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Reducing Zero-point Systematics in Dark Energy Supernova Experiments

Description: We study the effect of filter zero-point uncertainties on future supernova dark energy missions. Fitting for calibration parameters using simultaneous analysis of all Type Ia supernova standard candles achieves a significant improvement over more traditional fit methods. This conclusion is robust under diverse experimental configurations (number of observed supernovae, maximum survey redshift, inclusion of additional systematics). This approach to supernova fitting considerably eases otherwise stringent mission cali- bration requirements. As an example we simulate a space-based mission based on the proposed JDEM satellite; however the method and conclusions are general and valid for any future supernova dark energy mission, ground or space-based.
Date: April 1, 2011
Creator: Faccioli, Lorenzo; Kim, Alex G; Miquel, Ramon; Bernstein, Gary; Bonissent, Alain; Brown, Matthew et al.
Partner: UNT Libraries Government Documents Department

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

Search for MACHOs in the galactic dark matter

Description: Machos (Massive Compact Halo Objects) might be a significant constituent of the dark matter that dominates the Milky Way. (Machos are a form of baryonic dark matter.) This article describes the experimental searches for Machos that exploit the gravitational microlens magnification of extragalactic stars. These surveys monitor millions of stars, in some cases every night, looking for magnification events. The early results from the surveys have yielded some spectacular events. It appears that Machos do comprise a significant fraction of the galactic dark matter. It also appears that the central bar of the Milky Way is very massive.
Date: January 2, 1996
Creator: Alcock, C.
Partner: UNT Libraries Government Documents Department

Searching for MACHOs with microlensing

Description: Baryonic matter, in the form of Machos (Massive Compact Halo Objects), might be a significant constituent of the dark matter that dominates the Milky Way. This article describes the experimental searches for Machos that exploit the gravitational microlens magnification of extragalactic stars. These surveys monitor millions of stars, in some cases every night, looking for magnification events. The early results from the surveys have yielded some spectacular events, and pose a significant new puzzle for galactic structure: toward the Large Magellanic Cloud we see fewer events than anticipated for a standard dark halo dominated by Machos, but toward the galactic bulge, the event rate is much higher than anticipated. This is a field of research that is ripe with opportunities for beginning (and senior) scientists.
Date: April 1996
Creator: Alcock, C.
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

What is the spectrum of cold dark matter particles on Earth?

Description: It is argued that the spectrum of cold dark matter particles on Earth has peaks in velocity space associated with particles falling onto the Galaxy for the first time and with particles which have fallen in and out of the Galaxy only a small number of times in the past. Estimates are given for the sizes and velocity magnitudes of the first few peaks. The estimates are based on the secondary infall model of halo formation which has been generalized to include the effect of angular momentum.
Date: August 1, 1996
Creator: Sikivie, P.
Partner: UNT Libraries Government Documents Department

Caustic rings of dark matter

Description: It is shown that the infall of collisionless dark matter onto isolated galaxies produce a series of caustic rings in the halo dark matter distribution. The properties of these caustics are investigated. It is found in particular that the density profile of the caustic behaves as the inverse distance to the ring. Bumps in the rotation curve of NGC 3198 are interpreted as due to caustic rings of dark matter.
Date: May 6, 1997
Creator: Sikivie, P.
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

Gravitational microlensing searches and results

Description: Baryonic matter, in the form of Machos (MAssive Compact Halo Objects), might be a significant constituent of the dark matter that dominates the Milky Way. This article describes how surveys for Machos exploit the gravitational microlens magnification of extragalactic stars. The experimental searches for this effect monitor millions of stars, in some cases every night, looking for magnification events. The early results of these surveys indicate that Machos make up a significant fraction of the dark matter in the Milky Way, and that these objects have stellar masses. Truly substellar objects do not contribute much to the total. Additionally, the relatively high event rate towards the Galactic bulge seems to require that the bulge be elongated, and massive.
Date: May 8, 1997
Creator: Alcock, C.
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

