energy physics
    accelerator facilities for the express purpose of carrying out high
    energy density physics studies, such as the development of
    ultra-high-gradient accelerator concepts.

3.  The use of intense relativistic electron beams to develop unique
    radiation sources ranging from the infrared to gamma-ray regimes.

4.  The development of optimized plasma lens concepts to charge
    neutralize intense positron beams, thereby focusing the beam to a
    small spot size in a short distance.

5.  Develop a fundamental understanding of nonlinear space-charge
    effects on the propagation, acceleration and compression of
    high-current, low-emittance, heavy ion beams, including
    identification of optimum operating regimes for heavy ion fusion
    applications.

![](media/image6.jpeg){width="3.826388888888889in"
height="3.826388888888889in"}

Gold on Gold Phenix event at RHIC with magnetic field off (courtesy
S.Ozaki, BNL)

The machines needed for exploring these important issues span the full
gamut of accelerators, so that most of the advances listed in Appendix
III will advance high energy density studies: brighter and more intense
sources; superconducting magnets; improved simulation; beam cooling; new
materials; neutral beam acceleration; traveling wave laser pumping; beam
measurement with nanometer spatial resolution and femtosecond time
resolution; real time, single shot, beam distribution function
measurement instrumentation.

***Education and Training Needs***

As can be easily seen from the number of advertisements that appear
monthly in Physics Today and the CERN Courier, there is a dearth of
personnel trained in accelerator physics and related technology. It is
widely agreed that the expansion of just synchrotron sources alone, to
meet the growing research need, is limited by the availability of expert
personnel. If the role of universities in accelerator development is to
be enhanced that will put further pressure on the limited pool of
accelerator experts. A similar statement can be made about the need for
beam line designers and builders for both synchrotron sources and
neutron facilities. This points to the need to draw more students into
accelerator science and engineering through making the opportunities
more widely known and offering easily available training and education
in accelerator work either in and of itself or in conjunction with the
pursuit of some other scientific area that uses accelerators such as
particle and nuclear physics or the many branches of x-ray science. This
combined training and education is very valuable, since it is ultimately
the science practitioners using accelerators that know best what they
need and, if accelerator wise, will see best how to get it.

Currently most NSF education and training in accelerator physics and
technology takes place at the university accelerator laboratories
supported by the NSF. This takes the form of formal on campus courses,
degree granting distance learning courses, distance learning technology
courses without formal credit, and apprentice like programs where the
students gain most of their experience working on and around the
accelerators supplemented by tutoring. In all of these the USPAS (US
Particle Accelerator School), supported by joint efforts of the US
accelerator labs -- NSF and DoE together) plays an important role. It
offers twice a year high quality courses and hands on experience to
students, provided by outstanding accelerator scientists and
technologists from across the country. In total, the number of PhD
students in accelerator physics produced by NSF supported accelerator
facilities is about 6 -- 7 per year along with about 5 MS students per
year. Note that the DoE HEP Technology program, and the DOE Basic Energy
Sciences program, support significant work in accelerator R&D at
universities. (see Appendix 4)

For a certain perspective it is to be noted that of the 2850
experimental high-energy physicists in the US, 13% emphasize accelerator
research. Three quarters of all high-energy physics experimentalists
reside in universities while 2/3 of the accelerator scientists involved
in accelerator research reside in the national laboratories.

### Current Level of University Involvement in Accelerator R/D

At present there are three major NSF supported accelerator user
facilities conducting research in nuclear, particle and synchrotron
radiation science. Each of them carries out accelerator R&D largely
focused on their own programs but a with a modest portion having a more
general character as well. Given the need to boost such activities for
the health of the future accelerator based research programs,
enhancement of support for R&D at these facilities is a natural step.
Some of the subjects of this R&D and NSF accelerator facilities are
superconducting radiofrequency accelerating devices both for velocity of
light and slow particles, materials and surface science relevant to high
power rf devices, medical accelerators, optics and beam theory, full non
linear simulations of accelerator operation including beam-beam effects,
IR edge radiation, beam lifetime issues, and design of low energy
compact storage rings.

