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 Existing Facilities

E-Linac Photo-Fission Driver for RIB at TRIUMF 2 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 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 .4th Generation Light Source Testbed – CSS (x-ray), CSR (IR, THz)

E-Linac Photo-Fission Driver for RIB at TRIUMF 4 What is photo fission?

Electron γ-ray Radioactive ions beam photons Tungsten (Hg) Uranium oxide converter target production target

Production efficiency: one γ-photon Photo-fission cross-section high for 15 for three electrons (30 MeV) MeV γ due to Giant Dipole Resonance

E-Linac Photo-Fission Driver for RIB at TRIUMF 5 E-linac photofission

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

E-Linac Photo-Fission Driver for RIB at TRIUMF 6 E-Linac Specification Beam power (MW) 0.5 Duty Factor 100% Average current (mA) 10 Kinetic energy (MeV) 50

Photo-fission products distribution using 50 MeV 10 mA electrons on to Hg convertor &

UCx 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 E-Linac Beam Specification

Practical Bunch charge (pC) 16 considerations Bunch repetition rate (GHz) 0.65 (beam diagnostics) Radio frequency (GHz) 1.3 motivate bunch Average current (mA) 10 rep rate The requirement: Kinetic energy (MeV) 50 50 MeV × 10 mA = ½ MW beam Beam power (MW) 0.5 power eliminated Duty Factor 100% on target.

Bunch vital statistics (rms) inject eject Normalized emittance (μm) <30π <100π Not critical; Longitudinal emittance (eV.ns) <20π <40π beam Bunch length (FW), inject (ps) <170 <30 dumped on target Energy spread (FW) <1 keV <1%

E-Linac Photo-Fission Driver for RIB at TRIUMF 8 E-linac layout Thermionic gun: 100 keV; triode operation: 650 MHz Injector: Main linac: 10 Solenoids 10 MV/m, Q=10 Two cryomodules 10 mA, 5-10 MeV gain Two cavities/module, ≤ 100 kW beam power 10 MV/m, Q=1010 10 mA, 40 MeV gain ≤ 400 kW beam power NC Buncher SC Capture Cavities Solenoid

9-cell Cavities Division into injector & main linacs allows: .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 2008 Baseline E-linac for 2010-2015

2x5 kW 25 kW 50 kW 50 kW 50 kW 50 kW

e-GUN

BEAM TRANSPORT MAIN LINAC LINE BUNCHER INJECTOR MAIN LINAC CAVITY LINAC CRYOMODULE #1 CRYOMODULE #2

E-linac power distribution Final E-linac in 2015-2020 plan: 500 kW, 50 MeV

2x5 kW 50 kW 50 kW 50 kW 50 kW 50 kW 10 MeV 50 e-GUN MeV

BEAM TRANSPORT MAIN LINAC LINE BUNCHER INJECTOR MAIN LINAC CAVITY LINAC CRYOMODULE #1 CRYOMODULE #2 50 kW 50 kW 50 kW 50 kW 50 kW

E-Linac Photo-Fission Driver for RIB at TRIUMF 10 Beam Dynamics Studies for E-Linac Design Design Considerations • Input beam • RIB beam RIB 100 10 • Light-source beam 16 pC per bunch keV MeV • Beam property requirements N transverse (m) 7.5 12.5 • Optimized at 10 MeV & 50 MeV • 16 pC / 100 pC per bunch Bunch length (cm) 2.8 0.6 • Constraints Energy spread (keV) 1 40 • Physical dimensions • Diagnostics/control configurations • Hardware strength/power/hardware cost • Solution robustness • Sensitivity to input & hardware perturbations Light source 200 50 • Ability to recover from perturbations 100 pC per bunch keV MeV Tools Used

