Jeffrey Donenfeld

Tag: bicep2

  • First Results From The BICEP2 CMB Telescope Announced re: Gravitational Waves in the Cosmic Microwave Background

    First Results From The BICEP2 CMB Telescope Announced re: Gravitational Waves in the Cosmic Microwave Background

    A little over a year ago, I had the extraordinary opportunity to work with scientists John Kovac, Jon Kaufman, Howard Hui, and others at the Amundsen-Scott South Pole Station, Antarctica (summary of my experience living and working at the south pole) on the BICEP2 and KECK Array Microwave Telescopes. Learning about how the telescopes worked, as well as the science behind what they were doing directly from the scientists involved was a great opportunity, and I was happy to be able to make my small contribution to the project.

    RESULTS

    “Researchers from the BICEP2 collaboration today announced the first direct evidence for this cosmic inflation. Their data also represent the first images of gravitational waves, or ripples in space-time. These waves have been described as the “first tremors of the Big Bang.” Finally, the data confirm a deep connection between quantum mechanics and general relativity.”

    Announcement from NASA JPL:

    Astronomers are announcing today that they have acquired the first direct evidence that gravitational waves rippled through our infant universe during an explosive period of growth called inflation. This is the strongest confirmation yet of cosmic inflation theories, which say the universe expanded by 100 trillion trillion times, in less than the blink of an eye.

    The findings were made with the help of NASA-developed detector technology on the BICEP2 telescope at the South Pole, in collaboration with the National Science Foundation.

    “Operating the latest detectors in ground-based and balloon-borne experiments allows us to mature these technologies for space missions and, in the process, make discoveries about the universe,” said Paul Hertz, NASA’s Astrophysics Division director in Washington.

    This morning, they announced their first set of results from Bicep2 at the Harvard Center for Astrophysics:

    From Sean Carrol:
    Monday morning: here are results! First, the best fit to r, the ratio of gravitational waves to density perturbations:
    bicep-r1

    And a bit of press from around the web:

    Snowmobiling to the Dark Sector Laboratory
    2012-11-20 Bicep2 - IMG_0813-1600-80

    Physicist Jon Kaufman stands on top of the Martin A. Pomerantz Observatory.
    2012-11-25 Bicep2 2 - IMG_1163-1600-80

    Physicist Jon Kaufman gives me a tour of the BICEP2 Telescope..

    Pics from working on KECK…

    2012-11-27 Keck Array Disassembly - DSC02245-1600-80
    2012-11-27 Keck Array Disassembly - IMG_1418-1600-80
    2012-11-27 Keck Array Disassembly - DSC02268-1600-80

    Appearing on front page of NY Times
    Appearing on front page of NY Times
  • Cryo Barn’s Last Liquid Helium Transfer

    Cryo Barn’s Last Liquid Helium Transfer

    The South Pole Cryogenics Laboratory, usually known as Cryo Barn, was originally established to service various telescopes and science experiments with cryogenic cooling liquids such as Liquid Helium and Liquid Nitrogen. However, in recent years, most new experiments which operate at cold temperatures have been of the “closed loop” variety – that is, they don’t vent or leak any of their coolant. Therefore, most of the new experiments don’t need the regular coolant refils that Cryo Barn was built to provide. Last week, I got to watch as the last Liquid Helium dewar was filled from the main tank, and then shipped off to the Bicep2 CMB Telescope.

    Cryogenics Technician Flint Hamblin prepares the main Liquid Helium holding tank for transfer to the smaller transport dewar.
    Fill volume of the dewar is measured by weight, and here Flint is seen checking the dewar weight as it’s suspended from the ceiling.
    Liquid Helium is at about 4 Kelvin, or -452.2 degrees Fahrenheit. During the fill, the valves and piping that handle the liquid helium get extremely cold. In fact, they get cold enough to condense out the gasses from the air, turning the air into liquid. In this picture, the wet drips seen coming off the exhaust nozzle are drips of liquid nitrogen and oxygen condensed out of the surrounding air. Basically liquid air. The small grey plume coming out of the tip of the nozzle is actually a small amount of liquid helium, instantly vaporizing. The small white crust seen at the tip of the nozzle is solid air.
    The dewar is transported from Cryo to MAPO on a sled pulled by a snowmobile. Here’s Flint and Physicist Jon Kaufman on the snowmobile, as I ride on the sled with the dewar.
    The final step of the process, hoisting the dewar up into MAPO, where it’s used to fill the Bicep2 CMB telescope.

