September 23, 2005ISS Plenary Meeting - Zisman International Scoping Study Accelerator Working...

September 23, 2005 ISS Plenary Meeting - Zisman

International Scoping Study Accelerator Working Group:

Tasks and Plans

Michael S. ZismanCenter for Beam Physics

Accelerator & Fusion Research DivisionLawrence Berkeley National Laboratory

ISS Plenary Meeting–CERNSeptember 22-24, 2005

September 23, 2005 ISS Plenary Meeting - Zisman 2

Introduction•This marks the first time the ISS Accelerator Group has met together— welcome to all of you who will help us complete this

task in the upcoming year— please continue to encourage your colleagues to join

the effort

•We have a full agenda!— any interested members of the ISS are welcome to

attend and contribute to the Accelerator Groupo in particular, we welcome input from Detector Group on requirements that impact our design specifications

•Accomplishments here and plans for next meeting will be summarized tomorrow by Chris Prior


Yesterday’s Agenda

Thursday, September 22, 2005304-1-001A&B

Time Topic Speaker10:30 - 11:00 Discussion and Planning (Logistics) Council + Coordinators

11:00 - 11:30 C O F F E E

11:30 - 13:00 Discussion and Planning Council + Coordinators

13:00 - 14:00 L U N C H

14:00 - 14:30 Choice of Optimum Proton Energy Brooks14:30 - 14:50 Update on HARP Results Grossheim

14:50 - 15:30 High-Gradient RF Issues and 88 MHz Test Results Vretenar

15:30 - 16:00 C O F F E E

16:00 - 16:25 Superbeam Requirements and Issues Campagne16:25 - 16:55 Proton Driver: Status, Issues, and Plans Mori16:55 - 17:25 Target: Status, Issues, and Plans Lettry17:25 - 17:45 nTOF11 Status and Plans Kirk17:45 - 18:05 MICE Status and Plans Sandström18:05 - 18:30 Study II Costing and Proposed Costing Approach Palmer


Today’s Agenda

Friday, September 23, 2005304-1-001A&B

Time Topic Speaker

14:00 - 14:25 Cooling System Comparisons Palmer14:25 - 14:45 Cooling: Issues and Plans Fernow14:45 - 15:10 Acceleration System Comparisons Machida15:10 - 15:30 Acceleration: Issues and Plans Berg

15:30 - 16:00 C O F F E E

16:00 - 16:30 Storage Ring: Status, Issues, and Plans Rees16:30 - 17:15 Machine Working Group Summary Talk (Dry Run) Prior17:15 - 17:45 Discussion of Summary Talk content All17:45 - 18:30 General discussion on activities for Phase 1 and beyond All

Palmer talk


Neutrino Factory Ingredients•Proton Driver

— primary beam on production target

•Target, Capture, Decay— create , decay into

•Bunching, Phase Rotation— reduce E of bunch

•Cooling— reduce transverse emittance

•Acceleration— 130 MeV 20 GeV

•Storage Ring— store for ~500 turns; long

straight section

1-4 MWProtonSource

Hg-Jet TargetDecay

Channel

Linear Cooler

Buncher

Pre Accel-erator

Acceleration

StorageRing ~

1 km5-10 GeV

10-20GeV

1.5-5 GeV


FFAG-Based Neutrino Factory

•Alternative design concept based on FFAG rings for phase rotation and acceleration is under study in Japan— this approach will be evaluated and compared with

other designs as part of our task


NF Design: Driving Issues•Constructing a muon-based NF will be challenging— muons have short lifetime (2.2 s at rest)

o puts premium on rapid beam manipulations– requires high-gradient NCRF for cooling (in B

field)– requires presently untested ionization cooling

technique– requires fast acceleration system

— muons are created as a tertiary beam (p)o low production rate

– target that can handle multi-MW proton beamo large muon beam transverse phase space and large energy spread – high acceptance acceleration system and storage

ring


Challenges•Challenges go well beyond those of standard beams— developing solutions requires substantial R&D effort

o R&D should aim to specify: – expected performance, technical feasibility/risk,

approximate cost


History (1)•There have been 4½ previous NF “feasibility” studies— 1 in Japan— 1 in Europe— 2½ in the U.S.