Of at least equal importance is the need to engage the accelerator user
scientific community in the strengthening of accelerator R&D.
Considerable progress has been made in this direction recently. For
several years now there has been a grass roots organization known as the
Muon Collider and Neutrino Factory Collaboration, or MC, which devotes
itself to those subjects. Currently there are 22 universities
participating in various accelerator R&D projects associated sponsored
by the MC with support from both NSF and DoE. Unfortunately the support
level has been modest and in fact has recently been cut. Total annual
support is approximately \$4 M. The work is a combination of work done
at the individual universities, and collaborative work utilizing
infrastructure at the traditional accelerator laboratories. Every
subsystem of these complex accelerators has enormous technical and
economic challenges (see
http://www.fnal.gov/projects/muon_collider/prstab/prstab.pdf). For these
challenges to be met the support level needs to be raised substantially.

In another positive development there has recently been the formation of
two groups of university physicists to engage in R&D for the e+e- linear
collider, the LCRD (Linear Collider R&D group), and the UCLC (University
Consortium for the Linear Collider). Proposals have been submitted to
the DoE and NSF respectively. Forty seven universities are involved,
with a total of seventy one individual projects, about equally divided
between detector and accelerator R&D projects. Again some of these
include collaborations with traditional accelerator laboratories, using
existing accelerators and some involve work at collaborating or
individual universities (see http://www.lns.cornell.edu/public/LC/UCLC).
The combined support level requested for this year is \$2.5M, keeping
the individual university involvements at a very modest level. The
challenges in linear collider accelerator technology and physics reach
far beyond this level of support.

Basic research in beam physics is being supported at a small number of
universities by DoE. Examples are UCLA, Maryland, and SUNY Stony Brook.
These university groups are engaged in the experimental and theoretical
study of beam-plasma, beam-laser, and beam-laser-plasma intreractions,
high phase-space density electron sources, and collective instabilities.
They are also working on the development of advanced numerical codes,
including non-linear dynamics and collective effects and the complete
simulation of complex experiments. University groups at these
institutions offer undergraduate and graduate courses in accelerator
physics and technology, and training in in-house laboratories. They
produce about five PhDs per year, and some masters degrees.

### Enhancing the University Role

As noted in the previous section, there has been a positive trend in the
involvement of universities in accelerator work directed at rather
specific goals of neutrino factories, muon colliders and
electron-positron linear collider. This is all to the good since
particle science is being limited while these needed techniques are
being developed. However most of the universities involved in this
research do not offer a complete undergraduate and graduate training.
The number of faculty positions in accelerator physics in universities
is also quite limited. For this reason we believe that it will be
important to cultivate more university involvement in advanced
accelerator R&D so that sufficient work on basic particle beam physics
and on developing the next generation of accelerators can extend over a
sufficiently long time scale. Improving the effectiveness of university
involvements will require both improved organizational arrangements and
resource levels.

On the organizational side we note that there are very few remaining
university accelerator facilities where student and faculty involvement
in accelerator work, training and R&D, comes most naturally. As part of
a program directed at enlarging university involvement, we should study
how to increase the number of university based accelerator facilities
for beam physics research, and to make existing university facilities
available to the wider university community by providing opportunities
and the needed mentoring. The accelerators at national laboratories tend
to be less accessible for training and accelerator R&D owing to their
need to be factories for science. There are, of course, notable and
important exceptions. These exceptions can serve as models of how to
expand the accessibility of our accelerator infrastructure to university
participants. Here again work needs to be done to provide the
organizational means for this access, including provision of the needed
mentoring and service personnel.

On the resource side it will be necessary to make available additional
resources for some infrastructure at the universities, as well as for
carrying out research work. One needs to create the conditions to have
more faculty positions at universities, with the support needed to carry
out significant research and attract undergraduate and graduate
students. For existing accelerator facilities, university or national
lab resources will be needed to provide for the services needed by the
new university users. Today, a rough estimate of funds available
annually to university scientists for accelerator work is about 20\$M so
that to make a significant impact on university involvements would
require adding a comparable amount.

## 

## 

## References

1\. Amaldi, U. The Importance of Particle Accelerators, Europhysics News
2000 , V31, No. 6 -http://www.europhysicsnews.com/full/06/article1.html

2\. Alonso, J. Medical Applications of Accelerators in Handbook of
Accelerator Physics and Technology, A. Chao, M. Tigner Eds,World
Scientific, 2nd printing, 2002

3\. Norton, G., Duggan, J.L. Industrial Applications of Electrostatic
Accelerators, ibid

4\. Livingston, M.S. and Blewett, J.P. Particle Accelerators, McGraw
Hill, 1962

5\. Tigner, M. Accelerator Science Needs More Brainpower, CERN Courier,
May 2002

6\. Muon Collider/Neutrino Factory Collaboration, Status of Neutrino
Factory and Muon Collider R&D and Future Plans, hep-ex/0207031
(submitted to PRSTAB)

