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Search for Halo Axions

Description: A collaboration of MIT, LLNL, Univ. of Florida, FNAL, UC Berkeley and INR Moscow have built a large-scale RF cavity axion detector. The experiment has been taking production data since February of 1996 and is sensitive enough to detect plausible dark matter axions comprising a reasonable fraction of the mass in our galactic halo. After a brief introduction to axion physics, I discuss details of our instrumentation, our analysis methodology, our run plan and future goals of the experiments.
Date: January 1, 1998
Creator: Daw, E. J., & van Bibber, K.
Partner: UNT Libraries Government Documents Department

Large-scale search for dark-matter axions

Description: Early results from a large-scale search for dark matter axions are presented. In this experiment, axions constituting our dark-matter halo may be resonantly converted to monochromatic microwave photons in a high-Q microwave cavity permeated by a strong magnetic field. Sensitivity at the level of one important axion model (KSVZ) has been demonstrated.
Date: January 1, 1998
Creator: Hagmann, C. A.; Kinion, D.; Stoeffl, W.; Van Bibber, K.; Daw, E. J.; McBride, J. et al.
Partner: UNT Libraries Government Documents Department

Large scale U.S. dark matter Axion search

Description: We describe the instrumentation and operations of the microwave cavity axion detector presently taking data at Lawrence Livermore National Laboratory This experiment, in collaboration of LLNL, MIT, Univ of Florida, LBNL, Univ of Chicago, FNAL, and INR/Moscow, has been operating with greater than 90% live time since February 1996 with the objective of exploring the region from 0 5 to 1 9 GHz (2 1 to 7 9 ยต<i>eV</i>) at greater than KSVZ sensitivitv In a com~&on paper (E Daw) in these proceedings, the data analysis and Iirst results will be described (See also
Date: August 1, 1998
Creator: Kinion, D
Partner: UNT Libraries Government Documents Department

Axion overview and the U.S. RF cavity axion search

Description: The axion, a hypothetical elementary particle, originally emerged from a solution to the strong CP problem in QCD. Later, axions were recognized as good dark matter candidates. Dark matter axions have only feeble couplings to matter and radiation, so their detection offers considerable challenge. Nonetheless, a new generation of exquisitely sensitive searches is underway. One such effort, in the United States, has already achieved sensitivity to plausible halo dark matter axion to photon couplings.
Date: January 1, 1998
Creator: Rosenberg, L. J. & van Bibber, K. A.
Partner: UNT Libraries Government Documents Department

Axions from string decay

Description: We have studied numerically the evolution and decay of axion strings. These global defects decay mainly by axion emission and thus contribute to the cosmological axion energy density. The relative importance of this source relative to misalignment production of axions depends on the spectrum. Radiation spectra for various string loop configurations are presented. They support the contention that the string decay contribution is of the same order of magnitude as the contribution from misalignment.
Date: July 9, 1998
Creator: Hagmann, C., LLNL
Partner: UNT Libraries Government Documents Department

Status of the large-scale dark-matter axion search

Description: If axions constitute the dark matter of our galactic halo they can be detected by their conversion into monochromatic microwave photons in a high-Q microwave cavity permeated by a strong magnetic field. A large-scale experiment is under construction at LLNL to search for halo axions in the mass range 1.3 - 13 {mu}eV, where axions may constitute closure density of the universe. The search builds upon two pilot efforts at BNL and the University of Florida in the late 1980`s, and represents a large improvement in power sensitivity ({approximately}50) both due to the increase in magnetic volume (B{sup 2}V = 14 T{sup 2}m{sup 3}), and anticipated total noise temperature (T{sub n} {approximately}3K). This search will also mark the first use of multiple power-combined cavities to extend the mass range accessible by this technique. Data will be analyzed in two parallel streams. In the first, the resolution of the power spectrum will be sufficient to resolve the expected width of the overall axion line, {approximately}{bigcirc} (1kHz). In the second, the resolution will be {bigcirc}(O.01-1 Hz) to look for extremely narrow substructure reflecting the primordial phase-space of the axions during infall. This experiment will be the first to have the required sensitivity to detect axions, for plausible axion models.
Date: September 1, 1994
Creator: Van Bibber, K.; Hagmann, C.; Stoeffl, W.; Daw, E.; Rosenberg, L.; Sikivie, P. et al.
Partner: UNT Libraries Government Documents Department

