Minutes of the Booster Commissioning Working Group held on 11th of March 2010

Present: G. Bellodi, V. Boccone, C. Carli, R. Chamizo, J-M. Cravero, F. Formenti, K. Hanke, T. Hermanns, B. Mikulec, A. Newborough, D. Nisbet and V. Vlachoudis.


  1. Communications
  2. Follow-up of open actions
  3. First Results on LBS Line Dump Simulations (V. Boccone)
  4. AOB

1. Communications

The last minutes have been approved.

K. Hanke informed everybody that the 1 year shift for the PSB start with Linac4 is now official. All concerned EVM documents should be adapted accordingly, which has been done for his work package. D. Nisbet commented on this subject and mentioned that he had taken over the work package from C. De Almeida Martins, containing simply an overall budget estimate. He wondered where to get an accurate information on the equipment expected from him. K. Hanke replied that A. Lombardi was the person to contact for the Linac4 line as well as new and old transfer line, B. Mikulec and T. Hermanns for Linac4 dump line, LBE and LBS, whereas W. Weterings could provide the required information for the new PSB injection region. K. Hanke proposed to summarise the needs in terms of power converters in one BCC meeting once the information will be available, and he contacted M. Vretenar on this subject after the meeting.
He also asked M. Vretenar to give an official statement if Linac2 has to be kept as backup in parallel to Linac4 and for how long, as this is a concern for the equipment groups.

2. Follow-up of open actions

The list of open actions has been updated after the meeting.

3. First Results on LBS Line Dump Simulations

V. Boccone presented first simulation results concerning the dump in the LBS line (see Linac4_LBSdump.pdf). The dump has to be integrated in the ceiling due to the vertical arrangement of the LBS line. A distance of 20 cm from the last element in the line (SEM grid) has been specified. As a first iteration, a simple dump model of a graphite cube of 50 cm side length with an opening hole of 15 cm depth has been assumed in order to fit into the concrete layer of the ceiling. It should be avoided to activate the earth above that layer. A reduced Linac4 current of 8 mA (reduction due to LBS line slit) with a bunch length of 100 us at 1.11 Hz repetition rate defined the beam parameters. 1-2 months of running at 12h/day have been assumed for the commissioning phase, whereas the max. operational period extends to ~24 months at a reduced repetition rate of 0.1x1.11 Hz twice per week during 8 hours. Activation is dominated by the commissioning and not the operational phase.

The back-scattered particle distribution at the SEM grid location comprises protons, neutrons, electrons and photons. In particular the photon part could be an issue due to Compton scattering and increased background noise and should therefore be studied by the BI group.

Plots have been presented of fluence/cm^2 versus position, equivalent dose and activation for the commissioning and operational scenarios. A scenario using 400 us long pulses instead of 100 us long pulses should be added.

With this information, detailed discussions have to take place between EN/STI and DGS/RP and BE/BI. Discussion subjects will have to deal with activation of the earth (is this acceptable for RP or is e.g. injection of concrete or other measures required), studies of the SEM grid signal taking into account the back-scattered radiation, potential radiation damage to the SEM grid electronics and activation of the SEM grid (precise material composition needed).
After these discussions, another iteration can be launched taking into account all the inputs. After R. Chamizo it is not difficult for civil engineering to make a hole in the ceiling, but additional work changing the earth layer might add complexity. If it turns out that the earth activation couldn't be accepted by RP, other solutions should be envisaged like shortening the hole in the dump or increasing the dump size upstream (this would deteriorate the measurement resolution if the SEM grid has to be displaced accordingly, but would still be within the measurement specifications).

Assigned to Start date Description State Result
R.Chamizo 2010-03-16 Initiate discussions with RP and BI concerning the LBS line dump. Re-iterate simulations if modifications are needed for the dump design. This will be followed up by Cesare Maglioni. edit

3. AOB

Bipolar power supplies
Emittance measurement at Linac4 exit: As the optics have to be changed between measurements in the horizontal and vertical plane, the first quadrupole after the PIMS exit and the quadrupole after the horizontal bending magnet in the dump line have to be bipolar. D. Nisbet added this request to his list of power converters. The following specifications have been sent to D. Nisbet and J-M. Cravero:
  • Duration of unchanged polarity: ~30-60s
  • Delay to switch between polarities: of the order of a few seconds is acceptable
  • Frequency of polarity switching: During the commissioning phase, the Linac4 dump and LBE lines will be used about 100 times per day. Therefore, corresponding to the worst case, about 200 switching cycles per day have to be planned.