7\. E. Esarey, Plasma Accelerators op. cit. \[2\]

APPENDICES

Appendix 1 \[1\]

Enumeration of Accelerators now in use

+--------------------------------------------------------+-------------+
| ## Category                                            | ### Number  |
+--------------------------------------------------------+-------------+
| Ion implanters and surface modifications               | 7,000       |
+--------------------------------------------------------+-------------+
| Accelerators in Industry                               | 1,500       |
+--------------------------------------------------------+-------------+
| Accelerators in non-nuclear research                   | 1,000       |
+--------------------------------------------------------+-------------+
| Radiotherapy                                           | 7,500       |
+--------------------------------------------------------+-------------+
| Medical isotope production                             | 200         |
+--------------------------------------------------------+-------------+
| Hadron therapy                                         | 20          |
+--------------------------------------------------------+-------------+
| Synchrotron radiation sources                          | 70          |
+--------------------------------------------------------+-------------+
| Research in nuclear and particle physics               | 110         |
+--------------------------------------------------------+-------------+

Appendix II

ACCELERATOR FACT SUMMARY

+-----------+-----------------+--------+-----------------------------+
| Support   | Sub-unit        | Type   | Uses                        |
| body      |                 | used   |                             |
+-----------+-----------------+--------+-----------------------------+
| NSF       |                 |        |                             |
+-----------+-----------------+--------+-----------------------------+
|           | NP              | e,p,I  | nuclear physics             |
+-----------+-----------------+--------+-----------------------------+
|           | EPP             | e,p,   | particle physics            |
+-----------+-----------------+--------+-----------------------------+
|           | AMO             | e(X),? | structures                  |
+-----------+-----------------+--------+-----------------------------+
|           | DMR             | e(     | materials, imaging          |
|           |                 | X),n,μ |                             |
+-----------+-----------------+--------+-----------------------------+
|           | CHEM            | e,     | materials, reaction         |
|           |                 | e(X),μ | enhancement                 |
+-----------+-----------------+--------+-----------------------------+
|           | GEO             | e(X),n | mineral phase diagrams,     |
|           |                 |        | prospecting                 |
+-----------+-----------------+--------+-----------------------------+
|           | BIO             | e(X),n | bio structure               |
|           |                 |        | determination, imaging      |
+-----------+-----------------+--------+-----------------------------+
|           | ENG             | I,     | nanostructures,             |
|           |                 | e(X)   | micromachining, lithography |
+-----------+-----------------+--------+-----------------------------+
| DOE       |                 |        |                             |
+-----------+-----------------+--------+-----------------------------+
|           | BES             | e(     | materials research, FEL, em |
|           |                 | X),n,μ | sources devt                |
+-----------+-----------------+--------+-----------------------------+
|           | BER             | e(X),n | Bio structures              |
+-----------+-----------------+--------+-----------------------------+
|           | HENP            | e,p,I  | nuclear and particle        |
|           |                 |        | physics                     |
+-----------+-----------------+--------+-----------------------------+
|           | FUSION          | I,     | heavy ion fusion, high      |
|           |                 | e(X)   | energy density physics      |
+-----------+-----------------+--------+-----------------------------+
|           | DP              | e,     | explosion physics, FEL,     |
|           |                 | e(X),p | radiography                 |
+-----------+-----------------+--------+-----------------------------+
|           |                 |        | waste transmutation,        |
|           |                 |        | tritium production          |
+-----------+-----------------+--------+-----------------------------+
| DOD       |                 |        |                             |
+-----------+-----------------+--------+-----------------------------+
|           | NAVY            | e,I    | FEL, fusion                 |
+-----------+-----------------+--------+-----------------------------+
|           | QUARTERMASTER   | e(X)   | food sterilization          |
|           | CORPS           |        |                             |
+-----------+-----------------+--------+-----------------------------+
|           | "GENERAL"       | e(X)   | inspection                  |
+-----------+-----------------+--------+-----------------------------+
|           |                 |        |                             |
+-----------+-----------------+--------+-----------------------------+
| NASA      |                 |        |                             |
+-----------+-----------------+--------+-----------------------------+
|           |                 | p,I    | detector calibration,       |
|           |                 |        | radiation damage, health    |
+-----------+-----------------+--------+-----------------------------+
|           |                 |        |                             |
+-----------+-----------------+--------+-----------------------------+
| NIH       |                 |        |                             |
+-----------+-----------------+--------+-----------------------------+
|           | GENERAL MED     | e(X),n | bio structures              |
|           |                 |        | determination               |
+-----------+-----------------+--------+-----------------------------+
|           |                 |        |                             |
+-----------+-----------------+--------+-----------------------------+
|           |                 |        |                             |
+-----------+-----------------+--------+-----------------------------+
| PRIVATE   |                 | e(     | therapy, isotope            |
| MEDICAL   |                 | X),p,I | production, radiography     |
| SECTOR    |                 |        |                             |
+-----------+-----------------+--------+-----------------------------+
|           |                 |        |                             |
+-----------+-----------------+--------+-----------------------------+
| DOC       |                 |        |                             |
+-----------+-----------------+--------+-----------------------------+
|           | NIST            | e(X),e | optical radiometry,         |
|           |                 |        | materials/biological        |
|           |                 |        | structures, dosimetry,      |
|           |                 |        | calibration, radiation      |
|           |                 |        | effects, imaging            |
+-----------+-----------------+--------+-----------------------------+
|           |                 |        |                             |
+-----------+-----------------+--------+-----------------------------+
| INDUSTRY  |                 | e,e(   | analysis, inspection,       |
|           |                 | X),n,I | implantation,               |
|           |                 |        | sterilization,              |
|           |                 |        | polymerization, mass        |
|           |                 |        | spectroscopy, radiation     |
|           |                 |        | damage                      |
+-----------+-----------------+--------+-----------------------------+
|           |                 |        |                             |
+-----------+-----------------+--------+-----------------------------+
| HOMELAND  |                 | e(X),  | sterilization, inspection   |
|           |                 | n      |                             |
| SECURITY  |                 |        |                             |
+-----------+-----------------+--------+-----------------------------+

