R.G. – 17/03/2003 MORIOND Workshop 2003 1 The SPL* at CERN OUTLINE Why ? How ? Roadmap Summary...

1R.G. – 17/03/2003 MORIOND Workshop 2003

The SPL* at CERNThe SPL* at CERN

OUTLINEOUTLINE

Why ? Why ? How ?How ? RoadmapRoadmap SummarySummary

* SPL = Superconducting Proton LinacA concept for improving the performance of the proton beams at CERN, A concept for improving the performance of the proton beams at CERN, ultimately based on a high-energy Superconducting Linear Acceleratorultimately based on a high-energy Superconducting Linear Accelerator


The SPL Working GroupThe SPL Working Group

- Conceptual Design of the SPL, a High Power Superconducting Proton Linac at CERN, ed. M. Vretenar, CERN 2000-012

- SPL web site: http://cern.web.cern.ch/CERN/Divisions/PS/SPL_SG/

REFERENCES


(from CERN/SPC/811)

Period of interest…

LHC

SPSFixedtarget

PSB&

PS

14 CERN/SPC/811CERN/FC/4567

= Approved = UnderConsideration

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

LHCATLAS

CMS

ALICE

LHCb

Other LHC experiments

(e.g. TOTEM)

SPSHeavy ions

COMPASS

NA48

Test Beams

North Areas

West Areas

Neutrino / CNGS

Other FacilitiesTOF Neutron

AD

ISOLDE

CAST

DIRAC

HARP

Test beams

East Hall

R&D(Detector & Accelerator)

Long–term Scientific Long–term Scientific Programme at CERNProgramme at CERN


To consolidate the injectors’complex and be ready to provide enough To consolidate the injectors’complex and be ready to provide enough protons to all usersprotons to all users

Why ?Why ?

For the approved physics programmes:For the approved physics programmes:

PS supercyclefor LHC

PS supercyclefor CNGS Remaining PSB & PS

pulses to be shared between nTOF, AD, ISOLDE, East Hall,Machine studies…


Because higher beam performance (brightness*) will be first, Because higher beam performance (brightness*) will be first, welcome, and later, necessary to:welcome, and later, necessary to:

Reliably deliver the ultimate beam actually foreseen for LHC, Reduce the LHC filling time, Increase the proton flux onto the CNGS target, Increase the proton flux to ISOLDE, Prepare for further upgrades of the LHC performance beyond the present ultimate.

Why ?Why ?

* For protons, brightness can only degrade along a cascade of accelerators Any improvement has to begin at the low energy (linac) end

For the approved physics programmes:For the approved physics programmes:


Neutrino Physics with a successive set of instruments of increasing Neutrino Physics with a successive set of instruments of increasing complexity:complexity:

Super-Beam (= conventional but very intense

proton beam) generating an intense neutrino flux

towards a remote (~ 150 km) underground experiment “beta” beams generating electron neutrinos and

anti-neutrinos towards the same underground experiment Neutrino Factory sending neutrinos to very remote

(up to 3000 km) underground experiment(s)

Nuclear Physics with a Radio-Active Ion Beam Facility of the second Nuclear Physics with a Radio-Active Ion Beam Facility of the second generation ?generation ?

Why ?Why ?

For possible new physics programmes:For possible new physics programmes:


For improvements of the present accelerator complex, the For improvements of the present accelerator complex, the energy of the linac injecting into the first synchrotron has to be energy of the linac injecting into the first synchrotron has to be increased (50 MeV today)increased (50 MeV today)

Comparing a Linac + fixed energy rings set-up with a 2-3 GeV Comparing a Linac + fixed energy rings set-up with a 2-3 GeV Rapid Cycling Synchrotron (RCS) :Rapid Cycling Synchrotron (RCS) : The linac set-up can accommodate more users since its beam power can be

increased, Some users prefer the long beam pulse delivered by a linac, The RCS construction cost could be smaller, but this is moderated by the

availability of the LEP RF equipment which a linac will re-use Linac maintenance is likely to require less manpower

Why a high energy linac ?Why a high energy linac ?