o studies I, II, IIa

The Study of a European Neutrino Factory Complex, P. Gruber et al.,

CERN/PS/2002-080 (PP), CERN-NUFACT 122, December, 2002;http://slap.web.cern.ch/slap/NuFact/NuFact/nf122.pdf


History (2)•Most studies focused on feasibility and performance— cost optimization was secondary, or ignored

•U.S. Study IIa attempted to maintain performance while reducing costs— succeeded in keeping both sign muons and substantially

lowering hardware cost estimateo ISS needs to build on this philosophy (i.e., high performance, optimized cost)


Why Another Study?•Many different approaches have been considered— we must compare them to assess which features are

optimalo in terms of performanceo in terms of cost

— we must include the detector in such optimizationso and the latest understanding of the physics requirements

•To select best approaches, must study and understand what the different regions have done— partly a team-building exercise

o number of facilities likely to be built worldwide 1– voluntarily working together toward a single design

increases odds of some facility being built

•Prepares the way for WDS in 2007


Lessons Learned

•Do “local” optimizations first

•Work as partners with engineers to converge on buildable design— scoping study does need some engineers as

“consultants”

•Simulate entire concept before developing detailed engineering approaches — develop self-consistent solution— complete this step by the end of scoping study

•Facility is costly, O(€1B)


Accelerator WG Organization•Accelerator study program managed by “Machine Council”— R. Fernow, R. Garoby, Y. Mori, R. Palmer, C. Prior, M.

Zisman

•Aided by Task Coordinators— Proton Driver: R. Garoby, H. Kirk, Y. Mori, C. Prior— Target/Capture: J. Lettry, K. McDonald— Phase Rotation/Bunching/Cooling: R. Fernow, K. Yoshimura— Acceleration: S. Berg, Y. Mori, C. Prior— Storage Ring: C. Johnstone, G. Rees

•All these people serve as “assistant pests”— recruiting people to help— assigning and coordinating tasks

o we could not hope to succeed if this were a “one person show”


Accelerator Study Phase 1•Study alternative configurations; arrive at baseline specifications for a system to pursue— examine both cooling and no-cooling options

•Develop and validate tools for end-to-end simulations of alternative facility concepts— correlations in beam and details of distributions have

significant effect on transmission at interfaces (muons have “memory”)

— simulation effort will tie all aspects together

•Goal is to complete this work within 6 months— then reach consensus on which option(s) to pursue further

•Making choices requires (“top-down”) cost evaluation— ISS will require engineering resources knowledgeable in

accelerator and detector design


Accelerator Study Phase 2

•Focus on selected option(s)— as prelude to subsequent World Design Study

o WDS will have more of an engineering aspect than the ISS

•Must develop R&D list as we proceed— identify activities that must be accomplished to

develop confidence in the community that we have arrived at a design that is:

o credibleo cost-effective

— until construction starts, R&D is what keeps the effort alive


Accelerator Study Comments

•Must ensure common understanding of, and buy-in for, the results— best if trade-off studies include those from all regions

•Goal is to examine possibilities to choose the best ones— not easily done if each group “defends its own

choices”

•Study leadership needs to foster this “regional mixing”


Proton Driver Questions

•Optimum beam energy— depends on choice of target

o consider C, Ni, Ta, Hg

•Optimum repetition rate— depends on target and downstream RF systems

•Bunch length trade-offs— need (and approaches) for bunch compression— performance implications for downstream systems

•Hardware options— FFAG, linac, synchrotron

o compare performance, cost


Proton Driver Phase 1•Examine candidate machine types for 4 MW operation— FFAG (scaling and/or non-scaling)— Linac (SPL and/or Fermilab approach)— Synchrotron (J-PARC and/or AGS approach)

o consider – beam current limitations (injection, acceleration, activation)– bunch length limitations and schemes to provide 1-3 ns

bunches– repetition rate limitations (power, vacuum chamber,…)– tolerances (field errors, alignment, RF stability,…)– optimization of beam energy

•Compare and contrast Superbeam and Neutrino Factory requirements— required emittance and focusing— how do we migrate from one to the other?


