R. L. Cooper - University of Illinois

R. L. Cooper
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Name
R. L. Cooper
Affiliation
University of Illinois
City
Champaign
Country
United States

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Nuclear Experiment (24)
 
Astrophysics (14)
 
High Energy Physics - Experiment (13)
 
Physics - Instrumentation and Detectors (10)
 
High Energy Physics - Phenomenology (7)
 
High Energy Astrophysical Phenomena (4)
 
Solar and Stellar Astrophysics (2)
 
Nuclear Theory (2)
 
Physics - Superconductivity (2)
 
Physics - Strongly Correlated Electrons (2)
 
Physics - Materials Science (2)
 
Cosmology and Nongalactic Astrophysics (2)
 
Physics - Other (1)
 
Physics - Plasma Physics (1)
 
Statistics - Computation (1)
 
Statistics - Applications (1)
 
Quantum Physics (1)
 
Physics - Fluid Dynamics (1)

Publications Authored By R. L. Cooper

The MiniBooNE-DM collaboration searched for vector-boson mediated production of dark matter using the Fermilab 8 GeV Booster proton beam in a dedicated run with $1.86 \times 10^{20}$ protons delivered to a steel beam dump. The MiniBooNE detector, 490~m downstream, is sensitive to dark matter via elastic scattering with nucleons in the detector mineral oil. Read More

We numerically study the evolution of a small turbulent region of quantised vorticity in superfluid helium, a regime which can be realised in the laboratory. We show that the turbulence achieves a fluctuating steady-state in terms of dynamics (energy), geometry (length, writhing) and topology (linking). After defining the knot spectrum, we show that, at any instant, the turbulence consists of many unknots and few large loops of great geometrical and topological complexity. Read More

2016Aug
Authors: Jim Alexander, Marco Battaglieri, Bertrand Echenard, Rouven Essig, Matthew Graham, Eder Izaguirre, John Jaros, Gordan Krnjaic, Jeremy Mardon, David Morrissey, Tim Nelson, Maxim Perelstein, Matt Pyle, Adam Ritz, Philip Schuster, Brian Shuve, Natalia Toro, Richard G Van De Water, Daniel Akerib, Haipeng An, Konrad Aniol, Isaac J. Arnquist, David M. Asner, Henning O. Back, Keith Baker, Nathan Baltzell, Dipanwita Banerjee, Brian Batell, Daniel Bauer, James Beacham, Jay Benesch, James Bjorken, Nikita Blinov, Celine Boehm, Mariangela Bondí, Walter Bonivento, Fabio Bossi, Stanley J. Brodsky, Ran Budnik, Stephen Bueltmann, Masroor H. Bukhari, Raymond Bunker, Massimo Carpinelli, Concetta Cartaro, David Cassel, Gianluca Cavoto, Andrea Celentano, Animesh Chaterjee, Saptarshi Chaudhuri, Gabriele Chiodini, Hsiao-Mei Sherry Cho, Eric D. Church, D. A. Cooke, Jodi Cooley, Robert Cooper, Ross Corliss, Paolo Crivelli, Francesca Curciarello, Annalisa D'Angelo, Hooman Davoudiasl, Marzio De Napoli, Raffaella De Vita, Achim Denig, Patrick deNiverville, Abhay Deshpande, Ranjan Dharmapalan, Bogdan Dobrescu, Sergey Donskov, Raphael Dupre, Juan Estrada, Stuart Fegan, Torben Ferber, Clive Field, Enectali Figueroa-Feliciano, Alessandra Filippi, Bartosz Fornal, Arne Freyberger, Alexander Friedland, Iftach Galon, Susan Gardner, Francois-Xavier Girod, Sergei Gninenko, Andrey Golutvin, Stefania Gori, Christoph Grab, Enrico Graziani, Keith Griffioen, Andrew Haas, Keisuke Harigaya, Christopher Hearty, Scott Hertel, JoAnne Hewett, Andrew Hime, David Hitlin, Yonit Hochberg, Roy J. Holt, Maurik Holtrop, Eric W. Hoppe, Todd W. Hossbach, Lauren Hsu, Phil Ilten, Joe Incandela, Gianluca Inguglia, Kent Irwin, Igal Jaegle, Robert P. Johnson, Yonatan Kahn, Grzegorz Kalicy, Zhong-Bo Kang, Vardan Khachatryan, Venelin Kozhuharov, N. V. Krasnikov, Valery Kubarovsky, Eric Kuflik, Noah Kurinsky, Ranjan Laha, Gaia Lanfranchi, Dale Li, Tongyan Lin, Mariangela Lisanti, Kun Liu, Ming Liu, Ben Loer, Dinesh Loomba, Valery E. Lyubovitskij, Aaron Manalaysay, Giuseppe Mandaglio, Jeremiah Mans, W. J. Marciano, Thomas Markiewicz, Luca Marsicano, Takashi Maruyama, Victor A. Matveev, David McKeen, Bryan McKinnon, Dan McKinsey, Harald Merkel, Jeremy Mock, Maria Elena Monzani, Omar Moreno, Corina Nantais, Sebouh Paul, Michael Peskin, Vladimir Poliakov, Antonio D Polosa, Maxim Pospelov, Igor Rachek, Balint Radics, Mauro Raggi, Nunzio Randazzo, Blair Ratcliff, Alessandro Rizzo, Thomas Rizzo, Alan Robinson, Andre Rubbia, David Rubin, Dylan Rueter, Tarek Saab, Elena Santopinto, Richard Schnee, Jessie Shelton, Gabriele Simi, Ani Simonyan, Valeria Sipala, Oren Slone, Elton Smith, Daniel Snowden-Ifft, Matthew Solt, Peter Sorensen, Yotam Soreq, Stefania Spagnolo, James Spencer, Stepan Stepanyan, Jan Strube, Michael Sullivan, Arun S. Tadepalli, Tim Tait, Mauro Taiuti, Philip Tanedo, Rex Tayloe, Jesse Thaler, Nhan V. Tran, Sean Tulin, Christopher G. Tully, Sho Uemura, Maurizio Ungaro, Paolo Valente, Holly Vance, Jerry Vavra, Tomer Volansky, Belina von Krosigk, Andrew Whitbeck, Mike Williams, Peter Wittich, Bogdan Wojtsekhowski, Wei Xue, Jong Min Yoon, Hai-Bo Yu, Jaehoon Yu, Tien-Tien Yu, Yue Zhang, Yue Zhao, Yiming Zhong, Kathryn Zurek

