D. Leitner, D. Alt, T. M.Baumann, C. Benatti, B. Durickovich, K. Kittimanapun, A. Lapierre, L. Ling-Ying, S. Krause, F. Montes, D. Morrissey, S. Nash, R. Rencsok, A. Rodriguez, C. Sumithrarachchi, S. Steiner, S. Schwarz, M. Syphers, S. Williams, W. Wittmer, X. Wu and others Georg Bollen Michigan State University ReA12 -Update

Facility for Rare Isotope Beams Fast, Stopped, and Reaccelerated Beams for Science Rare isotope production via in-flight technique with primary beams up to 400 kW, 200 MeV/u uranium Fast, stopped and reaccelerated beam capability NSCL will provide pre-FRIB science opportunities with fast, stopped and reaccelerated beams New equipment must integrate into FRIB in the future ReAccelerator Facility G. Bollen, Recoil Separator for ReA12 Workshop, MSU 2014

FRIB Construction Underway FRIB project completion in 2022 –managed to early completion in 2020

NSCL only Facility in the World that Provides Fast, Stopped, and Reaccelerated Beams of Rare Isotopes Fast Beams Gas Stopper Stopped beams Reaccelerated Beams Space for future expansion of the science program ReAccelerator Facility Gas Stopper A1900 Fragment Separator K1200 Cyclotron K500 Cyclotron MoNA LISA Sweeper Magnet SECAR (design) JENSA ANASEN, FSU SuN CFFD JANUS.. SEETF SeGA HiRA Triplex Plunger CAESAR LENDA GRETINA (DOE national user facility) BCS NERO DDAS CAESAR RFFS Momentum Compression Beam Line) BECOLA S800 AT-TPC Cycstopper off line commissioning 20 meter ReA3 Hall ReA6-12 Hall LEBIT, Minitrap G. Bollen, Recoil Separator for ReA12 Workshop, MSU 2014

In-flight Fragmentation Offers A Wide Variety Of Rare Isotopes NSCL’s Coupled Cyclotron Facility has produced >1000 RIBs and >870 RIBs have been used in experiments with > 90% availability FRIB will provide times higher beam rates FRIB CCF

Fast Rare Isotope Beam Production at NSCL and FRIB FRIB CCF 1000x higher primary beam power G. Bollen, Recoil Separator for ReA12 Workshop, MSU 2014

The ReAccelerator (ReA) From fast to stopped to reaccelerated beams He gas-cell Room-temperature RFQ  =4.1% > 80 MeV/u EBIT charge breeder 1+  Q+ Trapped ions ~ 200 eV ≤ 60 keV Highly charged ion beam, 12 keV/u x A (2≤A/Q≤5) Magnetic sector Achromatic Q/A separator Electrostatic sector Continuous stable heavy ion beam>80 MeV/u Superconducting RF linac Thin foil target <1 eV  =8.5% 600 keV/u 80.5 MHz MHB RB **Production & In-flight separation “Stopping” area 12 keV/u 48 Ca MeV/u 238 U MeV/u Final configuration, ReA12 Initial configuration, ReA3: 48 Ca MeV/u 238 U MeV/u A few MeV’s/u Continuous injection (currently) & accumulation (~1 s ms) Pulsed extraction (~ Hz) G. Bollen, Recoil Separator for ReA12 Workshop, MSU 2014

Stopped Beam Facilities Ready to Deliver Beams DC beams > 80 MeV/u Thermalizae iosn in gas cell with helium as a buffer gas Rare-isotope beams from the production area Analyzing dipole magnet Si detectors to measure  -decay activity for particle ID & beam transport optimization DC beams, up to 60 keV Purpose of beam stopping:  Decelerate the rare-isotope beams  Reduce the emittance for reacceleration Si detector to measure  -decay activity for particle ID & beam transport optimization G. Bollen, Recoil Separator for ReA12 Workshop, MSU 2014

