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Fermilab | Batavia, IL | USA

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Dark Energy Camera: The wave-like behavior of postdocs

DES First Light Countdown, seven months to go

At the time of my first post in the countdown to first light series, some people suggested that I write more on what I really do and what it is like to be a postdoc in the Dark Energy Survey, DES. And as much as I feel hesitant to turn the spotlight to myself, I would hate to let my very first readers down. So read along and you will learn, from a very particular perspective, how much progress we have made in the last two months.

DECam focal plane at Fermilab almost full of CCDs. Credit: Marcelle Soares-Santos

 Being a postdoc is like being a photon. You have a wave function and, while your career momentum may be well determined, your location in the multiverse of projects, working groups, meetings and responsibilities is very uncertain.

 During the Dark Energy Camera, DECam, test phase on the telescope simulator my wave function nearly collapsed around the Fermilab Silicon Facility, or SiDet. I was sitting right next to the camera, testing the ever evolving data acquisition system and the new components (shutter, filter changer, hexapod…) as they came online. This phase was completed in February and since then my wave-like behavior is more evident again. We have changed gears towards filling the focal plane with our brand new CCDs and preparing the camera for shipment to the Blanco telescope at Cerro Tololo Inter-American Observatory, or CTIO, in Chile. This week I am in Chile, attending the DECam integration meeting. It is my first time at the observatory and not only I am having a great time, but I am also learning a lot!      

Cerro Tololo Inter-American Observatory in Chile. Credit: NOAO

But being a photon also means that your rest mass is zero and your wave length is inversely proportional to the energy you dedicate to each particular task. Supervisors and project managers seem to know this very well and deliberately loosen or tighten their grip as they see fit. But it actually depends on the time scale of each project. The fact is that from time to time you feel the stress decrease in one area and your wave function automatically stretches to other activities.

DES simulated image. Credit: DES collaboration

I am also working on the cluster finders comparison project, which will help DES identify, with high efficiency, a sample of more than 100,000 galaxy clusters, the largest gravitationally bound objects in the universe. This area is where most of my science interest lies. I developed

a galaxy cluster finder and tested it on DES simulations, computed the selection functions to be applied to our data and studied the systematics. That meant time in front of a computer terminal, programming instead of testing camera components. I find programming a lot more fun and I like the flexibility to work from virtually anywhere. My office (well, it is a cube really) is the natural choice, but I do a lot of this work at home too (yes, work-life balance is that concept from the seventies that I haven’t internalized yet).

Last week we finished the installation of the software framework for the cluster finders comparison project — we have a handful of cluster finding algorithms in our collaboration.  This fall we will conduct a comprehensive test of our pipeline, through what is called the Blind Cosmology Challenge. The idea is to verify that we can recover the right answer in a simulated data set. This would prove our ability to measure the dark energy parameters DES wants to study. A great overview of this challenging project was presented by one of our collaborators in a talk at the KITP Conference last month.

So here is where we stand, at the seven-month mark. Integration and commissioning phases are imminent. And we are working hard to get ready on several fronts simultaneously. This requires a very broad wave function!

— Marcelle Soares-Santos




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