(A PDF version of my CV is available here)
Our understanding of what parts the universe is made of and how they all interact with each other is detailed in a theory called the Standard Model (SM). This is one of the most precisely tested theories in science and (despite our hopes of finding new physics) has been confirmed to a stunning precision by nearly all laboratory experiments to date. However, the theory is still incomplete, unable to describe dark matter or even gravity. All this strongly hints at the existence of new as of yet undiscovered particles beyond the Standard Model (BSM).
We have tried searching for these particles for a long time, however since the Higgs discovery in 2012 we have not yet conclusively discovered any new particle. However, one key assumption that has been built into our searches at the LHC until somewhat recently is that whatever new particles we are searching for decaying instantly after they are made, and that the only things that make it through the detector are the decay products which should point back to the location of the proton-proton interaction in the centre of the detector.
However, why should the new particles we search for have such short lifetimes? Many regular standard model particles don’t have such short lifetimes. In fact many mechanisms, such as weak couplings or small mass differences between the particle and its decay products, or a decay via an off-shell mediator (i.e. some particle in the decay process is forced to have a virtual mass very far from its normal mass) can cause particles to have long lifetimes. Depending on the type of particle and decay, different long-lived particles (LLPs) will have different signatures in the detector.
I specifically focus on displaced vertex (DV) signatures, which are the case where the “new” particle lives long enough to travel somewhat through the pixel inner detector in ATLAS before decaying into many tracks, where some number of them are charged. This looks like a vertex of tracks in the detector that is displaced from the proton-proton collision point, hence the name. There are countless BSM models that have been developed by theorists trying to propose what could be the missing piece to the standard model, and quite a few do predict new long-lived particles that create displaced vertex signatures. In particular, supersymmetry (SUSY) with certain parameters, and the Higgs-portal model.
More specifically, I had contributed significantly to the DV+Jets analysis during my first few years in many different core aspects of the analysis and am now analysis contact (leader) of the DV+MET Full Run 2 analysis where our very international team overcomes the many scheduling issues that come with having everyone in the full gamut of timezones to search for new physics together.
The inner tracker of ATLAS is getting an upgrade (ITk) for the high-lumi LHC (Run 4). Part of it will comprise silicon semi-conductor strip sensors. These thousands of sensors need to be tested for quality control (QC) before being put into the detector. Technicians across 9 institutes around the world work to produce data for quality control tests. However this large amount of raw data needs to be processed automatically such that an evaluation on whether or not the sensor is suitable or not. Furthermore, results need to be centralized in an existing database, as well as compiled into reports for technicians and project leaders to use in both understanding, debugging, and communications with the suppliers.
I designed the software framework that is currently being used by the collaboration to do this and was the main developer for this, along with contributions from Dominic Jones (Cambridge ATLAS 2019).
I of course also did work in the cleanroom doing some sensor QC tests myself.
I supervised (the Cambridge version of TAing but with much fewer students) the Part IB (2nd year) Mathematical Methods, Part II (3rd year) Particle and Nuclear Physics, and Part III (Masters) Particle Physics modules.
As I started my PhD with no particle physics background, and found many resources confusing and inaccessible, I have along my learning and teaching journey been writing a textbook aimed at trying to get other students that were in my position with basic calculus knowledge to working particle physics knowledge. Although it is still a work in progress, it has already been a very useful aid in my own teaching as a good reference for when students ask certain questions. I will try to publish completed chapters or sections under Resources when possible.
Outreach is one of the most fun parts of what I do.
I am a mentor at the Hong Kong Academy for Gifted Education.
I have also given talks for the Congrès des Deux Infinis (high school students in La Réunion), the Tel Aviv University Future Scientists CERN Program (fast-tracked high school students taking university courses), and the Gates Teach-a-Thon (a pandemic Zoom event for middle school students in the UK).
I have also been a moderator for the CERN International Physics Masterclasses and a first-round evaluator for the Beamlines for Schools program.
I have also previously volunteered at the 2019 Intel ISEF, and at the Hong Kong New Generation Cultural Association Science Innovation Centre.
At CERN I am a tour guide for the visits service and the ATLAS secretariat for various visit points including the ATLAS cavern for both general public and internal tours.
A 5-year bachelor’s combined internship/research program under the Electrical Engineering, Chemical Engineering, and Chemistry Departments.
I had received a very broad STEM foundation with training in circuits, control systems, photonics, nanoelectronics, biochemistry, nanofabrication, numerical methods & multi-physics simulations, material & polymer science, statistical thermodynamics, nanotoxicology, and much more.
I had also done an exchange at the Hong Kong University of Science and Technology (Sept.-Dec. 2017).
My research experience (4 month terms each) is listed below. The Nano-Robotics group was not a research term but rather a student design team I was a part of throughout the study terms.
Does anti-matter fall up or down? We have no idea. I was part of a small project to try to figure this out.
