367 research outputs found
Luminosity, Energy and Polarization Studies for the Linear Collider: Comparing e+e- and e-e- for NLC and TESLA
We present results from luminosity, energy and polarization studies at a
future Linear Collider. We compare e+e- and e-e- modes of operation and
consider both NLC and TESLA beam parameter specifications at a center-of-mass
energy of 500 GeV. Realistic colliding beam distributions are used, which
include dynamic effects of the beam transport from the Damping Rings to the
Interaction Point. Beam-beam deflections scans and their impact for beam-based
feedbacks are considered. A transverse kink instability is studied, including
its impact on determining the luminosity-weighted center-of-mass energy.
Polarimetry in the extraction line from the IP is presented, including results
on beam distributions at the Compton IP and at the Compton detector.Comment: 17 pages, 12 figures. Presented at 5th International Workshop on
Electron-Electron Interactions at TeV Energies, December 12-14, 2003, Santa
Cruz, C
The Radio Recovery of SN 1970G: The Continuing Radio Evolution of SN 1970G
Using the Very Large Array, we have detected radio emission from the site of
SN 1970G in the Sc galaxy M101. These observations are 31 years after the
supernova event, making SN 1970G the longest monitored radio supernova. With
flux densities of 0.12 +/- 0.020 mJy at 6 cm and 0.16 +/- 0.015 mJy at 20 cm,
the spectral index of -0.24 +/- 0.20 appears to have flattened somewhat when
compared with the previously reported value of -0.56 +/- 0.11, taken in 1990.
The radio emission at 20 cm has decayed since the 1990 observations with a
power-law index of beta_20cm = -0.28 +/- 0.13. We discuss the radio properties
of this source and compare them to those of other Type II radio supernovae.Comment: 11 pages, 1 table and 2 figures; To appear in Astrophysical Journal
Letter
Recent Type II Radio Supernovae
We present the results of radio observations, taken primarily with the Very
Large Array, of Supernovae 1993J, 2001gd, 2001em, 2002hh, 2004dj, and 2004et.
We have fit a parameterized model to the multi-frequency observations of each
supernova. We compare the observed and derived radio properties of these
supernovae by optical classification and discuss the implications.Comment: 5 pages, 2 figures, 1 table Conference Proceedings: "Supernova 1987A:
20 Years After: Supernovae and Gamma-Ray Bursters" AIP, New York, eds. S.
Immler, K.W. Weiler, and R. McCra
Radio Emission from SN 2001gd in NGC 5033
We present the results of monitoring the radio emission from the Type IIb
supernova SN 2001gd between 2002 February 8 and 2002 October 28. Most of the
data were obtained using the Very Large Array at the five wavelengths of
1.3 cm (22.4 GHz), 2.0 cm (14.9 GHz), 3.6 cm (8.44 GHz), 6.2
cm (4.86 GHz), and 21 cm (1.4 GHz). Observations were also made with Giant
Meterwave Radio Telescope at 21 cm (1.4 GHz). The object was
discovered optically well after maximum light, making any determination of the
early radio evolution difficult. However, subsequent observations indicate that
the radio emission has evolved regularly in both time and frequency and is well
described by the SN shock/circumstellar medium interaction model.Comment: 16 pages 2 figures to appear in Astrophysical Journa
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