This report, based on the Dark Sectors workshop at SLAC in April 2016, summarizes the scientific importance of searches for dark sector dark matter and forces at masses beneath the weak-scale, the status of this broad international field, the important milestones motivating future exploration, and promising experimental opportunities to reach these milestones over the next 5-10 years. Read More

The standard model predicts that, in addition to a proton, an electron, and an antineutrino, a continuous spectrum of photons is emitted in the $\beta$ decay of the free neutron. We report on the RDK II experiment which measured the photon spectrum using two different detector arrays. An annular array of bismuth germanium oxide scintillators detected photons from 14 to 782~keV. Read More

The COHERENT collaboration's primary objective is to measure coherent elastic neutrino-nucleus scattering (CEvNS) using the unique, high-quality source of tens-of-MeV neutrinos provided by the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL). In spite of its large cross section, the CEvNS process has never been observed, due to tiny energies of the resulting nuclear recoils which are out of reach for standard neutrino detectors. The measurement of CEvNS has now become feasible, thanks to the development of ultra-sensitive technology for rare decay and weakly-interacting massive particle (dark matter) searches. Read More

The compositional dependence of thermal expansion behaviour in 19 different perovskite-like metal-organic frameworks (MOFs) of composition [AI][MII(HCOO)3] (A = alkylammonium cation; M = octahedrally-coordinated divalent metal) is studied using variable-temperature X-ray powder diffraction measurements. While all systems show essentially the same type of thermomechanical response-irrespective of their particular structural details-the magnitude of this response is shown to be a function of AI and MII cation radii, as well as the molecular anisotropy of AI. Flexibility is maximised for large MII and small AI, while the shape of AI has implications for the direction of framework hingeing. Read More

We present measurements of nonproportionality in the scintillation light yield of bismuth germanate (BGO) for gamma-rays with energies between 6 keV and 662 keV. The scintillation light was read out by avalanche photodiodes (APDs) with both the BGO crystals and APDs operated at a temperature of approximately 90 K. Data were obtained using radioisotope sources to illuminate both a single BGO crystal in a small test cryostat and a 12-element detector in a neutron radiative beta-decay experiment. Read More

2015Mar
Authors: C. Adams, J. R. Alonso, A. M. Ankowski, J. A. Asaadi, J. Ashenfelter, S. N. Axani, K. Babu, C. Backhouse, H. R. Band, P. S. Barbeau, N. Barros, A. Bernstein, M. Betancourt, M. Bishai, E. Blucher, J. Bouffard, N. Bowden, S. Brice, C. Bryan, L. Camilleri, J. Cao, J. Carlson, R. E. Carr, A. Chatterjee, M. Chen, S. Chen, M. Chiu, E. D. Church, J. I. Collar, G. Collin, J. M. Conrad, M. R. Convery, R. L. Cooper, D. Cowen, H. Davoudiasl, A. De Gouvea, D. J. Dean, G. Deichert, F. Descamps, T. DeYoung, M. V. Diwan, Z. Djurcic, M. J. Dolinski, J. Dolph, B. Donnelly, D. A. Dwyer, S. Dytman, Y. Efremenko, L. L. Everett, A. Fava, E. Figueroa-Feliciano, B. Fleming, A. Friedland, B. K. Fujikawa, T. K. Gaisser, M. Galeazzi, D. C. Galehouse, A. Galindo-Uribarri, G. T. Garvey, S. Gautam, K. E. Gilje, M. Gonzalez-Garcia, M. C. Goodman, H. Gordon, E. Gramellini, M. P. Green, A. Guglielmi, R. W. Hackenburg, A. Hackenburg, F. Halzen, K. Han, S. Hans, D. Harris, K. M. Heeger, M. Herman, R. Hill, A. Holin, P. Huber, D. E. Jaffe, R. A. Johnson, J. Joshi, G. Karagiorgi, L. J. Kaufman, B. Kayser, S. H. Kettell, B. J. Kirby, J. R. Klein, Yu. G. Kolomensky, R. M. Kriske, C. E. Lane, T. J. Langford, A. Lankford, K. Lau, J. G. Learned, J. Ling, J. M. Link, D. Lissauer, L. Littenberg, B. R. Littlejohn, S. Lockwitz, M. Lokajicek, W. C. Louis, K. Luk, J. Lykken, W. J. Marciano, J. Maricic, D. M. Markoff, D. A. Martinez Caicedo, C. Mauger, K. Mavrokoridis, E. McCluskey, D. McKeen, R. McKeown, G. Mills, I. Mocioiu, B. Monreal, M. R. Mooney, J. G. Morfin, P. Mumm, J. Napolitano, R. Neilson, J. K. Nelson, M. Nessi, D. Norcini, F. Nova, D. R. Nygren, G. D. Orebi Gann, O. Palamara, Z. Parsa, R. Patterson, P. Paul, A. Pocar, X. Qian, J. L. Raaf, R. Rameika, G. Ranucci, H. Ray, D. Reyna, G. C. Rich, P. Rodrigues, E. Romero Romero, R. Rosero, S. D. Rountree, B. Rybolt, M. C. Sanchez, G. Santucci, D. Schmitz, K. Scholberg, D. Seckel, M. Shaevitz, R. Shrock, M. B. Smy, M. Soderberg, A. Sonzogni, A. B. Sousa, J. Spitz, J. M. St. John, J. Stewart, J. B. Strait, G. Sullivan, R. Svoboda, A. M. Szelc, R. Tayloe, M. A. Thomson, M. Toups, A. Vacheret, M. Vagins, R. G. Van de Water, R. B. Vogelaar, M. Weber, W. Weng, M. Wetstein, C. White, B. R. White, L. Whitehead, D. W. Whittington, M. J. Wilking, R. J. Wilson, P. Wilson, D. Winklehner, D. R. Winn, E. Worcester, L. Yang, M. Yeh, Z. W. Yokley, J. Yoo, B. Yu, J. Yu, C. Zhang

The US neutrino community gathered at the Workshop on the Intermediate Neutrino Program (WINP) at Brookhaven National Laboratory February 4-6, 2015 to explore opportunities in neutrino physics over the next five to ten years. Scientists from particle, astroparticle and nuclear physics participated in the workshop. The workshop examined promising opportunities for neutrino physics in the intermediate term, including possible new small to mid-scale experiments, US contributions to large experiments, upgrades to existing experiments, R&D plans and theory. Read More

A low-background, high-purity germanium detector has been used to search for evidence of low-energy, bremsstrahlung-generated solar axions. An upper bound of $1.36\times 10^{-11}$ $(95% CL)$ is placed on the direct coupling of DFSZ model axions to electrons. Read More

