FLAIR 2 February 2009T. Eriksson CERN BE/OP1 The CERN Antiproton Decelerator (AD) Status and Future

FLAIR 2 February 2009 T. Eriksson CERN BE/OP 1

The CERN Antiproton Decelerator (AD)

Status and Future


Introduction

•Based on a previous CERN machine (the

Antiproton Collector – AC), AD started producing low-energy antiproton beams for physics in

2000. Here we will discuss problems linked to AD:s co-existance with CERN main programs

and recent decisions taken with regard to AD:s future.


Background• 1980-1986 AA

– 3.57 GeV/c Antiproton Accumulator ring;– 1012 pbars stored (peak). p/pbar collisions in SPS

• 1986-1996 AAC (AA+AC)– Large acceptance Antiproton Collector ring added. Production rate

increased 10-fold to 6*1010 pbars/h– + low energy experiments in LEAR

• 1998 - ? AD– AC converted from fixed energy storage ring to Decelerator. 5*107

pbars slowed down to 100 MeV/c (5.3MeV kinetic). Local experimental area.

– Fast extraction for Penning traps + other low energy exp.:• ATRAP: Production and study of trapped Hbars• ALPHA: Production and study of trapped Hbars• ASACUSA: Spectroscopy on Antiprotonic helium, traps etc. etc.• ACE: Biological effect of Pbars => tumor treatment



AD

• Basic Parameters– Circumference 182 m

– Production beam 1.5*1013protons/cycle

– Injected beam 5*107 pbars/cycle

– Beam momenta max-min 3.57 – 0.1 GeV/c

– Momenta for beam cooling• Stochastic 3.57 and 2.0 GeV/c

• Electron 0.3 and 0.1 GeV/c

– Transverse emittances h/v 200 – 1 mm.mrad

– Momentum spread 6*10-2 – 1*10-4 dp/p

– Vacuum pressure, average 4*10-10 Torr

– Cycle length 100 s

– Deceleration efficiency 85 %


Operation statisticsRun time

(h)2000 2001 2002 2003 2004 2005 2006 2007 2008

Total 3600 3050 2800 2800 3400 0 2925 3800 3340

Physics 1550 2250 2100 2300 3090 0 2765 3760 3240

Md 2050 800 700 500 310 0 160 40 200

Beam available for physics (%)

86 89 90 90 71 65 76 81

Uptime AD machine (%)

89 74 81 93


2009 run

Key dates:•23/4: Ring closure, start HW-tests•11/5: Start setting up with beam•8/6: start physics


AD Consolidation• Many HW breakdowns of major components since 2004: several ring/transferline

magnets, vacuum leaks, power supplies etc.• Lengthy repairs due to lack of spares, need for vacuum bakeout, obsolete

equipment, loss of know-how etc.• Reduced AD maintenance/support due to other CERN priorities=>• Limited consolidation budget for urgent measures granted following

approval of AD running 2007 - 2010 • Consolidation budget requested in 2008 for continued AD operation in the

medium/long term• Focus is mainly on consolidating existing equipment• The two scenarios under consideration are:

– (1) Continued operation until the end of 2012 with no major modifications to the AD machine

– (2) Operation until the end of 2016 with the possibility to implement the proposed ELENA upgrade.


AD Consolidation•Analysis of breakdown risks, identification of items and costs for consolidation was done as well as a risk score classification.•Some 40 items have been identified, costs (manpower+material) estimated and summed up for the 2 scenarios 2012/2016.•The matter was discussed at the Research Board meeting 5/12/09; It was decided to execute approx. 1/3 of the proposed 2016 consolidation program. Quote:

“Since AD operation will be incompatible with the new PS2, this sets a clear end-point to the programme in 2017. It was agreed that the strategy to be followed should have the aim of maintaining the AD facility operational until then, but consistent with the budgetary constraints.”


Proposed new experiment: AEGIS

• The proposed AEGIS experiment was in principle approved as AD-6 at the RB meeting 5/12/09. Budgetary details remain to be worked out.

• Standard fast extraction of the 100 MeV/c beam

• The extension of the existing ACE beamline has been foreseen since the beginning of AD and requires manufacturing and installation of 2 quadrupoles, 1 dipole, 3 combined H/V corrector magnets and 3 bpm:s as well as vacuum chambers and equipment.

