Juan I. Collar, Assistant 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 all risky business but I am equally interested in journey and destination: the extreme levels of sensitivity sought in some of these experiments force us in the field to devise new detection approaches and to try to stay aware of the latest advances in particle detector technology. It is all 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 to do with 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, now in the process of merging with PICASSO). On my arrival to Chicago I decided to start investigating the possibility of making large bubble chambers stable enough for the same goal. We have made much progress since and our 2 kg CF₃I bubble chamber will make its underground debut during 2004 (The Chicago Observatory for Underground Particle Physics, COUPP). 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 started work on the application of new detector technologies to neutrino detection via coherent nuclear scattering. There are other projects that I would like to get off the ground one day, given the time and manpower (and why not admit it, $$$ and presence of spirit too).

Recent publications:

• A Bubble Chamber for Dark Matter Detection (The COUPP Project Status)
  W.J. Bolte, J.I. Collar, M. Crisler, J. Hall, D. Holmgren, D. Nakazawa, H. Nguyen, B. Odom, K. O'Sullivan, R. Plunkett, E. Ramberg, A. Raskin, A. Sonnenschein, J.D. Vieira
  Journal of Physics: Conference Series, Volume 39, Issue 1, pp. 126-128 (2006)
• First results from the CAST experiment
  CAST Collaboration (J.I. Collar, J. Vieira)
  Journal of Physics: Conference Series, Volume 39, Issue 1, pp. 117-119 (2006)
• 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
  submitted to Phys. Rev. Lett.
  PDF
• Development of bubble chambers with sensitivity to WIMPs
  L. Bond, J. I. Collar, J. Ely, M. Flake, J. Hall, D. Jordan, D. Nakazawa, A. Raskin, A. Sonnenschein and K. O'Sullivan
  Nuclear Physics B (Proc. Suppl.) 138 (2005) 68–71
• COUPP: A Heavy-Liquid Bubble Chamber for WIMP Detection
  J. Bolte, J.I. Collar, M. Crisler, D. Holmgren, D. Nakazawa, B. Odom, K. O'Sullivan, R. Plunkett, E. Ramberg, A. Raskin, A. Sonnenschein, J.D. Vieira
  Proceedings from IDM2004, Edinburgh, Scotland (2004)
• First results from the CERN Axion Solar Telescope (CAST)
  CAST Collaboration (J.I. Collar)
  submitted to PRL (2004)
• Development of Bubble Chambers with Sensitivity to WIMPs
  L. Bond, J.I. Collar, J. Ely, M. Flake, J. Hall, D. Jordan, D. Nakazawa, A. Raskin, A. Sonnenschein, K. O'Sullivan
  DM (2004)
• 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
• Direct Detection of CDM: The Challenge Ahead
  J. I. Collar
  BC poster (2004)
• 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
• Toward Coherent Neutrino Detection Using Low-Background Micropattern Gas Detectors
  P. S. Barbeau, J. I. Collar, J. Miyamoto, and I. Shipsey
  IEEE TRANSACTIONS ON NUCLEAR SCIENCE, v. 50, No. 5 (2003) 1285-1289
• An Aging Study of Industrially Produced Micro-Patterned Gas Detectors
  P.S. Barbeau, J.I. Collar, J. Miyamoto, I. Shipsey
  IEEE (2003)
• Prospects for SIMPLE 2000: a large-mass, low-background superheated droplet detector for WIMP searches
  J.I. Collar, J. Puibasset, T.A. Girard, D. Limagne, H.S. Miley, G. Waysand
  New Journal of Physics v. 2 (2000) 14.1-14.14
• 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