We present a new experimental method for measuring the process of Coherent Elastic Neutrino Nucleus Scattering (CENNS). This method uses a detector situated transverse to a high energy neutrino beam production target. This detector would be sensitive to the low energy neutrinos arising from pion decays-at-rest in the target. Read More

2013Oct
Authors: A. de Gouvea, K. Pitts, K. Scholberg, G. P. Zeller, J. Alonso, A. Bernstein, M. Bishai, S. Elliott, K. Heeger, K. Hoffman, P. Huber, L. J. Kaufman, B. Kayser, J. Link, C. Lunardini, B. Monreal, J. G. Morfin, H. Robertson, R. Tayloe, N. Tolich, K. Abazajian, T. Akiri, C. Albright, J. Asaadi, K. S Babu, A. B. Balantekin, P. Barbeau, M. Bass, A. Blake, A. Blondel, E. Blucher, N. Bowden, S. J. Brice, A. Bross, B. Carls, F. Cavanna, B. Choudhary, P. Coloma, A. Connolly, J. Conrad, M. Convery, R. L. Cooper, D. Cowen, H. da Motta, T. de Young, F. Di Lodovico, M. Diwan, Z. Djurcic, M. Dracos, S. Dodelson, Y. Efremenko, T. Ekelof, J. L. Feng, B. Fleming, J. Formaggio, A. Friedland, G. Fuller, H. Gallagher, S. Geer, M. Gilchriese, M. Goodman, D. Grant, G. Gratta, C. Hall, F. Halzen, D. Harris, M. Heffner, R. Henning, J. L. Hewett, R. Hill, A. Himmel, G. Horton-Smith, A. Karle, T. Katori, E. Kearns, S. Kettell, J. Klein, Y. Kim, Y. K. Kim, Yu. Kolomensky, M. Kordosky, Yu. Kudenko, V. A. Kudryavtsev, K. Lande, K. Lang, R. Lanza, K. Lau, H. Lee, Z. Li, B. R. Littlejohn, C. J. Lin, D. Liu, H. Liu, K. Long, W. Louis, K. B. Luk, W. Marciano, C. Mariani, M. Marshak, C. Mauger, K. T. McDonald, K. McFarland, R. McKeown, M. Messier, S. R. Mishra, U. Mosel, P. Mumm, T. Nakaya, J. K. Nelson, D. Nygren, G. D. Orebi Gann, J. Osta, O. Palamara, J. Paley, V. Papadimitriou, S. Parke, Z. Parsa, R. Patterson, A. Piepke, R. Plunkett, A. Poon, X. Qian, J. Raaf, R. Rameika, M. Ramsey-Musolf, B. Rebel, R. Roser, J. Rosner, C. Rott, G. Rybka, H. Sahoo, S. Sangiorgio, D. Schmitz, R. Shrock, M. Shaevitz, N. Smith, M. Smy, H. Sobel, P. Sorensen, A. Sousa, J. Spitz, T. Strauss, R. Svoboda, H. A. Tanaka, J. Thomas, X. Tian, R. Tschirhart, C. Tully, K. Van Bibber, R. G. Van de Water, P. Vahle, P. Vogel, C. W. Walter, D. Wark, M. Wascko, D. Webber, H. Weerts, C. White, H. White, L. Whitehead, R. J. Wilson, L. Winslow, T Wongjirad, E. Worcester, M. Yokoyama, J. Yoo, E. D. Zimmerman

This document represents the response of the Intensity Frontier Neutrino Working Group to the Snowmass charge. We summarize the current status of neutrino physics and identify many exciting future opportunities for studying the properties of neutrinos and for addressing important physics and astrophysics questions with neutrinos. Read More

We propose the addition of scintillator to the existing MiniBooNE detector to allow a test of the neutral-current/charged-current (NC/CC) nature of the MiniBooNE low-energy excess. Scintillator will enable the reconstruction of 2.2 MeV $\gamma$s from neutron-capture on protons following neutrino interactions. Read More

The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory, Tennessee, provides an intense flux of neutrinos in the few tens-of-MeV range, with a sharply-pulsed timing structure that is beneficial for background rejection. In this white paper, we describe how the SNS source can be used for a measurement of coherent elastic neutrino-nucleus scattering (CENNS), and the physics reach of different phases of such an experimental program (CSI: Coherent Scattering Investigations at the SNS). Read More

A proposal submitted to the FNAL PAC is described to search for light sub-GeV WIMP dark matter at MiniBooNE. The possibility to steer the beam past the target and into an absorber leads to a significant reduction in neutrino background, allowing for a sensitive search for elastic scattering of WIMPs off nucleons or electrons in the detector. Dark matter models involving a vector mediator can be probed in a parameter region consistent with the required thermal relic density, and which overlaps the region in which these models can resolve the muon g-2 discrepancy. Read More

2012Oct
Affiliations: 1The. MAJORANA. Collaboration, 2The. MAJORANA. Collaboration, 3The. MAJORANA. Collaboration, 4The. MAJORANA. Collaboration, 5The. MAJORANA. Collaboration, 6The. MAJORANA. Collaboration, 7The. MAJORANA. Collaboration, 8The. MAJORANA. Collaboration, 9The. MAJORANA. Collaboration, 10The. MAJORANA. Collaboration, 11The. MAJORANA. Collaboration, 12The. MAJORANA. Collaboration, 13The. MAJORANA. Collaboration, 14The. MAJORANA. Collaboration, 15The. MAJORANA. Collaboration, 16The. MAJORANA. Collaboration, 17The. MAJORANA. Collaboration, 18The. MAJORANA. Collaboration, 19The. MAJORANA. Collaboration, 20The. MAJORANA. Collaboration, 21The. MAJORANA. Collaboration, 22The. MAJORANA. Collaboration, 23The. MAJORANA. Collaboration, 24The. MAJORANA. Collaboration, 25The. MAJORANA. Collaboration, 26The. MAJORANA. Collaboration, 27The. MAJORANA. Collaboration, 28The. MAJORANA. Collaboration, 29The. MAJORANA. Collaboration, 30The. MAJORANA. Collaboration, 31The. MAJORANA. Collaboration, 32The. MAJORANA. Collaboration, 33The. MAJORANA. Collaboration, 34The. MAJORANA. Collaboration, 35The. MAJORANA. Collaboration, 36The. MAJORANA. Collaboration, 37The. MAJORANA. Collaboration, 38The. MAJORANA. Collaboration, 39The. MAJORANA. Collaboration, 40The. MAJORANA. Collaboration, 41The. MAJORANA. Collaboration, 42The. MAJORANA. Collaboration, 43The. MAJORANA. Collaboration, 44The. MAJORANA. Collaboration, 45The. MAJORANA. Collaboration, 46The. MAJORANA. Collaboration, 47The. MAJORANA. Collaboration, 48The. MAJORANA. Collaboration, 49The. MAJORANA. Collaboration, 50The. MAJORANA. Collaboration, 51The. MAJORANA. Collaboration, 52The. MAJORANA. Collaboration, 53The. MAJORANA. Collaboration, 54The. MAJORANA. Collaboration, 55The. MAJORANA. Collaboration, 56The. MAJORANA. Collaboration, 57The. MAJORANA. Collaboration, 58The. MAJORANA. Collaboration, 59The. MAJORANA. Collaboration, 60The. MAJORANA. Collaboration, 61The. MAJORANA. Collaboration, 62The. MAJORANA. Collaboration, 63The. MAJORANA. Collaboration, 64The. MAJORANA. Collaboration, 65The. MAJORANA. Collaboration, 66The. MAJORANA. Collaboration, 67The. MAJORANA. Collaboration, 68The. MAJORANA. Collaboration, 69The. MAJORANA. Collaboration, 70The. MAJORANA. Collaboration, 71The. MAJORANA. Collaboration, 72The. MAJORANA. Collaboration, 73The. MAJORANA. Collaboration, 74The. MAJORANA. Collaboration, 75The. MAJORANA. Collaboration, 76The. MAJORANA. Collaboration, 77The. MAJORANA. Collaboration, 78The. MAJORANA. Collaboration, 79The. MAJORANA. Collaboration, 80The. MAJORANA. Collaboration, 81The. MAJORANA. Collaboration, 82The. MAJORANA. Collaboration, 83The. MAJORANA. Collaboration