Stopped Beam Facilities Continuing Upgrades Multifaceted approach –Linear gas stopper (heavier ion beams) –Cyclotron gas stopper (lighter ion beams) –Solid stopper (certain elements, highest intensity) Cyclotron gas stopper well underway –Yoke, poles, coils, cryostat fabricated, stopping chamber manufactured. System assembled –Cool down of magnet started –Ion transport and extraction techniques demonstrated Cryogenic linear gas stopper –Higher beam purity, faster extraction, higher beam rates –NSF-MRI funding (information received) G. Bollen, Recoil Separator for ReA12 Workshop, MSU 2014

Re-Accelerator ReA State-Of-The-Art RIB Post-Accelerator and the First Coupled to A Fragmentation Facility EBIT CB RFQ CM2 CM3 (2014) CM1 ReA3 ReA6 SECAR AT-TPC ReA6 Equipment & Beamlines TBD D-Line N4 Stopped beams A1900 L-Line General Purpose Line 2010/10: RFQ commissioning started 2011/04: CM1 first beam acceleration 2011/06: CM2 first beam acceleration 2012/04: first 1+-n+ acceleration 2013/06: Experimental hall beam line 2013/08: First rare isotope experiment 2014/05: Cryomodule 3 installation G. Bollen, Recoil Separator for ReA12 Workshop, MSU 2014

ReA Will Provide World Unique Beams Top Energies (ReA3 to ReA12) “n-rich”“n-deficient” Original cavity performance Measured cavity performance Original cavity performance Measured cavity performance ReA energy upgrade continues to be a key user demand G. Bollen, Recoil Separator for ReA12 Workshop, MSU 2014

ReA Design Choices: EBIT Charge Breeder module FY modules RT RFQ MHB Achromatic Mass Separator Pilot source for linac tuning n+ RIB beam EBIT 1+ RIB beam EBIT: Short breeding time High ionization efficiency Charge state flexibility Low beam contamination 0.5 ≥ Q/A ≥ 0.2 G. Bollen, Recoil Separator for ReA12 Workshop, MSU 2014

Charge Breeding In The EBIT Source q+ V Pulsed extraction 1+1 Radial electron-beam space- charge potential Axial potential well from the trap electrodes Highly charged ions Trap electrodes Magnetic field Electron collector Electron gun Electron beam Continuous injection and accumulation (~100 ms) A + Pulsed extraction (  s to ms) A Q+ Over-the-potential barrier injection Lower-the-barrier extraction V Continuous injection G. Bollen, Recoil Separator for ReA12 Workshop, MSU 2014

Measured Charge Breeding Efficiency Efficiency in single charge states of injected 39 K stable-isotope beams ReA EBIT not yet operated at full current G. Bollen, Recoil Separator for ReA12 Workshop, MSU 2014

Improving EBIT Efficiency with Beam Bunching Continuous injection into EBIT charge breeder –Ultimately needed for highest beam intensity (FRIB) –30% efficiency (for all charge states) demonstrated with present electron gun In-flight capture of ion bunches increases efficiency –Capture efficiency  capt = 30% (DC)   capt = 100% (pulsed) –Higher efficiency for breeding into single charges state –Reduced breeding times New beam buncher is under construction –Cryogenic cooler and buncher based on gas filled RFQ ion trap –Optimized for fast cooling and bunching (<100ms) –Optimized for high rate capability (10 7 ions per bunch  10 8 ions/s) - compatible with NSCL’s CCF beam rates Status –Assembly underway –Start commissioning in fall Dynamic capture of ion bunch doesn’t rely on 1+  2+ charge breeding G. Bollen, Recoil Separator for ReA12 Workshop, MSU 2014

0.085 module FY modules RT RFQ MHB Q/A Pilot source ReA Design Choices: RT-RFQ With External Buncher And High Efficiency SC-Linac n+ RIB beam EBIT 1+ RIB beam SRF LINAC  80.5 MHz RF frequency  Flexible energy range (deceleration 300keV/u to maximum linac energy in small steps  External multi harmonic buncher to minimize the longitudinal emittance G. Bollen, Recoil Separator for ReA12 Workshop, MSU 2014

