Minutes of the Booster Commissioning Working Group held on 25th of February 2010

Present: K. Hanke, T. Hermanns, A. Newborough

Agenda:

1. Communications
2. Follow-up of open actions
3. Update on Simulation Studies of LBS Line (T. Hermanns)
4. Progress Report on Dump/LBE/LBS Line Follow-up Aspects (T. Hermanns)
5. AOB

1. Communications

The last minutes have been approved.

2. Follow-up of open actions

The follow-ups will be treated in one of the coming meetings.

3. Update on Simulation Studies of LBS Line

T. Hermanns presented an update on the LBS line simulation studies. It is motivated by new constraints because of a more precise knowledge about the geometry of a potential beam dump installation at the end of the line.

In order to avoid the activation of the vegetation between the underground LBS line area and the surface building the beam and the secondary particles must be stopped within the range of the existing concrete ceiling of the LBS line area. Therefore, a hole will be drilled into the ceiling, in which the dump is to be installed. The dimensions will be determined by the final dump design, but a depth of 500 mm and a diameter of 500 mm will not be exceeded. However, this constraints the LBS line to a maximum length and therefore requires a displacement of the SEM grid compared to the original simulations. As the distance between the spectrometer magnet and the SEM grid becomes shorter, the edge angle focusing of the spectrometer magnet must be modified, while the loss in energy resolution can be compensated by a lower SEM grid wire distance. All other parameters (in particular magnet radius and magnet position) are left untouched.

In summary, the most relevant differences of this modified scenario compared to the first proposal are listed in the following table.

	First Solution	New Solution
Beam Size (1)	1.9595 mm	1.6959 mm
dE/dy	81.9 keV/mm	94.7 keV/mm
SEM Grid Wire Distance	0.75 mm	0.65 mm
SEM Grid Extension	13 mm	11 mm
Perturbation Coefficient	0.0842	0.0862
Spectrometer Edge Angles	10 deg	8 deg

This new working hypothesis is still considered to be preliminary as long as the dump dimensions are not finally be determined. Especially, the following questions must be clarified before the parameters of the LBS line layout will be finally frozen.

• Is the noise due to back-scattered particles from the dump acceptably low at the new SEM grid position?
• Is the radiation level at the new SEM grid position tolerable?

Dedicated simulations (responsibilties: R. Chamizo and V. Vlachoudis) are on-going. Depending on the results the design parameters for spectrometer magnet and SEM grid must be re-iterated.

4. Progress Report on Dump/LBE/LBS Line Follow-up Aspects

T. Hermanns presented a report about the discussions that has been held since the last meeting concerning various aspects for the integration of the three diagnostic lines.

4.1. Transport and Installation (Visit of LBE/LBS line area on 10.02.2010)

The LBE line is bounded on one side only by a wall, but no beam line prevents a free access. Appropriate equipment to install the new devices in the LBE line must be chosen by people from "Transport and Installation".
The main problem for the LBS line upgrade is to replace the spectrometer magnet, which must be lifted over the transfer line to the PS Booster. The weight of the magnet is 3000 kg, while an already installed crane can only handle up to 1000 kg. Two different proposal have been mentioned by the experts from "Transport and Installation":

• Usage of a fork-lift to replace the spectrometer magnet, if the available space is sufficiently large. This situation could improve if the LBE line is partially de-installed for its upgrade. However, A. Newborough mentioned that this should not be considered as a necessary requirement because then the magnet could not be exchanged in case of a severe failure without de-installing the LBE line.

• Install a rail system at the ceiling, if the ceiling can stand the weight of the magnet. It is estimated to last 2-4 weeks to install the rails. Therefore, it should be considered to already plan the installation one machine shut-down earlier than the LBS line upgrade is planned.

The decision, about which solution should be chosen, must clearly be taken by "Transport and Installation". In any case it must be respected that the new spectrometer magnet will be heavier than the current one due to the larger radius. A rough estimate reveals that the presently foreseen increase in radius by 25% implies that the magnet could be heavier by 25%, too.

