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Sunday, June 26, 2022

Changing Context (August 5, 2013)

 

My trip from Grenoble to San Francisco approaches, and as usual, I find conflicting feelings about planning for such a trip.  On the one hand I want to make sure I plan enough so that I have a place to stay, and don't get stranded somewhere.  On the other, I want to keep open possibilities and allow things to unfold organically and give me some freedom to act on possibilities.


This captures part of the dynamic that freezes me in my planning, but not all of it.  There is a part of me that refuses to plan, refuses to imagine myself in another place, refuses to believe that this other place exists, and refuses to believe that I have much understanding of how things will work in this other place.  I try to understand whether it is truly a refusal, or more a lack of ability.  Why does my otherwise creative, highly visual, often quite organized mind fail me in this basic act of imagination?

I know that this dynamic has at least some basis in the way I grew up in Santa Cruz, California.  My parents were divorced when I was three, and they had joint custody over me and my brothers.  Until the age of 18, I never spent more than one week at a time at one house.  I went between my mom's and dad's houses either once or twice a week.  The difference between the two houses was substantial enough that I would have the sense that the rules I know at one house do not apply at the other.  The day of transition became a kind of event horizon.  Not that I so much dreaded it, but that I just couldn't think past it in certain ways.

Sometimes I've likened the experience of going back and forth between houses to diving into a swimming pool.  One stands above the swimming pool looking down into the shimmering depths.  Its a hot day, and so one imagines it might be nice to cool down a bit.  However, one knows that the transition will involve a shock.  What one thinks now will be changed.  One's concerns, ideas, feelings in this moment will be interrupted.  There is a shock during that period while the water covers your skin.  Its as if you fall asleep for a moment and wake up in a new watery world.  There may be a brief moment of discomfort, but you quickly adjust, and get used to the new viscoscity of your environment.  You move your body in new ways.  The water supports you in new ways and impedes you in new ways.

At my dad's house, we were cooked and cleaned for.  My step-mother Judy was a never resting house-keeper, always offering, always doing, always giving.  We were always to be aware of her constant motion and constant doing.  Lying on the couch in the living room, one could be interrupted with the vacuum cleaner, or mopping, or sweeping,  perhaps a suggestion to go outside and play. One would return home from school to find beds made, closet rearranged, toys moved.  Dinner was regular, an enthusiastic call to join around the table.  Always cooked by Judy.  Always comments about how much work it was and how fast it was gone.  Not enough to call it bitterness, but enough to induce a steady undertoe of guilty conscience and awareness of the sacrafice and toils of another.  What have I done to deserve this steady flow of hard work and meals directed towards me?

This sense of induced guilt was supported by a foundation of the story of Judy's family history.  She grew up in Fresno, the child of Armenian immigrants who had come to the US following escape from the Turkish government and military intent on wiping out the entire Armenian population.  Her parents had walked across a desert in Syria and Lebanon.  Her father had lived in an orphanage, her mother with a Turkish family.  The story of the Armenian genocide was often present at my Dad's house, and provided a cultural background, but also a sense of unimpeachability to the value of Judy's hard work.  Both her and my father were working hard.  They ran a medical clinic together, doctor and nurse practitioner.  Judy came home and did double time keeping up a large house for five kids.

My father was born in New York, and grew up in Los Angeles.  He was the son of a Hungarian father and American mother who met in France.  He spent his life continuing the travelling momentum that had carried his father across the globe.  He sought out far away places, particularly liking the islands in the South Pacific, living with my mother on the island of Yap for a year while my older brother was a small child.  He was in college in the 60’s and was animated by the spirit of that time, going to the south to fight for civil rights (
1954 to 1968), and spending a few nights in jail for being a conscientious objector to the Vietnam war (1955 to 1975).  He was married to my mom for ten or so years and after three kids, and a feeling of inadequacy in the marriage, divorced my mom and married Judy, the nurse practitioner working in his medical office with two children of her own.

