Electron Linac Photo-Fission Driver for the Rare Isotope Beams at TRIUMF

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1 CANADA S NATIONAL LABORATORY FOR PARTICLE AND NUCLEAR PHYSICS Owned and operated as a joint venture by a consortium of Canadian universities via a contribution through the National Research Council Canada Electron Linac Photo-Fission Driver for the Rare Isotope Beams at TRIUMF S. Koscielniak, F. Ames, R. Baartman, P. Bricault, I. Bylinskii, Y.-C. Chao, K. Fong, R. Laxdal, M. Marchetto, L. Merminga, A. Mitra, I. Sekachev, V. Verzilov, V. Zgavintsev SRF 2009 Workshop, Berlin, 25 Sept 2009 LABORATOIRE NATIONAL CANADIEN POUR LA RECHERCHE EN PHYSIQUE NUCLÉAIRE ET EN PHYSIQUE DES PARTICULES Propriété d un consortium d universités canadiennes, géré en co-entreprise à partir d une contribution administrée par le Conseil national de recherches Canada

2 Existing Facilities E-Linac Photo-Fission Driver for RIB at TRIUMF 2

3 10-year plan: ARIEL project new isotope production facility for ISAC expansion Staged installation 5-Year Plan New complementary driver (e-linac): electron driver for photo-fission New target station and mass separator New p-beam line 10-Year Plan New front end and post accelerators Additional target station Three simultaneous radioactive beams E-Linac Photo-Fission Driver for RIB at TRIUMF 3

4 E-Linac Motivation/Impact New Science: Nuclear physics with neutron-rich RIBs High purity radioisotope beams Complementary & independent RIB driver Enhanced science output: multiple beams to multiple users Steady RIB production: staggered E-Linac & cyclotron shutdowns Leverages valuable existing infrastructure: Proton Hall: available shielded vault with services World-class RIB multiple experimental stations Expands SCRF in-house expertise Prepares Canada for SCRF projects world-wide (ILC, CERN-SPL) Qualifies commercial partner (PAVAC) to build SCRF cavities 4 th Generation Light Source Testbed CSS (x-ray), CSR (IR, THz) E-Linac Photo-Fission Driver for RIB at TRIUMF 4

5 What is photo fission? Electron γ-ray beam photons Tungsten (Hg) converter target Uranium oxide production target Radioactive ions Production efficiency: one γ-photon for three electrons (30 MeV) Photo-fission cross-section high for 15 MeV γ due to Giant Dipole Resonance E-Linac Photo-Fission Driver for RIB at TRIUMF 5

6 E-linac photofission Photofission of 238 U was proposed by W. T. Diamond (Chalk River) in 1999 [NIM, V 432] as an alternative production method for RIB. High energy Photon neutron neutron Fission fragments neutron Fission fragments E-linac Electron- Photon Converter 238 U Target Ion Source Mass Separator RIB User E-Linac Photo-Fission Driver for RIB at TRIUMF 6

7 Beam power (MW) 0.5 Duty Factor 100% Average current (ma) 10 Kinetic energy (MeV) 50 E-Linac Specification Photo-fission products distribution using 50 MeV 10 ma electrons on to Hg convertor & UC x target Number of photo-fission /second versus electron energy for 100 kw e-beam on Ta convertor and U target. E-Linac Photo-Fission Driver for RIB at TRIUMF 7

8 Practical considerations (beam diagnostics) motivate bunch rep rate E-Linac Beam Specification Bunch charge (pc) 16 Bunch repetition rate (GHz) 0.65 Radio frequency (GHz) 1.3 Average current (ma) 10 Kinetic energy (MeV) 50 Beam power (MW) 0.5 Duty Factor 100% The requirement: 50 MeV 10 ma = ½ MW beam power eliminated on target. Bunch vital statistics (rms) inject eject Normalized emittance (μm) <30π <100π Longitudinal emittance (ev.ns) <20π <40π Bunch length (FW), inject (ps) <170 <30 Energy spread (FW) <1 kev <1% Not critical; beam dumped on target E-Linac Photo-Fission Driver for RIB at TRIUMF 8

9 Thermionic gun: 100 kev; triode operation: 650 MHz Solenoids NC Buncher SC Capture Cavities E-linac layout Injector: 10 MV/m, Q= ma, 5-10 MeV gain 100 kw beam power Solenoid Main linac: Two cryomodules Two cavities/module, 10 MV/m, Q= ma, 40 MeV gain 400 kw beam power Division into injector & main linacs allows: 9-cell Cavities Possible expansion for: Energy Recovery Linac (ERL) e.g. 10 ma, 80 MeV Recirculating Linear Accelerator (RLA) e.g. 2 ma, 160 MeV E-Linac Photo-Fission Driver for RIB at TRIUMF 9