e -- electron

e(X) -- UV and x-ray generated by electrons

p -- proton

n - neutron

I -- ion

μ - muon

Appendix III

Progress Needed in Accelerator Science and Technology and Related
Apparatus

#### Accelerator Basic Science

1.  Physics of coherent synchrotron radiation

2.  FEL physics

3.  Beam and plasma diagnostics with nanometer spatial resolution and
    femtosecond time resolution

4.  Real time, single shot, beam distribution function measurement
    instrumentation.

#### Accelerator Applied Science

1.  Brighter sources (e,p,I)

2.  Higher current sources (e,p,I)

3.  High power x-ray optics

4.  Micro x-ray beam development

5.  Higher gradients in both SC and NC structures

6.  Better HOM damping in SC and NC structures

7.  AC -- beam power efficiency improvements in all accelerator types,
    laser, conventional

8.  Improved devices for beam manipulation (plasma, pulsed and cw
    electric and magnetic)

9.  Superconducting magnets

10. Improved cradle to grave simulation including non-linearities,
    vibration, wakes, beam-beam etc.

11. More cost effective means for manufacture of major accelerator
    components

12. New approaches for high flux, high brightness femtosecond x-ray
    sources

13. Practical optical wavelength acceleration and manipulation schemes

14. Very compact accelerators for medicine and inspection

15. Beam cooling methods (radiation, stochastic, electron, ionization)

16. X-ray imaging

17. Materials (new materials, radiation resistant materials, new
    magnetic and superconducting materials)

18. Neutral particle acceleration

19. Traveling wave laser pumping with beams

20. Beam measurement instrumentation with nanometer spatial and
    femtosecond temporal resolution

21. Megawatt capable targets for muon and neutron production

22. Muon accelerators (induction, low frequency linac, FFAG, low
    frequency superconducting, high gradient, cavities)

23. Energy recovery at high current and brightness

24. Improved insertion devices for FEL and spontaneous synchrotron
    radiation as well as for use in emittance control in storage rings

25. Real time, single shot, beam distribution function measurement
    instrumentation.

Appendix IV

DoE University Program

The DoE HEP Technology program also supports university participation in
accelerator R&D. Currently the support level is \$12.7M annually with 10
to the universities and 2.7 supporting infrastructure at the national
labs (mostly BNL) for the benefit of the universities. About 35
universities are in the program. In existence since 1982, the program
has averaged 10 PhD degrees annually between then and now.

Details of the DoE university program can be found at
[http://doe-hep.hep.net/Yearbook%202000/](http://doe-hep.hep.net/Yearbook 2000/)
(DoE/SC -- 0032 is the report number)