Like my dad, my mom was also a child of the 60's.  She also grew up in Los Angeles, with Jewish immigrant parents, and later spent time at UC Berkeley studying literature and dance before her father pushed her into the more practical career of teaching.  She had her wild years as a younger woman, but was shy and delicate in some ways, suffering from asthma and lacking self confidence.  I don't know whether she was introduced to Transcendental Meditation before or after marrying my dad, but it became a fixture and a point of stability in her life.  She says that it cured her asthma and gave her a confidence and a calm that she had lacked before.

My mom's meditations were a steady element of our life at her house many years later, as well.  For one hour in the morning and one hour in the evening, she would stay in her room meditating.  Besides an occasional reminder to be a little quieter during these times, my mom's meditation was not much of an imposition on our life.  Although we learned the technique of Transcendental Meditation and did occasionally meditate separately or together, there was never any pressure to practice this technique or to get involved in the heavier side of this Hindu derived new religious movement (which, during less generous moments, I might classify as a cult).  I did struggle to understand some of the philosophy and basis for the wilder claims such as the yogic flying and the Maharishi effect, but this was mainly out of an interest in finding common ground and to be able to be enthusiastic about some of what my mother believed and what grounded her.

At my mom's house, we usually all helped out with the cooking, and usually went grocery shopping together.  Having some digestive problems, my mother ate very bland foods.  Although she would offer her own food to us (rice and lentils or a soup of ground green vegetables she called "green soup") she knew that we enjoyed a broader set of foods and so would encourage us to cook these ourselves.  So we would shop together at a few local Organic markets in preparation for our meals.  I remember particularly enjoying cooking burritos and lasagna.

Thinking back on these years, the odd thing is that life at each house feels so self contained.  I feel like I had two separate childhoods.  I don't feel particularly negative about either house, but I just can't seem to visualize the whole thing as one piece.  I was either at mom's house, or I was at dad's house.  I adjusted myself after the transition.  But the sense of the worlds not mixing remained, and still remains today.

Today I find myself living in a different culture from the US, in a different country from the US, on the other side of a large ocean.  I adjust.  I find myself pretty easilly fitting into new surroundings.  I slowly but surely learn a new language.  But these questions about separation vs. integration remain.

I am brought to these contemplations as my trip to the US approaches.  I try to understand why I plan so little.  Why do I leave things so open?  Why am I so slow in responding to emails that ask me to articulate my plans?  My feeling is that its like diving into the swimming pool.  New rules will apply on the other side.  Once I'm there, I will find my way. 

Sunday, July 11, 2021

Artist Statement

I had to create an artist's statement along with a portfolio on https://www.callforentry.org/
So here it is:

I have been doing abstract painting for over 30 years. I am largely self taught, although I have attended several courses throughout my life. I am a physicist by training and profession and the painting has complemented this work throughout my education and career.

 

To me, painting is a playground where conflicts and disparate elements may be resolved visually. I draw a lot from the natural world, having grown up spending a lot of time in redwood forests of California, and since then in the Alps and now the Rocky Mountains.

 

My painting process is interactive. I start with certain shapes or colors and then I seek to integrate them into a coherent whole, iterating periodically, reevaluating as the work develops. Growing up in a divorced family, going between two different homes, painting provided a way to play with integration of elements that seemed to come from completely different worlds. Painting became a practice for me to find a vision of integration, or to at least practice with dissonance. I have mainly worked with acrylic paints which dry quickly and allow for multiple layers as well as blending.

 

My profession as a particle accelerator physicist leads me down long and narrow paths in my mind to understand subtle dynamics of relativistic particle motion and creation and evolution of radiation resulting from these high energy particles. I have recently been experimenting with integrating some of the equations from my work into the abstract forms in my paintings, attempting to find peace between the technical mind and the mind engaged in the human or natural world. I hope that my artistic work may have a broad resonance in the world today where humanity depends on highly technical systems that for many are inscrutable. Bringing some of the concepts and artifacts underlying our technical infrastructure into the human and natural world feels integrating for myself, and I hope could have a similar effect on others.