Neutrino masses at v3/2

Description: Theories in which neutrino masses are generated by a conventional see-saw mechanism generically yield masses which are O(v{sup 2}) in units where M{sub Pl} = 1, which is naively too small to explain the results from SuperKamiokande. In supersymmetric theories with gravity mediated supersymmetry breaking, the fundamental small parameter is not v/M{sub Pl}, but m{sub I}/M{sub Pl}, where m{sub I} is the scale of supersymmetry breaking in the hidden sector. We note that m{sub I}{sup 3}/M{sub Pl}{sup 2} is only slightly too large to explain SuperKamiokande, and present two models that achieve neutrino masses at this order in m{sub I}, one of which has an additional suppression {lambda}{sub {tau}}{sup 2}, while the other has additional suppression arising from a loop factor. The latter model shares a great deal of phenomenology with a class of models previously explored, including the possibility of viable sneutrino dark matter.
Date: October 10, 2000
Creator: Arkani-Hamed, Nima; Hall, Lawrence; Murayama, Hitoshi; Smith,David & Weiner, Neal
Partner: UNT Libraries Government Documents Department

The Sloan Digital Sky Survey: Status and prospects

Description: The Sloan Digital Sky Survey (SDSS) is a project to definitively map {pi} steradians of the local Universe. An array of CCD detectors used in drift-scan mode will digitally image the sky in five passbands to a limiting magnitude of r{prime} {approximately} 23. Selected from the imaging survey, 10{sup 6} galaxies and 10{sup 5} quasars will be observed spectroscopically. I describe the current status of the survey, which is due to begin observations early in 1997, and its prospects for constraining models for dark matter in the Universe. 8 refs., 7 figs.
Date: May 1, 1996
Creator: Loveday, J. & Collaboration, SDSS
Partner: UNT Libraries Government Documents Department

The velocity peaks in the cold dark matter spectrum on earth

Description: The cold dark matter spectrum on earth is expected to have peaks in velocity space. We obtain estimates for the sizes and locations of these peaks. To this end we have generalized the secondary infall model of galactic halo formation to include angular momentum of the dark matter particles. This new model is still spherically symmetric and it has self-similar solutions. Our results are relevant to direct dark matter search experiments.
Date: April 13, 1995
Creator: Sikivie, P.; Tkachev, I.I. & Wang, Y.
Partner: UNT Libraries Government Documents Department

Dissecting Biological Dark Matter: Single Cell Genetic Analysis of TM7, a Rare and Uncultivated Microbe from the Human Mouth

Description: We have developed a microfluidic device that allows the isolation and genome amplification of individual microbial cells, thereby enabling organism-level genomic analysis of complex microbial ecosystems without the need for culture. This device was used to perform a directed survey of the human subgingival crevice and to isolate bacteria having rod-like morphology. Several isolated microbes had a 16S rRNA sequence that placed them in candidate phylum TM7, which has no cultivated or sequenced members. Genome amplification from individual TM7 cells allowed us to sequence and assemble &gt;1,000 genes, providing insight into the physiology of members of this phylum. This approach enables single-cell genetic analysis of any uncultivated minority member of a microbial community.
Date: July 1, 2007
Creator: Fenner, Marsha W; Marcy, Yann; Ouverney, Cleber; Bik, Elisabeth M.; Losekann, Tina; Ivanova, Natalia et al.
Partner: UNT Libraries Government Documents Department

Dark Matter before the LHC in a Natural Supersymmetric StandardModel

Description: We show that the solid lower bound of about 10{sup -44} cm{sup 2} is obtained for the cross section between the supersymmetric dark matter and nucleon in a theory in which the supersymmetric fine-tuning problem is solved without extending the Higgs sector at the weak scale. This bound arises because of relatively small superparticle masses and a fortunate correlation that the two dominant diagrams for the dark matter detection always interfere constructively if the constraint from the b {yields} s{gamma} measurements is obeyed. It is, therefore, quite promising in the present scenario that the supersymmetric dark matter is discovered before the LHC, assuming that the dark matter is the lightest supersymmetric particle.
Date: September 21, 2005
Creator: Ryuichiro, Kitano & Yasunori, Nomura
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

