The experiments Dr. Hagar Landsman-Peles particpates in together with scientists from many different countries, will help us understand the makeup of our universe
Dr. Hagar Landsman-Peles builds detectors for the smallest particles
To catch a particle of dark matter, build a very large tank, fill it with very cold, very pure liquid xenon and bury it deep underground. No one has yet conclusively found such a particle, but simple physics tells us that the visible mass of the galaxies that we can observe is not enough to hold them together. That has led scientists to the idea that most of the matter in the Universe is dark – invisible to all lengths of light.
“Just because we have not yet found particles of dark matter does not mean they don’t exist,” says Dr. Hagar Landsman-Peles, who is working with the XENON project underneath Gran Sasso Mountain, in Italy. The thinking behind this project is that dark matter may be all around us, but it almost never interacts with the normal, everyday stuff. That means a unique trap is required: A very large tank of pure liquid xenon, placed under layers of Earth to filter out the more common particles that endlessly bombard the surface, topped by detectors capable of capturing an exceptionally brief, minuscule and weak signal.
Landman’s specialty is the extra-sensitive detectors that can detect the light of single photon. This is something like building a telescope to observe from Earth the light of a small candle on the Moon. But this resolution is necessary: If and when a particle of dark matter interacts with a single atom of xenon, that interaction will cause a photon to be emitted from the atom, along with an electron or two.The newest iteration of the xenon project, Xenon 1t, holds over one ton of the liquid element. Dr. Ran Budnik leads the Weizmann Institute of Science group that participates in the experiment, along with researchers from 10 other countries. Landsman-Peles leads the statistical methods team. Along with Dr. Alessandro Manfredini, the methods she uses were first developed by the Institutes’ Prof. Eilam Gross and Dr. Ofer Vitells. The new method she is developing, together with research student Nadav Priel, is multidimensional and is meant to help with the statistical problem of calculating the small amount of background noise that is predicted to occur in the experiment. She also worked with the Institute’s Prof. Ehud Duchovni in planning the outer shell of the detector – a wheel ten meters high.
Participating in Xenon are groups from the USA, Italy, Germany, Switzerland, Portugal, the Netherlands, United Arab Emirates (Abu Dhabi), Sweden, France and Israel.
In addition to working in the Weizmann Institute of Science lab and beneath an Italian mountain, Landsman-Peles is a member of another experiment – this one at the South Pole. The ARA project involves deeply-buried radio detectors placed at one km intervals over 100 sq. km. “ARA is a giant network, planned to catch especially fat fish – high-energy neutrinos.” says Landsman-Peles. The origins of these high-energy neutrinos are still a mystery – one the experimenters hope to help solve.
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