LBE line: The same situation and specifications apply to the LBE line. The 2 bipolar power converters for the quadrupoles have to be added to the list of D. Nisbet. In case the line would continue to be used for ion beam emittance measurements, it has been clarified by A. Lombardi that an optics change in the triplet of the ITH line would be sufficient to transport the beam into the LBE line, therefore avoiding to request bipolar power supplies for the quadrupoles between LT.BHZ30 and LTB.BHZ40. Nevertheless, it is now under study by R. Scrivens if the emittance measurement and also the energy measurement for ions could be displaced to leave LBE/LBS exclusively to Linac4 measurements.

LBS line: It has to be clarified if the LBS line will still be required for ion measurements (see above).

Transport facilities in LBE/LBS
The transport group has confirmed that the lifting equipment in the LBE/LBS lines has to be renovated. A new crane should be budgeted.

Cooling of quadrupole magnets in LBE line
A. Newborough mentioned that the upgrade of the quadrupoles in the LBE line from SMIT air cooling to SMIT water cooling has been decided and the request sent to T. Zickler to change his work package accordingly. The switching of polarity has to be slow. The discussion with S. Baird to see whether part of the cost can come from the consolidation budget is currently suspended, waiting for a decision on the PSB 2 GeV upgrade study. The reasoning behind is that the coils of these quadrupoles are the same as installed in the quadrupoles of the BI and BTP line, for which spares might be needed as well.

LBS line slit
C. Carli mentioned that the LBS line slit was an even more critical equipment than the LBS line dump as it effectively acts like a dump. He asked if somebody was studying the slit design. R. Chamizo replied that it was not clear under which responsibility the slit lies and would like to have clarification on the subject. K. Hanke contacted M. Vretenar after the meeting to get an official reply. It seems more natural that the slit falls under EN/STI responsibility as it absorbs a large fraction of the incoming beam. B. Mikulec added that an EDMS document is under preparation detailing the slit specifications. With parallel H- and ion measurement, the slit diameter would have to change, complicating a lot the proposed design that up to now was based on a fixed opening; therefore it should first be clarified if ion operation can be suspended in the LBS line. It has been acknowledged that this object is indeed a very delicate and critical object (cooling and integration in the very limited space available) that should be studied as soon as possible.

Water connections of LT, LTB, LBE and LBS lines
B. Mikulec reported on her discussion with Y. Body concerning the future cooling water connections of the LT, LTB, LBE and LBS lines running with Linac4. Currently the lines are connected to the Linac3 water station that is already overloaded. The idea is to evaluate if it would be feasible to separate the LHC proton chain from the LHC ion chain and connect these lines to the new Linac4 water station. The Linac2 superintendent C. Mastrostefano supports this idea as it also offers the possibility to have power converters and magnets connected to the same cooling source (which is at the moment not always the case). He has provided a list with the cooling parameters of the currently installed equipment that needs to be updated in case the requirements would change with Linac4 operation.
*Y. Body* mentioned that there was already a design idea for the Linac4 water station, but that maybe the scheme could be adapted to integrate these lines. To give a definite reply, the equipment specialists with cooling needs will have to fill in an Excel sheet that he provided with the required cooling parameters. B. Mikulec will report this to the BCC with the hope that this will be followed up by the Linac4 technical coordinator and the equipment specialists.

Drawings and integration of LT, LTB, LBE and LBS lines
B. Mikulec mentioned that a few meetings have taken place with J-P. Corso as the main person. M. Vretenar proposed that priority should be given to produce integration drawings of the LBE and LBS lines (together with the BI line that is located between these 2 lines) due to the restricted space to evaluate if the proposed layout with the modified elements was feasible. For this purpose laser scanning of the lines is planned during the technical machine stop on 15/16 March. At a later stage, it would also be very desirable to produce 3D drawings of the LT and LTB lines as only 2D paper drawings are currently available and as it would be the only part of the Linac4 machine and transfer lines without 3D drawings. Details (manpower, budget) for this second step still has to be defined.

-- BettinaMikulec - 15-Mar-2010

  • Linac4_LBSdump.pdf: First simulations of LBS line dump.%META:FILEATTACHMENT{name="Linac4_LBSdump.pdf" attachment="Linac4_LBSdump.pdf" attr="" comment="First simulations of LBS line dump." date="1268670753" path="Linac4_LBSdump.pdf" size="1470296" stream="Linac4_LBSdump.pdf" tmpFilename="/usr/tmp/CGItemp49691" user="bettina_2emikulec_40cern_2ech" version="1"}%
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