57 research outputs found
On the non-paraxial modes of two-dimensional nearly concentric resonators
to be published in Applied OpticsA non-paraxial scalar diffraction integral is used to determine numerically the resonance modes of a two dimensional nearly concentric Fabry-Perot resonator. Numerical examples are provided and results are compared to those published by Laabs and Friberg [IEEE J. Quant. El., vol. 35, pp. 198-207, 1999]. Discrepancies are reported and further discussed on the basis of the difference between the solution space supported by the numerical method used in the present work and the one used by Laabs and Friberg
PHIL photoinjector test line
LAL is now equiped with its own platform for photoinjectors tests and
Research and Developement, named PHIL (PHotoInjectors at LAL). This facility
has two main purposes: push the limits of the photoinjectors performances
working on both the design and the associated technology and provide a low
energy (MeV) short pulses (ps) electron beam for the interested users. Another
very important goal of this machine will be to provide an opportunity to form
accelerator physics students, working in a high technology environment. To
achieve this goal a test line was realised equipped with an RF source, magnets
and beam diagnostics. In this article we will desrcibe the PHIL beamline and
its characteristics together with the description of the first two
photoinjector realised in LAL and tested: the ALPHAX and the PHIN RF Guns
Design of a Polarised Positron Source Based on Laser Compton Scattering
We describe a scheme for producing polarised positrons at the ILC from
polarised X-rays created by Compton scattering of a few-GeV electron beam off a
CO2 or YAG laser. This scheme is very energy effective using high finesse laser
cavities in conjunction with an electron storage ring.Comment: Proposal submitted to the ILC workshop, Snowmass 2005. v2: note
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Laser frequency stabilization using folded cavity and mirror reflectivity tuning
International audienceA new method of laser frequency stabilization using polarization property of an optical cavity is proposed. In a standard FabryâPerot cavity, the coating layers thickness of cavity mirrors is calculated to obtain the same phase shift for sand p-wave but a slight detuning from the nominal thickness can produce sand p-wave phase detuning. As a result, each wave accumulates a different round-trip phase shift and resonates at a different frequency. Using this polarization property, an error signal is generated by a simple setup consisting of a quarter wave-plate rotated at 45°, a polarizing beam splitter and two photodiodes. This method exhibits similar error signal as the PoundâDreverâHall technique but without need for any frequency modulation. Lock theory and experimental results are presented in this paper.
High flux polarized gamma rays production: first measurements with a four-mirror cavity at the ATF
The next generation of e+/e- colliders will require a very intense flux of
gamma rays to allow high current polarized positrons to be produced. This can
be achieved by converting polarized high energy photons in polarized pairs into
a target. In that context, an optical system consisting of a laser and a
four-mirror passive Fabry-Perot cavity has recently been installed at the
Accelerator Test Facility (ATF) at KEK to produce a high flux of polarized
gamma rays by inverse Compton scattering. In this contribution, we describe the
experimental system and present preliminary results. An ultra-stable
four-mirror non planar geometry has been implemented to ensure the polarization
of the gamma rays produced. A fiber amplifier is used to inject about 10W in
the high finesse cavity with a gain of 1000. A digital feedback system is used
to keep the cavity at the length required for the optimal power enhancement.
Preliminary measurements show that a flux of about /s with
an average energy of about 24 MeV was generated. Several upgrades currently in
progress are also described
Non-planar four-mirror optical cavity for high intensity gamma ray flux production by pulsed laser beam Compton scattering off GeV-electrons
As part of the R&D toward the production of high flux of polarised Gamma-rays
we have designed and built a non-planar four-mirror optical cavity with a high
finesse and operated it at a particle accelerator. We report on the main
challenges of such cavity, such as the design of a suitable laser based on
fiber technology, the mechanical difficulties of having a high tunability and a
high mechanical stability in an accelerator environment and the active
stabilization of such cavity by implementing a double feedback loop in a FPGA
CLIC Polarized Positron Source Based on Laser Compton Scattering
We describe a possible layout and parameters of a polarized positron source for CLIC, where the positrons are produced from polarized gamma rays created by Compton scattering of a 1.3-GeV electron beam off a YAG laser. This scheme is very energy effective using high finesse laser cavities in conjunction with an electron storage ring. We point out the differences with respect to a similar system proposed for the ILC
Production of gamma rays by pulsed laser beam Compton scattering off GeV-electrons using a non-planar four-mirror optical cavity
As part of the positron source R&D for future colliders and Compton
based compact light sources, a high finesse non-planar four-mirror Fabry-Perot
cavity has recently been installed at the ATF (KEK, Tsukuba, Japan). The first
measurements of the gamma ray flux produced with a such cavity using a pulsed
laser is presented here. We demonstrate the production of a flux of 2.7
0.2 gamma rays per bunch crossing ( gammas per second) during
the commissioning
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