Juan I. Collar, Associate Professor
PhD: University of South Carolina, 1992
Thesis advisor: Frank T. Avignone III

Location: LASR 241
Phone: (773) 702-4253
E-mail: collaruchicago.edu


Currently Working On: Axions, Neutrino Detectors, WIMP Detectors

My main interest is in the development of innovative methods for the detection for hypothetical astroparticles (WIMPs, axions, magnetic monopoles, any yet-to-be-discovered component of cosmic rays that might constitute a fraction of the 'dark matter'). Needless to say, this is a risky business, but I am equally interested in the journey and the destination: the extreme levels of sensitivity required in some of these experiments force us to devise new detection technologies, in an endless quest for the 'better mouse-trap'. It is a very enjoyable challenge. I am also attracted to other exotica such as double-beta decay and some 'hard' problems in neutrino detection (coherent neutrino scattering, detection of the relic neutrino sea). I enjoy the condensed-matter aspects of detector development and anything having to do with the interactions between radiation and matter. I get easily excited about cross-disciplinary endeavors and real-life applications of detectors that might otherwise be chasing ghost particles.

Together with collaborators at the Groupe de Physique des Solides (Universite Paris VII), University of Lisbon, and Pacific Northwest National Laboratory, I developed large-mass, low-background superheated droplet detectors (SDDs) dedicated to WIMP (Weakly Interacting Massive Particle) searches (The SIMPLE dark matter search). On my arrival to Chicago I started investigating the possibility of making large bubble chambers stable enough for the same goal, using CF₃I, a target ideal for WIMP detection. Our collaboration with FNAL and Indiana University (The Chicago Observatory for Underground Particle Physics, COUPP) has already led to the best sensitivity to spin-dependent WIMP interactions. We presently work on a 60 kg and 500 kg CF₃I chamber. We expect the first, to be installed in SNOlab during 2010, to provide a similar leading sensitivity also to spin-independent WIMP couplings. At CERN I am involved in CAST, a search for solar axions using a decommissioned LHC test magnet, an interesting astroparticle spin-off from the Large Hadron Collider effort. More recently, I have worked on the application of P-type Point Contact germanium detectors to coherent neutrino-nucleus scattering, double beta decay and searches for light dark matter candidates. These devices have already produced some very interesting results within the CoGeNT and MAJORANA experiments.

Recent publications:

• Results from a Search for Light-Mass Dark Matter with a P-type Point Contact Germanium Detector
  C.E. Aalseth, P.S. Barbeau, N.S. Bowden, B. Cabrera-Palmer, J. Colaresi, J.I. Collar, S. Dazeley, P. de Lurgio, G. Drake, J.E. Fast, N. Fields, C.H. Greenberg, T.W. Hossbach, M.E. Keillor, J.D. Kephart, M.G. Marino, H.S. Miley, M.L. Miller, J.L. Orrell, D.C. Radford, D. Reyna, R.G.H. Robertson, R.L. Talaga, O. Tench, T.D. Van Wechel, J.F. Wilkerson, K.M. Yocum (CoGeNT collaboration)
  Submitted Phys. Rev. Lett.
• Search for solar axion emission from 7Li and D(p,gamma)3He nuclear decays with the CAST gamma-ray calorimeter
  CAST Collaboration: S. Andriamonje, S. Aune, D. Autiero, K. Barth, A. Belov, B. Beltran, H. Brauninger, J. M. Carmona, S. Cebrian, J. I. Collar, T. Dafni, M. Davenport, L. Di. Lella, C. Eleftheriadis, J. Englhauser, G. Fanourakis, E. Ferrer. Ribas, H. Fischer, J. Franz, P. Friedrich, T. Geralis, I. Giomataris, S. Gninenko, H. Gomez, M. Hasinoff, F. H. Heinsius, D. H. H. Hoffmann, I. G. Irastorza, J. Jacoby, K. Jakovcic, D. Kang, K. Konigsmann, R. Kotthaus, M. Krcmar, K. Kousouris, M. Kuster, B. Lakic, C. Lasseur, A. Liolios, A. Ljubicic, G. Lutz, G. Luzon, D. W. Miller, J. Morales, A. Ortiz, T. Papaevangelou, A. Placci, G. Raffelt, H. Riege, A. Rodriguez, J. Ruz, I. Savvidis, Y. Semertzidis, P. Serpico, L. Stewart, J. D. Vieira, J. Villar, J. Vogel, L. Walckiers, K. Zioutas
  JCAP 1003:032, 2010
• Experimental constraints on a dark matter origin for the DAMA annual modulation effect
  C.E. Aalseth, P.S. Barbeau, D.G. Cerdeno, J. Colaresi, J.I. Collar, P. de Lurgio, G. Drake, J.E. Fast, C.H. Greenberg, T.W. Hossbach, J.D. Kephart, M.G. Marino, H.S. Miley, J.L. Orrell, D. Reyna, R.G.H. Robertson, R. Talaga, O. Tench, T.D. Van Wechel, J.F. Wilkerson, K.M. Yocum
  Phys.Rev.Lett. 101:251301, 2008
• Improved Spin-Dependent WIMP Limits from a Bubble Chamber
  E. Behnke, J.I. Collar, P.S. Cooper, K. Crum, M. Crisler, M. Hu, I. Levine, D. Nakazawa, H. Nguyen, B. Odom, E. Ramberg, J. Rasmussen, N. Riley, A. Sonnenschein, M. Szydagis, R. Tschirhart
  Science 319:933-936, 2008
• WIMP identification through a combined measurement of axial and scalar couplings
  G. Bertone, D.G. Cerdeno, J.I. Collar, B. Odom
  Phys.Rev.Lett. 99:151301, 2007
• Large-Mass Ultra-Low Noise Germanium Detectors: Performance and Applications in Neutrino and Astroparticle Physics
  P.S. Barbeau, J.I. Collar, O. Tench
  JCAP 0709:009, 2007
• Design and Characterization of a Neutron Calibration Facility for the Study of sub-keV Nuclear Recoils
  P.S. Barbeau, J.I. Collar, P.M. Whaley
  Nucl.Instrum.Meth. A574:385-391, 2007
• An improved limit on the axion-photon coupling from the CAST experiment
  CAST Collaboration (J.I. Collar)
  JCAP 0704:010, 2007
• Development of Bubble Chambers With Enhanced Stability and Sensitivity to Low-Energy Nuclear Recoils
  W.J Bolte, J. I. Collar, M. Crisler, J. Hall, D. Holmgren, D. Nakazawa, B. Odom, K. O'Sullivan, R. Plunkett, E. Ramberg, A. Raskin, A. Sonnenschein and J.D. Vieira
  Nucl.Instrum.Meth. A577:569, 2007
  PDF
• First results from the CERN Axion Solar Telescope (CAST)
  CAST Collaboration (J.I. Collar)
  Phys.Rev.Lett. 94:121301, 2005
• Electron transparency, ion transparency and ion feedback of a 3M GEM
  P.S. Barbeau, J. Collar, J. Miyamoto, I. Shipsey
  Nuclear Instruments and Methods in Physics Research A 525 (2004) 33-37
• A first mass production of gas electron multipliers
  P.S. Barbeau, J.I. Collar, J.D. Geissinger, J. Miyamoto, I. Shipsey, R. Yang
  Nuclear Instruments and Methods in Physics Research A 515 (2003) 439-445
• First Dark Matter Limits from a Large-Mass, Low-Background, Super-heated Droplet Detector
  J.I. Collar, J. Puibasset, T.A. Girard, D. Limagne, H.S. Miley, G. Waysand
  Phys. Rev. Letters v. 85, No. 15 (2000) 3083-3086
• A decommissioned LHC model magnet as an axion telescope.
  K. Zioutas, C.E. Aalseth, D. Abriola, F.T. Avignone, R.L. Brodzinski, J.I. Collar, R. Creswick, D.E. Di Gregorio, H. Farach, A.O. Gattone, C.K. Guerard, F. Hasenbalg, M. Hasino, H. Huck, A. Liolios, H.S. Miley, A. Morales, J. Morales, D. Nikas, S. Nussinov, A. Ortiz, E. Savvidis, S. Scopel, P. Sievers, J.A. Villar, L. Walckiers
  Nuclear Instruments and Methods in Physics Research A 425 (1999) 480-487
• Neutrinoless double-beta decay of Ge-76.: First results from the International Germanium Experiment (IGEX) with six isotopically enriched detectors
  C.E. Aalseth et al. (J.I. Collar)
  Phys. Rev. C 59 (1999) 2108
• Constraints on Exotic Heavily Ionizing Particles from the Geological Abundance of Fullerenes
  J.I. Collar, K. Zioutas
  Phys.Rev.Lett. 83 (1999) 3097
• Experimental Search for Solar Axions via Coherent Primakoff Conversion in a Germanium Spectrometer
  F.T. Avignone, D. Abriola, R.L. Brodzinski, J.I. Collar, R.J. Creswick, D.E. DiGregorio, H.A. Farach, A.O. Gattone, C.K. Guerard, F. Hasenbalg, H. Huck, H.S. Miley, A. Morales, J. Morales, S. Nussinov, A. Ortiz de Solorzano, J.H. Reeves, J.A. Villar, K. Zioutas
  Phys.Rev.Lett. 81 (1998) 5068-5071
• Superheated Microdrops as Cold Dark Matter Detectors
  J.I. Collar
  Phys. Rev. D v. 54, No. 2 (1996) R1247-1251