Ion beams for NA61

SPSC 29-30 September 2009 NA61/ S. Maury 1

Ion beams for NA61

Agenda:

– Primary beam for physics• Context

• Technical studies

– Resources– Tentative schedule– Conclusion


Context• Reminder: SPSC has recommended the first NA61 ion run with primary S

beam. It was recommended by the RB to work with the same ion species as LHC and to use fragmented beam produced by Pb beam sent on the target. In January 2009, SPSC has proposed to make a fragmented beam test in 2010. Scientific Director suggested in 2009 to make ion Physics in SPS and LHC independent.

• Taking into account that: - there is no shutdown in 2009/2010 - iThemba Lab in South Africa is building a clone of our ion source (a

collaboration could be established) - new ion types have been chosen by NA61 compatible with LHC

preliminary requests (easier for the source point of view)


Ion beams for NA61

• Investigations have been carried out for– Making a test with fragmented beam in 2010– Providing primary beams Argon and Xenon species

suggested by the experiment respectively for the year 2011 and 2013 at 6 different energies 10, 20, 30, 40, 80 and 158 GeV/n

– Using the fragmented beam in 2012 .


Source and Linac3• ECR source built in 2004 to produce lead ion beams for LHC has never

produced lighter ions for operation (apart from Oxygen for LEIR tests).

• Operation with other ions requires the following studies:

- the intensity,

- the parameters for the source operation,

- Linac measurements to learn about the efficiency of the transmission through the RFQ and Linac3.

Element Source LEIR/PS SPS

Ar 5+,10+,

11+,8+

10+,11+,16+

18+

Xe 16+,32+,25+

32+,39+ 54+


Source and Linac3• To prepare studies for each species one needs: - a complete set of plasma chamber, - extraction electrodes and insulators - to improve the Linac3 diagnostics for the new type of ion with an interest

for LHC as well • The estimated manpower to prepare and study the new ion species, to run

Linac3 and to switch the source between species required by the experiment is in total 3.1m.y

• A complete answer on the feasibility of the proposed ion species can only be given at the end of the above studies.

• Collaboration with South Africa is of great interest for this study and for the use of light ions in the future.


LEIR• The magnetic rigidity is lower for some species compared to lead, it necessitates to rebuild

all magnetic cycles.

• There is no particular problem for the transfer from Linac3 to LEIR but the optics need to be carefully checked.

• As the injection relativistic beta is the same as for lead, the electron cooling system can be used knowing that for lighter elements the cooling time will be longer. The cycle could be lengthened if necessary.

• The beam is then accelerated with the present rf system to the maximum magnetic rigidity and transferred bunch to bucket to the PS (to be optimized with the PS).

• There are no technical obstacles in LEIR for the operation with lighter ion species, but additional people are needed for the commissioning


Ar: PS and SPS(1) Boundary condition: assume acceleration in PS to 25.98 GeV/c proton

equivalent momentum for all ion species

PS: 40Ar16+ stripped to 40Ar18+ in transfer line to SPS

Frequencies in PS just in range to use the same scheme as for p-LHC for the synchronization and transfer to the SPS.

SPS: 200 MHz TWC system h=4620 with 199.6 MHz is below today’s regular operating frequency for pFT (14 GeV/c, 199.95 MHz), but feasible: loss of ~20 % voltage, requires coupler conditioning.


SPS: Tentative scheme for Ar• Transfer 4 bunches of ~1010 charges from PS in single cycle

• No capture in SPS before debunching at injection energy

• Capture and acceleration with 10.7 MHz IF-analog beam control– use of high sensitive pick-ups at 4x1010 charges possible

• Assuming a transmission of 75 % and a spill length of 10 s– SPS cycle length 15.6s

– 8.3x107 ions /s extracted, collimation by factor 2800 to 3x104 ions /s in transfer line to experiment; on average less than one ion per SPS turn

• need for debunching at all ?

