23 research outputs found
Vibrating Wire for Beam Profile Scanning
The method for measurement of transverse profile (emittance) of the bunch by
detecting of radiation arising scattering at of the bunch on the scanning wire
is wide-spread. In this work the information about scattering bunch is proposed
to measure using the oscillation frequency of the tightened scanning wire. In
such way the system of radiation (or secondary particles) extraction and
measurement can be removed. Dependence of oscillations frequency on beam
scattering is determined by several factors, including changes of wire tension
caused by transverse force of the beam, influence of beam self field.
Preliminary calculations show that influence caused by wire heating will
dominate. We have studied strain gauges on the basis of vibrating wire from
various materials (tungsten, beryl bronze, niobium zirconium alloys). A scheme
of self oscillations generation by alternating current in autogeneration
circuit with automatic frequency adjustment was selected. Special method of
wire fixation and elimination of transverse degrees of freedom allow to achieve
relative stability better than 1E-5 during several days. For a tungsten wire
with a fixed end dependence of frequency on temperature was 1E-5/K.
Experimental results and estimates of wire heating of existing scanners show,
that the wire heats up to a few hundred grades, which is enough for
measurements
Dilation of the Giant Vortex State in a Mesoscopic Superconducting Loop
We have experimentally investigated the magnetisation of a mesoscopic
aluminum loop at temperatures well below the superconducting transition
temperature . The flux quantisation of the superconducting loop was
investigated with a -Hall magnetometer in magnetic field intensities
between . The magnetic field intensity periodicity observed in
the magnetization measurements is expected to take integer values of the
superconducting flux quanta . A closer inspection of the
periodicity, however, reveal a sub flux quantum shift. This fine structure we
interpret as a consequence of a so called giant vortex state nucleating towards
either the inner or the outer side of the loop. These findings are in agreement
with recent theoretical reports.Comment: 12 pages, 5 figures. Accepted for publication in Phys. Rev.
Precise out-vacuum proton beam monitoring system based on vibrating wire
As an instrument for Korea Multi-purpose Accelerator Complex (KOMAC) facility proton beam profiling, a vibrating wire monitor (VWM) has been installed and tested at TR23 target room. Experiments were done at very low (100 nA) beam current conditions. At the number of particles about 10(11) proton/train and trains repetition rate of 0.1 Hz we have measured the beam profile by a few scanning steps. The experience accumulated in these experiments turned out to be useful for the VWM upgrades (e. g. understanding interactions of protons with wire materials and heat transfer processes) and will be particularly helpful for the KOMAC beam halo measurements in the future high-current operation
Vibrating wire scanner: First experimental results on the injector beam of the Yerevan synchrotron
This paper presents the first experimental results of the transverse profile measurements using a vibrating wire scanner at the Yerevan synchrotron injector electron beam (6 nA after collimation). The advantage of this novel technique is that there is no need for secondary radiation or particle detectors. The local beam intensity is measured using the natural oscillation frequency of the wire, which is a function of the wire temperature