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CALIFES Beam Parameters

The following parameters are taken from Fabrolini et al., LINAC10.

Parameter Value
Energy/MeV 178
Energy spread/% ±2
Number of bunches 1-300
Bunch separation/ns 0.667
Single bunch charge/nC 0.65
Multibunch (>32) total charge/nC 19.2
Normalised RMS emittance/π·mm·mrad 8
RMS bunch length/ps 1.42
Beam jitter ~1σ

Since the above was published, the electron source was upgraded. Because of this, it is no longer possible to run with only one bunch. The multibunch total charge is limited by beam loading in the accelerating structures but was also hard to reach anyway because of the photocathode source. The bunch length is minimised by adjusting the phase of the first accelerating structure and using it as a buncher. This, however, limits the maximum energy to 135 MeV.


The cavity BPM will be installed directly downstream of the spectrometer at the end of the probe beamline. In this location, there are three dumps: one for the drive beam, one for the probe beam deflected by the spectrometer and one for the probe beam going straight and the deflected drive beam combined.


A close up of the area (left) and from above (right). Space is limited by current instruments.


The electronics must be nearby to limit the signal attenuation. It may be necessary to have lead shielding to prevent radiation damage to the electronics. The drive beam BPM in the picture below shows the part of CLEX with the most radiation. Less is expected around the probe beam though.


It should be possible to achieve a beam size as small as 50 μm which has already been shown in a similar location upstream where there is also a quadrupole triplet similar to the one shown below. The beam jitter was measured simultaneously to be much less that 100 μm.


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Topic revision: r8 - 29 Aug 2012 - FrankieCullinan

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