Present: C.Dutriat, E.Sargsyan, U.Raich, L.Soby, J.Tan, G.Tranquille, E.Bravin, K.Hanke, B.Mikulec.

Agenda:

1. Communications

2. Follow-up of open actions

3. Spectrometer design for Linac4 (U.Raich)

4. AOB

1. Communications

K.Hanke reported that there has been a meeting of the workpackage holders with M.Vretenar. The EVM documents are close to termination. A work package description is required as well. Work on this issue has anyway to be done to be included in the technical design report.

K.Hanke has asked for a fellow to help on LBE/LBS line simulations.

2. Follow-up of open actions

-. Beam loss distribution along Linac4: Studies by E.Sargsyan are in progress. This action is related to the open action to determine the final number and location of BLMs along the line.

-. BLMs in PSB injection period: B.Goddard has to be recontacted to follow up this issue.

-. Software for 3 MeV test stand: For the readout of the emittance meter an analysis of the SEMgrid data is required. K.Hanke still has to discuss this subject with R.Scrivens. Maybe a software status report for the 3 MeV test stand can be prepared for the next meeting.

-. EVM document, budget breakdown: close to termination (see above).

3. Spectrometer design for Linac4

U.Raich presented first estimations for the spectrometer parameters at the various foreseen locations along Linac4 (see spectro.pdf). The energy spread given in the presentation corresponds to 1 sigma. Arbitrary values to characterise the magnet were chosen for the calculations (corresponding to the magnet in the LBS line; a max. field of 0.8 T was chosen). With these values the deflection angle was calculated once for the nominal energy and then adding the energy spread, which resulted in a certain measurement resolution. The SEMgrid was placed at 3 m distance from the magnet entrance, and a conservative wire spacing of 1 mm was assumed.

The last page of the attached document shows a table with the resulting energy resolution at the four beam energies. For lower energies it can be seen that one would have to approach the SEMgrid up to about 50 cm. Therefore it might be required to use a shorter magnet for the lowest energy measurement and thus 2 different spectrometer designs to cover the full Linac4 energy range.

The way to advance is to first identify a (or two) appropriate magnets with T.Zickler, then redo the calculations, add slits and do final precise optics simulations to confirm whether additional equipment is needed for beam transport.

It should be mentioned that only the absolute energy can be determined with other methods like the Time-of-Flight or using an energy degrader, but not the energy spread.

U.Raich has already communicated first estimates for the required beam dump to the relevant people. Probably another refinement is needed once the design is final.

-- BettinaMikulec - 08 May 2008

• spectro.pdf: Spectrometer design for Linac4.