Abstracts Brochure - CERN

WEPLS — Poster Session 28-Jun-06 16:00 - 18:00
concern the diagnostic beam line of the gun, the new cathode preparation and cathode transfer system, the driver
laser and the LHe transfer line.
High-field Design of a Superconducting Cavity for a SRF Photoinjector
In a collaboration between BESSY, DESY,
FZR, MBI and BINP a 3-1/2 cell supercon- D. Janssen (FZR) V. Volkov (BINP SB RAS)
ducting RF electron gun is under development
at the FZ - Rossendorf. The status of the project and the progress obtained in the last year is reported on this
conference. The motivation for the design of a new gun cavity, presented in this paper, is the new FEL project at
BESSY. This FEL is designed for a bunch charge of 2.5 nC and the transverse emittance should be comparable with
that of the current SRF gun project. In order to compensate the high bunch charge a high electric field on the cavity
axis is necessary. In the present paper we will present the design of a 1-1/2 cell cavity for a superconducting RF gun.
The active length of the cavity (without beam tube) is 14.4 cm. For the magnetic peak field the conservative value
of 130 mT is assumed. The obtained particle energy is 6.6 MeV, corresponding to an accelerating field strength of
45.6 MV/m . In the TESLA cavity the same magnetic peak field is connected with an accelerating field strength of
approximately 31 MV/m. Tracking calculation of electron bunches are in progress and will be also reported.
Study on Low-energy Positron Polarimetry
For the design of the International Linear
Collider (ILC) a polarised positron source
based on a helical undulator system has been
proposed. In order to optimise the positron
beam, i.e., to ensure high intensity as well as
A. Schaelicke, K. Laihem, S. Riemann, A. Ushakov (DESY Zeuthen)
R. Dollan, Th. Lohse (Humboldt University Berlin, Institut für
Physik)
high degree of polarisation, a measurement of the polarisation close to the positron creation point is envisaged. In
this contribution methods to determine the positron polarisation at low energies are investigated. These studies are
based on simulations with an extended version of Geant4, which allows the tracking of polarised particles taking into
account the spin effects.
Radiation Levels and Activation at the ILC Positron Source
An undulator-based positron source is recommended
as baseline design for the Inter- A. Ushakov (DESY Zeuthen) K.N. Sanosyan (CANDLE)
national Linear Collider (ILC). Photons generated
by electrons passing an undulator hit a rotating target and create electron-positron pairs. The positrons are
captured and used for acceleration. An advantage of this source is the significantly lower radiation level in comparison
to a conventional positron source which uses the electron beam directly to produce electron-positron pairs. The fluxes
of neutrons and photons have been calculated with the particle transport code FLUKA. The activation of the positron
source components has been estimated depending on the parameters of the source. The results for undulator-based
and conventional positron sources will be compared and presented.
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