Dark Matter workshop
V. Burdyuzha, Observatoire de la Cote d'Azur and Astro-Space Center of the Lebedev Physical Institute
If the preon structure of quarks, leptons and gauge bosons (the next fundamental level of matter) occurs then dark matter must consist of familons containing a hot component from massless particles and a cold component from massive particles. During evolution of the Universe this dark matter was undergone to late-time phase transitions temperatures of which were different. Fluctuations created by these phase transitions have had fractal character. In the result the structurization of dark matter (and therefore the baryon subsystem) has taken place and in the Universe some characteristic scales which have printed this phenomenon arise naturally. In this case familons are collective excitations of nonperturbative preon condensates which could be produced during more early relativistic phase transition. For structurization of dark matter (and baryon component) three generations of particles are necessary. The first generation of particles has produced the observed baryon world. The second and third generations have produced dark matter from particles which appeared when symmetry among generations was spontaneously broken.
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Detection of Dark Matter in Gamma Astronomy: Experimental Results and Prospects
A Jacholkowska, Groupe d'Astroparticules de Montpellier
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Liquid Xenon as a WIMP Target: the ZEPLIN Programme
R. Luscher, Rutherford Appleton Laboratory
As part of the WIMP dark matter search program at Boulby Mine, the UKDMC and new international collaborators are developing a diagnostic array of detectors with Liquid Xenon (LXe) as the target material. The ZEPLIN project (Zoned Proportional scintillation in LIquid Noble gases) takes advantage of the particularly appropriate properties of Xe. ZEPLIN-1 contains 4kg of LXe used as a simple scintillator. It is currently running in the underground laboratory at Boulby Mine. Two more advanced setups are in construction. They both will feature improved background discrimination tools: an electric field is applied to prevent the ionization to recombine; this allows the latter to be recorded as well. ZEPLIN-2 has an increased fiducial mass of 20 kg. The smaller ZEPLIN-3 (6kg) design uses a higher electric field, which will increase even more the discrimination power. As a consequence, both of them are predicted to have similar sensitivity to rate of 0.1-0.01 events/kg/day within 2 years of data taking. Furthermore, new ideas for lower background readout devices are studied, in order to avoid the use of PhotoMultiplier Tubes (PMTs). This R&D program is very important in view of creating a detector array with a total detecting mass of 1 ton.
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G. Chardin, DAPNIA/SPP, CEN Saclay
Results obtained with 320g bolometers with simultaneous ionization and heat measurements are presented. After a few weeks of data taking, data accumulated with one of these detectors are beginning to exclude the upper part of the DAMA region. Prospects for the present run and the second stage of the experiment, EDELWEISS-II, using an innovative reversed cryostat allowing data taking with 100 detectors, are briefly described.
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The Cryogenic Dark Matter Search: Present Status and Future
L. Baudis, Stanford University
The Cryogenic Dark Matter Search (CDMS) uses phonon and ionization mediated Ge and Si detectors operated below 50 mK to search for weakly interacting massive particles (WIMPs), which are excellent candidates for the dark matter in our Universe. Limits on WIMP nucleon cross sections, the status of the current run at the Stanford Underground Facility as well as the status of the construction at the Soudan mine, the final location of the experiment, are presented.
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The Large Scale U.S. Dark-Matter Axion Search
D. Kinion, LLNL/UC Berkeley
An experiment to look for galactic halo axions has been operating at Lawrence Livermore National Laboratory for the past six years using a Sikivie-type microwave cavity detector. A summary of its current status and results will be given as well as plans for improving the sensitivity and mass coverage.
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Y. Le Du, Oxford University
Dark matter exists under different forms, one of them being
the MACHO, or Massive Compact Halo Object, well described by the idea of
"failed stars". It has been shown by observation of resolved stars
toward nearby
structures like the galactic bulge, the Large Magallanic Cloud (LMC) and the
Small Magellanic Cloud (SMC) that MACHOs do not make up most of the Galactic
halo. However, better information on the contribution of MACHOs to galactic dark
matter can be gathered from the observation of distant galaxies, but, because
the stars are then unresolved, this necessitates the use of an extremely
sensitive detection procedure known as "pixel lensing". The
POINT-AGAPE collaboration looks for microlensing events on unresolved stars in
the M31 galaxy, which particular geometry makes it an ideal target, using CCD
cameras that produce millions of lightcurves, and has already found an
interesting microlensing candidate using a detection pipeline that relies on a
number of statistical criterias to uncover interesting lightcurves. In order to
improve the efficiency and reliability of the detection, a new pipeline is now
being developed that relies on supervised neural networks, these being capable
of reproducing expert-type selection on massive amounts of data.
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Dark Matter Search Potential With AMS02
C. Goy, LAPP
The Neutralino is a plausible candidate to explain the missing mass in the universe. It may be probed by the observation an additional spectra of antiprotons, antideuterons, positrons or gamma that would result from its annihilations into fermions, bosons, gluons and photons. The potential of AMS on the International Space Station to observe such a signal will be described.
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WIMP Searches with Gamma Ray Telescopes
P. Ullio, SISSA
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New Limits and Progress from the Boulby Dark Matter Programme
N. Spooner, University of Sheffield
We present the status of the NAIAD, ZEPLIN and DRIFT dark matter experiments at Boulby including new limits and developments towards scale-up detectors
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S. Basa, last update: 02/27/02