Kavli IPMU Joins POLARBEAR Cosmic Microwave Background Experiment

April 26, 2013
Kavli Institute for the Physics and Mathematics of the Universe

On April 2013, Kavli IPMU joined the POLARBEAR experiment, which is a ground-based CMB (Cosmic Microwave Background) polarization experiment in the Atacama desert in Chile.

POLARBEAR is an international collaboration with scientists from the USA, Canada, France, Japan and UK. Kavli IPMU is the second institute after KEK (High Energy Accelerator Research Organization) from Japan joining POLARBEAR and its upgrade named POLARBEAR-2.

The CMB is a remnant light that has been propagating through the universe since 380,000 years after the big bang. Precise measurements of the temperature fluctuations of CMB over the past decades have provided us rich information on the early universe.

The current frontier in the CMB field is polarization measurements. Inflation theories, which describe the exponential expansion of the universe at the very beginning, predict a primordial gravitational wave background that can be observable as a CMB polarization pattern called B-mode polarization. A measurement of the CMB B-mode has the potential to provide new insight on inflation that has not been available from only the temperature fluctuations.

However, the CMB B-mode polarization signal is so weak that previous experiments have not been sensitive enough to detect it. With a high sensitivity detector array consisting of 1,274 superconducting transition edge sensors, POLARBEAR is expected to achieve unprecedented sensitivity to reveal the B-mode polarization from the early universe.

Kavli IPMU is expected to significantly contribute to the progress of the projects by playing an important role on data analyses, especially on detector calibration analyses for polarization measurements.

Prof. Nobuhiko Katayama, who is an associate director of Kavli IPMU and leading the POLARBEAR group at the Kavli IPMU, says "Kavli IPMU is leading the research on the accelerating expansion of the recent universe with the SuMIRe project. We now have another probe to reveal the accelerating expansion during the inflation era. I feel like our car now has a full set of wheels."

Prof. Masashi Hazumi, who is leading the POLARBEAR group at KEK, says "I’m very glad that Kavli IPMU has joined POLARBEAR. Close coordination between KEK and Kavli IPMU is the key for the success of the POLARBEAR project".

Prof. Adrian Lee, Principal Investigator of POLARBEAR at University of California at Berkeley, says "We are all very excited that Kavli IPMU has joined the POLARBEAR collaboration.   The addition of Kavli IPMU will be very important for the success of the overall project". 

Huan Tran Telescope dedicated to POLARBEARHuan Tran Telescope dedicated to POLARBEAR 

Kavli IPMU POLARBEAR group members

Nobuhiko Katayama, Associate Director, Professor
Haruki Nishino, Postdoctoral Fellow

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