Room Temperature Radio Frequency Quadrupole (RFQ) –Pulsed operation (160kW, 25%) –Energy Boost: 12 keV/u keV/u –4-rod structure, 92 cells, 3.3 m long –Buncher : 80.5MHz, 161MHz, (241.5 MHz) –Nom 82 % beam capture measured Longitudinal acceptance (white area) Beam at the entrance of RFQ Beam bunch after RFQ MHB G. Bollen, Recoil Separator for ReA12 Workshop, MSU 2014

Cryomodule 3 Makes ReA3 Complete Installation on Platform Started Ten β=0.085 cavities were redesigned to reliably provide high gradient acceleration fields CM4 (FRIB prototype phase I, 2014) Cryomodule 3 G. Bollen, Recoil Separator for ReA12 Workshop, MSU 2014

Reaccelerator Testing with Pilot Beam EBIT CB RFQ CM2 CM3 (2014) CM1 SECAR AT-TPC D-Line N4 Stopped beams A1900 First RIB beam delivered Low Energy Experimental hall Pilot Beam Charge Bred Beam Rb + → Rb 28+ from the EBIT Linac transmission RIB beams ≈ 70% G. Bollen, Recoil Separator for ReA12 Workshop, MSU 2014

ANASEN Detector JENSA Gas Jet Target (SECAR) At-TPC Line Experimental Equipment for ReA3 Installation Started in May 2013 First radioactive beam experiment with ReA3 (8/2013) G. Bollen, Recoil Separator for ReA12 Workshop, MSU 2014

Optimizing ReA Beam Time Structure Investigating Different Beam Scenario with EBIT EBIT provides flexibility in time structure of extracted beams, ranging from release of very short to long pulses. 2nd EBIT would provide option for near continuous beam. Study of extraction of very short pulses (50 ns) underway  D. Bazin G. Bollen, Recoil Separator for ReA12 Workshop, MSU 2014

Optimizing ReA Beam Time Structure Investigating ReA Bunch Spacing Options With 80.5 MHz ReA components, bunch spacing is 12.4 ns TOF experiments require larger bunch spacing Designing 16 MHz “pre-buncher” (Alt, Syphers, et al.) RFQ Proposing different frequency re-buncher after RFQ or Linac to remove “satellite” bunches Can create continuous 62 ns spacing; a pulsed EBIT in conjunction would allow greater spacing 3D EM design of PB electrodes EBIT  D. Bazin G. Bollen, Recoil Separator for ReA12 Workshop, MSU 2014

Optimizing ReA Beam Time Structure Investigating ReA Bunch Spacing Options Very short pulses  50 ns from EBIT –No principal show stopper to reach very short pulses (50 ns) »Being investigated »May require trap electrode optimization Maximizing beam throughput –Extraction pulse length determines number of ions –Desired repetition rate may not empty EBIT before next injection/breeding cycle –May require trap electrode optimization and more sophisticated in trap ion gymnastics G. Bollen, Recoil Separator for ReA12 Workshop, MSU 2014

Summary ReA is the first re-accelerator coupled to a fragmentation facility –First reaccelerated radioactive ion beam to users was delivered 8/2013 Beam stopping commissioned and being upgraded –Linear gas catcher (FRIB R&D provided by ANL) operational and improved –Cyclotron gas stopper construction underway –Linear cryogenic gas cell development scheduled for funding Charge breeding –Demonstrated and efficiencies good starting point –Parallel approach to further increase efficiencies »Adding dedicated cryogenic beam cooler and buncher »Increasing current densities Accelerator –Better-than-design performance –3rd cryomodule assembled and being installed  ReA3 nears completion –Adding more β=0.085 cryomodules will lead to ReA12 ReA has significant potential to taylor beam properties to experiment needs –Developments are under way G. Bollen, Recoil Separator for ReA12 Workshop, MSU 2014