Saturday, April 10, 2021

Across the Ocean

    Hungary, Moldova, Ukraine, Lithuania,  These modern day countries during the 1800's up until 1917 were part of the Pale of Settlement. There were Jewish communities in each of them, still surviving from the original Exodus, not so much from Egypt to the Sinai Peninsula as from Judah and Israel to Babylon. A common thread held these communities together that slid back into time through the Talmud to the Mishnah to the Torah. 

    And there was another thread would connect the Jewish communities in these four cities. This thread would wind its way around the leaves, branches and trunk that would become my own family tree, leading to my being born in Santa Cruz, California, America in 1976.

    The Nasch family lived in the Hungarian city of Nagyv├írad, which later became the Romanian city of Oradea following the treaty of Trianon in 1920. Akos Nasch was born in a smaller town of Poklostelek (later known as Poclusa de Barcau), 40 km northwest of Oradea. The Bernsteins came from Lithuania, my great grandfather Herman from Vladislavov, then on the border of Russia and Germany. At the turn of the century, the Finegoods and Silberts lived in Bessarabian Shtetls in Ananyev, Kherson, and Odessa. They would soon be driven out by the anti-Semitism fueled blood libel leading to the Khishinev massacre.

    Nasch, Bernstein, Finegood, Silbert, these surnames for my grandparents form the trunk and primary branches of my family tree, leading eventually to my parents Patricia and Peter who would grow up in Los Angeles, California, America.

    The Silberts and Finegoods leave the hatred of Bessarabia in the early 1900's and resettle in only somewhat more hospitable lands of central Canada, arriving in Saskatchewan and Manitoba, where my grandma Mary would be born in the city of Winnipeg.

    Akos grew up and became a medical student, the first in his town to leave, having earned a scholarship at the university of Tours in the Loire region of western France. There he met Dorothy Bernstein at a Purim party a cold February afternoon. A spark was lit that day as they wrote each other letters, from initial furtive visits to growing love. The letter continued as Dorothy and Violet left Tours to Grenoble, and eventually traveled through Europe and then back to America with their famous father, the journalist and patriarch, Herman Bernstein.

    Meanwhile, the Finegoods and Silberts have started a store they manage during the cold Canadian winters. Mary Finegood meets Joe Silbert. She admires his piano playing and soon they are married. The families together encompassed close to 30 siblings. The Jewish thread now having crossed the Atlantic and spinning out new threads pushing forward into time through their three children, John, Andy and Patty.

    In New York, 1929, Herman's connections to Herbert Hoover have earned him the position of the US ambassador to Albania and the family sets sail back across the Atlantic to take up the post in Tirana, meanwhile leading Dorothy and Akos back together again having continued their courtship by letter in secret. Dorothy had come to call Akos by the name Nicky, and these letters, primarily in French became known later by Dorothy, as the Dorothy-Nicky  correspondence, a joke echoing the Willy-Nicky correspondence, uncovered and published by Herman a decade earlier, encompassing secret letters between the Czar of Russia and the Kaiser of Germany. Whereas the Willy-Nicky correspondence led to war, the Dorothy-Nicky correspondence led to marriage.

    

Tuesday, December 08, 2020

Finding the big picture

 

Regarding conflicts, often times the problem is that there's just not enough space and resources for all involved. When I think of old conflicts, such as the messy divorce and trajectory of my parents and step-parents, I try to imagine a larger space in which they exist.

I try to create enough space in my mind that each person can have their own cohesive existence. Each one of them has a story and is part of a family. I trace those families back to Los Angeles, Canada, Hungary, Armenia, Bessarabia and more.

There is immigration that is a new start, but there is also continuity in religions: Judaism and Christianity, artistic continuity of architecture, cultural traditions of cooking and languages.