A large inventory of LEP RF equipment is available (SC cavities, cryostats, klystrons, waveguides, circulators, etc.)which can drastically reduce the cost of construction

LEP cavity modules in storage

Stored LEP klystrons


SPL lay-outSPL lay-out


SPL cross sectionSPL cross section


SPL design parametersSPL design parameters

H-

RFQ RFQ1 chop. RFQ2 RFQ1 chop. RFQ2 0.52 0.7 0.8 dump

Source Low Energy section DTL Superconducting section

45 keV 3 MeV 120 MeV 2.2 GeV

40MeV 237MeV

6 m 64 m 584 m

PS / Isolde

Stretching andcollimation line

Accumulator Ring

Debunching

383MeV

668 m

DTL CCDTLchopping

For neutrino physics, it has to be compressed with an

Accumulator and aCompressor ring into

140 bunches, 3 ns long,forming a burst of 3.3 s

Ion species H-Kinetic energy 2.2 GeVMean current during the pulse 13 mADuty cycle 14.0 %Mean beam power 4 MWPulse frequency 50 HzPulse duration 2.80 msDuty cycle during the beam pulse 61.6 %Maximum bunch current 22.7 mABunch length (total) 0.5 nsEnergy spread (total) 0.5 MeVNormalised rms horizontal emittance 0.4 mm mradNormalised rms vertical emittance 0.4 mm mradLongitudinal rms emittance (352 MHz) 0.3 deg MeV


Accumulator and Compressor Accumulator and Compressor Rings (“PDAC”)Rings (“PDAC”)

T= 2.2 GeVIDC = 13 mA (during the pulse)IBunch= 22 mA3.85 108 protons/bunchlb(total) = 44 ps*H,V=0.6 m r.m.s

(140 + 6 empty)per turn

845 turns( 5 140 845 bunches per pulse)

no beam

2.8 ms

20 ms

140 bunches

20 ms

3.2 s

Charge exchangeinjection

845 turns

PROTON ACCUMULATORTREV = 3.316 s

(1168 periods @ 352.2 MHz)

1 ns rms(on target)

22.7 ns

TARGET

H+140 bunches1.62 1012 protons/bunchlb(rms) = 1 ns (on target)

Fast ejection

KICKER20 ms

3.3 slb(total) = 0.5 ns

DRIFT SPACE+

DEBUNCHER

H-

11.4 ns

22.7 ns

5bunches

Fast injection(1 turn)

BUNCH COMPRESSORTREV = 3.316 s

(1168 periods @ 352.2 MHz)

BUNCHROTATIONRF (h=146)

Fast ejection

RF (h=146)

3 emptybuckets

17.2 ms

2 synchrotron ringsin the ex-ISR tunnel


H-




40MeV 237MeV

6 m 64 m 584 m

PS / Isolde


Accumulator Ring

Debunching

383MeV

668 m

DTL CCDTLchopping

SPL designSPL design

Input Output No. of Peak RF No. of No. of No. of Lengthenergy energy cavities power klystrons tetrodes Quads(MeV) (MeV) (MW) (m)

Source, LEBT - 0.045 - - - - - 1

RFQ 0.045 3 1 0.5 1 - - 2.4Chopper line 3 3 3 0.06 - 3 6 3.6

DTL 7 120 13 11.8 15 - 160 64 120 236 42 1.5 - 42 28 101 236 383 32 1.9 - 32 16 80 383 1111 52 9.5 13 - 26 166 1111 2235 76 14.6 19 - 19 237Debunching 2235 2235 4 - 1 - 2 13

Total 223 39.9 49 77 257 668

Section

55 cryostats, 33 from LEP, 22 using components(68 total available)