• Work is planned to be started in 2009, first beam in 2011


Long-term AD future• AD and antiprotons. According to the planning of the FAIR

project, the antiproton facility in GSI should have succeeded to the AD after the year 2017. The continuation of antiproton experiments at CERN after the PS complex is decommissioned is therefore unlikely. In spite of this, if an antiproton facility is still needed on the CERN site, the following scenarios can be envisaged:– For a limited period of time (1-2 years) the old PS complex could be

kept active and dedicated to the production of antiprotons.– For continuation in the medium term, the AD target could receive a

proton beam from PS2 via a 1.3 km transfer line, using a new 650 m long tunnel and passing through 3/4 of the PS ring.

– For continuation in the long term, a new and modern antiproton facility with its target area should be built in a cavern close to PS2.


•Connection to AD for continued Pbar physics in the medium term.


In the long term, a new antiproton facility could be built either 40m underground or in a surface building further away from PS2

Possible PS2 surface experimental area

Possible PS2 underground experimental areas


Sideview of baseline scheme


Long-term AD future• May 09 meeting to discuss Non-LHC physics

• Objective is to define strategies for optimizing physics output at CERN… and world-wide

• We might know more about the future of low-energy pbar physics after that…..


AD – future improvements: ELENA


ELENA basic parametersEnergy, MeV 5.3 – 0.1

Circumference, m 25.6

Emittances at 100 keV, π mm mrad 5 / 5

Intensity limitation by space charge 1 107

Maximal incoherent tune shift 0.10

Bunch length at 100 keV, m / ns 1.3 / 300

Expected cooling time at 100 keV, sec 1

Required vacuum* for Δε=0.5π mm mrad/s,Torr

3 10-12

IBS blow up times for bunched beam* (εx,y=5π mm mrad, Δp/p=1 10-3), s

1.1 / -9.1 / 0.85

* No electron cooling is assumed


AD – future improvements: ELENA

•3,5 years project duration•10 MCHF + 50 Man-years needed•CERN approval conditioned to external funding 50/50•ELENA was not discussed during RB 5/12/09•External partners interested in participating in the project


TSR => ELENA ?• A visit to the TSR facility at MPI-K Heidelberg has enabled us to verify the

feasibility of using an appreciable amount of the TSR machine components for the construction of the proposed low energy antiproton ring, ELENA. Even thought the TSR ring size (53 m) does not fit the dimensions of the ELENA ring, which would have a circumference of about 30 m, most of the TSR elements could be used for the smaller ring.

• Magnets: All 8 bending magnets fit the requirements.• 20 quadrupole magnets are available, 8 are required for use in

ELENA and the rest will be used in the transfer line or kept as spares.• Orbit correction: The 8 backleg windings on the main bends will be used for the

horizontal orbit correction. A total of 12 dipoles are available to correct the vertical orbit or to provide extra elements for the horizontal correction.

• Injection & ejection: The magnetic and electrostatic septa of TSR could be adapted for use in ELENA. The kickers, however, do not fit the requirements. In addition an number of magnetic correctors can be used in the AD-ELENA transfer line.

• Electron cooling: It is proposed to use the electron target experiment as an electron cooler for ELENA. This device comes complete with the Faraday cage and high voltage platform. A modification to the electron gun will be needed in order to exchange the photocathode with a conventional thermionic cathode.


TSR => ELENA ?• Vacuum:All vacuum chambers are made of 316LN stainless steel and are

bakeable. Turbo molecular pumps, ion pumps and Ti sublimation pumps can all be re-used in ELENA. In addition 5 sector valves are also available as well as vacuum gauges and residual gas analysers. Only the pumps and the valves are equipped with bakeout jackets. The rest of the machine is equipped with heating strips and insulating material. The complete control of the bakeout could also be used.

• Instrumentation: 8 horizontal/vertical pick-ups (LEAR type, fully bakeable) can be used to measure the closed orbit. The intensity is measured with a standard Bergoz BCT and the circulating beam profile is measured with ionization profile monitors and a scraper. Schottky pick-ups are installed but their use in ELENA might be limited due to the low number of particles. They would be useful for the tune measurement where a dedicated BTF kicker is available.

• Taking the above into consideration, we estimate that between 2.5 to 3 MCHF could be saved by using TSR elements in the construction of the ELENA post-decelerator ring. This represents about 25% of the total budget.


TSR => ELENA ?• Proposed

ELENA/TSR lattice


THANK YOU

Documents

FLAIR 2 February 2009T. Eriksson CERN BE/OP1 The CERN Antiproton Decelerator (AD) Status and Future