There are tragedies both personal and on larger scales. The Jews and the Armenians. Pogroms and genocide. But drawing out even further, there are empires and nations collapsing and forming. 

Judea and Israel, Canaan. The Assyrian empire and the Seleucid empire. Biblical narratives of judges, then kings: first temple, then second temple, then collapse and diaspora.  Resistance to Christianity and tenacious survival via consistency of literature and practice.

Likewise, the Ottoman empire, growing then collapsing and forming Turkey. Armenians caught in between.

Drawing back this far, one sees a bigger picture, and perhaps some actions, while locally selfish and inscrutable at times, sit within a larger context that holds them and provides a certain kind of explanation.

Monday, November 16, 2020

Resolutions 1922, Herman Bernstein

 

This is the day of new resolutions. I promise myself to jot down a few lines in this book daily. Impressions, incidents, thoughts.

 

I have just returned from Europe to Sheffield. Europe- the madhouse of slaughter a few years ago- is now a madhouse of speculation and profiteering. Everybody is speculating there- old and young, rich and poor – from abject minister to cook – irrespective of race or creed.

 

The visa for America is the most coveted thing in Europe. People struggle and starve for it – people fight and lie – and sometimes die for it. “Self determination of nations” has created the need for a multitude of visas to the traveler in Europe.  People stand in line for days – paying high prices, maintaining large staffs of visa officials – people are happy when they get the stamp upon their passports – and then they are searched and scrutinized at the frontiers – they are roused at night, examined and cross-examined. But the experienced traveller quickly discovers that the whole affair is but a new source of graft for the underpaid petty officials, for conductor and frontier guards. Children often are heard crying that they and their parents can’t get visas. All Europe is visa-ridden. To return home- to Sheffield- to the peaceful, beautiful Berkshires now covered with snow- the golden sunbeams playing upon the bluish white mountains- what a joy! What a relief! Away from the turmoil of the profiteers from the plunders of the statesmen – from the artificial glamor of the “antics” and eruption of the conference, “movements” or reforms, and the clap-trap of world saviors.

Sunday, May 03, 2020

Responsible private behavior in a viral pandemic

I’m trying to figure out how to apply Kant’s categorical imperative to the present situation of viral pandemic. How should I behave such that I would be ok if everyone behaved in the same way as I do? I should also specify that although I hope that I won’t personally get covid-19, I think of myself as in the low risk group, so my own health is not my primary concern. (Of course, If I get very sick, this attitude would change quickly.)

To make it simple, I’d like to allow two types of behavior regarding care in minimizing spread of the virus. With the public (large numbers of people), I am very careful. I don’t go to a large gathering without a mask, shaking many people’s hands, hugging them, and generally sneezing and touching many surfaces over an extended period of time. When I go to the grocery store, I wear a mask and keep my distance. I wash my hands before and after (or wear gloves).

Next, there are a small number of people that I do not practice such a careful approach with. If I were quarantined with my family, that would be the model, but as I am by myself, I should be allowed a certain number of people to see that I have a higher chance of spreading or recieving the virus from. I want to behave in such a way that if everyone followed similar principles, the virus would stay contained and the number of cases would go to zero. Suppose we know the probability of spreading the virus publicly (p_pub) and the number of people I interact with in the public (n_pub). And likewise we know the probability of spreading the virus privately (p_priv) and the nunber of people we interact with privately. From our assumptions, n_pub >> n_priv and p_pub << p_priv. Suppose that for everyone, these numbers were the same (clearly not true, but fits with the Kantian thought experiment). If we know n_pub and p_pub and p_priv what is n_priv so that the global R_0, (the average number of persons infected per infected individual) is less than 1?

Friday, October 25, 2019

Talk at my thesis advisor's retirement


Thank you to the organizers, Zhirong Huang, Tor Raubenheimer, Yunhai Cai, and Naomi Nagahashi, for inviting me to participate in this symposium honoring the career of Alex Chao.