49 klystrons (44 used in LEP)


Superconducting cavities in the Superconducting cavities in the LEP tunnelLEP tunnel


Roadmap (1)Roadmap (1)

1) 3 MeV pre-injector1) 3 MeV pre-injector 2006 at CERN2006 at CERNOn-going collaboration with CEA (Saclay-F) and CNRS (Orsay-F) to build, test and

install at CERN a 3 MeV pre-injector based on the “IPHI” RFQ (Injecteur de Protons de Haute Intensité)

E C R S IL H I sou rcean d L E B T

R F Q H E B T w ithB e a m D ia g n o stic s

sp ectrom eter

B e a mStopper

B ea m P o w er : 3 0 0 k W

9 5 K e V

2 R F S y s te m s3 5 2 M H z - 1 .3 M W

3 M e V

1 0 0 K VH V p la tform

8,6 m 6 m 14 m



2) Linac 4 in the South Hall of the CERN PS2) Linac 4 in the South Hall of the CERN PS

E.U. support for R. & D. on crucial componentsis being requested in the frame of a Joint Research Activity on “High Intensity Pulsed Proton Injectors” (HIPPI).

Goal: improved performance of the proton beam for the approved physics programme (LHC, CNGS, ISOLDE, AD,…) at a minimal cost

Principles: normal conducting linac (120 – 160 MeV / H-) which can later serve as the low energy part of the

SPLreplace (and improve upon) the present linac 2 (50 MeV / protons) as the proton source at CERNminimise cost by re-using buildings and LEP RF equipment

Main characteristicsMain characteristics

Energy: originally 120 MeV. Now increased to 160 MeV for the needs of the PSB (= factor 2 in 2 )

Intensity goal: 5x1013 in the PSB (CNGS, ultimate LHC in one PSB pulse)Emittance: 0.4 mm mrad (rms, norm.) – (3 times smaller)


Linac4 layoutLinac4 layout

H-

RFQ RFQ1 chop. RFQ2DTL CCDTL

95 keV 3 MeV 120 MeV 150 MeV

40MeV 6 m 64 m

chopping

4 m

SCL/SC

Basic layout:120 MeV, 80 m, 16 LEP klystrons

Costing exercise still in progress (finished in fall?)First estimates at 60 MCHF

source


Linac4 parametersLinac4 parameters

PARAMETERS Phase 1 (PSB)

Phase 2 (SPL)

Maximum repetition rate 2 50 Hz

Source current * 50 30 mA

RFQ current * 40 21 mA

Chopper beam-on factor 75 62 %

Current after chopper * 30 13 mA

Pulse length (max.) 0.5 2.8 ms

Average current 15 1820 A

Max. beam duty cycle 0.1 14 %

Max. number of particles per pulse 0.9 2.3 · 1014

Transverse norm. emittance (rms) 0.25 0.25 mm mrad

Longitudinal emittance (rms) 0.3 0.3 deg MeV

Maximum design current 30 A

Note: Linac4 is designed to be the first part of a future SPL for 14% duty cycle & very low loss


Linac4 layout in South HallLinac4 layout in South Hall

"NEW LINAC" Layout in the PS South Hall - version 5.2.2002

12.0

m

PS Access

RF Workshop

Loading Area

Storage AreaRFQ Test stand352 MHz Test StandLoading

Area

to inflector & PSB


Linac4 R&D (low energy part of SPL)Linac4 R&D (low energy part of SPL)

H-

RFQ RFQ1 chop. RFQ2DTL CCDTL

95 keV 3 MeV 120 MeV 150 MeV

40MeV 6 m 64 m

chopping

4 m

SCL/SC

H- source, 25 mA14% duty

Collaboration with IPHI (CEA-IN2P3), building an RFQ that will come to CERN in 2006

Design and construction of a chopping line to be tested with beam in 2006:

- chopper structure- chopper pulser- 3 bunching cavities

Construction of a hot model of CCDTL (Cell-Coupled Drift Tube Linac

Chopper prototype

CCDTL prototype

(chopping=removing at low energy the linac bunches that would fall outside of the PSB bucket)


An example of R&D: the CCDTLAn example of R&D: the CCDTL

CCDTL = Cell Coupled Drift Tube Linac, a simpler and cheaper alternative to DTL for energy > 40 MeV

quadrupolecoupling cell

DTL-like accelerating cell(2 or 3 drift tubes)

CCDTL prototype



3) Full performance / high power proton injector / driver3) Full performance / high power proton injector / driver

Preliminary step: Design optimisation / successful hardware prototyping

Next steps: Positive decision for a physics programme needing such a driver Attribution of resources for machines, targets and experiments Authorisation of construction (INB procedure etc.)


H-




40MeV 237MeV

6 m 64 m 584 m

PS / Isolde


Accumulator Ring

Debunching

383MeV

668 m

DTL CCDTLchopping

H- source, 25 mA14% duty cycle

Fast chopper

(2 ns transition time)

Normal conducting (NC) cavities

Superconducting (SC) cavities: =0.52, 0.7, 0.8

Beam dynamics studies aiming at minimising losses (activation!)

Vibrations of SC cavities: analysis, compensation schemes.

RF system: 352 MHz (LEP klystrons)

SPL R&D (high energy part)SPL R&D (high energy part)


R&D topics – low R&D topics – low SC cavities SC cavities

The =0.7 4-cell prototype

CERN technique of Nb/Cu sputtering excellent thermal and mechanical stability

(important for pulsed systems) lower material cost, large apertures, released

tolerances, 4.5 K operation with Q = 109

Bulk Nb or mixed technique for =0.52 (one 100 kW tetrode per cavity)

(E. Chiaveri, R. Losito)


R&D topics - vibrationsR&D topics - vibrations

Effect on field regulation

Effect onthe beam

vector sum feedback can compensate only for vibration amplitudes below 40 Hz

possible remedies: piezos and/or high power phase and amplitude modulators

(prototype ordered - H. Frischholz)

+ possible chaotic effects(J. Tückmantel)


R&D topics – loss managementR&D topics – loss management

For hands-on maintenance, the generally accepted figure is a particle loss < 1 W/m

For the SPL, 10 nA/m (10-6/m) @ 100 MeV, 0.5 nA/m (10-7/m) @ 2 GeV

Present Linac2 loss level (transfer line): 25W/80m = 0.3 W/m (but hot spots at > 1 W/m !)

Mechanism of beam loss in the SPL: 1. H- stripping < 0.01 W/m in quads for an off-axis beam 2. Residual gas < 0.03 W/m @ 10-8 mbar, 2 GeV (but 0.25 W/m @ 10-7)

3. Halo scraping more delicate, requires: large apertures (SC is good!) careful beam dynamics design


SummarySummary

At CERN:At CERN:

High intensity protons beams will remain a strong asset High intensity protons beams will remain a strong asset beyond 2010. Improving their performance is a logical and beyond 2010. Improving their performance is a logical and necessary path for the approved physics programme.necessary path for the approved physics programme.

The SPL would be a high potential upgrade, preparing for the The SPL would be a high potential upgrade, preparing for the addition of new physics goals.addition of new physics goals.


Conclusion / RecommendationConclusion / Recommendation

A large effort in R. & D. is required, with very similar A large effort in R. & D. is required, with very similar goals and technologies than for EURISOLgoals and technologies than for EURISOL

Close coordination between teams is absolutely Close coordination between teams is absolutely necessary to share the effort and present a necessary to share the effort and present a

coherent set of requests to the E.U..coherent set of requests to the E.U..

R.G. – 17/03/2003 MORIOND Workshop 2003 1 The SPL* at CERN OUTLINE Why ? How ? Roadmap Summary...

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