Dark Energy Spectroscopic Instrument (DESI)

meet a DESI member

Duan Yutong

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What is your position or role in the DESI project?

Having been a DESI member as a graduate student for four years, I became a postdoc at Boston University Physics Department months ago, working on instrument commissioning, primarily the focal plane system.

Where were you born?

I was born and raised by middle-class parents in Tianjin, China, a harbour city next to Beijing. I came to the US in 2009 to attend a liberal arts college hoping to enjoy greater freedom and a more nurturing academic environment. In 2013 I moved to Boston for graduate school, where it has become my second hometown.

Where do you live now?

I have been living in the Boston area for over six years and really enjoying the life here. It is intellectually stimulating and culturally vibrant. The diversity in New England is impressive, always possible to meet people with similar interests or visions. There is a world-class symphony orchestra as well as an abundance of shows of nearly all types. Massachusetts prides itself on carrying the spirit of America from the colonial past through the civil war to the present day, and the New England states have been taking the lead in defining the structural reforms this country needs in order to evolve and stay in the economic, technological, and moral high ground on the world stage. There is also a special sentiment to be found in the nostalgic English names of local towns.

What do you do as part of DESI? (both generally and day-to-day activities)

Over the past four years, I have worked on a variety of things within or related to DESI involving very different skills which all become part of a physicist’s bag of tricks. I started out helping build ProtoDESI at Berkeley Lab, a proof-of-concept focal plane instrument consisting of only 3 fibre positioners. A fibre photometry camera (FPC) was installed at the output ends of the optical fibres in place of spectrographs, and I characterised the FPC and analysed its data after a successful run at KPNO.

Then Boston University’s machine shop (Scientific Instrument Facility, SIF), with its proven track record and unbeatable price, got the contract to fabricate the DESI focal plate structure, on a tight schedule and within micron-level tolerances. My advisor Prof. Steve Ahlen and I worked hard with the machinists to refine the quality of the petals, found the right coating, and measured 100% of the critical dimensions of each petal on a Zeiss CMM with an automated CMM programme we developed together with Zeiss.

These focal plane metrology data were instrumental in our later alignment of the focal plate structure, as each petal is machined slightly differently and needs to be individually adjusted when bolted to the integration ring. At the end of the alignment, my colleagues and I achieved around 99.9% projected optical throughput using another CMM at Berkeley Lab, meeting the micron-level precision requirement and science requirement of the project. I was also an active observer for MzLS of the Legacy Surveys.

Having completed and delivered the focal plate structure for integraiton with the robotic fibre positioners, I started working with Prof. Daniel Eisenstein at the Harvard-Smithsonian Center for Astrophysics on a halo occupation distribution (HOD) forward-modelling project with significant implications for surveys like DESI. This was a terrific opportunity for me to embrace the theoretical and computational side of observational cosmology. We employed high-fidelity N-body cosmological simulations, created a number of mock galaxy catalogues, and determined the systematics due to the HOD parameters assumed in measuring baryion acoustic oscilaltions (BAO), a key signature in large-scale structure.

Recently I have been working on petal assembly testing, positioner calibration, and essentially software development for instrument control, monitoring, and analysis. My day-to-day activities include attending telecons, coding, running focal plane tests, supporting DESI commissioning tasks, and travelling to KPNO for day and night shifts from time to time.

What is the most interesting or exciting thing about DESI (and/or your job and/or astronomy in general)?

DESI has great potential to make the next big discovery in cosmology and particle physics. 35 million galaxy spectra is an unprecedented order of magnitude for this sort of data, only achievable with the state-of-the-art DESI positioners. It is extremely exciting and fortunate for me to be able to contribute to this project. I don’t have to describe how or why fundamental physics is interesting or exciting. To me DESI is the perfect blend of cosmology, particle physics, and astronomy, and my work has had the right balance between software and hardware.

What do you do for fun?

There is a vast universe of fun to be had in books, music, and films. They not only provide fun, but also make me relax and contemplate. I am also an amateur music producer, racing driver, and lapsed pianist. In the old days I used to be a cyberathelete playing competitive Counter-Strike and e-sports commentator.

Michael Wilson

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What is your role in the DESI project ?

In the past, I’ve largely taken highly polished versions of data and attempted to draw definite conclusions about our Universe, in particular whether we understand gravity as well as we think we do.

For DESI, I’ve gotten closer to the dark art of creating this data and tried to better understand how this might affect the conclusions we can draw.  On a day-to-day basis, I mostly plug gaps by trying to solve the latest problems, which is great.  I enjoy the freedom and learn a lot, but anticipate a more coherent role in the future.
 
Where were you born?  Where do you live now ?
Glengormley, Northern Ireland.  Slightly different from my current abode of Berkeley, CA!
 