New dark matter candidates motivated from superstring derived unification

Description: Perturbative gauge coupling unification in realistic superstring models suggest the existence of additional heavy down-type quarks, beyond the minimal supersymmetric standard model. The mass scale of the heavy down-type quarks is constrained by requiring agreement between the measured low energy gauge parameters and the string-scale gauge coupling unification. These additional quarks arise and may be stable due to the gauge symmetry breaking by ``Wilson lines`` in the superstring models. We argue that there is a window in the parameter space within which this down-type quark is a good candidate for the dark matter. 18 refs.
Date: March 1, 1996
Creator: Chang, Sanghyeon; Coriano, C. & Faraggi, A.E.
Partner: UNT Libraries Government Documents Department

Constraints on inelastic dark matter from XENON10

Description: It has been suggested that dark matter particles which scatter inelastically from detector target nuclei could explain the apparent incompatibility of the DAMA modulation signal (interpreted as evidence for particle dark matter) with the null results from CDMS-II and XENON10. Among the predictions of inelastically interacting dark matter are a suppression of low-energy events, and a population of nuclear recoil events at higher nuclear recoil equivalent energies. This is in stark contrast to the well-known expectation of a falling exponential spectrum for the case of elastic interactions. We present a new analysis of XENON10 dark matter search data extending to E{sub nr} = 75 keV nuclear recoil equivalent energy. Our results exclude a significant region of previously allowed parameter space in the model of inelastically interacting dark matter. In particular, it is found that dark matter particle masses m{sub x} {approx}&gt; 150 GeV are disfavored.
Date: November 23, 2009
Creator: Angle, J; Aprile, E; Arneodo, F; Baudis, L; Bernstein, A; Bolozdynya, A et al.
Partner: UNT Libraries Government Documents Department

MACHO project 2nd year LMC microlensing results and dark matter implications

Description: The MACHO Project is searching for galactic dark matter in the form of massive compact halo objects (Machos). Millions of stars in the Large Magellanic Cloud (LMC), Small Magellanic Cloud (SMC), and Galactic bulge are photometrically monitored in an attempt to detect rare gravitational microlensing events caused by otherwise invisible Machos. Analysis of two years of photometry on 8.5 million stars in the LMC reveals 8 candidate microlensing events, far more than the one event expected from lensing by low-mass stars in known galactic populations. Five these eight events we estimate the optical depth towards the LMC from events with 2 < i < 200 days to be r2 280 about 2.9+1 4/-0.8 X 10-7. This exceeds the optical depth of 0.5 x 10-7 expected for known stars and is to be compared with an optical depth of 4.7 X 10-7 predicted for a `standard` halo composed entirely of Machos. The total mass in this lensing population is 2 +1.2/-0.7 x 10+11 Mo (within 50 kpc from the Galactic center). Event timescales yield a most probable Macho Mass of 0.5 +0.3/-0.2 Mo, although this value is quite model dependent. -0.2
Date: February 1996
Creator: Alcock, C.; Allsman, R. A. & Alves, D.
Partner: UNT Libraries Government Documents Department

Search for earth mass planets and dark matter too

Description: Gravitational microlensing is known for baryonic dark matter searches. Here we show that microlensing also provides a unique tool for the detection of low mass planets (such as earths and neptunes) from the ground. A planetary system forms a binary lens (or, a multi-point lens), and we can determine the mass ratio of the planet with respect to the star and relative distance (= separation/Einstein ring radius) between the star and planet. Such a microlensing planet search project requires a {approx} 2 m survey telescope, and a network of 1.5 - 2 m follow-up telescopes capable of monitoring stars in the Bulge on a 24-hour basis. During the off-season of the Galactic bulge, this network can be used for dark matter search by monitoring the stars in the LMC and SMC.
Date: February 1, 1996
Creator: Rhie, S.H. & Bennett, D.P.
Partner: UNT Libraries Government Documents Department

Study of Dark Matter inspired cMSSM scenarios at a TeV-class Linear Collider

Description: The accuracy in the measurement of the masses of sleptons and heavy Higgs bosons in cMSSM scenarios, compatible with the WMAP result on cold dark matter, has been re-analysed in view of the requirements for predicting this density to a few percent level from SUSY measurements at the linear collider.
Date: October 8, 2004
Creator: Battaglia, Marco
Partner: UNT Libraries Government Documents Department