Abstracts Brochure - CERN

TUPCH077
TUPCH078
TUPCH079
27-Jun-06 16:00 - 18:00 TUPCH — Poster Session
of relative velocity in particle collisions inside the beam. For this purpose, the transverse momentum distribution
function is properly modified. Calculations performed for the VEPP-4M storage ring-collider show that the jump may
depend significantly on the ratio between the vertical and radial beam emittance. We present results of our recent
experiments on study of this dependence.
Beam Phase Measurement in a 200 MeV Cyclotron
J.L. Conradie, A.H. Botha, P.J. Celliers, J.H. Du Toit, D.T. Fourie, P.F.
Rohwer, M.J. Van Niekerk (iThemba LABS)
182
New phase measuring equipment is being
planned for the K 200 variable frequency,
separated-sector cyclotron at iThemba LABS
near Cape Town. A commercial lock-in am-
plifier is used to measure the beam phase over the full radial range. Measurements are made at the third and fifth
harmonics of the main RF frequency to limit pick-up from the flat-topping and main dees. Computer-generated
signals, with phase and amplitude control, at the same harmonics, are used to cancel the signals coupled from the
dees to the phase probes. In addition the signals without beam are vectorially subtracted from those with beam to
enhance the sensitivity and accuracy. Results of measurements, using these techniques, on existing phase probes in
the cyclotron, will be presented.
BPM Design for the ALBA Synchrotron
ALBA is a 3 GeV, low emittance, 3rd gen-
F. Pérez, A. Olmos (ALBA) T.F. Günzel (ESRF)
eration synchrotron light source that is in
the construction phase in Cerdanyola, Spain.
Vertical beam sizes down to a few microns will require beam stabilities on the submicron level. The BPM has to be
designed in order to provide reliable and accurate beam position readings. Simulation and computational codes have
been used to optimise, for a given vacuum chamber dimension, the BPM design. The optimisation has taken into
account the usual sensitivity and intrinsic resolution parameters, but as well, the wakefield loss factor of the buttons.
Due to the small vertical vacuum chamber dimension and the high design current, the beam power deposited in the
buttons is becoming a concern due to the thermal deformation effects that can introduce errors at the submicron level.
A compromise between a higher intrinsic resolution from one side, and a low power deposited by the beam in the
buttons from the other, define the final buttons dimensions.
Characterisation of the MAX-II Electron Beam
Over the last year investigations of the MAX
M. Sjöström, H. Tarawneh, E.J. Wallén (MAX-lab)
II electron beam characteristics have been
made. Examples of investigated parameters
include the beam size, bunchlength, vacuum and Touschek lifetimes, and the machine functions. Since MAX II was
commissioned in 1995 machine models have not been updated in a systematic fashion. As no realignment has been
made and several new insertion devices have been installed, the situation necessitated characterisation of the electron
beam in order to verify the validity of existing machine models.