The MAJORANA DEMONSTRATOR will search for the neutrinoless double-beta decay of the 76Ge isotope with a mixed array of enriched and natural germanium detectors. The observation of this rare decay would indicate the neutrino is its own anti-particle, demonstrate that lepton number is not conserved, and provide information on the absolute mass-scale of the neutrino. The DEMONSTRATOR is being assembled at the 4850 foot level of the Sanford Underground Research Facility in Lead, South Dakota. Read More

We propose adding 300 mg/l PPO to the existing MiniBooNE detector mineral oil to increase the scintillation response. This will allow the detection of associated neutrons and increase sensitivity to final-state nucleons in neutrino interactions. This increased capability will enable an independent test of whether the current excess seen in the MiniBooNE oscillation search is signal or background. Read More

A study of signals originating near the lithium-diffused n+ contact of p-type point contact (PPC) high purity germanium detectors (HPGe) is presented. The transition region between the active germanium and the fully dead layer of the n+ contact is examined. Energy depositions in this transition region are shown to result in partial charge collection. Read More

As part of an experiment to measure the spectrum of photons emitted in beta-decay of the free neutron, we developed and operated a detector consisting of 12 bismuth germanate (BGO) crystals coupled to avalanche photodiodes (APDs). The detector was operated near liquid nitrogen temperature in the bore of a superconducting magnet and registered photons with energies from 5 keV to 1000 keV. To enlarge the detection range, we also directly detected soft X-rays with energies between 0. Read More

We use variable-temperature (150--300\,K) single-crystal X-ray diffraction to re-examine the interplay between structure and dynamics in the ambient phase of the isotropic negative thermal expansion (NTE) material Cd(CN)$_2$. We find strong experimental evidence for the existence of low-energy vibrational modes that involve off-centering of Cd$^{2+}$ ions. These modes have the effect of increasing network packing density---suggesting a mechanism for NTE that is different to the generally-accepted picture of correlated Cd(C/N)$_4$ rotation modes. Read More

Background: Time-reversal-invariance violation, or equivalently CP violation, may explain the observed cosmological baryon asymmetry as well as signal physics beyond the Standard Model. In the decay of polarized neutrons, the triple correlation D\cdot(p_{e}\timesp_{\nu}) is a parity-even, time-reversal- odd observable that is uniquely sensitive to the relative phase of the axial-vector amplitude with respect to the vector amplitude. The triple correlation is also sensitive to possible contributions from scalar and tensor amplitudes. Read More