Target/Capture/DecayQuestions

•Optimum target material— solid or liquid

o low, medium, or high Z

•Intensity limitations— from target

•Superbeam vs. Neutrino Factory trade-offs — horn vs. solenoid capture

o can one solution serve both needs?— is a single choice of target material adequate for both?


Target/Capture/Decay Phase 1

•Production rates as f(E) for C, Ni, Hg— do reality check with HARP data if possible

•Target limitations for 4 MW operation— use guidance from FEA and experiments

o consider bunch intensity, spacing, repetition rate

•Implications of 1 vs. 3 ns bunches on delivered beam— for various downstream rf systems

•Superbeam vs. Neutrino Factory comparisons — horn vs. solenoid— selected targets


Bunching/ Rotation/Cooling Questions

•Practical accelerating gradient and cost per GeV at several frequencies (5, 88, 201 MHz)— include power sources as well as cavities

•Relative performance of existing schemes (KEK, CERN, U.S.-FS 2b)

•Optimization of cooling vs. acceleration acceptance


Bunching/ Rotation/CoolingPhase 1 (1)

•Compare performance of existing schemes (KEK, CERN, U.S.-FS 2b)— use common proton driver and target configuration(s)— consider possibility of both signs simultaneously— conclusions will require cost comparisons, which will come later

•Evaluate implications of reduced VRF for each scheme— take Vmax = 0.75 Vdes and 0.5 Vdes

o re-optimize system based on new Vmax, changing lattice, absorber, no. of cavities, etc.

•Optimize U.S. Rotation/Bunching scheme with lower gradients and/or fewer frequencies— evaluate performance— costs will come later


Bunching/ Rotation/CoolingPhase 1 (2)

•Evaluate trade-offs between cooling efficacy and downstream acceptance— consider several values of downstream acceptance

(longitudinal and transverse)o small, medium, and large (or extra-large?)o see how much cooling channel can be simplified

— develop agreed-upon figure-of-merit (e.g., /Pprot)

— consider need/merits of longitudinal cooling— costs will come later

•Evaluate performance issues and limitations— absorbers (LH2, LiH, Be or plastic)

o consider implications of both sign muons— RF gradient (e.g., due to windows)— interactions with Target group recommended for this

topic


Acceleration Phase 1•Compare different schemes on an even footing

— RLA, scaling FFAG, non-scaling FFAG, linaco consider implications of keeping both sign muonso consider not only performance but relative costs

•Prepare scenarios for different values of acceptance — transverse and longitudinal

o small, medium, large (or extra-large?)— identify cost drivers

o these will be used later to assess cost vs. acceptance

•Consider matching between acceleration subsystems— are there simplifications in using fewer types of machines?


Storage Ring Phase 1•Design implications of final energy (20 vs. 50 GeV)

•Optics requirements vs. beam emittance— arcs, injection and decay straight sections

•Implications of keeping both sign muons— can there be both injection and decay optics in this case?

•Implications of two simultaneous baselines

•Radiation issues at 1021 useful neutrinos per year— liner vs. open-midplane magnets

•Cost implications of design will be dealt with later


Detector•Not our responsibility…but

— need to understand cost trade-offs of higher neutrino intensity vs. bigger detector

— need to understand issues related to simultaneous use of both sign muons


Summary•Challenge is to try to reach consensus on a single optimized Neutrino Factory scheme — if we can do this ourselves, without requiring an uninvolved

panel of “wise persons” to do it for us, we have truly accomplished a lot as an international community

•Even if we don’t quite succeed in selecting a single design, whatever convergence we attain will improve the probability of having a future international facility

•Developing optimal design requires an adequately-funded accelerator R&D program— we need to articulate this need and define the ingredients

of the program

September 23, 2005ISS Plenary Meeting - Zisman International Scoping Study Accelerator Working...

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