    Liquid helium plays a crucial role in the operation and effectiveness of microwave telescopes. Here are five key points about its use:1

    1. Cooling of Instruments: Liquid helium is used to cool the sensitive instruments and detectors of microwave telescopes to extremely low temperatures, often close to absolute zero (approximately -273.15°C or -459.67°F). This is essential because it significantly reduces thermal noise, which can obscure the weak microwave signals from space that the telescopes are trying to detect.
    2. Increased Sensitivity: By reducing thermal noise through cooling, liquid helium enhances the sensitivity of microwave telescopes. This increased sensitivity allows astronomers to detect faint microwave emissions and cosmic microwave background radiation with greater clarity, leading to more accurate measurements and observations.
    3. Maintenance of Superconducting States: Certain components within microwave telescopes, such as superconducting magnets and quantum sensors, require a superconducting state to function optimally. Liquid helium is used to maintain the temperature conditions necessary for these components to achieve and sustain superconductivity, thereby ensuring the high performance of the telescope’s systems.
    4. Long-duration Observations: The use of liquid helium enables microwave telescopes to conduct extended observations without the need for frequent recalibrations due to thermal fluctuations. This stability is crucial for long-term studies of the universe, such as monitoring the cosmic microwave background over time to understand the evolution of the universe.
    5. Enabling Ground-based and Space-based Observations: While liquid helium is a critical resource for ground-based microwave telescopes, it is also vital for space-based telescopes. In the vacuum of space, where radiative cooling is limited, liquid helium is used to cool instruments to the necessary temperatures for observing the universe in microwave frequencies without the interference from Earth’s atmosphere.

    In summary, liquid helium is indispensable for the operation of microwave telescopes, enhancing their performance by cooling sensitive components, reducing noise, maintaining superconductivity, allowing for prolonged observations, and enabling both ground-based and space-based astronomy.

    1. Generated by ChatGPT-4, 2024-03 ↩︎
  • Refilling the Liquid Helium of Bicep2

    Refilling the Liquid Helium of Bicep2

    A week or two ago, Physicist Jon Kaufman gave me a brief tour of the Bicep2 Microwave Telescope, operating here at the South Pole. Aa I reported earlier, the telescope operates at a very very low temperature – only a few millikelvin above absolute zero. In this particular telescope, to get down to that temperature, liquid helium is used in a series of nested cryostats – each reducing the temperature further. In order to maintain the cold temperature needed, liquid helium must periodically be added from an outside source. A few photos of Jon performing a recent refill of liquid helium:

    Here’s what the master control console looks like.
    2012-11-25 Bicep2 2 - IMG_1052-1600-80

    Jon taking a few notes before beginning the fill
    2012-11-25 Bicep2 2 - IMG_1056-1600-80

    That grey puff coming out of the tip of the filling hose is actually liquid helium. Strangely, as we were working around the telescope as it was off-gassing lots and lots of helium, we could breathe in deeply near the vent hose (warmer, gaseous helium) and our voices would get high – just like sucking on a party balloon.
    2012-11-25 Bicep2 2 - IMG_1118-1600-80
    2012-11-25 Bicep2 2 - IMG_1144-1600-80

    The exhaust hose gets so cold that it actually condenses gas from the air into liquid. That’s liquid nitrogen and oxygen (and a blend of others) dripping off the hose.
    2012-11-25 Bicep2 2 - DSC02225-1600-80

    A quick trip up to the roof just to check things out on a nice day. This is a look inside the groundshield, at the moveable top of the telescope.
    2012-11-25 Bicep2 2 - IMG_1163-1600-80
    2012-11-25 Bicep2 2 - IMG_1169-1600-80

  • Touring the Bicep2 Microwave Telescope with Physicist Jonathan Kaufman

    Touring the Bicep2 Microwave Telescope with Physicist Jonathan Kaufman

    South Pole is home to many, many world-class science experiments, laboratories, and telescopes. One such telescope is the Bicep2 Microwave Telescope. On the ice this year working on the hardware and software is Physicist Jonathan Kaufman. Yesterday, Jon was nice enough to give me a quick tour of the telescope and lab, as well as an opportunity to see them send the liquid helium dewier off to the Cryogenics Lab for a refill. Here’s video of Jon giving a tour, and photos of the dewier.

    About Bicep2, from Caltech:

    The primary goal of BICEP2 is to measure the polarization of the cosmic microwave background (CMB). The CMB is a nearly perfect, uniform black body at 2.7 K, with degree-scale temperature anisotropy of about 0.1 mK and polarization on the order of microkelvin. This radiation was emitted 380,000 years after the Big Bang, at the time of recombination, when the Universe first became transparent to light. The temperature anisotropy and polarization of the CMB are some of the most powerful ways of understanding the early Universe. Cosmologists believe the Universe experienced a rapid period of cosmic inflation during its first fraction of a second, exponentially expanding from a dense, hot subatomic volume. Many models of inflation predict that this rapid acceleration would have generated gravitational waves that would remain energetic enough 380,000 years later to leave an imprint on the CMB. BICEP2 is searching for this imprint by measuring the pure-curl component of the CMB polarization on degree angular scales, which is largely free of contamination from sources other than primordial gravitational waves.

    More on Bicep, Bicep2, and Keck from Christopher Sheehy. (PDF Link)

    Snowmobiling out to the Bicep2 Telescope’s Lab, which also shares space with the South Pole Telescope.
    2012-11-20 Bicep2 - IMG_0813-1600-80

    Liquid Helium dewier, and Jon
    2012-11-20 Bicep2 - IMG_0823-1600-80

    Looking off the roof of the Bicep2 across to the SPT
    2012-11-20 Bicep2 - IMG_0841-1600-80

    Lowering the dewier
    https://www.flickr.com/photos/jamfan2/8205021288/lightbox/

    Bicep2
    2012-11-20 Bicep2 - IMG_0891-1600-80