235 research outputs found
X-ray interferometry with transmissive beam combiners for ultra-high angular resolution astronomy
Interferometry provides one of the possible routes to ultra-high angular
resolution for X-ray and gamma-ray astronomy. Sub-micro-arc-second angular
resolution, necessary to achieve objectives such as imaging the regions around
the event horizon of a super-massive black hole at the center of an active
galaxy, can be achieved if beams from parts of the incoming wavefront separated
by 100s of meters can be stably and accurately brought together at small
angles. One way of achieving this is by using grazing incidence mirrors. We
here investigate an alternative approach in which the beams are recombined by
optical elements working in transmission. It is shown that the use of
diffractive elements is a particularly attractive option. We report
experimental results from a simple 2-beam interferometer using a low-cost
commercially available profiled film as the diffractive elements. A
rotationally symmetric filled (or mostly filled) aperture variant of such an
interferometer, equivalent to an X-ray axicon, is shown to offer a much wider
bandpass than either a Phase Fresnel Lens (PFL) or a PFL with a refractive lens
in an achromatic pair. Simulations of an example system are presented.Comment: To be published in "Experimental Astronomy
Prospect of determining the Dirac/Majorana state of neutrino by Multi-OWL experiment
We consider the non-radiative two body decay of a neutrino to a daughter
neutrino with degraded energy and a very light particle (Majoron). Ultrahigh
energy neutrinos from an astrophysical source like a Gamma Ray Burst undergoing
this decay process are found to produce different number of events in the
detector depending on whether they are Majorana or Dirac particles. The next
generation large scale experiments like Multi-OWL is expected to provide us an
accurate determination of the flux of neutrinos from astrophysical sources and
this may enable us to distinguish between the Dirac and Majorana nature of
neutrino.Comment: 18 pages latex, no figure. Journal of Phys. G in pres
POEMMA: Probe Of Extreme Multi-Messenger Astrophysics
The Probe Of Extreme Multi-Messenger Astrophysics (POEMMA) mission is being
designed to establish charged-particle astronomy with ultra-high energy cosmic
rays (UHECRs) and to observe cosmogenic tau neutrinos (CTNs). The study of
UHECRs and CTNs from space will yield orders-of-magnitude increase in
statistics of observed UHECRs at the highest energies, and the observation of
the cosmogenic flux of neutrinos for a range of UHECR models. These
observations should solve the long-standing puzzle of the origin of the highest
energy particles ever observed, providing a new window onto the most energetic
environments and events in the Universe, while studying particle interactions
well beyond accelerator energies. The discovery of CTNs will help solve the
puzzle of the origin of UHECRs and begin a new field of Astroparticle Physics
with the study of neutrino properties at ultra-high energies.Comment: 8 pages, in the Proceedings of the 35th International Cosmic Ray
Conference, ICRC217, Busan, Kore
Performance and science reach of the Probe of Extreme Multimessenger Astrophysics for ultrahigh-energy particles
The Probe Of Extreme Multi-Messenger Astrophysics (POEMMA) is a potential
NASA Astrophysics Probe-class mission designed to observe ultra-high energy
cosmic rays (UHECRs) and cosmic neutrinos from space. POEMMA will monitor
colossal volumes of the Earth's atmosphere to detect extensive air showers
(EASs) produced by extremely energetic cosmic messengers: UHECRs above 20 EeV
over the full sky and cosmic neutrinos above 20 PeV. We focus most of this
study on the impact of POEMMA for UHECR science by simulating the detector
response and mission performance for EAS from UHECRs. We show that POEMMA will
provide a significant increase in the statistics of observed UHECRs at the
highest energies over the entire sky. POEMMA will be the first UHECR
fluorescence detector deployed in space that will provide high-quality
stereoscopic observations of the longitudinal development of air showers.
Therefore, it will be able to provide event-by-event estimates of the
calorimetric energy and nuclear mass of UHECRs. The particle physics in the
interactions limits the interpretation of the shower maximum on an event by
event basis. In contrast, the calorimetric energy measurement is significantly
less sensitive to the different possible final states in the early
interactions. We study the prospects to discover the origin and nature of
UHECRs using expectations for measurements of the energy spectrum, the
distribution of arrival direction, and the atmospheric column depth at which
the EAS longitudinal development reaches maximum. We also explore supplementary
science capabilities of POEMMA through its sensitivity to particle interactions
at extreme energies and its ability to detect ultra-high energy neutrinos and
photons produced by top-down models including cosmic strings and super-heavy
dark matter particle decay in the halo of the Milky Way.Comment: 40 pages revtex, with 42 figure
Measurement of 0.25-3.2 GeV antiprotons in the cosmic radiation
The balloon-borne Isotope Matter-Antimatter Experiment (IMAX) was flown from Lynn Lake, Manitoba, Canada on 16–17 July 1992. Using velocity and magnetic rigidity to determine mass, we have directly measured the abundances of cosmic ray antiprotons and protons in the energy range from 0.25 to 3.2 GeV. Both the absolute flux of antiprotons and the antiproton/proton ratio are consistent with recent theoretical work in which antiprotons are produced as secondary products of cosmic ray interactions with the interstellar medium. This consistency implies a lower limit to the antiproton lifetime of ∼10 to the 7th yr
In-flight Performance of the ISOMAX TOF
A state-of-the-art time-of-flight (TOF) system has been developed for the ISOMAX balloon-borne cosmic ray instrument. ISOMAX was built to measure the isotopic composition of the light elements in the cosmic rays,
(3<Z<8), in particular beryllium. In-flight performance of the TOF, during the first flight in August
of 1998, and some isotopic results are presented. The uncorrected timing resolution for a single paddle was
determined to be ~47 ps for helium and ~23 ps for carbon
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