Alex was my PhD supervisor from 2000 to 2006.  When I first joined the PhD program in physics at Stanford in 1999, I had never heard of accelerator physics as a discipline and had not imagined that this would be my path.  I had studied math and physics at Reed College (a small liberal arts college in Portland, Oregon), and, in starting the PhD program at Stanford, thought that I might pursue condensed matter physics or possibly particle physics.

I had taken a year off after graduating from Reed, because initially, I didn’t get into the physics programs I applied to:  Princeton, Harvard, and Cal Tech, if I recall correctly…. I spent a year in Portland, working for Dr. Richard Crandall in a basement of a small house above Reed College called “The Center for Advanced Computation.”

This year, I learned how to program computers more rigorously for the first time, worked on some interesting algorithmic problems relating to (among other things), data compression for Pixar movies, and studied and improved my physics GRE scores, such that I now had a more respectable application, and was accepted to Stanford, along with Columbia University, and UC Santa Cruz.

To say a little more about my undergraduate experience, I initially heard about Reed because my father, Peter Nash, went there in the 1950’s planning to study medicine.  Like Steve Jobs, however, he didn’t finish at Reed. Instead, he took a year traveling around Europe, trying to be a writer and find his direction in life.  He finally returned to the US, finishing undergraduate education at San Francisco State University and going on to earn his MD at University of Southern California.

I was at Reed from 1994 to 1998, and I found it highly stimulating intellectually, although a bit unbalanced socially.  I enjoyed the universal humanities requirements, covering Greek and Roman history, literature, and philosophy.  And I took some more modern philosophy and literature courses as well.

I started at Reed as a biology major, thinking I would ultimately study mathematical biology, but the physics department was more flexible, and allowed me to take advanced courses earlier on.  I took electrodynamics, quantum mechanics, and particle physics from David Griffiths, a wonderful teacher and expositor.

As a senior, all Reed students are required to conduct original research in terms of a senior thesis.  All of the theses are then collected and displayed in a “thesis tower” in a actual tower atop the Reed College library.  I worked with Drs. Nicholas Wheeler of the physics department and Thomas Wieting of the math department.  It was Nick Wheeler who first gave me my thesis problem, asking the rather general question of what it means to move a physics system around in the world (a problem that would have many echoes with my later career in accelerator physics).  As a kid who grew up with divorced parents moving between houses twice a week, this problem had a certain emotional and psychological appeal to me.  I simplified the problem to be a single particle moving in a potential energy function and asked what happened to that particle as the system was moved from point A to point B.  This problem led me to issues such as adiabatic invariance and pushed me to read VI Arnold’s classical mechanics text that defined action-angle variables for a variety of physical systems.

In my Reed thesis, I treated the Foucault pendulum, a clock on a rocket ship, and transport of a central Coulomb potential such as a hydrogen atom.

Although I was satisfied with what I accomplished in this thesis, I was so focused on this work that I failed to get into graduate school.  As mentioned, however, after a year working with Dr Crandall, I was ready to start at Stanford.

At Stanford, one has a full year to find a research group and I started in my first quarter in experimental particle physics.  I was not very satisfied with this work and continued to explore my options.  Sometime during that quarter, there was an event where all the different research groups were represented, and one could ask questions and find an appropriate group.  I spoke with someone at this event and described my undergraduate research.  They suggested that I talk to Ron Ruth at SLAC and consider accelerator physics.  I had little idea what that might involve, but I followed up on this.  I talked to Ron and he arranged that I give a talk on my undergraduate work in the ARDA BIG (Beam Instability Group) meeting.  Alex was there at this meeting and we started to talk about working together after that.

The first problem that Alex gave me was a two macroparticle model for the head-tail instability.  I like that it was something I could get to work on immediately and feel like I might make a contribution to the field.  He showed me data about the so-called “sawtooth instability” and suggested a simple model may be able to explain it.

