258 research outputs found
Commissioning Status of the CTF3 Delay Loop
The CLIC Test Facility CTF3, built at CERN by an international collaboration, aims at demonstrating the linear collider by 2010. In particular, one of the main goals is to study the generation of high-current electron pulses by interleaving bunch trains in delay lines and rings using transverse RF deflectors. This will be done in the 42 m long delay loop, built under the responsibility of INFN/LNF, and the 84 m long combiner ring that will follow it. The delay loop installation was completed and its commissioning started at the end of 2005. In this paper the commissioning results are presented, including the first tests of beam recombination
Positron Production and Capture based on Low Energy Electrons for SuperB
TUPEB057International audienceProviding a high quality and sufficient high current positron beam for the ultra high luminosity B-factory SuperB is a major goal. In this paper a proposition for positrons production and capture scheme based on low energy electrons up to1 GeV is presented. For this technique, several types of flux concentrator used to capture the positrons are being studied. The following accelerating section bringing the positrons up to 280 MeV and the total yield for L-band and S-band type accelerators are given. Also the result of the benchmark between ASTRA and a LAL code based on Geant4 toolkit simulation is discussed
Status of the Super-B factory Design
The SuperB international team continues to optimize the design of an
electron-positron collider, which will allow the enhanced study of the origins
of flavor physics. The project combines the best features of a linear collider
(high single-collision luminosity) and a storage-ring collider (high repetition
rate), bringing together all accelerator physics aspects to make a very high
luminosity of 10 cm sec. This asymmetric-energy collider
with a polarized electron beam will produce hundreds of millions of B-mesons at
the (4S) resonance. The present design is based on extremely low
emittance beams colliding at a large Piwinski angle to allow very low
without the need for ultra short bunches. Use of crab-waist
sextupoles will enhance the luminosity, suppressing dangerous resonances and
allowing for a higher beam-beam parameter. The project has flexible beam
parameters, improved dynamic aperture, and spin-rotators in the Low Energy Ring
for longitudinal polarization of the electron beam at the Interaction Point.
Optimized for best colliding-beam performance, the facility may also provide
high-brightness photon beams for synchrotron radiation applications
A study of the prompt and afterglow emission of the Short GRB 061201
Our knowledge of the intrinsic properties of short duration Gamma-Ray Bursts
has relied, so far, only upon a few cases for which the estimate of the
distance and an extended, multiwavelength monitoring of the afterglow have been
obtained. We carried out multiwavelength observations of the short GRB 061201
aimed at estimating its distance and studying its properties. We performed a
spectral and timing analysis of the prompt and afterglow emission and discuss
the results in the context of the standard fireball model. A clear temporal
break was observed in the X-ray light curve about 40 minutes after the burst
trigger. We find that the spectral and timing behaviour of the X-ray afterglow
is consistent with a jet origin of the observed break, although the optical
data can not definitively confirm this and other scenarios are possible. No
underlying host galaxy down to R~26 mag was found after fading of the optical
afterglow. Thus, no secure redshift could be measured for this burst. The
nearest galaxy is at z=0.111 and shows evidence of star formation activity. We
discuss the association of GRB 061201 with this galaxy and with the ACO S 995
galaxy cluster, from which the source is at an angular distance of 17'' and
8.5', respectively. We also test the association with a possible undetected,
positionally consistent galaxy at z~1. In all these cases, in the jet
interpretation, we find a jet opening angle of 1-2 degrees.Comment: 10 pages, 7 figures, accepted for publication in A&
The PLASMONX Project for advanced beam physics experiments
The Project PLASMONX is well progressing into its
design phase and has entered as well its second phase of
procurements for main components. The project foresees
the installation at LNF of a Ti:Sa laser system (peak
power > 170 TW), synchronized to the high brightness
electron beam produced by the SPARC photo-injector.
The advancement of the procurement of such a laser
system is reported, as well as the construction plans of a
new building at LNF to host a dedicated laboratory for
high intensity photon beam experiments (High Intensity
Laser Laboratory). Several experiments are foreseen
using this complex facility, mainly in the high gradient
plasma acceleration field and in the field of mono-
chromatic ultra-fast X-ray pulse generation via Thomson
back-scattering. Detailed numerical simulations have
been carried out to study the generation of tightly focused
electron bunches to collide with laser pulses in the
Thomson source: results on the emitted spectra of X-rays
are presented
Multiwavelength observations of 3C 454.3. I. The AGILE 2007 November campaign on the "Crazy Diamond"
[Abridged] We report on a multiwavelength observation of the blazar 3C 454.3
(which we dubbed "crazy diamond") carried out on November 2007 by means of the
astrophysical satellites AGILE, INTEGRAL, Swift, the WEBT Consortium, and the
optical-NIR telescope REM. 3C 454.3 is detected at a level
during the 3-week observing period, with an average flux above 100 MeV of
\phcmsec. The gamma-ray
spectrum can be fit with a single power-law with photon index between 100 MeV and 1 GeV. We detect significant
day-by-day variability of the gamma-ray emission during our observations, and
we can exclude that the fluxes are constant at the 99.6% ()
level. The source was detected typically around 40 degrees off-axis, and it was
substantially off--axis in the field of view of the AGILE hard X-ray imager.
However, a 5-day long ToO observation by INTEGRAL detected 3C 454.3 at an
average flux of about \phcmsec with
an average photon index of between 20--200
keV. Swift also detected 3C 454.3 with a flux in the 0.3--10 keV energy band in
the range \phcmsec{} and a photon index in the
range . In the optical band, both WEBT and REM
show an extremely variable behavior in the band. A correlation analysis
based on the entire data set is consistent with no time-lags between the
gamma-ray and the optical flux variations. Our simultaneous multifrequency
observations strongly indicate that the dominant emission mechanism between 30
MeV and 30 GeV is dominated by inverse Compton scattering of relativistic
electrons in the jet on the external photons from the broad line region.Comment: Accepted for publication in ApJ. Abridged Abstract. 37 pages, 14
Figures, 3 Table
AGILE detection of delayed gamma-ray emission from GRB 080514B
GRB 080514B is the first gamma ray burst (GRB), since the time of EGRET, for
which individual photons of energy above several tens of MeV have been detected
with a pair-conversion tracker telescope. This burst was discovered with the
Italian AGILE gamma-ray satellite. The GRB was localized with a cooperation by
AGILE and the interplanetary network (IPN). The gamma-ray imager (GRID)
estimate of the position, obtained before the SuperAGILE-IPN localization, is
found to be consistent with the burst position. The hard X-ray emission
observed by SuperAGILE lasted about 7 s, while there is evidence that the
emission above 30 MeV extends for a longer duration (at least ~13 s). Similar
behavior was seen in the past from a few other GRBs observed with EGRET.
However, the latter measurements were affected, during the brightest phases, by
instrumental dead time effects, resulting in only lower limits to the burst
intensity. Thanks to the small dead time of the AGILE/GRID we could assess that
in the case of GRB 080514B the gamma-ray to X-ray flux ratio changes
significantly between the prompt and extended emission phase.Comment: A&A letters, in pres
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