26 research outputs found
Search for Gravitational Waves from Primordial Black Hole Binary Coalescences in the Galactic Halo
We use data from the second science run of the LIGO gravitational-wave
detectors to search for the gravitational waves from primordial black hole
(PBH) binary coalescence with component masses in the range 0.2--.
The analysis requires a signal to be found in the data from both LIGO
observatories, according to a set of coincidence criteria. No inspiral signals
were found. Assuming a spherical halo with core radius 5 kpc extending to 50
kpc containing non-spinning black holes with masses in the range 0.2--, we place an observational upper limit on the rate of PBH coalescence
of 63 per year per Milky Way halo (MWH) with 90% confidence.Comment: 7 pages, 4 figures, to be submitted to Phys. Rev.
All-sky search for gravitational-wave bursts in the second joint LIGO-Virgo run
We present results from a search for gravitational-wave bursts in the data
collected by the LIGO and Virgo detectors between July 7, 2009 and October 20,
2010: data are analyzed when at least two of the three LIGO-Virgo detectors are
in coincident operation, with a total observation time of 207 days. The
analysis searches for transients of duration < 1 s over the frequency band
64-5000 Hz, without other assumptions on the signal waveform, polarization,
direction or occurrence time. All identified events are consistent with the
expected accidental background. We set frequentist upper limits on the rate of
gravitational-wave bursts by combining this search with the previous LIGO-Virgo
search on the data collected between November 2005 and October 2007. The upper
limit on the rate of strong gravitational-wave bursts at the Earth is 1.3
events per year at 90% confidence. We also present upper limits on source rate
density per year and Mpc^3 for sample populations of standard-candle sources.
As in the previous joint run, typical sensitivities of the search in terms of
the root-sum-squared strain amplitude for these waveforms lie in the range 5
10^-22 Hz^-1/2 to 1 10^-20 Hz^-1/2. The combination of the two joint runs
entails the most sensitive all-sky search for generic gravitational-wave bursts
and synthesizes the results achieved by the initial generation of
interferometric detectors.Comment: 15 pages, 7 figures: data for plots and archived public version at
https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=70814&version=19, see
also the public announcement at
http://www.ligo.org/science/Publication-S6BurstAllSky
Alpha-decay half-life of 253Es in metallic Fe at temperatures between 4 K and 50 mK
It has been claimed recently that half-lives of radioactive nuclei embedded in metals would be significantly affected by electron screening provided by the metal. The effectwould further be strengthened at low temperatures. We have determined the half-life-of 253Es nuclei embedded in iron at temperatures between 4 K and 50 mK. Our results agree with the room temperature literature value within about 2% and show no dependence on temperature over a range of almost two orders of magnitude.status: publishe
Hyperfine field of einsteinium in iron and nuclear magnetic moment of 254Es
The angular distributions of γ rays and α particles from oriented 250Bk, 253,254Es, and 255Fm nuclei were
investigated to extract hyperfine interaction information for these actinide impurities in an iron host lattice. The
hyperfine field of einsteinium in iron was found to be |Bhf (EsFe|) = 396(32) T. With this value the magnetic
moment of 254Es was then determined as |Ό| = 4.35(41) ΌN.status: publishe