I worked on a number of such “small” problems with Alex before finding a larger thesis project to develop.  I worked out analytic expressions for fringe fields for a solenoid, and though about whether one could observe quantum effects in beam dynamics by analyzing the evolution of the Wigner function.  These problems all planted seeds that I would later return to, with other instability problems, and use of the Wigner function to describe partially coherent synchrotron radiation.

I remember the day that Alex had an idea that was to form the foundation for my thesis work.  He drew a simple diagram on his white board with two particles performing Coulomb scattering.  Given the initial positions and momenta of the particles, one could compute the change in momentum resulting from the scattering.  Now apply this to al the particle pairs in the beam distribution, and one has a new way to analyze intrabeam scattering.  By forgoing the use of cross sections, and just computing classical orbits directly, there was a hope that we might be able to formulate the IBS growth rates in a way that avoided the logarithmic divergences of the usual approaches.

By considering the time to the distance of closest approach t_min and limiting the scatterers in a time Delta t to t_min < Delta t, I was able to derive expressions for IBS diffusion and damping coefficients that did not have the logarithmic divergence.  I was even able to reduce the 12-D integral to a 2-D bounded integral in the case of a Gaussian distribution.  So the result could be computed without too much difficulty!  I showed how this formulation could be reduced to all other IBS formulations that I knew of.  By comparing to results such as those of Piwinski and Bjorken-Mtingwa, one could “derive” the Coulomb logarithm rather than have to put it in by hand with an ill-defined b_min and b_max cut-off.

Through the whole process, Alex was always available and always able to give just enough feedback to encourage me to continue and occasionally to discourage me from following unpromising lines of research.  Piece by piece, and conversation by conversation with Alex, the work came together.  [PAC PAPER]

Now that we had a general approach for deriving the diffusion and damping in IBS, I needed to better understand the Gaussian beam distributions in electron storage rings.  These distributions arise by equilibrium between diffusion and damping from synchrotron radiation.

Alex proposed that I look at what happens near a synchro-betatron coupling resonance, particularly when the coupling term came from dispersion at an RF cavity, or due to a crab cavity, which is a topic of interest in colliders, creating so called “crabbed collisions “.

I tried to formulate the problem using perturbation theory, considering the coupling term as small.  It toom me some time to realize that working near a resonance means that one needs to do degenerate perturbation theory.  On resonance, two eigenvalues are equal, and on needs to find the right way to break this degeneracy and find the “good” linear combinations of eigenvectors.  Using the tools of degenerate perturbation theory in quantum mechanics that I had learned from David Griffiths at Reed but applied to symplectic matrices instead of Hermitian operators from QM, I could solve this problem.  After finding the expressions for the eigenvalues an eigenvectors near resonance, I included the damping and diffusion from synchrotron radiation to find equilibrium eigen-emmitance and beam second moments.

Of course, everyone has heard of Alex’s so-called SLIM formalism.  My contribution was to find analytic expressions near resonances.

The last piece was to add on the effect of IBS to get a theory that included coupling and IBS together.  I wrote all this up in my thesis. 

I want to take a moment to acknowledge some of the other people besides Alex who helped me with my PhD thesis.  First, and foremost, I’d like to acknowledge Juhao Wu.  It was really a pleasure to work with him, and he helped a lot both with talking through the concepts, and with implementation of the equations to get concrete numerical results out of it. 

Overall, I enjoyed interacting with all the members of the Beam Instability group in ARDA at SLAC.  Notably, Karl Bane also helped with the work on IBS and I had many helpful discussions with Sam Heiffets, Ron Ruth, and Gennady Stupakov.

Another memory I have of this time is a period of at least 6 weeks when my main activity was trying to track down a factor of 2 in the overall normalization of the IBS formulas.  I’m appreciative to Alex for letting me move along at my own slow pace, with confidence that I would finally solve the given issue in a finite amount of time.

I finally finished my thesis in 2006 and defended it to achieve my doctorate degree!