4.2. Technical Drawings (Meeting with J.-P.Corso and A. Dallocchio on 12.02.2010)

For the dump line a 3d-toy model can be quite easily be obtained because it is considered as part of Linac4. Therefore, it is already included in the drawings as an empty line so far. The information about the dump line equipment will be sent to J.P. Corso as soon as the part between the Linac4 exit and the first bending magnet is defined. As in this section a quadrupole magnet is placed, which is used for the simulations of the dump line, the positions of the equipment in the dump line might still be modified.
For the LBE/LBS lines an overlap between the devices of either of the diagnostic lines and the transfer line in between is possible because all three lines are very close to each other. Therefore, it is strongly recommended to create 3d-drawings to already avoid overlaps of equipment in the planning phase. However, so far neither a model of the transfer-line downstream of LTB.BHZ20 (this includes the LBE/LBS lines) is available, nor it is planned/budgeted to create such a drawing. In order to solve this problem a discussion with the project leader must be initiated. T. Hermanns and B. Mikulec will take care of that.

In general, J.-P.Corso added that the drawing should include the support structures and should be provided by the responsible work-packages. In the best case already 3d-drawings are created and sent to the drawing office. There, the single parts are merged into a global layout of the diagnostic lines. Regular updates will be essential if more detailed information on equipment and refined drawings are available to finally obtain integration drawings of all three lines.

A. Newborough mentioned that J.-M. Lacroix is preparing 3d-drawings of Linac3. Maybe the transfer line as well as the LBE/LBS lines are included in this project. T. Hermanns will find out if this is the case.

4.3. Power Converters (Meeting with J.-M. Cravero, A. Newborough and D. Nisbet on 18.02.2010)

For the dump line a power converter for one additional quadrupole is required. As this magnet is of the TL-type, the power converter should be of the TL-type as well.
For the LBS line a power converter for the spectrometer magnet is needed. However, the choice can only be made if the magnet parameters are available. Nevertheless, it must be respected that providing a dedicated power converter can last up to 18-24 months if a special design becomes necessary. In this case the parameters must be provided by the end of 2011. If a conventional device can be picked a time delay of about 9 months must be foreseen.
For the LBE line two power converters for the refurbished qudrupole magnets are required. A commercial solution can be chosen, which allows to exploit 90% of the magnet performance, while the simulation studies only ask for 45% of the maximum performance. A less performing device would not save money, so that it is advisible to aim at this gain in flexibility in operation. The time to be reserved to deliver these devices should be 9 months as well.

Open Questions

• Who is responsible for the cabling and does take over the costs? Maybe WP 5.3 "Electrical Systems"?
• Which location should be chosen for the installation of the power converters for the LBE/LBS lines (keep present in Linac2 building or move elsewhere)? A. Newborough mentioned a recently circulated information by M. Vretenar that the Linac2 equipment has potentially to be available for 2-3 years after Linac4 commissioning in case of a severe Linac4 accident scenario when one might be forced to switch back to Linac2 operation.

A. Newborough drew the attention to the different operation modes of the transfer line and the LBE/LBS lines with positively charged heavy ions and negatively charged hydrogen ions. In this case the power converters must be bi-polar between LTB.BHZ30 and LTB.BHZ40 as well as for the LBE/LBS lines. For the LBE line also different powering schemes for the operation modes of horizontal and vertical emittance measurements for the same type of ions must be respected. K. Hanke added that they should also be capable of switching from pulse to pulse within the modulation period of 1.2 s (ppm mode).

In the case of a bi-polar operation remanent fields in the quadrupole and corrector magnets could be a concern. T. Hermanns will collect information about this topic.

4. AOB

The next meeting is planned to take place on 11th of March 2010. It is intended to have presentations about the dump designs for the diagnostic lines. A formal inviation will be sent out, if the presentations will be confirmed.

-- ThomasHermanns - 24-Feb-2010%META:FILEATTACHMENT{name="1002_LBSSimulations_Update.pdf" attachment="1002_LBSSimulations_Update.pdf" attr="" comment="Update of LBS Line Simulations" date="1267110491" path="1002_LBSSimulations_Update.pdf" size="2586996" stream="1002_LBSSimulations_Update.pdf" tmpFilename="/usr/tmp/CGItemp44848" user="thomas_2ehermanns_40cern_2ech" version="1"}%%META:FILEATTACHMENT{name="1002_DiagLines_FollowUpReport.pdf" attachment="1002_DiagLines_FollowUpReport.pdf" attr="" comment="Report on Diagnostic Lines Follow-Up" date="1267110545" path="1002_DiagLines_FollowUpReport.pdf" size="10326137" stream="1002_DiagLines_FollowUpReport.pdf" tmpFilename="/usr/tmp/CGItemp49902" user="thomas_2ehermanns_40cern_2ech" version="1"}%