30th April 2007
Dr. John Womersley, Director of Strategy, STFC
Prof. Robert J. Donovan, Univ. of Edinburgh
(Coordinators of UK Light Source Review)
Dear John and Bob:
I was grateful for the invitation last Friday,
April 27, 2007 that allowed me a glimpse at the initial strategy
for the Review of UK Light Sources being planned this summer by
STFC, and in particular, the Review Panel as it stands now. As
a newcomer to the UK science enterprise, I would like to comment
on it, if I may, and not in the capacity as part of any light
source project in the UK, which I am not. But I would like to
deposit my thoughts rather as someone who has been associated
with and steeped for the past two and a half decades in light
source developments and the associated science around the world.
This has included both conventional storage ring-based SR facilities
as well as contributions to the progress on the conception and
subsequent developments on ultra-fast techniques at Berkeley and
then subsequently worldwide, then on to FELs at Jefferson Lab,
and to the underlying emerging technologies of SCRF and ERLs.
I have been embedded in the US/global light sources community
starting with the conception, design, construction and operation
of the ALS at Berkeley, later on contributing to the SPEAR 3 and
LCLS developments, development of the Jefferson lab ERL/FEL and
Cornell ERL-based facilities, advising the APS ERL-Upgrade team
and counselling the NSLS-II team at BNL spanning nearly 25 years.
All these in my case, were synergistic with the other half of
my professional canvas which deals with the accelerators and colliders
for high energy and nuclear physics, where development of intense
and bright beams of electrons and positrons provided unparalleled
synergy between the two fields.
It is my perception that the chosen panel represents
the hard X-ray community extremely ably, with notable members
known for their judgment and wisdom in the community. I however
feel that that this panel could be made more complete by adding
one or two extra members who can offer wisdom and counsel to the
UK community on the longer wavelength IR, VUV and soft X-ray regimes
towards which 4GLS is targeted by design. 4GLS is not a facility
directed towards research of complex structures via X-rays per
se, but is rather aimed towards spectroscopy and functional
time-domain analysis of complex processes including collective
dynamics on surfaces, ultrafast phenomena, biological function
and high field physics. This community complements rather than
competes with the conventional hard X-ray facilities. It should
be stressed that it is also very different from the high energy
X-FELs being contemplated at DESY and being built at SLAC (LCLS)
based upon SASE. In fact 4GLS is a mezzo-scale, longer wavelength,
coherent and bright source of controllable light, made robust,
predictive, reproducible, brilliant and flexible in its time structure
by the now-established technology of SCRF in combination with
the emerging Energy Recovery and various laser seeding techniques.
Facilities similar to this are under early stages of consideration
at various sites world-wide, 4GLS being the first of its kind.
It thereby promises to be pioneering in the field at its cutting
edge, potentially placing the UK in the premier seat globally
with discovery-calibre science and all the rewards which this
brings. However, the chosen panel will find it difficult to appreciate
these aspects, given the absence of 4GLS's projection on the "hard
With this preamble, I take the liberty of suggesting
to you a few names who may complete the panel in terms of its
knowledge/experience base and who would bring wisdom to the whole
scientific scope of 4GLS in advising the UK research and funding
agencies. I speak solely on the basis of their scientific and
technological merit. Eventually the composition of this panel
has to be acceptable to the community as well as to the agency.
The names of Profs. Roger Falcone and/or Ron
Shen from Berkeley come to mind. Roger is currently the Director
of the Advanced Light Source at Berkeley. He was also the Chair
of the Scientific Policy Committee of the LCLS at SLAC. As a professor
in the Physics department of Univ. of California at Berkeley,
including his tenure as its Head, as well as via his involvement
at the ALS beam lines and Lawrence Livermore National Laboratory's
large laser facilities, Roger is a world renowned expert on Higher
Harmonic Generation, High-field Atomic Physics, Femto- and Atto-second
Physics etc., all in the soft X-ray and VUV regions. He is an
esteemed reviewer in many international reviews, is courteous
and gracious, and would be highly desirable as an international
reviewer with integrity and scientific stature for this review.
Prof. Ron Shen, is an expert on IR physics,
including IR lasers, ALS beam lines and IRFELs and general non-linear
multi-photon processes. He is highly esteemed in the US and international
community and would add significant value to the review as well.
The names of Steve Leone and Graham Fleming
crossed my mind, but past interactions with SLAC will shadow their
effectiveness in this committee from a socio-political perspective,
and I would not recommend them as panel members for this review.
Finally, there are other international names
to bear in mind: Joe Bisognano from Univ. of Wisconsin at Madison
and Executive Director of SRRC, Prof. Chuck Fadley from UC Davis,
and Prof. Robert Austin from Princeton (member of US National
Academy of Sciences).
I am sure one can carefully add a name or two
to balance out the portfolio of this panel, allowing it the proper
experience base necessary to evaluate the diverse facilities which
it has to consider, particularly the novel, but unfortunately
still somewhat misunderstood, facilities of the future like 4GLS.
I thank you for your attention to my remarks
and wish you success in this important yet non-trivial light source
review for the UK.
Prof. Swapan Chattopadhyay, Ph. D. (Berkeley)
Director, Cockcroft Institute and
First Chair of Accelerator Physics, UK