Supersymmetry breaking in superstring theory by Gaugino condensation and its phenomenology

Description: Weakly-coupled heterotic string is known to have problems of dilaton/moduli stabilization, supersymmetry breaking (by hidden-sector gaugino condensation), gauge coupling unification, QCD axion, as well as cosmological problems involving dilaton/moduli and axion. The author studies these problems by adopting the point of view that they arise mostly due to limited calculational power, little knowledge of the full vacuum structure, and an inappropriate treatment of gaugino condensation. It turns out that these problems can be solved or are much less severe after a more consistent and complete treatment. There are two kinds of non-perturbative effects in the construction of string effective field theory: the field-theoretical non-perturbative effects of gaugino condensation (with an important constraint ignored in the past) and the stringy nonperturbative effects conjectured by S. Shenker, which are best described using the linear multiplet formalism. Stringy non-perturbative corrections to the Kaehler potential are invoked to stabilize the dilaton at a value compatible with a weak coupling regime. Modular invariance is ensured through the Green-Schwarz counterterm and string threshold corrections which, together with hidden matter condensation, lead to moduli stabilization at the self-dual point where the vev`s of moduli`s F components vanish. In the vacuum, supersymmetry is broken at a realistic scale with vanishing cosmological constant. As for soft supersymmetry breaking, this model always leads to a dilaton-dominated scenario. For the strong CP problem, the model-independent axion has the right properties to be the QCD axion. Furthermore, there is a natural hierarchy between the dilaton/moduli mass and the gravitino mass, which could solve both the cosmological moduli problem and the cosmological problem of the model-independent axion.
Date: May 1, 1997
Creator: Wu, Yi-Yen
Partner: UNT Libraries Government Documents Department

The pooltable analogy to axion physics

Description: An imaginary character named TSP finds himself in a playroom whose floor is tilted to one side. However, the pooltable in the playroom is horizontal. TSP wonders how this can be. In doing so, he embarks upon an intellectual journey which parallels that which has been travelled during the past two decades by physicists interested in the Strong CP Problem and axion physics.
Date: January 1, 1996
Creator: Sikivie, P.
Partner: UNT Libraries Government Documents Department

A dark matter solution from the supersymmetric axion model

Description: We study the effect of the late decaying saxino (the scalar superpartner of the axion) and find out that there is a possible dark matter solution from a class of supersymmetric extensions of the invisible axion model. In this class of models, the saxino which decays into two axions acts as the late decaying particle which reconciles the cold dark matter model with high values of the Hubble constant. Recent observations of the Hubble constant are converging to H{sub 0} = 70--80 km sec{sup {minus}1} Mpc{sup {minus}1}, which would be inconsistent with the standard mixed dark matter model. This class of models provides a plausible framework for the alternative cold dark matter plus late decaying particle model, with the interesting possibility that both cold dark matter and the extra radiation consist of axion. 15 refs.
Date: May 1, 1996
Creator: Chang, Sanghyeon & Kim, Hang Bae
Partner: UNT Libraries Government Documents Department

Axions from cosmic string and wall decay

Description: If inflation occurred with a reheat temperature &gt; T{sub PQ}, axions from the decay of global axion strings and domain walls would make an important contribution to the cosmological energy density, comparable to that from vacuum misalignment. Several groups have numerically studied the evolution of axion strings and walls in the past, however substantial uncertainties remain in their contribution to the present density {Omega}{sub a,string+wall} {approx} 1-100 (f{sub a}/10{sup 12} GeV){sup 7/6}, where f{sub a} is the axion decay constant. I will describe the numerical methods used in our simulations and show results for several string and wall configurations.
Date: March 10, 2010
Creator: Hagmann, C A
Partner: UNT Libraries Government Documents Department