The idea was to do this by dropping muonium (positive heavy anti-muon with an electron orbiting it). (We’d like to drop something neutral as the gravitational force is several orders of magnitude weaker than the electromagnetic force so we need to be not be sensitive to noise. Dropping an anti-muon vs an anti-proton for example also has an advantage, as most of the mass of the anti-proton comes from the binding energy of the gluons rather than the actual anti-particles it is made of, whereas the anti-muon is just one fundamental anti-particles).
Anti-muons are produced in the beam at PSI. We need to 1) stop them in material to allow them to combine with electrons 2) cool down and collimate so they aren’t moving in random directions that could affect the measurement 3) but have them be able to escape the material so that we can actually measure them.
This would mean shooting the anti-muons at something like a carbon nanotube forest coated with superfluid helium inside a cryostat. We needed to characterize the beam that was coming out of this thing, and designing this characterization system such that we could extract beam properties was the bulk of my project.
Of course, anybody who was worked with muons know they don’t live very long, and things don’t tend to fall very far in 2.2 $\mu$s. We need to use some sort of interferometry, and so another aspect of my project was the preliminary trials in doing quantum Bohmian mechanics simulations to try to see how we would simulate this.
I was a program manager on a consumer Microsoft Office app, doing some UX design. The bulk of my work, however, was on designing the team’s internal workflow for dealing with customer feedback and consequently backlog prioritization. Due to the team structure I also did development work as well in natural language processing for classification as well as implementing existing convolutional neural networks for applications in input recognition.
This has surprisingly been the experience that has probably helped me the most, teaching me skills in how to formulate “good” questions, thinking in terms of the purpose of the things we do, as well as putting yourself in the mind of the user/receiver (skills which I have very evidently not put to good use in my very quick and dirty temporary bodging together of this website).
When you cool bosonic atoms to just above absolute zero, a new state of matter can emerge: a Bose-Einstein Condensate (BEC). This occurs since the “wavelength” of an atom will be inversely proportional to its speed. Since temperature is just the speed of the atoms, at a low enough temperature all of the atoms wavefunctions begin to overlap and so they all act together as one giant coherent wave.
I developed a Raman laser system designed to rapidly switch the scattering length of the BEC with the goal of investigating the weak-collapse phenomenon.
I also did some simulations in trying to help understand the Bloch-Siegart effect.
In collaboration with a start-up based at the Harvard Business school, my supervisor and I were the only researchers tasked with designing and fabricating the photonic/plasmonic nanotechnology behind the biosensor product.
We had tried many different possible solutions, and I had gained experience in hydrogel synthesis, colloidal crystals, plasmonic systems, photonic crystals, actuating microfins, as well as being trained in a wide variety of micro- and nano-fabrication and metrology characterization techniques at the Centre for Nanoscale Systems cleanroom. I also did photonic simulations in Lumerical FDTD and from scratch.
Lenses work by having a different thickness of glass at different parts of the lens. Since light slows down in glass, and since light is a wave, this means that the waves of incoming light at different points of the lens will be at different phases when they leave the lens. One can think of this phase difference across the lens as what is causing the light to bend and focus. However, if you have nanostructures around the size of the wavelength of light, you can do crazy things with light, including imparting whatever phase difference you want.
This means that, with just some nanostructures on a thin flat glass substrate, called a “metasurface”, you can do almost anything you want with light.
To correct for chromatic aberration, you typically need very thick glass doublet lenses, which aren’t suited for certain applications where you need very non-heavy things like satellites. So you can replace this all with a metasurface that just bypasses the chromatic aberration in the first place. I worked on such a project as well as making colour holograms and chirality-separating lenses.
The dimensions and locations of the nanostructures need to be determined via simulation, which was my primary responsibility, done using Lumerical FDTD, before exporting the design to be fabricated in the cleanroom, after which we could test the device.
Advisor (2017-2019), Technical Director (2017), Team Lead (2015-2016), Member (2014-2015)
At the time, ICRA hosted a micromobility competition, where research teams from around the world could develop microbots and come to compete in challenges. We were the only fully undergraduate team that competed.
We had several sub-teams working on various robot ideas ranging from well-established to very experimental. After starting out as a team member on a mercury-droplet-based robot, later leading that team, and then finally directing the full research group, I equally worked on setup experimentation and microbot/field fabrication as well as giving technical guidance to the various sub-teams.
Due to the complete mess that is the above, I have resided in 6 different countries and visited 51 UN member states (plus approximately 10 other territories that people would normally consider countries).
My mother tongue is English, however I also speak French as I had done most of my schooling prior to undergrad in French. I am learning German, and have previously learned to a very elementary level the languages from the countries I have resided in. Linguistics, particularly phonetics, phonology, and morphology have accordingly grown to become one of my side interests.
Prior to my undergrad I had trained as a classical pianist, obtaining an Associate Diploma (ARCT) in Piano Performance as well as Elementary Piano Pedagogy of the Canadian Royal Conservatory of Music.
I enjoy hiking, skiing, and coxing (the person in a rowing boat team that doesn’t do any exercise but steers and yells at the people doing the actual exercise), and enjoy writing. However my favourite hobby is exploring new places and experiencing obscure traditional cultural festivals.