What would you say is the most interesting or exciting thing about DESI?
I’ve never been this close to a telescope before so everything is new.  The people are great and my primary motivation is what we will learn about the birth of the Universe.  It’s fantastic that we can say anything at all.  I confess that I also spend a lot of time thinking about what we might do better next time around.
 
If you were not a scientist, what would your dream job be?
Likely something soccer related.
 
Any advice for aspiring scientists?
Get involved early and ask around.  There’s often a snowball effect and you won’t know where you will end up.
 
Finally, what do you do for fun?
Surfing, sailing, cycling and soccer.  Not necessarily in that order.  I’m also a budding wood working enthusiast.

 

 

Tammie Lavoie

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What is your position or role in the DESI project? 
Safety Manager for Kitt Peak/on-site DESI

Where were you born?
Hanover, NH

Where do you live now?
Arizona City, AZ

What do you as part of DESI? 
I try to make sure everyone has what they need for safety equipment, as well as, review procedures and plans to make sure that safety concerns are addressed.

What is the most interesting or exciting thing about DESI?
For me, the most interesting thing is working with a diverse group of people and watching how well they all work together as a team.  It has been a learning experience to help meet the needs of the various folks working at Kitt Peak.

What do you do for fun?
My husband and I are both Hot Air Balloon pilots – so we have fun flying our balloons in various locations throughout the world and meeting people from all over.  It is so much fun to watch a smile come over someone’s face during our flight.

James Farr

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What is your position or role in the DESI project?
I’m a 3rd year PhD student at University College London (UCL), and have been an active member of the Lyman-alpha working group in DESI for the last 2 years or so.

Where were you born?
I was born in the UK, about 40 miles south of London. I grew up in the same area, in a small village surrounded by countryside – I love going back to visit my parents there and going for long walks in the hills.

Where do you live now?
I now live in London itself, close to UCL. It’s not that far from where I grew up but it feels like a completely different world. Sometimes it’s great to be in the heart of a city like London but sometimes a bit more peace and quiet is nice too!

What do you do as part of DESI?
Within DESI I’ve been working on making mock datasets for the Lyman-alpha working group. These are essentially very computationally-efficient simulations which are designed to produce “synthetic” versions of DESI’s Lyman-alpha survey which we can then use to carry out a number of different tests. In particular, we use them to make sure that our analysis methods are not biased, and to understand the impact that systematic errors can have on our measurements.

What is the most interesting or exciting thing about DESI?
DESI is exciting for so many different reasons, but I find the global nature of the collaboration particularly exciting – when we have our collaboration meetings, it’s like a big family that’s spread all over the world coming together again. I also find the instrumentation side of things really fascinating, and the sheer number of hours that have been spent building all of DESI’s component parts blows my mind!

What do you do for fun?
In summer I try to get outdoors as much as possible and love playing all kinds of sports – cricket is a particular favourite. When the weather closes in for winter, though, I’m very happy to stay warm and dry indoors with a good book or film!

Steve Kent

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What is your position or role in the DESI project?
I am a senior scientist at Fermilab.  I am responsible for a program called “PlateMaker” that is part of the instrument control system.

Where were you born?
I was born in the town of West Orange, New Jersey, where Thomas Edison had his laboratory and built the first movie studio.

Where do you live now?
I live in the town of Geneva, Illinois, close to Fermilab.  It is a scenic town with many shops, restaurants, bike trails, and an authentic Dutch windmill.

What do you do as part of DESI?  The PlateMaker program maps the positions of galaxies on the sky to the DESI focal plane and tells the fiber positioners where to move. Because the DESI corrector introduces a large amount of distortion, the mapping
requires understanding the corrector properties to high accuracy.  While the corrector was being fabricated, I was part of the optics team, evaluating the impact of things like glass homogeneity and polishing errors on our eventual ability to accurately position the fibers.

What is the most interesting or exciting thing about DESI? You never know where your work will lead you.  In order to model distortion patterns in the corrector, I developed some new mathematical techniques that turned out to be similar to those used to analyze the microwave background polarization and gravity waves.  I wrote this up as a journal paper, and it is the second paper to be published by the DESI collaboration.

What do you do for fun?
I enjoy hiking, “peak-bagging,” and other outdoor activities.  I also spent time trying to predict the location of where Malaysian Airlines Flight MH370 disappeared (not yet found).

Srivatsan Sridhar

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What is your position or role in the DESI project?
I am a postdoctoral researcher at the Korea Astronomy and Space Science Institute.
My main research topic is large-scale clustering analysis, with a special focus on Baryon Acoustic Oscillations (BAO).

Where were you born?
I was born in Madras (now Chennai), the capital city of the state of Tamilnadu, in India.
Fun fact: The Marina beach in Chennai is considered the world’s second longest urban beach !

