Minutes from Beamdynamics meeting

The meeting starts with Daniel reporting about the ILC GDE Meeting in China. Then, we go around the table:

Maxim : reports about CLIC BDS alignment. He misaligned the Quadrupoles, leaving the BPMs aligned. He uses Dispersion Free Steering with 1 test beam whose energy is -2% the nominal one. In his simulations he tracks a single macroparticle, then the correction is applied.

Preliminary result of his simulations is that with a BPM resolution of 100 microm the Luminosity reduction is 15%, whereas with a BPM resolution of 100 nm the Luminosity reduction is only 3-5%.

Daniel : proposes to Maxim to perform a 'weight' scan for DFS.

Warner : is performing simulations for Oleg Malyshev . He said that there will not be e-cloud in the ILC damping rings, but he computed with (too) long bunches (20 cm).

When he computes with the correct bunch length (9mm) he gets e-clouds. He is implementing the creation of photo-electrons.

Andrea : reports about the ILC BC alignment : he run the simulations to isolate the individual contribution of elements misalignments. Then he also reported about some news concerning the placet code:

he has made a script ./configure for placet which already compiles and installs placet under Linux 32 or 64 bits, and MacOS.

Riccardo : is running the simulations for the CLIC Main Linac structures, using GdfidL . He is obtaining good results, but the computational time (1 week) is too big. He has been discussing

with Warner the idea of creating a 2d code, to speed up the simulations. Daniel proposes to use the new cluster (lxscd01-08) for these simulations.

Peter : reports about the status of the tests of the Precision BPMs. There will be three BPMs available for these tests. The first step is to find the right place

where these BPMs should be put, according also to some optics calculations. A place could be the pipe of the Frascati chicane. The resolution of these BPMs is 0.6 / 0.7 microm and their length is 50 cm.

Roberto suggests to have a mover on each of them.

Erik : is testing the 12GHz kickers. The coupler shows some stationary waves. Igor is working to dump these modes.

Yannis : is getting into the group's works. He have had discussions with Frank Zimmermann. He also needs to talk to Maxim to simulate the damping rings. Daniel stresses out that we should probably make a better model for the longitudinal phase space : perhaps we could do better than a Gaussian distribution. We should ask the PSI collaboration about this.

Maybe also the data from ATF can be used. Rogelio agrees and reminds that Lionel has done something similar. We shall discuss with him as well.

Piotr : reports about the news in MadX-PTC. He implemented higher order moments in MadX-PTC. They are still under testing. Rogelio asks for considering sigma instead of the emittance.

Rogelio : has tried the Piotr's code to optimize the lens of the FF. Actually it does not work as he expected, yet. Nevertheless, he has made the optimization anyway. He has optimized the spot size and he has got an increment in the luminosity by 10%. Piotr's code, which implements all moments, could be really useful for this optimization.

It follows a small discussion about the "quality function" that must be optimized : should it be only the spot size? or this could hide a folding of the tails? (i.e. a distorted beam implies lower luminosity).

Daniel : has been working on the design for the diagnostics for CLIC and making some simulations for the new parameters set. He also mentions that there is a new fellow in the group, Ilya Agapov, who is working on the ILC Collimators and is expert of laserwires simulations.

Roberto : starts off a discussion about Beam Dynamics simulations for CTF3. Hamed is running PLACET to test the longitudinal Beam Dynamics of the CTF3 LINAC. It seems that the Cavity model implemented in PLACET is even too realistic, for he needs to study at the moment. This points out the need for a reference model for the lattices, maybe simpler than the present one.

Peter has some tables containing the basic data of the CTF3 accelerating structures. He will send them to Andrea in order to use them with PLACET. Andrea and Roberto agree about meeting to discuss in detail this issue.

Ted Wilson : says that he is rather busy with teaching at the moment, but that he would like to contribute to the group's activities in some way. His teaching brought him in contact with students that are willing to come to CERN for some summer stages (as long as about 6 weeks). As they are already familiar with MADX and some cavity design, we should find some useful task for them.