2012May
Authors: J. L. Hewett, H. Weerts, R. Brock, J. N. Butler, B. C. K. Casey, J. Collar, A. de Gouvea, R. Essig, Y. Grossman, W. Haxton, J. A. Jaros, C. K. Jung, Z. T. Lu, K. Pitts, Z. Ligeti, J. R. Patterson, M. Ramsey-Musolf, J. L. Ritchie, A. Roodman, K. Scholberg, C. E. M. Wagner, G. P. Zeller, S. Aefsky, A. Afanasev, K. Agashe, C. Albright, J. Alonso, C. Ankenbrandt, M. Aoki, C. A. Arguelles, N. Arkani-Hamed, J. R. Armendariz, C. Armendariz-Picon, E. Arrieta Diaz, J. Asaadi, D. M. Asner, K. S. Babu, K. Bailey, O. Baker, B. Balantekin, B. Baller, M. Bass, B. Batell, J. Beacham, J. Behr, N. Berger, M. Bergevin, E. Berman, R. Bernstein, A. J. Bevan, M. Bishai, M. Blanke, S. Blessing, A. Blondel, T. Blum, G. Bock, A. Bodek, G. Bonvicini, F. Bossi, J. Boyce, R. Breedon, M. Breidenbach, S. J. Brice, R. A. Briere, S. Brodsky, C. Bromberg, A. Bross, T. E. Browder, D. A. Bryman, M. Buckley, R. Burnstein, E. Caden, P. Campana, R. Carlini, G. Carosi, C. Castromonte, R. Cenci, I. Chakaberia, M. C. Chen, C. H. Cheng, B. Choudhary, N. H. Christ, E. Christensen, M. E. Christy, T. E. Chupp, E. Church, D. B. Cline, T. E. Coan, P. Coloma, J. Comfort, L. Coney, J. Cooper, R. J. Cooper, R. Cowan, D. F. Cowen, D. Cronin-Hennessy, A. Datta, G. S. Davies, M. Demarteau, D. P. DeMille, A. Denig, R. Dermisek, A. Deshpande, M. S. Dewey, R. Dharmapalan, J. Dhooghe, M. R. Dietrich, M. Diwan, Z. Djurcic, S. Dobbs, M. Duraisamy, B. Dutta, H. Duyang, D. A. Dwyer, M. Eads, B. Echenard, S. R. Elliott, C. Escobar, J. Fajans, S. Farooq, C. Faroughy, J. E. Fast, B. Feinberg, J. Felde, G. Feldman, P. Fierlinger, P. Fileviez Perez, B. Filippone, P. Fisher, B. T. Flemming, K. T. Flood, R. Forty, M. J. Frank, A. Freyberger, A. Friedland, R. Gandhi, K. S. Ganezer, A. Garcia, F. G. Garcia, S. Gardner, L. Garrison, A. Gasparian, S. Geer, V. M. Gehman, T. Gershon, M. Gilchriese, C. Ginsberg, I. Gogoladze, M. Gonderinger, M. Goodman, H. Gould, M. Graham, P. W. Graham, R. Gran, J. Grange, G. Gratta, J. P. Green, H. Greenlee, R. C. Group, E. Guardincerri, V. Gudkov, R. Guenette, A. Haas, A. Hahn, T. Han, T. Handler, J. C. Hardy, R. Harnik, D. A. Harris, F. A. Harris, P. G. Harris, J. Hartnett, B. He, B. R. Heckel, K. M. Heeger, S. Henderson, D. Hertzog, R. Hill, E. A Hinds, D. G. Hitlin, R. J. Holt, N. Holtkamp, G. Horton-Smith, P. Huber, W. Huelsnitz, J. Imber, I. Irastorza, J. Jaeckel, I. Jaegle, C. James, A. Jawahery, D. Jensen, C. P. Jessop, B. Jones, H. Jostlein, T. Junk, A. L. Kagan, M. Kalita, Y. Kamyshkov, D. M. Kaplan, G. Karagiorgi, A. Karle, T. Katori, B. Kayser, R. Kephart, S. Kettell, Y. K. Kim, M. Kirby, K. Kirch, J. Klein, J. Kneller, A. Kobach, M. Kohl, J. Kopp, M. Kordosky, W. Korsch, I. Kourbanis, A. D. Krisch, P. Krizan, A. S. Kronfeld, S. Kulkarni, K. S. Kumar, Y. Kuno, T. Kutter, T. Lachenmaier, M. Lamm, J. Lancaster, M. Lancaster, C. Lane, K. Lang, P. Langacker, S. Lazarevic, T. Le, K. Lee, K. T. Lesko, Y. Li, M. Lindgren, A. Lindner, J. Link, D. Lissauer, L. S. Littenberg, B. Littlejohn, C. Y. Liu, W. Loinaz, W. Lorenzon, W. C. Louis, J. Lozier, L. Ludovici, L. Lueking, C. Lunardini, D. B. MacFarlane, P. A. N. Machado, P. B. Mackenzie, J. Maloney, W. J. Marciano, W. Marsh, M. Marshak, J. W. Martin, C. Mauger, K. S. McFarland, C. McGrew, G. McLaughlin, D. McKeen, R. McKeown, B. T. Meadows, R. Mehdiyev, D. Melconian, H. Merkel, M. Messier, J. P. Miller, G. Mills, U. K. Minamisono, S. R. Mishra, I. Mocioiu, S. Moed Sher, R. N. Mohapatra, B. Monreal, C. D. Moore, J. G. Morfin, J. Mousseau, L. A. Moustakas, G. Mueller, P. Mueller, M. Muether, H. P. Mumm, C. Munger, H. Murayama, P. Nath, O. Naviliat-Cuncin, J. K. Nelson, D. Neuffer, J. S. Nico, A. Norman, D. Nygren, Y. Obayashi, T. P. O'Connor, Y. Okada, J. Olsen, L. Orozco, J. L. Orrell, J. Osta, B. Pahlka, J. Paley, V. Papadimitriou, M. Papucci, S. Parke, R. H. Parker, Z. Parsa, K. Partyka, A. Patch, J. C. Pati, R. B. Patterson, Z. Pavlovic, G. Paz, G. N. Perdue, D. Perevalov, G. Perez, R. Petti, W. Pettus, A. Piepke, M. Pivovaroff, R. Plunkett, C. C. Polly, M. Pospelov, R. Povey, A. Prakesh, M. V. Purohit, S. Raby, J. L. Raaf, R. Rajendran, S. Rajendran, G. Rameika, R. Ramsey, A. Rashed, B. N. Ratcliff, B. Rebel, J. Redondo, P. Reimer, D. Reitzner, F. Ringer, A. Ringwald, S. Riordan, B. L. Roberts, D. A. Roberts, R. Robertson, F. Robicheaux, M. Rominsky, R. Roser, J. L. Rosner, C. Rott, P. Rubin, N. Saito, M. Sanchez, S. Sarkar, H. Schellman, B. Schmidt, M. Schmitt, D. W. Schmitz, J. Schneps, A. Schopper, P. Schuster, A. J. Schwartz, M. Schwarz, J. Seeman, Y. K. Semertzidis, K. K. Seth, Q. Shafi, P. Shanahan, R. Sharma, S. R. Sharpe, M. Shiozawa, V. Shiltsev, K. Sigurdson, P. Sikivie, J. Singh, D. Sivers, T. Skwarnicki, N. Smith, J. Sobczyk, H. Sobel, M. Soderberg, Y. H. Song, A. Soni, P. Souder, A. Sousa, J. Spitz, M. Stancari, G. C. Stavenga, J. H. Steffen, S. Stepanyan, D. Stoeckinger, S. Stone, J. Strait, M. Strassler, I. A. Sulai, R. Sundrum, R. Svoboda, B. Szczerbinska, A. Szelc, T. Takeuchi, P. Tanedo, S. Taneja, J. Tang, D. B. Tanner, R. Tayloe, I. Taylor, J. Thomas, C. Thorn, X. Tian, B. G. Tice, M. Tobar, N. Tolich, N. Toro, I. S. Towner, Y. Tsai, R. Tschirhart, C. D. Tunnell, M. Tzanov, A. Upadhye, J. Urheim, S. Vahsen, A. Vainshtein, E. Valencia, R. G. Van de Water, R. S. Van de Water, M. Velasco, J. Vogel, P. Vogel, W. Vogelsang, Y. W. Wah, D. Walker, N. Weiner, A. Weltman, R. Wendell, W. Wester, M. Wetstein, C. White, L. Whitehead, J. Whitmore, E. Widmann, G. Wiedemann, J. Wilkerson, G. Wilkinson, P. Wilson, R. J. Wilson, W. Winter, M. B. Wise, J. Wodin, S. Wojcicki, B. Wojtsekhowski, T. Wongjirad, E. Worcester, J. Wurtele, T. Xin, J. Xu, T. Yamanaka, Y. Yamazaki, I. Yavin, J. Yeck, M. Yeh, M. Yokoyama, J. Yoo, A. Young, E. Zimmerman, K. Zioutas, M. Zisman, J. Zupan, R. Zwaska