Axions from wall decay

Description: The authors discuss the decay of axion walls bounded by strings and present numerical simulations of the decay process. In these simulations, the decay happens immediately, in a time scale of order the light travel time, and the average energy of the radiated axions is &lt;w{sub a}&gt; {approx_equal} 7m{sub a} for v{sub a}/m{sub a} {approx_equal} 500. &lt;w{sub a}&gt; is found to increase approximately linearly with ln(v{sub a}/m{sub a}). Extrapolation of this behavior yields &lt;w{sub a}&gt; {approx_equal} 60 m{sub a} in axion models of interest.
Date: January 8, 2001
Creator: Chang, S.; Hagmann, C. & Sikivie, P.
Partner: UNT Libraries Government Documents Department

Sources and distributions of dark matter

Description: In the first section, the author tries to convey a sense of the variety of observational inputs that tell about the existence and the spatial distribution of dark matter in the universe. In the second section, he briefly reviews the four main dark matter candidates, taking note of each candidate`s status in the world of particle physics, its production in the early universe, its effect upon large scale structure formation and the means by which it may be detected. Section 3 concerns the energy spectrum of (cold) dark matter particles on earth as may be observed some day in a direct detection experiment. It is a brief account of work done in collaboration with J. Ipser and, more recently, with I. Tkachev and Y. Wang.
Date: December 31, 1995
Creator: Sikivie, P.
Partner: UNT Libraries Government Documents Department

Experimental overview of axion searches

Description: Experimental methods to search for the ``invisible axion`` (f{sub a} {much_gt} 250 GeV) are reviewed. The report focuses on the axion-photon coupling, both for laboratory experiments as well as those looking for stellar or cosmologically produced axions. The conclusion is that while the axion-photon mixing in principle would permit laboratory axion searches which are broadband in mass, in fact no such experiment could have the sensitivity to the axion, where m{sub afa} {approx} m{sub {pi}f{pi}}. The only experiments which promise to have any chance to find the axion are the microwave cavity experiments, which presume axions to constitute our galactic halo dark matter. The conversion of axions into a monochromatic microwave signal in a resonant circuit affords the experiment the extraordinary sensitivity required to see the axion, at the expense of being narrow-band in mass, i.e. a tuning experiment. Two such efforts are underway in the world.
Date: June 28, 1995
Creator: van Bibber, K.
Partner: UNT Libraries Government Documents Department

Task A: Research in theoretical elementary particle physics at the University of Florida; Annual progress report

Description: This is the Annual Progress Report of the theoretical particle theory group at the University of Florida under DoE Grant DE-FG05-86ER40272. At present our group consists of four Full Professors (Field, Ramond, Thorn, Sikivie) and three Assistant Professors (Qiu, Woodard, Kennedy). Dallas Kennedy recently joined our group increasing the Particle Theory faculty to seven. In addition, we have three postdoctoral research associates, an SSC fellow, and eight graduate students. The research of our group covers a broad range of topics in theoretical high energy physics with balance between theory and phenomenology. Included in this report is a summary of the last several years of operation of the group and an outline of our current research program.
Date: November 1, 1993
Creator: Field, R.D.; Ramond, P.M.; Sikivie, P. & Thorn, C.B.
Partner: UNT Libraries Government Documents Department

A second-generation cosmic axion experiment

Description: An experiment is described to detect dark matter axions trapped in the halo of our galaxy. Galactic axions are converted into microwave photons via the Primakoff effect in a static background field provided by a superconducting magnet. The photons are collected in a high Q microwave cavity and detected by a low noise receiver. The axion mass range accessible by this experiment is 1.3 {minus} 13 {mu}eV. The expected sensitivity will be roughly 50 times greater than achieved by previous experiments in this mass range. The assembly of the detector is well under any at LLNL and data taking will start in mid-1995.
Date: May 1, 1995
Creator: Hagmann, C.; Stoeffl, W. & van Bibber, K.
Partner: UNT Libraries Government Documents Department