Where do you live now?
I currently live in Daejeon, which is South Korea’s fifth-largest metropolis.
Fun fact: Daejeon has earned it’s name as “Asia’s Silicon valley”.

What do you do as part of DESI? The DESI part of my work involves analyzing the large-scale clustering from DESI like simulations. Each object that will be observed via DESI will be assigned a “priority”. I am, in particular, trying to find out the effects that these “priorities” will have on the large-scale clustering. I am also working on trying to recover the BAO signal from photometric catalogues and compare it’s accuracy with the same obtained from spectroscopic catalogues.

What is the most interesting or exciting thing about DESI? From my perspective, as a junior scientist, being part of DESI gives me the opportunity to meet and discuss my work with many veterans and influential people from my field. From a scientific perspective, the fact that DESI will be covering 14,000 sq degrees and going to deeper redshifts gives all cosmologists a hope that the influence of dark energy on the expansion history of the Universe can be studied in more detail than ever before.

What do you do for fun?
I am an avid football (my fellow Americans, it’s not soccer!) and cricket enthusiast. Hindu philosophy and archaeology are some of my other interests.

Jessica Aguilar

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What is your position or role in the DESI project?
I’m a Manufacturing Coordinator for the mechanical engineering department at Lawrence Berkeley National Laboratory and I currently support the DESI fiber assemblies, positioners, petal, and science cable splicing full-time.
Where were you born? 
I was born in Dallas, TX where I lived my entire life until moving to California.
Where do you live now?
I moved to California in 2014 and I live in Emeryville (right next to Berkeley and Oakland).
What do you as part of DESI? (both generally and day-to-day activities)
For all of the assemblies I cover I make sure procedures are documented, people are trained, and quality checks are in place. Daily I create work assignments for the manufacturing team to meet our schedule requirements.
What is the most interesting or exciting thing about DESI (and/or your job and/or astronomy in general)?
The range of assemblies I support means there is always a new challenge. I’m very excited about the eventual science this complex instrument will yield.
What do you do for fun? 
For fun I enjoy cooking, and being out in nature spotting birds and animals while hiking.

Alma Xochitl Gonzalez Morales

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What is your position or role in the DESI project? I’m a junior researcher at the University of Guanajuato. I was recently appointed to be co-chair of the Lyman-alpha working group.

Where were you born? I was born in Metepec, a small town in Estado de México in  México country. This town is nowadays considered a “Pueblo Mágico” (Magic or charming town)

Where do you live now? I’m now based at León city in the state of Guanajuato. It is very close to Guanajuato, one of the most beautiful cities in México. Interestingly León, and Guanuajuato,  host many international events annually, like a Ballon festival, the Rally, and the Cervantino, just to mention some.

What do you as part of DESI?  As co-chair of the Lyman-alpha WG I’m starting to help coordinate the WG tasks.  I also test and help to improve some of the code used in the WG. For example, I’ve been working with  the code that will be used to determine the quasar redshifts, using it in simulated quasars, where we know the truth, so that we can know how well this codes performs. I also help graduate students, mostly from  the University of Guanajuato, to develop their projects within DESI.

What is the most interesting or exciting thing about DESI? For me the most intriguing aspect of astronomy/cosmology is the nature of Dark Energy and  Dark Matter. Contributing to know more about this two mysterious components of our Universe is just astounding.  Even though DESI is mostly focused on Dark Energy (as the name says so), the gathered information will also be very helpful to understand Dark Matter. Now that I’m closely following the status of the project I realize how much work is involved, and that is truly a huge effort from many people. I’m so excited about all the science and knowledge that is being developed every day. 

What do you do for fun? I walk my dogs, morning and afternoon. I enjoy having BBQs and cooking  at home, specially if we have friends over. I’m really interested in the popularization of science, for girls mostly, so I dedicate some of my free time to a community, where we organize and give small workshops, talks, and  science shows. I hope some of them in the future will become scientists.

Charles-Antoine Claveau

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What is your position on DESI? I am a PhD student at CEA Saclay working on two aspects of DESI project, namely the selection of the quasar targets as well as the integration and testing of the cryostats fitted to the spectrographs.

Where were you born? I was born in a town called Montluçon in central France.

Where do you live now? I currently live in the south of Paris, not far from my workplace.

What do you in your position on DESI? I work on the selection of quasar candidates, the more distant objects that will be observed by DESI, based on their photometry properties by making use of machine learning tools. I am also in charge of developing an optical bench in order to validate the accuracy of the positioning of the CCD sensors mounted within the crysotat vessels. Basically, an array of microlens is used to project very precisely a grid of spots on the CCD. Then, we are able to infer the possible misalignment of the CCD according to the observed distortion of the grid of spots.