The Proceedings of the 2011 workshop on Fundamental Physics at the Intensity Frontier. Science opportunities at the intensity frontier are identified and described in the areas of heavy quarks, charged leptons, neutrinos, proton decay, new light weakly-coupled particles, and nucleons, nuclei, and atoms. Read More

2011Nov
Authors: S. Akkoyun, A. Algora, B. Alikhani, F. Ameil, G. de Angelis, L. Arnold, A. Astier, A. Ataç, Y. Aubert, C. Aufranc, A. Austin, S. Aydin, F. Azaiez, S. Badoer, D. L. Balabanski, D. Barrientos, G. Baulieu, R. Baumann, D. Bazzacco, F. A. Beck, T. Beck, P. Bednarczyk, M. Bellato, M. A. Bentley, G. Benzoni, R. Berthier, L. Berti, R. Beunard, G. Lo Bianco, B. Birkenbach, P. G. Bizzeti, A. M. Bizzeti-Sona, F. Le Blanc, J. M. Blasco, N. Blasi, D. Bloor, C. Boiano, M. Borsato, D. Bortolato, A. J. Boston, H. C. Boston, P. Bourgault, P. Boutachkov, A. Bouty, A. Bracco, S. Brambilla, I. P. Brawn, A. Brondi, S. Broussard, B. Bruyneel, D. Bucurescu, I. Burrows, A. Bürger, S. Cabaret, B. Cahan, E. Calore, F. Camera, A. Capsoni, F. Carrió, G. Casati, M. Castoldi, B. Cederwall, J. -L. Cercus, V. Chambert, M. El Chambit, R. Chapman, L. Charles, J. Chavas, E. Clément, P. Cocconi, S. Coelli, P. J. Coleman-Smith, A. Colombo, S. Colosimo, C. Commeaux, D. Conventi, R. J. Cooper, A. Corsi, A. Cortesi, L. Costa, F. C. L. Crespi, J. R. Cresswell, D. M. Cullen, D. Curien, A. Czermak, D. Delbourg, R. Depalo, T. Descombes, P. Désesquelles, P. Detistov, C. Diarra, F. Didierjean, M. R. Dimmock, Q. T. Doan, C. Domingo-Pardo, M. Doncel, F. Dorangeville, N. Dosme, Y. Drouen, G. Duchêne, B. Dulny, J. Eberth, P. Edelbruck, J. Egea, T. Engert, M. N. Erduran, S. Ertürk, C. Fanin, S. Fantinel, E. Farnea, T. Faul, M. Filliger, F. Filmer, Ch. Finck, G. de France, A. Gadea, W. Gast, A. Geraci, J. Gerl, R. Gernhäuser, A. Giannatiempo, A. Giaz, L. Gibelin, A. Givechev, N. Goel, V. González, A. Gottardo, X. Grave, J. Grȩbosz, R. Griffiths, A. N. Grint, P. Gros, L. Guevara, M. Gulmini, A. Görgen, H. T. M. Ha, T. Habermann, L. J. Harkness, H. Harroch, K. Hauschild, C. He, A. Hernández-Prieto, B. Hervieu, H. Hess, T. Hüyük, E. Ince, R. Isocrate, G. Jaworski, A. Johnson, J. Jolie, P. Jones, B. Jonson, P. Joshi, D. S. Judson, A. Jungclaus, M. Kaci, N. Karkour, M. Karolak, A. Kaşkaş, M. Kebbiri, R. S. Kempley, A. Khaplanov, S. Klupp, M. Kogimtzis, I. Kojouharov, A. Korichi, W. Korten, Th. Kröll, R. Krücken, N. Kurz, B. Y. Ky, M. Labiche, X. Lafay, L. Lavergne, I. H. Lazarus, S. Leboutelier, F. Lefebvre, E. Legay, L. Legeard, F. Lelli, S. M. Lenzi, S. Leoni, A. Lermitage, D. Lersch, J. Leske, S. C. Letts, S. Lhenoret, R. M. Lieder, D. Linget, J. Ljungvall, A. Lopez-Martens, A. Lotodé, S. Lunardi, A. Maj, J. van der Marel, Y. Mariette, N. Marginean, R. Marginean, G. Maron, A. R. Mather, W. Mȩczyński, V. Mendéz, P. Medina, B. Melon, R. Menegazzo, D. Mengoni, E. Merchan, L. Mihailescu, C. Michelagnoli, J. Mierzejewski, L. Milechina, B. Million, K. Mitev, P. Molini, D. Montanari, S. Moon, F. Morbiducci, R. Moro, P. S. Morrall, O. Möller, A. Nannini, D. R. Napoli, L. Nelson, M. Nespolo, V. L. Ngo, M. Nicoletto, R. Nicolini, Y. Le Noa, P. J. Nolan, M. Norman, J. Nyberg, A. Obertelli, A. Olariu, R. Orlandi, D. C. Oxley, C. Özben, M. Ozille, C. Oziol, E. Pachoud, M. Palacz, J. Palin, J. Pancin, C. Parisel, P. Pariset, G. Pascovici, R. Peghin, L. Pellegri, A. Perego, S. Perrier, M. Petcu, P. Petkov, C. Petrache, E. Pierre, N. Pietralla, S. Pietri, M. Pignanelli, I. Piqueras, Z. Podolyak, P. Le Pouhalec, J. Pouthas, D. Pugnére, V. F. E. Pucknell, A. Pullia, B. Quintana, R. Raine, G. Rainovski, L. Ramina, G. Rampazzo, G. La Rana, M. Rebeschini, F. Recchia, N. Redon, M. Reese, P. Reiter, P. H. Regan, S. Riboldi, M. Richer, M. Rigato, S. Rigby, G. Ripamonti, A. P. Robinson, J. Robin, J. Roccaz, J. -A. Ropert, B. Rossé, C. Rossi Alvarez, D. Rosso, B. Rubio, D. Rudolph, F. Saillant, E. Şahin, F. Salomon, M. -D. Salsac, J. Salt, G. Salvato, J. Sampson, E. Sanchis, C. Santos, H. Schaffner, M. Schlarb, D. P. Scraggs, D. Seddon, M. Şenyiğit, M. -H. Sigward, G. Simpson, J. Simpson, M. Slee, J. F. Smith, P. Sona, B. Sowicki, P. Spolaore, C. Stahl, T. Stanios, E. Stefanova, O. Stézowski, J. Strachan, G. Suliman, P. -A. Söderström, J. L. Tain, S. Tanguy, S. Tashenov, Ch. Theisen, J. Thornhill, F. Tomasi, N. Toniolo, R. Touzery, B. Travers, A. Triossi, M. Tripon, K. M. M. Tun-Lanoë, M. Turcato, C. Unsworth, C. A. Ur, J. J. Valiente-Dobon, V. Vandone, E. Vardaci, R. Venturelli, F. Veronese, Ch. Veyssiere, E. Viscione, R. Wadsworth, P. M. Walker, N. Warr, C. Weber, D. Weisshaar, D. Wells, O. Wieland, A. Wiens, G. Wittwer, H. J. Wollersheim, F. Zocca, N. V. Zamfir, M. Ziȩbliński, A. Zucchiatti

