Acc App 17 Quebec City Quebec Canada July

Acc. App’ 17, Quebec City, Quebec, Canada July 31, 2017 Electron ERL for Isotope Production V. S. Morozov, H. Areti, S. Benson, Y. S. Derbenev, D. Douglas, A. Kimber, G. A. Krafft, A. Sy Thomas Jefferson National Accelerator Facility R. P. Johnson, T. J. Roberts Mu. Plus, Inc. C. Boulware, T. Grimm, V. Starovoitova Niowave, Inc. Supported by DOE NP STTR Grant DE-SC 0013123 to Mu. Plus, Inc. , a wholly-owned subsidiary of Muons, Inc.

Electron Beam for Isotope Production Advantages – Electron linacs are inexpensive compared to nuclear reactors and ion accelerators – Higher isotope production yields compared to more conventional techniques Disadvantages of conventional straight-through electron linacs – Relatively low specific activity Isotope separation from the target material – Majority of electrons do not produce useful gammas – Radioactivation of shielding components Proposed solution: SRF Energy Recovery Linac (ERL) – Significant fraction of beam power is recycled – Reduced radioactivation due to low beam energy at the dump Acc. App’ 17, Quebec City, QC, Canada July 31, 2017 2

Schematic of Isotope Production Facility Electron beam accelerated in SRF linac Electrons pass through thin radiator Bremsstrahlung photons hit production target outside of the beam Electrons not producing high-energy gammas recirculated and energy recovered in SRF linac Decelerated low-energy beam dumped with minimum radioactivation Acc. App’ 17, Quebec City, QC, Canada July 31, 2017 3

Advantages of ERL Technology Higher isotope production yields No admixture of unwanted long-life isotopes in contrast to nuclear reactors Tunable electron energy for optimal isotope production Greater energy efficiency due to energy recovery Lower energy deposited in the beam dump with minimum radioactivation Reasonably simple to operate and maintain Can be powered down quickly unlike a nuclear reactor Simpler, cleaner and less costly decommissioning Small footprint Acc. App’ 17, Quebec City, QC, Canada July 31, 2017 4

Available Isotopes Electron ERL opens access to high-threshold isotopes that have not been available earlier Radioisotope Reaction Threshold, Me. V V-51(γ, 3 n)V-48 32 Cr-50(γ, np)V-48 21 Cr-48 Cr-50(γ, 2 n)Cr-48 24 Zn-62 Zn-64(γ, 2 n)Zn-62 21 Co-56 Ni-58(γ, np)Co-56 20 Cs-136 Ba-138(γ, np)Cs-136 16 Sm-145(γ, 2 n)Sm-147 20 Ag-111 Cd-113(γ, np)Ag-111 16 Sc-47 Ti-48(γ, p)Sc-47 11 Y-88 Y-89(γ, n)Y-88 11 Cu-67 Zn-68(γ, p)Cu-67 10 V-48 Acc. App’ 17, Quebec City, QC, Canada July 31, 2017 5

Comparison of ERL and Conventional Linac Acc. App’ 17, Quebec City, QC, Canada July 31, 2017 6

Main Challenges Acc. App’ 17, Quebec City, QC, Canada July 31, 2017 7

Liquid High-Power Radiator Niowave, Inc. has developed several types of high-power-density liquid metal x-ray converter radiators Ribbon of lead-bismuth eutectic flowing between two thin windows 10 k. W and higher-power radiators are technically feasible Windowless designs are possible for thinner radiators Acc. App’ 17, Quebec City, QC, Canada July 31, 2017 8

Solid High-Power Radiator Acc. App’ 17, Quebec City, QC, Canada July 31, 2017 9

Energy Spread after Radiator 100 Me. V electron beam incident on 0. 25 mm (3. 5%) LBE radiator GEANT 4/Mu. Sim simulation Average energy loss is about 3. 5% Distribution peaks at 99. 8 Me. V with FWHM of about 0. 1 Me. V Momentum acceptance of > 10% has been demonstrated in JLab’s LERF Acc. App’ 17, Quebec City, QC, Canada July 31, 2017 10

Angular Spread after Radiator Acc. App’ 17, Quebec City, QC, Canada July 31, 2017 11

Recoverable Beam Fraction Acc. App’ 17, Quebec City, QC, Canada July 31, 2017 12

Beam Parameters at Radiator Acc. App’ 17, Quebec City, QC, Canada July 31, 2017 13

Post-Radiator Region Optics First quads are as close to the radiator as possible to minimize functions More compact optics also provides shorter distance to production target Match to regular FODO by linear matching section for ease of beam smear studies some linear matching section radiator check beam phase space at this point thin octupoles production target Acc. App’ 17, Quebec City, QC, Canada July 31, 2017 14

Geometric Aberrations Uniform transverse distribution: 3 60 mrad in each plane, p/p = 0 After octupole compensation of spherical aberrations Acc. App’ 17, Quebec City, QC, Canada July 31, 2017 15

Chromatic Aberrations Add uniform p/p spread of 3% Chromatic compensation is needed Acc. App’ 17, Quebec City, QC, Canada July 31, 2017 16

Chromaticity Compensation Chromaticity compensation block in the post-radiator section to compensate chromatic beta beat – beta beating in four 90 FODO cells – designed to minimize geometric impact of sextupoles – performance can be improved by optimization observation point radiator match CCB match Acc. App’ 17, Quebec City, QC, Canada July 31, 2017 ~ Chromatic beta function: / 17

Phase Space after Correction x = y = 60 mrad, p/p = 3%, no correction After initial sextupole and octupole compensation Acc. App’ 17, Quebec City, QC, Canada July 31, 2017 18

Protection of SRF Linac x' x' x Acc. App’ 17, Quebec City, QC, Canada July 31, 2017 x 19

Summary of ERL Beam Parameters Injector beam energy Beam energy in the radiator section Beam energy at the dump Beam current Bunch frequency Bunch charge Radiator material Radiation length Radiator thickness Side of the radiator Twiss function Transverse geometric emittance (rms) Longitudinal emittance (rms) Bunch length (rms) Momentum spread (rms) Transverse acceptance Momentum acceptance Acc. App’ 17, Quebec City, QC, Canada July 31, 2017 3 Me. V 100 Me. V 3 Me. V 10 m. A 352 MHz 28. 5 p. C LBE (or possibly W) 7. 1 mm 0. 25 mm (3. 5% r. l. ) Before After 4 mm 0. 5 mm 25 nm ~200 nm 50 ke. V-ps To be optimized ~0. 1% Not an issue ~5 m Not an issue ~15% 20

Proposed R&D Collaboration of Jlab, Mu. Plus, Inc. and Niowave, Inc. developed R&D plan to demonstrate feasibility of ERL for isotope production Develop complete conceptual design of ERL-based isotope production complex Complete an end-to-end simulation of the developed design Study existing data, prototype and experimentally test key components - High-power radiator - Beam dynamics after radiator - Collimation Beam after radiator can be experimentally characterized at JLab’s Upgraded Injector Test Facility (UITF) Acc. App’ 17, Quebec City, QC, Canada July 31, 2017 21

Summary ERL technology has a lot of potential for efficient production of high-value isotopes Facility design has been laid out Main challenges have been identified and their solutions outlined Further design and R&D work is needed Plan for feasibility demonstration has been developed Acc. App’ 17, Quebec City, QC, Canada July 31, 2017 22