Status of the EBIT in the ReA3 reaccelerator at NSCL

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1 Status of the EBIT in the ReA3 reaccelerator at NSCL ReA3 concept and overview: - Gas stopping EBIT RFQ LINAC EBIT commissioning National Science Foundation Michigan State University S. Schwarz, TCP-2010, Apr 2010

2 Why reaccelerated beams at the NSCL? NSCL: User facility, RIB production by projectile fragmentation and fission > 900 RIBs made > 600 RIBs used in experiments NSCL has successful program with stopped beams LEBIT facility for Penning trap mass spectrometry of projectile fragments laser spectroscopy under preparation ReA3 new science opportunities with rare isotopes from projectile fragmentation Nuclear astrophysics: key reactions at near-stellar energies Nuclear structure via Coulomb excitation or transfer reactions MSU concept for FRIB: includes fast, stopped, and reaccelerated beams - ReA3 provides pioneering beams for research in one of the pillars of FRIB. - Develop programs and techniques in reaccelerated beams before FRIB operation SCS 4/10 2

3 ReA3 - The MSU N + reacceleration concept Q/A Separator Multi Harmonic Buncher 1 + N + 80 MHz RFQ 80 MHz SRF β=4.1% Mass separator 80 MHz SRF β=8.5% up to 3 MeV/u beam (upgrade to 12 MeV/u) Gas stopper Charge Breeder > 50 MeV/u Beams Next generation gas stopping Various optimized stopping techniques Multiple stations in future to avoid single-point failure Advanced n + reacceleration scheme to maximize science reach; best achieved with an EBIT charge breeder Maximize efficiency by avoiding stripping losses Provide variable duty factor to best serve experiments Deliver clean beams to avoid background and ambiguities Sufficient and expandable space for experiments SCS 4/10 3

4 From fast to not-so-fast Coupled Cyclotron Facility Production Target Fragment Separator 100MeV/u SCS 4/10 4

5 ReA3 layout 3 MeV/u experimental area 9,100 sq ft - ready since June 2009 Stopped beam area - Relocated LEBIT (Redshaw, Ringle) - Laser spectroscopy LINAC Beam stopping vault EBIT charge breeder SCS 4/10 5

6 NSCL beam stopping Reconfiguration of N4 beam stopping vault (2013+) ReA3 CCF Stopper options: ReA3: Large linear gas stopper - Low-pressure with RF carpets - Cryogenic - Collaboration with ANL (FRIB R&D) l>1.5m: increases rate capability Ion collection at walls, Selective transport for A >> He 2 Maximum gas purity for clean beams Future: Cyclotron stopper NSF funded FRIB: Solid stopper Clean beams, fast extraction <50 ms High efficiency for beam rates >10 8 /s High stopping efficiencies for light ions For the stopping of high intensity beams (>10 10 /s) of certain elements SCS 4/10 6

7 ReA3 EBIS/T charge breeder e-gun Magnet Trap e-collector Continuous 1 + beam Pulsed N + beam Expected performance - Breeding times << 50 ms - Efficiency > 50% - Beam rates > 10 9 /s - Variable duty cycle - Clean beams superior to ECRs EBIT: Key parameters: magnetic field: up to 6 T I e = A, E e < 30keV current density: up to ~10 4 A/cm 2 Fast and selective breeding: Breeding time [s] E-3 1E-4 1E-5 σ: W. Lotz Z. Phys. 206 (1967) 205 bare He-like Ne-like E ele = 2 * E bdg 1E Z j = 10 4 A/cm Charge state abundance E ele = 5 kev Ti 20+ 1E-5 1E-4 1E breeding time [s] SCS 4/10 7

8 ReA3 EBIS/T design In Collaboration with J. R. Crespo López-Urrutia J. Dilling SCS 4/10 8

9 An EBIS / EBIT hybrid e-beam B [T] T-6T 6T-6T 6T-1T cryocooler extended split coil coil z [m] Capture probability Emittance [π mm mrad] 1T-6T 6T-6T 6T-1T Moderate compression + large e-beam current + longer trap needed = good acceptance Two traps for high acceptance and fast breeding Capture probability (E. Gavartin) Emittance [π mm mrad] Magnet: ordered (Cryomagnetics), expect April Trap: ~ 0.8m long, 4K 21 segments for flexibility Center electrode 8fold split I = 2.5 A I = 1.5 A I = 0.5 A SCS 4/10 9

10 High current electron guns The electron gun assembled Simulations - TriComp: 1/4 - cathode: 1.4 A housing cathode anode kv e-beam Core 1/2 - cathode: 2.4 A = cathode, focus + anode cathode anode kv e-beam SCS 4/10 10

11 Commissioning of e-gun and collector The electron gun Test setup with 0.4 T RT coil to test e-gun / collector assembled Core = cathode, focus + anode collector test coil e-gun with provision to insert C-foil SCS 4/10 11

12 Extraction tests with mid-size cathode Measured extracted current: ¼ cathode 1000 Extracted current [ma] E-beam radius: Extraction voltage [kv] > 800mA so far Perveance ~ 0.84 µp Measured beam r 95% ~ 0.58 mm agrees well with r Herrmann SCS 4/10 12

13 Commissioning of the Q/A separator E Design parameters: 12 kev/u, A/Q = 2 to 5 ε n = 0.6 π mm mrad R > 100 Achromatic: de > ±0.2% MCP m For now, just a temp ion source EBIT Beam optics: M. Portillo RFQ SCS 4/10 13

14 Q/A separator results Mass spectrum (from He-discharge) He N H Na K 41 2 O CO K Beam current [pa] Energy acceptance: Magnet current [A] It separates masses with expected dispersion, ~10 mm/% (and R>100) position [mm] beam current [pa] Beam energy [ev] It accepts energy spread of about ±1.5 % SCS 4/10 14

15 ReA3 - LINAC MHB 12 kev/u Energy range MeV/u for 238 U Higher energies for lighter ions Energy spread 1keV Pulse length 1 ns 600 kev/u 238 U MeV/u 48 Ca MeV/u Modern compact linac LEBT with multi-harmonic buncher Radio frequency quadrupole (RFQ) Superconducting RF linac HEBT with rebuncher Collaboration with Univ. Frankfurt, INFN Legnaro, TRIUMF Just arrived! 1 st CM installed 2 nd CM: mid April 3 rd CM: summer SCS 4/10 15

16 Outlook ReA3- EBIT: Finish commissioning of e-gun/collector Complete EBIT with SC magnet (summer) 2010: Accelerated highly-charged beams 2011: Reaccelerated HC RIBs ReA3-BEAM Thanks to ReA3-EBIT: G. Bollen, S. Geyer, O. Kester, K. Kittimanapun, A. Lapierre, SCS J. R. Crespo Lopez-Urrutia, MPIK SCS 4/10 16