• Simulation N transverse (m) 1.0 10.0 • 100 keV eGun: GPT, SimIon • Injector and Linac: Astra, Parmela, Track: Bunch length (mm) 4.0 1.0 • Genetic Optimization Energy spread (keV) 0.5 50 • APISA* and locally added features • Robustness Analysis Programs under Development E-Linac Photo-Fission Driver for RIB at TRIUMF 11 * I. Bazarov and C. Sinclair, PRST-AB 8, 034202 (2005), & ref. therein. • 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 Pareto Front of 3-objective optimization

• Geometry EmitX • Hardware types 40 200 • Configuration layout

30 • Studying exception cases 150

• Robustness study to address MaxP 20 100 • Sensitivity to jitters

50 EmitZ95 • Design tolerance 20 30 40

10 • Ability to recover from errors 5 10 5 MaxZ EmitX 15 Performance comparison between normal and exception cases: red: =0.7+=1.0 capture Pareto fronts for 1.55 m (red) buncher-to- cavities, green: =0.7+=0.7, capture distance and 1.05 m distance (green) blue: 1st capture only (=0.7), pink: 2nd capture only (=1.0), E-Linac Photo-Fission Driver for RIB at TRIUMF olive: 2nd capture only (=0.7)12 . Beam dynamics: 100 keV - 50 MeV low charge (16pC)

elinac for ARIEL 5.0 5.0

2.5 2.5

0. 0.

-2.5 -2.5

xp vs. x yp vs. y -5.0-2.00 -1.00 0. 1.00 2.00 -5.0-2.00 -1.00 0. 1.00 2.00 element 23 Zpos= 1059.000 ngood= 10001 2.00 150

1.00 75

0. 0 rms normalized (cmmrad)normalized emittancerms

-1.00 -75

y vs. x e-es vs. phi-phis -2.00 -150 -2.00 -1.00 0. 1.00 2.00 -10.0es= 53.1447-5.0 ps=0. 113.195.0 z= 1059.010.0 Curves represent results of capture Beam portraits at the linac exit section optimization for Energy spread (3 rms): 0.32% combinations of single cells with Bunch length (3 rms): 6.4 ps different kinematic β

E-Linac Photo-Fission Driver for RIB at TRIUMF 13 E-Linac funding status is complicated by multiple sources/agencies

.Collaboration with Variable Energy Cyclotron Centre VECC (Kolkata, India) .Signed MOU in August 2008. Scope: build and beam- test 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 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 2nd 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 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

3

2

1

0

W (keV) W RMS Ellipse  -1

-2

-3 -30 -20 -10 0 10 20 30  (degree) Longitudinal emittance simulation (SIMION 3D ) at the gun exit Electron gun development stand

E-Linac Photo-Fission Driver for RIB at TRIUMF 16 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 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 2010.

E-Linac Photo-Fission Driver for RIB at TRIUMF 18 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 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 Production in limited area with the photo fission system

. E-linac provides unique area of chart of isotopes. at A=132 we have 17 isobars . Precise and accurate data needed! . Cleaner beams due to limited production (isobar suppression).

Here: 7 isobars! Use photo-production and advanced ionisation capabilities (resonant laser) to provide beams in best quality (low emittance) Photo fission and very clean (low or zero contamination). N

E-Linac Photo-Fission Driver for RIB at TRIUMF 21 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 ( > 1020 neutrons cm-3) . Observational and experimental constraints are crucial

E-Linac Photo-Fission Driver for RIB at TRIUMF 22 r-process path: measurements at ISAC Known mass Low isobaric contamination Known half-life r process waiting point (ETFSI-Q)

138Sn: 106/s

N=128

N=82 Sn-isotopes Photofission produces only neutron- rich nuclei with A > 70 N=82 Overlaps r-process progenitors, notably 50 ≤ N ≤ 62 and 82 ≤ N ≤ 90; 136 E.g., mass measurements ofE -LinacSn, Photo- Fission Driver for RIB at TRIUMF 23 139Sb, 142Te 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 rp- process, 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 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 2007.

E-Linac Photo-Fission Driver for RIB at TRIUMF 25 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