I applied for post-doctoral positions at this time and I recall that I was debating between working with Alex Dragt at University of Maryland on abstract beam dynamics and other mathematical topics, and a position in the design team for the NSLS-II at Brookhaven National Lab.  Although Alex Chao has the highest respect for Alex Dragt, he encouraged me to get involved with the more practical beam dynamics work at NSLS-II, and after some reflection, I followed this advice. 

At NSLS-II, I worked under the direction of Johan Bengtsson, moving from linear dynamics to non-linear dynamics, computing dynamics aperture and Touschek lifetime with errors for the NSLS-II lattice.  Although I ended up disagreeing with Johan on many things, I’m very thankful for how he pushed me to include so many realistic effects in my beam dynamics calculations.

In a way, this approach I learned from Johan was the opposite approach I had used during my PhD work with Alex, in which one seeks simple mechanisms underlying complex dynamics.  I came to appreciate that for machine design work, both approaches have their place.  I later worked under Sam Krinsky, doing both practical simulations and some theoretical work as well.

At the end of my post-doc position at NSLS-II, I found two options for my next position.  The first was in Campinas, Brazil, working on the design for the new Sirius light source.  The other position resulted from a visit from Pascal Elleaume from ESRF in Grenoble, France.  I emailed him asking about a position, and they opened one up, and I had an offer to work there with him and Laurent Farvacque.  I decided to take the position in France.

I spent 8 years in Grenoble at the ESRF first as a post-doc, and then as a scientist.  I had an opportunity to work on many electron beam dynamics topics, from collective effects to non-linear dynamics, and even spin dynamics via resonant depolarization.  In addition, one of my main interests while at ESRF was working with beamline scientists to understand their experiments and the relation to the electron beam dynamics.  In addition, I met experts on x-ray optics and learned about ray tracing and wave front propagation through x-ray beamlines.

I really liked the broad range of science being done on the x-ray beamlines and enjoyed explaining how the electron beam dynamics worked.  I was amazed to find out that very few beamline scientists knew even basics about accelerator physics and beam dynamics.  I prepared a series of lectures at ESRF with the help and encouragement of Luigi Paolasini, and explained to beamline scientists and other technicians at ESRF how radiation damping and diffusion works, about betatron and synchrotron motion and about beam growth and loss mechanisms such as IBS, Touschek scattering and collective instabilities driven by impedance.

I felt I was carrying on the tradition I had learned from Alex in which accelerator physics and beam dynamics is seen as a topic of great interest in its own right, with all the needs for development and academic rigor of any other physics domain.

After 8 years at ESRF, my time in France came to an end, and I decided to return to the US.  I found a position at RadiaSoft in Boulder, Colorado and have been working there for the past 2 years.  My work at RadiaSoft continues several threads that I have followed in my career in accelerator science.  One strong interest I developed throughout my several different positions was in ease of use issues with beam dynamics and x-ray optics codes.  At NSLS-II, I worked with the code Tracy, managed by Dr. Bengtsson.  At ESRF, I worked with Accelerator Toolbox (AT), first developed here at SLAC by Andrei Terebilo.  In both cases, I sought to develop an open source collaboration for the software.  There are so many codes, and each is very challenging in its own way.  Finding ways to develop collaboration and improve documentation and ease of use of these codes is something I believe I can continue with through my work at RadiaSoft.  At the same time, I continue with some of the challenging accelerator science, studying topics such as polarization evolution and preservation in electron ion colliders and magnetic undulator design and x-ray transport in synchrotron beamlines.

I would never have followed this journey through high energy, short wavelengths, and fantastic complexity manifesting out of simple mechanisms if I hadn’t had the good fortune to encounter and work with Alex Chao in my career.  And thus, I add my own story to all the others we hear today to get a glimpse of the impressive legacy that Alex has given us and how his may contributions and academic approach to accelerator science and beam dynamics will continue to bear fruit in future generations.  Thanks for all this, Alex.  And thanks to all of you today for listening to me tell my story!