The Advanced GAmma Tracking Array (AGATA) is a European project to develop and operate the next generation gamma-ray spectrometer. AGATA is based on the technique of gamma-ray energy tracking in electrically segmented high-purity germanium crystals. This technique requires the accurate determination of the energy, time and position of every interaction as a gamma ray deposits its energy within the detector volume. Read More

The observation of neutrinoless double-beta decay would resolve the Majorana nature of the neutrino and could provide information on the absolute scale of the neutrino mass. The initial phase of the Majorana experiment, known as the Demonstrator, will house 40 kg of Ge in an ultra-low background shielded environment at the 4850' level of the Sanford Underground Laboratory in Lead, SD. The objective of the Demonstrator is to determine whether a future 1-tonne experiment can achieve a background goal of one count per tonne-year in a narrow region of interest around the 76Ge neutrinoless double-beta decay peak. Read More

The SciBath-768 detector is a prototype neutral particle detector offering high-precision reconstruction of neutrino and neutron events. It consists of a three dimensional grid of 768 wavelength-shifting fibers immersed in 82 liters of liquid scintillator. Initially conceived as a charged particle detector for neutrino studies, it is also sensitive to fast neutrons (1-100 MeV). Read More

A brief review of the history and neutrino physics of double beta decay is given. A description of the MAJORANA DEMONSTRATOR research and development program including background reduction techniques is presented in some detail. The application of point contact (PC) detectors to the experiment is discussed, including the effectiveness of pulse shape analysis. Read More

Neutrinoless double-beta decay experiments can potentially determine the Majorana or Dirac nature of the neutrino, and aid in understanding the neutrino absolute mass scale and hierarchy. Future 76Ge-based searches target a half-life sensitivity of >10^27 y to explore the inverted neutrino mass hierarchy. Reaching this sensitivity will require a background rate of <1 count tonne^-1 y^-1 in a 4-keV-wide spectral region of interest surrounding the Q value of the decay. Read More

The observation of neutrinoless double-beta decay would determine whether the neutrino is a Majorana particle and provide information on the absolute scale of neutrino mass. The MAJORANA Collaboration is constructing the DEMONSTRATOR, an array of germanium detectors, to search for neutrinoless double-beta decay of 76-Ge. The DEMONSTRATOR will contain 40 kg of germanium; up to 30 kg will be enriched to 86% in 76-Ge. Read More

2011Apr
Affiliations: 1National Institute of Standards and Technology, Gaithersburg, MD, 2Physics Department, University of Michigan, Ann Arbor, MI, 3Physics Department, University of Michigan, Ann Arbor, MI, 4Physics Department, University of Michigan, Ann Arbor, MI, 5Physics Department, University of California at Berkeley and Lawrence Berkeley National Laboratory, Berkeley, CA, 6Physics Department, University of California at Berkeley and Lawrence Berkeley National Laboratory, Berkeley, CA, 7CENPA and Physics Department, University of Washington, Seattle, WA, 8Physics Department, Hamilton College, Clinton, NY, 9National Institute of Standards and Technology, Gaithersburg, MD, 10National Institute of Standards and Technology, Gaithersburg, MD, 11Physics Department, Tulane University, New Orleans, LA, 12Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC, 13Physics Department, Tulane University, New Orleans, LA

We report the results of an improved determination of the triple correlation $D P \cdot(p_{e}\times p_{\nu})$ that can be used to limit possible time-reversal invariance in the beta decay of polarized neutrons and constrain extensions to the Standard Model. Our result is $D=(-0.96\pm 1. Read More

The MAJORANA Collaboration is building the MAJORANA DEMONSTRATOR, a 60 kg array of high purity germanium detectors housed in an ultra-low background shield at the Sanford Underground Laboratory in Lead, SD. The MAJORANA DEMONSTRATOR will search for neutrinoless double-beta decay of 76Ge while demonstrating the feasibility of a tonne-scale experiment. It may also carry out a dark matter search in the 1-10 GeV/c^2 mass range. Read More

We analysed thermonuclear (type-I) X-ray bursts observed from the low-mass X-ray binary 4U1728-34 by RXTE, Chandra and INTEGRAL. We compared the variation in burst energy and recurrence times as a function of accretion rate with the predictions of a numerical ignition model including a treatment of the heating and cooling in the crust. We found that the measured burst ignition column depths are significantly below the theoretically predicted values, regardless of the assumed thermal structure of the neutron star interior. Read More

From analysis of the in-plane resistivity $\rho_{ab}(T)$ of La$_{2-x}$Sr$_x$CuO$_4$, we show that normal state transport in overdoped cuprates can be delineated into two regimes in which the electrical resistivity varies approximately linearly with temperature. In the low temperature limit, the $T$-linear resistivity extends over a very wide doping range, in marked contrast to expectations from conventional quantum critical scenarios. The coefficient of this $T$-linear resistivity scales with the superconducting transition temperature $T_c$, implying that the interaction causing this anomalous scattering is also associated with the superconducting pairing mechanism. Read More

We propose a new heating mechanism in magnetar crusts. Magnetars' crustal magnetic fields are much stronger than their surface fields; therefore, magnetic pressure partially supports the crust against gravity. The crust loses magnetic pressure support as the field decays and must compensate by increasing the electron degeneracy pressure; the accompanying increase in the electron Fermi energy induces nonequilibrium, exothermic electron captures. Read More

We address the asymptotic and approximate distributions of a large class of test statistics with quadratic forms used in association studies. The statistics of interest do not necessarily follow a chi-square distribution and take the general form $D=X^T A X$, where $X$ follows the multivariate normal distribution, and $A$ is a general similarity matrix which may or may not be positive semi-definite. We show that $D$ can be written as a linear combination of independent chi-square random variables, whose distribution can be approximated by a chi-square or the difference of two chi-square distributions. Read More

Observationally inferred superburst ignition depths are shallower than models predict. We address this discrepancy by reexamining the superburst trigger mechanism. We first explore the hypothesis of Kuulkers et al. Read More