What excites/interests you most about DESI? As a PhD student, DESI is a great opportunity to get a comprehensive overview of a large-scale science project conducted within an international collaboration. Moreover, my thesis related to DESI gets me involved in activities covering several disciplines ranging from data analysis, computer simulation to optics and mechanics.

What do you for fun? I like going back to my beautiful home region, in Auvergne, to see my family and my friends, do mountain hiking and biking and enjoy the local gastronomy.

Christopher Manser

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What is your position on DESI? I am a junior scientist in the DESI collaboration and part of the Milky Way Survey group. My current role is to produce software that will help calibrate the spectra that DESI collects by using stellar remnants known as “white dwarfs.”

Where were you born? I was born in a town called Sidcup in the United Kingdom.

Where do you live now? I currently live in Coventry in the United Kingdom, and work at the University of Warwick (which is in Coventry, not Warwick!).

What do you in your position on DESI? I work with the Milky Way Survey and the Data team to use white dwarfs (the cores of dead stars once they finish fusing Hydrogen and Helium) to help calibrate the spectra that will be obtained by DESI. These white dwarfs have relatively simple spectra, which make them great calibrators. This involves writing a lot of code and analyzing simulated DESI observations to ensure we have the best calibration possible!

What excites/interests you most about DESI? Doing research in astronomy has given me the ability to travel to amazing places to collect data, such as the island of La Palma in the Canary islands, or Kitt Peak to observe at the Mayall telescope. My research interests are mostly involved with white dwarf planetary systems. It is thought that up to half of all of these stellar remnants will still host planets, and we can use these systems to learn about the composition of asteroids and comets from other planetary systems. With the help of DESI, we will find more of these systems, and answer questions such as: What will happen to the solar system when the Sun runs out of fuel? Are the rocky bodies in our solar system standard or unusual?

I think one of the most interesting parts of DESI is the focal plane, with over 5000 fiber robots that will be automatically repositioning themselves while avoiding each other to allow us as observers to efficiently observe millions of sources in the night sky.

What do you for fun? I enjoy playing a lot of games: Video games, board games, Dungeons and Dragons! I also like to play Go (you may have heard of AlphaGo), practice in power-lifting, and have recently started using “perler” beads to make pixel art!

Richard Joyce

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What is your position on DESI? I am the telescope scientist for the Mayall Telescope on Kitt Peak

Where were you born? Wilmington, Delaware (the First State!)

Where do you live now? Tucson, Arizona (since 1973)

What do you in your position on DESI? In general, I have been involved in the Kitt Peak side of the DESI project, working on requirements and interfacing to ensure that DESI will fit on the telescope as planned.  I have participated in numerous reviews at Berkeley (my graduate school alma mater) as part of this work.  As the Mayall telescope scientist, I have been involved in the many upgrades we have made to the telescope and building to meet the operational requirements for the success of DESI.  More recently, since we have begun the actual deconstruction and installation part of the program, I work as one of the rotating “shift supervisors” at the Mayall telescope, keeping an eye on progress, safety issues, and taking pictures to document the process.

What excites/interests you most about DESI? Growing up in a rural area with (at that time) dark skies, I was always interested in astronomy.  From a professional viewpoint, as an experimental physicist and (now) instrumental astronomer, I enjoy building things and making them work.  The process of selecting an important scientific topic, designing an approach to attacking the problem, and then designing, building, and making the instrument work is a challenging and often frustrating process, but enormously satisfying when the plan comes together.  DESI is the largest project I have been involved in, and it has certainly had its share of challenges and frustration, but seeing the parts arriving and being assembled gives a real feeling of satisfaction and anticipation of some great science when DESI is up and running.

What do you for fun? A lot of my off time is spent walking the dogs through the desert and working around the house.  We enjoy traveling to visit our relatives, most of whom live on the East coast.  As a lapsed airplane pilot, I may resume that activity should I ever decide to retire and have more time on my hands.

 

Tami Blackwell

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Position on DESI: Administrator, Lawrence Berkeley National Laboratory

Where were you born? Berkeley, CA

What do you in your position on DESI? I work with the DESI group member overseeing and assisting with the day-to-day operations in a variety of ways including processing requisitions for equipment needed for The Dark Energy Spectroscopic Instrument (DESI) that will be mounted on the 4-Meter Mayall telescope at Kitt Peak National Observatory, in addition to coordinating travel, event planning of collaborations and reviews necessary for the experiments planning and operations phase.

What excites/interests you most about DESI? Since joining the DESI Group in April 2016 I look forward to the daily opportunities to learned more about the DESI Project while working with an estimated two hundred physicist and astronomers that make up the international DESI collaboration which is based at Lawerence Berkeley National Laboratory.

What do you for fun? Family, family, family time, is what I do for fun. I especially enjoy engaging in lego projects with my grandson where he is creating all sorts of awesome things, from aircrafts, robots, and buildings, telescopes are in the near future.