Detailed study needed


SPS: Tentative scheme for Xe

• PS: 129Xe32+ or 129Xe39+ stripped to 129Ar54+ in transfer line to SPS

• use scheme similar to I-LHC

• PS-SPS bunch to bucket transfer

• Fixed frequency acceleration in SPS

• if debunching required in SPS at an intermediate plateau: – stay with new I-LHC beam control system

– use high sensitive pick-up electronics for loop signals after re-capture

Detailed study needed


Extraction to the experiment• A first study showed the experimental requests can basically be met

• The high intensities requested by the collaboration (106 ions per spill) are much higher than the allowed limit. Additional shielding is needed near the experimental barracks and the downstream dump needs to be replaced by a thicker version.

• The North Area interlock system must be modified to avoid accidental extraction of protons to the secondary beams and experimental areas. A decision (based on transformers) has been made in collaboration with the access experts and safety officials (delivered in 2012).

• No fixed target ion physics is currently foreseen in the SPS. To restart such an activity, the safety implications must be studied and presented to the host states and INB authorities.


Fragmented beam test• Needs:

- to optimize the target and the secondary target

- to calculate the optics of the transfer line

- to improve the shielding around the experiment

to do so, 0.5 m.y is requested

• An optimized useful test cannot be done without these calculations

Proposal:

• 2010: to make a preliminary non-optimized test to validate the procedure during 2 MDs at safe energies (20, 80 GeV/A ) in agreement with the safety office

• 2011: after having validated all the calculation and the procedure, make a complete test with NA61 experiment in MDs at safe energies (safety hardware not delivered before 2012)


Resources Ion prog. NA61

• Source 80 kCHF 2.0m.y(studies)+1.1m.y(oper.)

• Linac3 250 kCHF to be defined

• LEIR 0.5m.y(commis.)+1.3m.y(super.)

• PS 30 kCHF 0.5m.y

• SPS 50 kCHF 1.0m.y+0.3m.y(commis.)

• BI (safety) 400 kCHF 1.0m.y

• Extraction :

Secondary beam 155 kCHF 1.5 m.y

North Area safety 70 kCHF 0.5 m.y

Safety doc. 10 kCHF 1.0 m.y

• Operation shift post +1m.y(PS/SPS supervision)

• Total 730 kCHF 315kCHF 11.7 m.y + shift post

• Grand total 1045kCHF

• In addition, availability of TE/VSC, CO, RF experts are needed


Tentative schedule• 2010 11w to study Ar source I-LHC with Pb ion Early beam 2 w Source 1.5w LEIR 1.5w PS Total 11w 2 w SPS 3 w LHC SU 4 w LHC Physics total: 14w From week 21 to 31 From week 35 to 48• 2011 2w Source Ar 2 w with Pb ion Early and Nominal beam 5w LEIR commissioning 2 w 3w PS commissioning 2 w Total 10w 2 w SPS 4 w LHC Physics total: 12w From week 24 to 33 From week 37 to 48• 2012: 2w source Ar 2 w with Pb ion Nominal beam 2w LEIR 2 w 2w PS 2 w 4w commissioning SPS 2 w 1w extraction line 4 w LHC Physics total: 12w 6w Physics (1w per energy) Total is 17w From week 17 to 33 From week 37 to 48


Tentative schedule

• 2013 6w Source Xe 2w with Pb ion Nominal beam 5w LEIR commissioning 2w 3w PS commissioning 2w Total 14w 2w SPS(+2w fragmented beam Phys) 4w LHC Physics total: 14wFrom week 18 to 31 From week 35 to 48• 2014: 2w source Xe 2w with Pb ion Nominal beam 2w LEIR 2w or p-Pb collision 2w PS 2w 4w commissioning SPS 2w 1w extraction line 1w LHC (SU p-Pb)

6w Physics (1w per energy) 4w LHC PhysicsTotal is 17w Total: 13wFrom week 16 to 32 From week 36 to 48


Summary• Year Source test Supplying Switching Pb for LHC Total• 2009• 2010 (Ar) 11 3 1st ion run in LHC with Pb• 2011(Ar) 2 8 (LEIR+PS) 3 12 25• 2012(Ar) 0 17 (SPS+phys) 3 12 32• 2013(Xe) 6 8 3 12 +2 31• 2014(Xe) 0 17 3 13 33

• 2010: 1st year of LHC Operation with p and Pb ion (28 weeks with ions)• 2011: 25 weeks with ions • 2012: 32 weeks with ions• 2013: (long shutdown needed for Linac4/PSB modifications), 31 weeks with

ions• 2014: (PSB commissioning with Linac4), 33 weeks with ions


General schedule• Ar ion could be studied with the CERN source from February 2010 and the preliminary test

with fragmented beam could take place during the LHC ion run (to profit of no shutdown, commissioning of LEIR and PS could be done).