We have undertaken a long-term project, Planets in Stellar Clusters Extensive Search (PISCES), to search for transiting planets in open clusters. In this paper we present the results for NGC 188, an old, rather populous cluster. We have monitored the cluster for more than 87 hours, spread over 45 nights. Read More

We investigate the crystallization rate of a one-component plasma (OCP) in the context of classical nucleation theory. From our derivation of the free energy of an arbitrary distribution of solid clusters embedded in a liquid phase, we derive the steady-state nucleation rate of an OCP as a function of the Coulomb coupling parameter. Our result for the rate is in accord with recent molecular dynamics simulations, but it is greater than that of previous analytical estimates by many orders of magnitude. Read More

I construct a simple model of the convective burning layer during a type I X-ray burst to investigate the effects convection has on the stability of the layer to nonradial oscillations. A linear perturbation analysis demonstrates that the region is stable to nonradial oscillations when energy transport is convection-dominated, but it is unstable when energy transport is radiation-dominated. Thus, efficient convection always dampens oscillations. Read More

The Rossi X-ray Timing Explorer has detected nearly coherent oscillations in the tails of type I X-ray bursts from 17 low-mass X-ray binaries. The oscillations are thought to be generated by brightness fluctuations associated with a surface mode on the rotating neutron star. The mechanism that drives the modes is, however, not understood, since the burning layer is stable to thermal perturbations. Read More

Neutron stars in close binary star systems often accrete matter from their companion stars. Thermonuclear ignition of the accreted material in the atmosphere of the neutron star leads to a thermonuclear explosion which is observed as an X-ray burst occurring periodically between hours and days depending on the accretion rate. The ignition conditions are characterized by a sensitive interplay between the accretion rate of the fuel supply and its depletion rate by nuclear burning in the hot CNO cycle and the rp-process. Read More

We use the two-zone model of Cooper & Narayan to study the onset and time evolution of hydrogen-triggered type I X-ray bursts on accreting neutron stars. At the lowest accretion rates, thermally unstable hydrogen burning ignites helium as well and produces a mixed hydrogen and helium burst. For somewhat higher accretion rates, thermally unstable hydrogen burning does not ignite helium and thus triggers only a weak hydrogen flash. Read More

We investigate the latitude at which type I X-ray bursts are ignited on rapidly rotating accreting neutron stars. We find that, for a wide range of accretion rates, ignition occurs preferentially at the equator, in accord with the work of Spitkovsky et al. However, for a range of accretion rates below the critical rate above which bursts cease, ignition occurs preferentially at higher latitudes. Read More

We present a generalized Drude analysis of the in-plane optical conductivity $\sigma_{ab}$($T$,$\omega$) in cuprates taking into account the effects of in-plane anisotropy. A simple ansatz for the scattering rate $\Gamma$($T$,$\omega$), that includes anisotropy, a quadratic frequency dependence and saturation at the Mott-Ioffe-Regel limit, is able to reproduce recent normal state data on an optimally doped cuprate over a wide frequency range. We highlight the potential importance of including anisotropy in the full expression for $\sigma_{ab}$($T$,$\omega$) and challenge previous determinations of $\Gamma$($\omega$) in which anisotropy was neglected and $\Gamma$($\omega$) was indicated to be strictly linear in frequency over a wide frequency range. Read More

We investigate the effect of the hot CNO cycle breakout reaction 15O(alpha,gamma)19Ne on the occurrence of type I X-ray bursts on accreting neutron stars. For f_rp <~ 0.1, where f_rp is a dimensionless factor by which we multiply the 15O(alpha,gamma)19Ne reaction rate of Caughlan & Fowler (1988), our model predicts that bursts should occur only for accretion rates below a critical value of approximately 0. Read More

We construct a two-zone model to describe H and He burning on the surface of an accreting neutron star and use it to study the triggering of type I X-ray bursts. Although highly simplified, the model reproduces all of the bursting regimes seen in the more complete global linear stability analysis of Narayan & Heyl (2003), including the regime of delayed mixed bursts. The results are also consistent with observations of type I X-ray bursts. Read More

We have undertaken a long-term project, Planets in Stellar Clusters Extensive Search (PISCES), to search for transiting planets in open clusters. In this paper we present the results for NGC 2158, an intermediate age, populous cluster. We have monitored the cluster for over 260 hours, spread over 59 nights. Read More

2005Sep
Affiliations: 1MIT Kavli Institute for Astrophysics and Space Research, and, 2MIT Kavli Institute for Astrophysics and Space Research, and, 3Harvard-Smithsonian Center for Astrophysics, 4Harvard-Smithsonian Center for Astrophysics
Category: Astrophysics

We measure the rates of type I X-ray bursts, as a function of the bolometric luminosity, from a likely complete sample of 37 non-pulsing transients (1996-2004). Our goals are to test the burst model for neutron stars and to investigate whether black holes have event horizons. We find 135 type I bursts in 3. Read More

(abridged) We have investigated the physical conditions under which accreting neutron stars can both produce and preserve sufficient quantities of carbon fuel to trigger superbursts. Our models span the plausible ranges of neutron star thermal conductivities, core neutrino emission mechanisms, and areal radii, as well as the CNO abundances in the accreted material. We find that neutron stars that accrete hydrogen-rich material with CNO mass fractions <~ that of the Sun will not exhibit superbursts under any circumstances. Read More

We carry out a general-relativistic global linear stability analysis of the amassed carbon fuel on the surface of an accreting neutron star to determine the conditions under which superbursts occur. We reproduce the general observational characteristics of superbursts, including burst fluences, recurrence times, and the absence of superbursts on stars with accretion rates below 10% of the Eddington limit. By comparing our results with observations, we are able to set constraints on neutron star parameters such as the stellar radius and neutrino cooling mechanism in the core. Read More

We describe an apparatus used to measure the triple-correlation term (\D \hat{\sigma}_n\cdot p_e\times p_\nu) in the beta-decay of polarized neutrons. The \D-coefficient is sensitive to possible violations of time reversal invariance. The detector has an octagonal symmetry that optimizes electron-proton coincidence rates and reduces systematic effects. Read More

2004Jan
Affiliations: 1University of Illinois, 2University of Illinois, 3University of Illinois, 4University of Illinois, 5University of Illinois, 6University of Illinois
Category: Astrophysics

We have analyzed Chandra archival observations of the Antennae galaxies to study the distribution and physical properties of its hot interstellar gas. Eleven distinct diffuse X-ray emission regions are selected according to their underlying interstellar structures and star formation activity. The X-ray spectra of these regions are used to determine their thermal energy contents and cooling timescales. Read More