10 2008 Baseline E-linac for x5 kw 25 kw 50 kw 50 kw 50 kw 50 kw e-gun BUNCHER CAVITY INJECTOR LINAC MAIN LINAC CRYOMODULE #1 MAIN LINAC CRYOMODULE #2 BEAM TRANSPORT LINE E-linac power distribution Final E-linac in plan: 500 kw, 50 MeV e-gun 2x5 kw 50 kw 50 kw 50 kw 50 kw 50 kw 10 MeV 50 MeV BUNCHER CAVITY INJECTOR LINAC MAIN LINAC CRYOMODULE #1 MAIN LINAC CRYOMODULE #2 BEAM TRANSPORT LINE 50 kw 50 kw 50 kw 50 kw 50 kw E-Linac Photo-Fission Driver for RIB at TRIUMF 10

11 Beam Dynamics Studies for E-Linac Design Design Considerations Input beam RIB beam Light-source beam Beam property requirements Optimized at 10 MeV & 50 MeV 16 pc / 100 pc per bunch Constraints Physical dimensions Diagnostics/control configurations Hardware strength/power/hardware cost Solution robustness Sensitivity to input & hardware perturbations Ability to recover from perturbations Tools Used Simulation 100 kev egun: GPT, SimIon Injector and Linac: Astra, Parmela, Track: Genetic Optimization APISA * and locally added features Robustness Analysis Programs under Development RIB 16 pc per bunch 100 kev 10 MeV N transverse ( m) Bunch length (cm) Energy spread (kev) 1 40 Light source 100 pc per bunch 200 kev 50 MeV N transverse ( m) Bunch length (mm) Energy spread (kev) E-Linac Photo-Fission Driver for RIB at TRIUMF 11 * I. Bazarov and C. Sinclair, PRST-AB 8, (2005), & ref. therein.

12 Multiple-objective optimization Good convergence to solution set (Pareto front) Solutions identified meet design requirements Trade-off between objectives maps out feasible operation envelope and options. Optimization provides unambiguous basis for Selecting among different configuration choices Geometry Hardware types Configuration layout Studying exception cases Robustness study to address Sensitivity to jitters Design tolerance Ability to recover from errors 5 10 EmitX 15 5 MaxZ 10 MaxP 100 Pareto fronts for 1.55 m (red) buncher-tocapture distance and 1.05 m distance (green) Pareto Front of 3-objective optimization E-Linac Photo-Fission Driver for RIB at TRIUMF EmitX Performance comparison between normal and exception cases: red: =0.7+ =1.0 capture cavities, green: =0.7+ =0.7, blue: 1 st capture only ( =0.7), pink: 2 nd capture only ( =1.0), olive: 2 nd capture only ( =0.7). EmitZ95

13 rms normalized emittance (cm mrad) Beam dynamics: 100 kev - 50 MeV low charge (16pC) elinac for ARIEL xp vs. x yp vs. y element 23 Zpos= ngood= y vs. x e-es vs. phi-phis es= ps= z= Curves represent results of capture section optimization for combinations of single cells with different kinematic β Beam portraits at the linac exit Energy spread (3 rms): 0.32% Bunch length (3 rms): 6.4 ps E-Linac Photo-Fission Driver for RIB at TRIUMF 13

14 E-Linac funding status is complicated by multiple sources/agencies Collaboration with Variable Energy Cyclotron Centre VECC (Kolkata, India) Signed MOU in August Scope: build and beamtest Injector Cryo-Module (VECC ICM) at 10MeV/50kW Collaboration with Canadian University Partners U.Vic and TRIUMF submitted October 2008 proposal to Canada Foundation for Innovation (CFI) for full elinac July 2009 CFI awarded Ca$17.76 million to elinac BUT must obtain matching funds for civil construction from Province (B.C.) before federal money is released. E-Linac Photo-Fission Driver for RIB at TRIUMF 14

15 Schedule October 2008 Start Injector Beam Dynamics design July 2009 Single cell β=1 prototyping and test December 2009 VECC ICM technical design November 2010 Assemble ICM1 May 2011 Beam test with VECC ICM in ISAC-II Build e-linac infrastructure in Proton Hall Start assembly 2 nd ICM for elinac December 2011 Test ICM2 in Proton Hall July 2013 E-linac beam test November 2013 Ready for RIB production up to 100 kw 2017 E-linac beam test at full energy and full power E-Linac Photo-Fission Driver for RIB at TRIUMF 15

16 W (kev) Electron Source Thermionic gun inexpensive, simple, low maintenance NIST/JLab electron gun was donated to TRIUMF Being converted from diode to triode RF modulated gun avoids chopping and high power beam dump at linac start RMS Ellipse (degree) Longitudinal emittance simulation (SIMION 3D ) at the gun exit Electron gun development stand E-Linac Photo-Fission Driver for RIB at TRIUMF 16

17 Use/adapt existing equipment designs wherever possible TTF 9-cell cavities with modified end cells and large diameter beam pipe Cornell/CPI 50 kw c.w. power couplers XFEL industrialisation makes Saclay Type I tuner a strong candidate. E-Linac Photo-Fission Driver for RIB at TRIUMF 17

