1,436 research outputs found
A new way to explain the 511 keV signal from the center of the Galaxy and its possible consequences
The first gamma-ray line originating from outside the solar system that was
ever detected is the 511 keV emission from the center of our Galaxy. The
accepted explanation of this signal is the annihilation of electrons and
positrons. However, despite 30 years of intense theoretical and observational
investigation, the main sources of positrons have not been identified up to
now. In this paper I propose an alternative explanation: the observed signal is
due to atomic transitions to "small hydrogen atom," where electron is captured
by proton on a small tight orbit around proton. I describe the status of the
experimental search to find the small hydrogen atom both in astrophysics data
and the lab, and propose new methods how to discover it in the lab directly.
The reason we are interested in this problem is that it could explain some
astrophysics observations.
Key words: 511 keV peak at the galactic center, small hydrogen atom, DDL
atom, dark matterComment: 10 page
A New Possible Way to Explain the DAMA Results
At present there is an effort to reconcile the results of the DAMA experiment
with those from other Dark Matter experiments such as CoGeNT, CRESST, CDMS, and
all LXe experiments. The author suggests a new model describing the Dark Matter
signal as the result of collisions of very light (1-to-few GeV/c^2) WIMPs with
hydrogen, and compares it with currently accepted models of collisions with
heavy nuclei (Na, Ge or Xe). The hydrogen target would come from
H-contamination of NaI(Tl), Ge and CaWO4 crystals. Initial tuning indicates
that one can explain the modulation amplitude of DAMA and CoGeNT with this
model, assuming a WIMP-proton cross section between 10^33 and 10^32 cm^2. This
paper should be considered to be a new idea which will need substantial new
experimental input from all involved experiments.Comment: 5 pages, 8 figure
A simple argument that small hydrogen may exist
This paper discusses a possible existence of small hydrogen, which may have
been created during the Big Bang before formation of normal hydrogen
Molecular excitations: a new way to detect Dark matter
We believe that the Dark Matter (DM) search should be expanded into the
domain of detectors sensitive to molecular excitations, and so that we should
create detectors which are more sensitive to collisions with very light WIMPs.
In this paper we investigate in detail di-atomic molecules, such as Fused
Silica material with large OH-molecule content, and water molecules. Presently,
we do not have suitable low cost IR detectors to observe single photons,
however some OH-molecular excitations extend to visible and UV wavelengths, and
can be measured by Bialkali photocathodes. There are many other chemical
substances with di-atomic molecules, or more complex oil molecules, which could
be investigated also. This idea invites searches in experiments having large
target volumes of such materials coupled to a large array of single-photon
detectors with Bialkali or infrared-sensitive photocathodes
Optical Properties of the DIRC Fused Silica Cherenkov Radiator
The DIRC is a new type of Cherenkov detector that is successfully operating
as the hadronic particle identification system for the BABAR experiment at
SLAC. The fused silica bars that serve as the DIRC's Cherenkov radiators must
transmit the light over long optical pathlengths with a large number of
internal reflections. This imposes a number of stringent and novel requirements
on the bar properties. This note summarizes a large amount of R&D that was
performed both to develop specifications and production methods and to
determine whether commercially produced bars could meet the requirements. One
of the major outcomes of this R&D work is an understanding of methods to select
radiation hard and optically uniform fused silica material. Others include
measurement of the wavelength dependency of the internal reflection
coefficient, and its sensitivity to surface contaminants, development of
radiator support methods, and selection of good optical glue.Comment: 36 pages, submitted to Nuclear Instruments and Methods
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Focusing DIRC Design for Super B
In this paper we present a new design of the Focusing DIRC for the Barrel PID to be used at the proposed Super-B factory. The new imaging optics is made of a solid Fused Silica block with a double folded optics using two mirrors, one cylindrical and one flat, focusing photons on a detector plane conveniently accessible for the detector access. The design assumes that the BaBar bar boxes are re-used without any modification, including the wedges and windows. Each bar box will have its own focusing block, which will contain 40 H-9500 (or H-8500) MaPMTs according to present thinking. There are 12 bar boxes in the entire detector, so the entire SuperB FDIRC system would have 480 MaPMTs. The design is very compact and therefore reduces sensitivity to the background. The chosen MaPMTs are fast enough to be able both to reject the background and to perform the chromatic correction. The 3D optics simulation is coded with the Mathematica program. The work in this paper was a basis of the LDRD proposal made to SLAC in 2009 [1]
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Search for the best timing strategy in high-precision drift chambers
Computer simulated drift chamber pulses are used to investigate various possible timing strategies in the drift chambers. In particular, the leading edge, the multiple threshold and the flash ADC timing methods are compared. Although the presented method is general for any drift geometry, we concentrate our discussion on the jet chambers where the drift velocity is about 3 to 5 cm/..mu..sec and the individual ionization clusters are not resolved due to a finite speed of our electronics
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