• Question: were was the coldest place you haveever done an experiment?

    Asked by bobchelsea to Mark, Matthew, Mike, Paul, Sabina on 13 Mar 2014.
    • Photo: Paul Coxon

      Paul Coxon answered on 13 Mar 2014:

      The coldest place I did an experiment was at Daresbury Laboratory during a very cold January.

      Daresbury was a large lab with lots of researchers working around a big electron accelerator called a synchrotron. A synchrotron produces intense beams of light by accelerating electrons around a circular path using massive bending magnets. We can tune the wavelength of the light to suit our different experiments. All the apparatus has to be kept under ultra high vacuum (equivalent to the vacuum in space) so that the electrons can keep accelerating and producing radiation for us to use.

      I was working with liquid helium, using it to cool down a piece of copper on which I had deposited some nanodiamond crystals to study. I was using the X-ray from the synchrotron to look at the chemical elements within the crystals, and how they were bonded together. This is useful because it lets us understand the strange properties diamond displays when it is shrunk down to nanoscale dimensions.

      Liquid helium is very cold, and keeping materials very cold helps slow down the vibrations of the atoms, freezing them into place, which helps us collect a better chemical spectrum from the sample. It makes the peaks in the spectrum much sharper and easier to identify. The temperature we work at is around 8 kelvin or -265 degrees, much colder than anywhere on Earth and only a couple of degrees above absolute zero. If we did the experiments at room temperature, the peaks would be all smoothed out and blurry.

      This time, one of the synchrotron pumps totally failed so the synchrotron was switched off. Normally when the synchrotron runs normally, big bending magnets create a lot of heat which helps keep the lab warm.

      With the synchrotron turned off in January the lab became very chilly, around 5 degrees. Not quite as cold as my nanodiamond, but not very nice to work in. It was freezing cold at night – I had to wear a gloves to types properly.

    • Photo: Mike Lee

      Mike Lee answered on 13 Mar 2014:

      I went to visit some friends in Bristol who liked to turn the air conditioning in the laboratory down really cold, about 17 degrees. It was so cold.

    • Photo: Mark Jackson

      Mark Jackson answered on 14 Mar 2014:

      I’m a theoretical physicist, so I don’t really do experiments. But I will tell you the coldest place I have been where *someone* has done an experiment, and the strange answer: Leiden, Holland.

      For years, Leiden was the coldest place on earth, thanks to an experiment by physicist Heike Kamerlingh Onnes. In 1908 his dream of making liquid helium came true: he managed to make liquid helium, just above the absolute zero point of -273.15 Celsius. Colder than that is not possible because atoms and molecules would come to a halt. In 1913, Kamerlingh Onnes was awarded the Nobel Prize for his research on the properties of matter at low temperatures.

    • Photo: Matthew Malek

      Matthew Malek answered on 17 Mar 2014:

      Hiya Bobchelsea! I’m going to give three answers to your question — the coldest place that I have done an experiment, the coldest place that I would like to do an experiment, and the coldest experiment that I have done. Three for one, that’s a good deal! 😀

      The coldest PLACE that I have ever done an experiment was probably the Argentine desert (or “pampas”) in August, which is the middle of Winter in the Southern hemisphere. It gets REALLY cold down there, especially when working at night! Take a look at my photos, and scroll down to the last one. See that “bear suit” that I’m wearing? It’s a thermal suit designed for working in cold conditions.

      The coldest place that I would like to do an experiment is the South Pole. There is a research station down there, with particle physics experiments that are in the same field that I work in. There is the IceCube neutrino detector, for instance, which is deep down in the ice itself. There is also the IceTop cosmic ray detector, which sits on the surface. I have worked with both neutrino astrophysics and cosmic rays, so both are interesting to me. Hard to get much colder than the South Pole, huh?

      Finally, the coldest experiment that I have ever done was a search for dark matter using a cryogenic experiment called CRESST. CRESST uses crystals cooled down to 0.005 Kelvin to look for dark matter. That’s 0.005 degrees above absolute zero — the coldest possible temperature! If you go into outer space, far from any stars or planets, the temperature is still about 2.7 Kelvin, due to light left over from the Big Bang (called the “cosmic microwave background”) heating up empty space just a little. Whereas I made experiments at 0.005 Kelvin — about 500 times colder than outer space! Pretty cool, huh? ;-D

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