What CMB instrumentation can teach young researchers?
A journey across the unexpected beyond a CMB telescope
I got interested in astronomy one day when I skipped school and went into a bookstore. I was nine years old.
As I was wandering in the kids’ section, a group of books with rigid black covers caught my attention: “Our Solar System,” by Isaac Asimov.
I grew up in the sign of Isaac Asimov. The biochemist and famous science writer, surprisingly, also wrote many good books on astronomy. Outreach events were very rare. From time to time, I asked my father to bring me to astronomy seminars run by retired Italian television employees. I was the only female. The only kid.
My maternal grandfather used to collect newspaper articles. I found myself doing the same: an avid scholar of astronomy newspaper articles from relatives and friends. One day I got one: “Cosmic Microwave Background, anisotropies, flat universe, BOOMERanG experiment, South Pole, P. de Bernardis Sapienza University of Rome”.
I chose to study at the Sapienza University of Rome, the physics department of E. Fermi, N. Cabibbo, P. de Bernardis and many more: I wanted to belong to that Roman school, I wanted to scientifically descend from them. The challenge of building myself an instrument to understand the Universe fascinated me; the attitude of building everything yourself with parts even from local hardware stores reconnected me to the boys of via Panisperna.
Despite my interest in CMB instrumentation and my almost perfect GPA at the university, no one would have ever bet on me. I had never been a nerd, like the ones who build rockets and telescopes in the garage. My afternoons had been spent playing. I excelled more easily in theoretical exams than lab ones. The first time I soldered a board, I put the components on the wrong side. My first CAD drawing of a mechanical component was not done to scale. Up to that point I had only studied the matter, the equations describing its behavior at cryogenic temperatures or under vacuum.
For my Master’s thesis, I started to work in the lab, every day from morning to evening, working with the matter, playing with the matter, experiencing the matter. I observed how tin melts and gets shaped in the pins I soldered, I touched the smooth and shiny surface of fresh sand-papered copper parts with my hands full of copper powder, I smelt the cutting oil heated by the rotating drill press chuck, I heard the sound of a turbo molecular pump when it started to suck the air from a cubic meter cryostat, I pushed the screwdriver against the resistance resulting from tightening screws in slightly misplaced hole positions, I breathed the residual fiberglass powder from meter-scale custom-designed fiberglass shells, I stretched copper wires of different springiness for twist-pairing them, laying down on the floor I untightened the M18 screws holding the Atacama Cosmology Telescope (ACT) cryostat, on my knees I filed the mounting holes of the AliCPT Telescope 4K shields. I let the matter teach me how it behaves, I learnt from the matter.
With time and the increasing complexity of my work, my body movements tuned to the experiment I was working on. Like in an untold dance choreography. With a firm, steady hand I precisely glued the ACT chips on a silicon wafer in the middle of the night. I quickly run all around AliCPT bending down to precisely slide in each jack stand when we flip upside down the 300kg of its bottom assembly. I let my body be cuddled by the strong stiff breeze blowing on Cerro Toco and I breathed, I breathed the immensity of the Atacama Desert and of its sky.
‘Chuf’, (silence), ‘chufsf’, (silence), ‘chuf’, (silence), ‘chufsf’, (silence), ‘chuf’, (silence), ‘chufsf’, (silence), ‘chuf’, (silence), ‘chufsf’, (silence), ‘chuf’, (silence), ‘chufsf’, (silence). ‘Chuf’ says the Lesker high vacuum e-beam evaporator (1) #1, ‘chufsf’ says the Lesker #2 in the MC2 cleanroom. Silent, I slowly walk, one step after the other, carrying on an array of fragile superconducting detectors. In the background, the sunset reddens the green copper roofs of the Göteborg houses. ‘Chuf’, (silence), ‘chufsf’, (silence), ‘chuf’, (silence), ‘chufsf’, (silence), ‘chuf’, (silence), ‘chufsf’, (silence), ‘chuf’, (silence), ‘chufsf’, (silence).
I define myself as a CMB artisan. Artisan was my paternal grandfather. Artisan is the humble worker who shapes the matter, creating every day something different, new, exciting that did not exist before. Artisan is the one who frees the matter -- Michelangelo would say (2).
Nanofabrication is a brain gym: it taught me, especially when processing six-inch diameter silicon wafers in a cleanroom facility set for wafers no more than four inches in diameter, to think outside the box and ahead before doing any work. I stared for hours to debug my hand-designed and hand-soldered boards; most of the time the reason was a tiny tiny tiny detail, so I had to become a sharp observer to fix my boards! Today, when I solder a cable, I don’t need to probe the connections with a multimeter: I feel, I flow with the matter, I know how it works. My CAD drawings are in scale but…. in designing an instrument, I use no software: I open and use the CAD software only after I completed the design: I actually design the instrument by hand.
‘Chuf’, (silence), ‘chufsf’, (silence), ‘chuf’, (silence), ‘chufsf’, (silence), ‘chuf’, (silence), ‘chufsf’, (silence), ‘chuf’, (silence), ‘chufsf’, (silence), ‘chuf’, (silence), ‘chufsf’, (silence).
In instrumentation you cannot cheat on what you’re doing: if it does not work, it doesn’t! In observations or in a theoretical work, if something does not work you can still switch to a different model. Here you cannot. Matter does not lie, so you don’t. Matter does not betray you.
Beyond all the brain gym, the matter behavior, the sharp attention to details, the honesty… Can you tell me what I learnt? Yes, you, you that are reading this text, tell me what I learnt.
Every single day I shape the matter, like in an act of unique creation.
And every single day the matter shapes me – every challenge, every failure, every success: never give up! Stand up! Fight for what you believe in!
Perseverance.
Since my very first failure when, as an MSc student, after eight months of work, I had to start over the working strategy of my thesis project: illuminated by a desk lamp on a shaky table in a basement lab in Rome I took a piece of paper and I started from scratch. Years later, on a calm and cold night in Ontario, that piece of paper had become a touching bright point in the sky: the cryogenic mechanical system of the PILOT balloon-borne experiment that has measured the Galactic magnetic field.
‘Chuf’, (silence), ‘chufsf’, (silence), ‘chuf’, (silence), ‘chufsf’, (silence), ‘chuf’, (silence), ‘chufsf’, (silence), ‘chuf’, (silence), ‘chufsf’, (silence), ‘chuf’, (silence), ‘chufsf’, (silence).
I was born and grew up in Rome, embedded in the beauty that lasts forever.
The pandemic kept me 3 years 20 days away from home. I missed Rome, I dreamed of being in Rome, I listened to Italian songs. But then I ran across the Varian stairs, down to Varian ground floor, across the PAB ground floor, across all the stairs in PAB, down to the PAB basement, back to the lab where AliCPT is. There ‘she’ was: Rome had always been there! In every set of holes I had drawn, in every cable I soldered, in every piece of metal I cut, in every piece of aluminized mylar I taped down, in every piece of dental floss I ran, in every mechanical design I made I had put the same beauty embedded in the city where I was born: the regular pouring down of the Trevi Fountain, the smooth and shiny marble of Michelangelo and Bernini, the humble solemnity of Raffaello paintings, the surprisingly seed-shaped chocolate in the Giolitti watermelon ice-cream, the breathing of the sunset down Saint Peter dome, the silent sound of a nighty piazza Navona.
Maria Salatino
marias5@stanford.edu
(1) The e-beam evaporator is a common nanofabrication tool, used to produce dense, high purity coatings by a thermal evaporator process.
(2) 'The sculpture is already complete within the marble block, before I start my work. It is already there, I just have to chisel away the superfluous material'.