Axionic hot dark matter in the hadronic axion window

Description: Mixed dark matter scenario can reconcile the COBE data and the observed large scale structure. So far the massive neutrino with a mass of a few eV has been the only discussed candidate for the hot dark matter component. We point out that the hadronic axion in the so-called hadronic axion window, f{sub a} {approx} 10{sup 6} GeV, is a perfect candidate as hot dark matter within the mixed dark matter scenario. The current limits on the hadronic axion are summarized. The most promising methods to verify the hadronic axion in this window are the resonant absorption of almost-monochromatic solar axions from M1 transition of the thermally excited {sup 57}Fe in the Sun, and the observation of the ''axion burst'' in water Cerenkov detectors from another supernova.
Date: May 23, 1998
Creator: Moroi, Takeo & Murayama, Hitoshi
Partner: UNT Libraries Government Documents Department

A SQUID-based microwave cavity search for dark-matter axions

Description: Axions in the {mu}eV mass range are a plausible cold dark matter candidate and may be detected by their conversion into microwave photons in a resonant cavity immersed in a static magnetic field. The first result from such an axion search using a superconducting first-stage amplifier (SQUID) is reported. The SQUID amplifier, replacing a conventional GaAs field-effect transistor amplifier, successfully reached axion-photon coupling sensitivity in the band set by present axion models and sets the stage for a definitive axion search utilizing near quantum-limited SQUID amplifiers.
Date: October 21, 2009
Creator: Asztalos, S J; Carosi, G; Hagmann, C; Kinion, D; van Bibber, K; Hotz, M et al.
Partner: UNT Libraries Government Documents Department

GammeV: Fermilab axion-like particle photon regeneration results

Description: GammeV is an axion-like particle photon regeneration experiment conducted at Fermilab that employs the light shining through a wall technique. They obtain limits on the coupling of a photon to an axion-like particle that extend previous limits for both scalar and pseudoscalar axion-like particles in the milli-eV mass range. They are able to exclude the axion-like particle interpretation of the anomalous PVLAS 2006 result by more than 5 standard deviations.
Date: September 1, 2008
Creator: Wester, William
Partner: UNT Libraries Government Documents Department

An Improved RF Cavity Search for Halo Axions

Description: The axion is a hypothetical elementary particle and cold dark matter candidate. In this RF cavity experiment, halo axions entering a resonant cavity immersed in a static magnetic field convert into microwave photons, with the resulting photons detected by a low-noise receiver. The ADMX Collaboration presents new limits on the axion-to-photon coupling and local axion dark matter halo mass density from a RF cavity axion search in the axion mass range 1.9-2.3 {micro}eV, broadening the search range to 1.9-3.3 {micro}eV. In addition, we report first results from an improved analysis technique.
Date: November 11, 2003
Creator: Asztalos, S; Bradley, R; Duffy, L; Hagmann, C; Kinion, D; Moltz, D et al.
Partner: UNT Libraries Government Documents Department

Finding the Axion: The Search for the Dark Matter of the Universe

Description: The nature of dark matter has been a mystery for over 70 years. One plausible candidate is the axion, an extremely light and weakly interacting particle, which results from the Peccei-Quinn solution to the strong CP problem. In this proceedings I will briefly review the evidence for dark matter as well as the motivation for the existence of the axion as a prime dark matter candidate. I will then discuss the experimental methods to search for axion dark matter focusing on a sensitive cavity experiment (ADMX) being run at Lawrence Livermore National Laboratory.
Date: November 3, 2006
Creator: Carosi, G
Partner: UNT Libraries Government Documents Department

Large-scale search for dark-matter axions

Description: We review the status of two ongoing large-scale searches for axions which may constitute the dark matter of our Milky Way halo. The experiments are based on the microwave cavity technique proposed by Sikivie, and marks a ''second-generation'' to the original experiments performed by the Rochester-Brookhaven-Fermilab collaboration, and the University of Florida group.
Date: August 30, 2000
Creator: Kinion, D & van Bibber, K
Partner: UNT Libraries Government Documents Department

Review of dark-matter axion experiments

Description: We review the status of two ongoing large-scale searches for axions which may constitute the dark matter of our Milky Way halo. The experiments are based on the microwave cavity technique proposed by Sikivie, and marks a 'second-generation' to the original experiments performed by the Rochester-Brookhaven-Fermilab collaboration, and the University of Florida group.
Date: August 30, 2000
Creator: van Bibber, K & Kinion, D
Partner: UNT Libraries Government Documents Department