• In 2011, LEIR and PS machines could be commissioned with Ar and the final test with fragmented beam could take place during the LHC ion run (or commissioning of the SPS could be done)

• In 2012, the SPS could be commissioned before starting physics for 6 weeks with primary Ar ion beam. In parallel, with South Africa’s source, studies can be done on the Xe ion (period with Ar for NA61 is reduced by 2 weeks).

• In 2013, using the source settings from South Africa, LEIR and PS could be commissioned with Xe. During the same LHC period run, NA61 could make physics with secondary beam (B ion) produced with Pb ion beam (2 weeks more should be added).

• In 2014, the SPS could be commissioned before starting physics with primary Xe ion beam for 6 weeks.


Impact on proton usersPositive impact on ISOLDE

– Up to six PSB cycles recuperated for Isolde

No impact on ADNo impact on CNGS

– Same number of cycles/supercycle

Some impact on East Hall / TOF– One 2.4s PS cycle used for ions during tests and setting up– Up to two additional 2.4s PS cycles used for ions during run

Obviously North Area proton users suffer the most– 1 week in 2010 (fragmentation test)– 1 week in 2011 (fragmentation test)– 11 weeks in 2012 (Ar primary: SU + run)– 7 weeks in 2013 (Pb fragmented: SU +run)– 11 weeks in 2014 (Xe primary: SU + run)


LEIR/Linac3 operation

• LEIR/Linac3 were supposed to only run outside AD runs, and be operated by the AD operations team.

• The assumption is no longer true, already for I-LHC, but even more so with a North Area ion programme: both facilities would run throughout the year.

• Under these conditions the operation of these machines must be covered by an additional shift post


Conclusion• Preliminary test is possible in 2010 and the final test possible in 2011

• To reduce the ion period length in 2012 and to profit there is no shutdown in 2009/10, LEIR and PS commissioning could be done in 2010 and the SPS commissioning in 2011

• NA61 Physics could be done in 3 years by combining Primary beams (2012 and 2014) and fragmented beams (2013)

• 2012, 2013, 2014 are very busy (32 weeks with ions): shift work and supervision work (ABP,OP,RF) should be reviewed (mainly for LEIR/L3)

• Collaboration with South Africa is of great interest for the use of light ions in the future

• Little time left for Pb development

• Necessary resources: - additional manpower of 11.7 m.y. +shift post (not in MTP)

- 1045 kCHF

• ALICE requests an ion run of the nominal length with 4 weeks of colliding beams. Pb ions are approved but a strategy should be defined for p-Pb and light ions. Paper study for p-Pb could be done in 2011, MDs in the injectors in 2012 and 2013 (if physics program approved in 2010)


Acknowledgements

• Thanks to all people who contributed actively to this study: T. Bohl, C. Carli, I. Efthymiopoulos, S. Hancock, W. Hofle, R. Jones, D. Kuchler, D. Manglunki, P. Odier, R. Scrivens

.


SPSC Recommendation• The SPSC notes with satisfaction the progress of NA61 in the installation and

commissioning the upgraded apparatus, and the advanced status of the analysis of the 2007 data.

• The SPSC also notes with pleasure that, so far in 2009 the required data with the T2K

replica target has been collected, and that NA61 continues to take data and to pursue its

program efficiently.

• The SPSC notes that secondary light ion beams can be used for atomic weights up to and

including Boron, but that primary beams are required for the heavier ion species necessary to complete the proposed NA61 program.

• The SPSC recommends that the necessary preparations for a secondary Boron beam be

started in 2010, and that an energy scan with this Boron beam be performed as soon as

technically possible. In addition, the SPSC also supports carrying out the necessary

preparatory work for possible energy scans with primary beams of heavier ion species in

timely manner.

SPSC 29-30 September 2009 NA61/ S. Maury 22SPSC 24-25 November 2009 22ELENA / S. Maury

Ion beams for NA61

Documents

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commissioningna61 primary

primary s beam

lighter ion species

new ion species

pb beam

proposed ion species