Department of Physics

Faculty Description


Contact
  • Office Location:  SERF 339 / MHA 5601
  • Office Phone:  858-534-2568 or 858-246-0405
  • Email:  hpaar@ucsd.edu
  • Administrative Contact:  Peggy McCoy
Research Statement
  • After spending most of my professional career in experimental particle physics I recently switched to observational cosmology. My current interest is characterizing the Cosmic Microwave Background, in particular its polarization.

    I am a member of the Polarbear Collaboration. Polarbear is the name of a campaign to measure the temperature and polarization properties of the CMB. With a UCSD colleague (Prof. Brian Keating) and colleagues from UC Berkely, Lawrence Berkeley Laboratory, the University of Colorado and colleagues from Canade and Europe I am preparing a telescope to execute this program. Funding for the telescope was provided by a charitable foundation (to Brian Keating) and by an anonymous donor (to me). A total of $1M was donated, sufficient to finance the purchase of the telescope and its controls. The National Science Foundation has agreed to fund its receiver and its operations for a five year period.
Awards & News
  • Physics professor Hans Paar and assistant professor Brian Keating are building what they call a POLARBEAR telescope to measure gravitational waves generated at the beginning of the universe.
  • La Jolla Village News, December 2007 - A POLARBEAR will soon reside in the Inyo Mountains, thanks to a couple of UCSD astrophysicists. Physics professor Hans Paar and assistant professor Brian Keating are building what they call a POLARBEAR telescope to measure gravitational waves generated at the beginning of the universe.

    Complete Story

  • UCSD's POLARBEAR experiment is moving to its permanent location in the Atacama Desert, Chile

  • Following a successful "first-light" four-month observing run, UCSD's POLARBEAR experiment on the Huan Tran Telescope at the James Ax Observatory located in the Inyo National Forest near Bishop, CA, is moving to its permanent location in the Atacama Desert, Chile.

    POLARBEAR is a collaboration between UC San Diego,
    UC Berkeley, University of Colorado, McGill University, Imperial College, the Japanese High Energy Research Organization, and the University of Paris.
    Polarbear's goal is to detect the gravitational waves produced during the era of inflation, shortly after the Big Bang by observing unique patterns of polarization of the Cosmic Microwave Background (CMB) radiation. These gravitational waves would be a telltale sign that inflation indeed took place. Additionally, measurement of the small angular scale polarization patterns have the capability to constrain the properties of Dark Matter and the mass of the neutrinos.

    POLARBEAR's receiver is able to detect the polarization of the CMB radiation through an array of over 1200 superconducting transition edge sensor bolometers cooled to 0.25 degrees Kelvin to reduce noise. Many months of observations must be combined to improve the signal to noise enough to observe the desired signals. Atmospheric water vapor is the enemy of ground-based
    microwave background measurements, hence the move to one of the driest sites on earth: the Atacama Desert, Chile where at an altitude of 16,500 feet, water vapor is greatly reduced.

    The POLARBEAR team has begun decommissioning the temporary observatory in the Inyo mountains which will be reassembled in Atacama for observations starting in early 2011.

    Polarbear team members from UC San Diego are David Boettger, George Fuller, Brian Keating, Nathan Miller, Hans Paar, and Ian Schanning.

  • UCSD Physicists To Assemble Microwave Telescope in Chile
  • The assembly of UCSD's telescope will commence shortly now that formal approval from the Chilean government for deployment in Chile's Atacama desert has been received. The telescope is part of the POLARBEAR project seeking to detect evidence for the inflationary epoch of the Big Bang.

    Please click on the following link for more information:
    http://sandiegouniontribune.ca.newsmemory.com/publink.php?shareid=1b98a071b

  • POLARBEAR experiment showing first microwave/radio "vision"
  • We are proud to announce that we got "first light/microwave" today with the POLARBEAR telescope in the Atacama Desert in Chile. We saw the planets Venus and Jupiter, not in the visible portion of the electromagnetic spectrum, but with microwave/radio "vision".

    Doesn't look too exciting at first glance but it's the start of big things for the project and team!

    It's an amazing place to be... very much like being an astronaut on Mars due to the high altitude (17,000') and the terrain. To complete the astronaut analogy most of us need to be on supplemental oxygen most of the time, which makes manual labor quite hard. But it sure beats the alternative!

    More pictures of POLARBEAR may be located on Flickr, and more detailed information about POLARBEAR may be found at the Huan Tran Telescope web page.

    Thanks to the whole collaboration and especially to the UCSD team (Darcy Barron, Dave Boettger, Frederick Matsuda, Nathan Miller, Stephanie Moyerman, Dr. Nathan Stebor, Praween Siritanasak) for all of their hard work and dedication!

Selected Publications
  • - N. Akchurin et al., "Comparison of high-energy hadronic shower profiles measured with scintillation and Cherenkov light," Nucl. Instrum. Meth. A584, 304 (2008).

  • - N. Akchurin et al., "Dual-readout calorimetry with lead tungstate crystals," Nucl. Instrum. Meth. A584, 273 (2008).

  • - N. Akchurin et al., "Measurement of the contribution of neutrons to hadron calorimeter signals," Nucl. Instrum. Meth. A581, 643 (2007).

  • - M. R. Convery, P. C. Kim, H. P. Paar, C. H. Rogers, R. H. Schindler, S. K. Swain and C. C. Young, "A novel technique for the production of large area z-coordinate readout planes for the BaBar muon system," Nucl. Instrum. Meth. A 556, 134 (2006).

  • - N. Akchurin et al., "Electron detection with a dual-readout calorimeter," Nucl. Instrum. Meth. A 536, 29 (2005).

  • - N. Akchurin et al., "Hadron and jet detection with a dual-readout calorimeter," Nucl. Instrum. Meth. A 537, 537 (2005).

  • - N. Akchurin et al., "Separation of scintillation and Cherenkov light in an optical calorimeter," Nucl. Instrum. Meth. A 550, 185 (2005).

  • - N. Akchurin et al., "Muon detection with a dual-readout calorimeter," Nucl. Instrum. Meth. A 533, 305 (2004).

  • - B. Aubert et al. [BABAR Collaboration], "Measurement of branching fractions of color-suppressed decays of the B0 meson to D(?)0?0, D(?)0?, D(?)0?, and D0??," Phys. Rev. D 69, 032004 (2004).

  • - K. Benslama et al. [CLEO Collaboration], "Anti-search for the glueball candidate fJ (2220) in two-photon interactions," Phys. Rev. D 66, 077101 (2002).

  • - R. A. Briere et al. [CLEO Collaboration], "Improved measurement of |Vcb| using B0 ! D??? decays," Phys. Rev. Lett. 89, 081803 (2002).

  • - A. Bornheim et al. [CLEO Collaboration], "Improved measurement of |Vub| with inclusive semileptonic B decays," Phys. Rev. Lett. 88, 231803 (2002).