18 Cavity Development with PAVAC PAVAC is a local company with EBW expertise Now produces 20 QW 141MHz cavities for ISAC-II PAVAC to produce two single cells in 2009 Dies sourced from FNAL/RRCAT Forming and welding tests underway (in copper and Nb) PAVAC to produce multicell cavity prototype in E-Linac Photo-Fission Driver for RIB at TRIUMF 18

19 Summary E-linac is a major new RIB source, complementary to cyclotron Opens new science horizons with neutron-rich RIB L-band SCRF cost effective MW-class fission driver Capitalization on world-wide SRF R&D Light source technology test bed Allows participation in other SRF projects (e.g. SPL, ILC etc.) E-Linac Photo-Fission Driver for RIB at TRIUMF 19

20 The Big Questions in Nuclear Structure What is the Structure of Nuclei and Nuclear Matter? What are the Limits of Nuclear Existence? (proton/neutron drip lines?) What are Nuclear Properties as Function of Neutron-to-Proton Asymmetry? Studies of the Evolution of Shell Structure at ISAC Nuclear Matrix Elements for Extracting Neutrino Masses Nuclear theory needs experimental input to refine the models. Mass spectrometry is a key field to provide basic and benchmark data for nuclear structure & for theory Mass spectroscopy often a discovery tool for new phenomena: Appearance/disappearance of Magic Numbers. Finding of new isomers in unexpected regions. E-Linac Photo-Fission Driver for RIB at TRIUMF 20

21 Production in limited area with the photo fission system at A=132 we have 17 isobars E-linac provides unique area of chart of isotopes. Precise and accurate data needed! Cleaner beams due to limited production (isobar suppression). N Here: 7 isobars! Photo fission Use photo-production and advanced ionisation capabilities (resonant laser) to provide beams in best quality (low emittance) and very clean (low or zero contamination). E-Linac Photo-Fission Driver for RIB at TRIUMF 21

22 Nuclear Astrophysics- The Big Questions How, when, and where were the chemical elements produced? What role do nuclei play in the liberation of energy in stars and stellar explosions? How are nuclear properties related to astronomical observables: solar neutrino flux, -rays emitted by astrophysical sources, light curves of novae, supernovae, and x-ray bursts of neutron stars/accretion disks? E-linac will focus on Nuclear Astrophysics with Neutron-Rich Nuclei r process: neutron captures on very rapid timescale (~ 1 s) in a hot (GK), dense environment ( > neutrons cm -3 ) Observational and experimental constraints are crucial E-Linac Photo-Fission Driver for RIB at TRIUMF 22

23 Known mass Known half-life r-process path: measurements at ISAC r process waiting point (ETFSI-Q) Low isobaric contamination N= Sn: 10 6 /s N=82 Sn-isotopes Photofission produces only neutronrich nuclei with A > 70 Overlaps r-process progenitors, notably 50 N 62 and 82 N 90; E.g., mass measurements of 136 Sn, 139 Sb, 142 Te N=82 E-Linac Photo-Fission Driver for RIB at TRIUMF 23

24 e-linac & new proton beam line A 10-Year Plan for ISAC A Critical Shortage of New Unstable Nuclei Beams at ISAC All the ISAC programs critically need more rare-isotope beams. More beam time, more beams delivered, and more science E-linac implements strategy of multiple beams (e, p) to multiple users to accelerate science output One electron and one proton beam line in a common tunnel using new common actinide target technology Physics Case: nuclear astrophysics (neutron rich r-process, proton rich rpprocess, element abundances, supernova explosion neutron density models, neutron star crusts and nuclear structure with actinides (unique in world), Begin fundamental symmetries, Allow beta-nmr to triple in running time (study interfaces at 4 nm longitudinal resolution, basic research of material boundaries, unique facility in world inflight laser spin polarization) Opportunity for new radio-tracer development with actinides. E-Linac Photo-Fission Driver for RIB at TRIUMF 24

25 We chose Superconducting RF because: Continuous operation is inconceivable with NC cavities for 50 MeV, need 4-8 MW wall-plug power. With SC cavities need 1.5 MW wall-plug power - enormous operational cost savings! We chose 1.3 GHz, 2K technology because: Enormous world-wide effort in this regime since the 1990s dedicated to TESLA at DESY and now to International Linear Collider (ILC). The Tesla Technology Collaboration (TTC) exists to promote, share and disseminate the remarkable results of the effort. Technology is mature with gradients 20 MV/m routine. Projects now include: DESY X-ray FEL, Cornell Energy Recovery Linac (ERL), Daresbury ERL Prototype, KEK-Free Electron Laser (FEL). KEK and FNAL efforts for ILC, Jefferson Lab upgrade, TRIUMF e-linac, etc. TRIUMF joined TTC in April E-Linac Photo-Fission Driver for RIB at TRIUMF 25

26 HP RF building block for e-linac 2008 Concept 50 kw coupler 130 kw klystron 50 kw coupler E-linac RF unit = 100 kw/cavity E-Linac Photo-Fission Driver for RIB at TRIUMF 26