Heavy Ion Accelerators for RIKEN RI Beam Factory and Upgrade Plans. Upgrade Injector

Transcription

1 Heavy Ion Accelerators for RIKEN RI Beam Factory and Upgrade Plans RI Beam Factory (1997-) Heavy Ion Beams (2007-) Low intensity Beam now (2008) (Goal: 1pμA U-ion beam) Upgrade Injector H. Okuno, et. al. (RIKEN Nishina Center) and P. Ostroumov (ANL)

2 Preview of the Talk Introduction of RIBF Status of the beam intensity Fixed Frequency Mode frc AVF CSM ECRIS RILAC SRC June 2007 July 2008 Ion ECRIS RFQ RILA C 1 st Str. FRC 2 nd Str. IRC SRC U U IRC Upgrade plans of the Injector 28GHz Simulation results using TRACK SC-ECRIS RFQ (4-rod) 36.6 MHz Rebuncher 36.6 MHz DTL1 ~ 3 (QWR) 36.6 MHz SOL TQ Prebuncher MHz SOL DQ DQ to 100 kev/u 680 kev/u TQ TQ 0 3 m 30 kw 30 kw 30 kw 30 kw Space Charge Forces

3 Introduction RIKEN RI Beam Factory The Old Facility (1975~1990) ECRIS RILAC RIBF (1997~(2012)) BigRIPS (Fragment Seperator) frc IRC SRC -- World s First!

4 Performance of the RIBF Cyclotrons Min. Energy for RI-Beam production

5 Symbolic photos and movie for RIBF construction and comissioning FirstBeam Beam from 4PM27on Dec Profile of SRC the firstatbeam: Al MeV/u H. Okuno, et. al., Commissioning of the Superconducting Ring Cyclotron for the RIKEN RI Beam Factory, IEEE Trans. Appl. Superconduct., vol. 18, no.2, pp226-pp231, June 2008.

6 Variable Frequency mode RFQ+ Example: The main parameters for Kr (345MeV/u) Freq. (MHz) RFQ+ RILAC 1 st Str. 2 nd Str. IRC SRC Q E (MeV/u) U (345 MeV/u) (Q@ > 70+)

7 Fixed Frequency Mode for U 345MeV/u acceleration RFQ+ Example: U (345MeV/u) Freq. (MHz) RFQ+ RILAC 1 st Str. FRC v gain =2 2 nd Str. IRC SRC Q E (MeV/u)

8 Ion Accelerated Beams so far T. Kubo, et. al., Identification of New Isotopes 125 Pd and 126 Pd Produced by In-Flight Fission of 345 MeV/nucleon 238 U: First Results from the RIKEN RI Beam Factory Fixed Frequency Mode 1 pna = 6 x 10 9, pps Journal of the Physical Society of Japan Vol. 77, No8, August, 2008 June 2007 July 2008 ECRIS RFQ RILA C 1 st Str. FRC 2 nd Str. IRC SRC U The F.C.s were not well calibrated (tend to show larger current than reality). 8 times? U Variable Frequency Mode Nov June 2008 Ion ECRIS RFQ RILAC 1 st Str. 2 nd Str. IRC Kr SRC Ca Good long term stability Goal intensity : 1000pnA

9 Key issues to increase the intensity of U beam Increase the beam intensity from the ion source New 28GHz Superconducting ECR ion source Goal intensity of U 35+ >15 pμ A ( SRC) Operation test will be started in January 2009 Improve transmission efficiency Flattop acceleration in the cyclotrons Careful tuning in each accelerator New injector (Efficient acceleration in the low energy region) Avoid the emittance growth due to the space charge. Make charge strippers with long lifetimes The 1 st stripper is critical. Max. lifetime after Searching another candidate: Rotating, Gas, Liquid Li Hasebe, Kuboki: France

10 Plan A: New injector to 28GHz SC-ECRIS RFQ (4-rod) 36.6 MHz Rebuncher 36.6 MHz DTL1 ~ 3 (QWR) 36.6 MHz SOL TQ Prebuncher MHz SOL DQ DQ to 100 kev/u 680 kev/u TQ TQ 0 3 m 30 kw 30 kw 30 kw 30 kw

11 Plan B: Put the 28GHz ECR ion source before the existing RILAC 5kV extraction MHz RFQ 28GHz SC-ECR 127kV injection 100kV Deck In the mode for U (345 MeV/u) acceleration Frequency of the injectors :18.25 MHz (Low) Extraction voltage : 5kV (Low) Acc. voltage after the RFQ :127kV (Low) put 28GHz ECR on the HV deck (127kV) to directly inject to RILAC, skipping RFQ

12 Plan B is easy for us. Now 18GHz ECR Room for 450kV Cockroft-Walton RFQ RILAC tank#1~#6 From April kv Deck 28GHz SC-ECR RILAC tank#1~#6 LEBT MEBT Beam Dynamics Study using the TRACK code

13 LEBT (Outline) 0 ma 36+,35+,34+ of 238 U x y Solenoid 90deg. Bending Magnet with fringing fields from Ion Source (27kV) to selection slit

14 LEBT (Neutralization of Space Charge Effect) % % en_rms*4 (cm mrad) ? Conditions εx,y = 200 π mm mrad 238U35+ = 0.5 ma Σ O(2+,3+,4+,5+,6+) = 10 ma exn_rms*4 eyn_rms*4 initial Neutralization effect (%)

15 MEBT (127kV, 0 ma and 0.5 ma) Transmission : % Buncher (1f+2f) Bunching efficiency ~ 52 % (+- 10deg, 0 ma and 0.5 ma) after acceleration tube (127 kv) to RILAC 127kV is enough high to suppress emittance growth.

16 RILAC (Wideroe Type, 0 ma and 0.5 ma) Transmission : % Tank #1 Tank #2 Tank #3 Tank #4 Tank #5 Tank #6

17 Emittance (r.m.s.) growth in the RILAC ma 0.0 ma *exn_rms[cm*mrad] 4*eyn_rms[cm*mrad] 4*exn_rms[cm*mrad] 4*eyn_rms[cm*mrad] ma 0.0 ma *ezn_rms[keV/u*ns] 4*ezn_rms[keV/u*ns] Efficiency in the succeeding cyclotrons will decrease. We need the new Injector (Plan A)!

18 Cyclotron Simulation using TRACK code B B B B B B B B B B B B rf gap rf gap rf gap rf gap rf gap

19 (0 ma and 0.5 ma) 0.5 ma 0 ma 73 turns 27 % of total turns Round Beam or Spiral instability: S. Adam/PSI Injector II?

20 Review of the Talk Introduction of RIBF Status of the beam intensity Fixed Frequency Mode frc AVF CSM ECRIS RILAC SRC June 2007 July 2008 Ion ECRIS RFQ RILA C 1 st Str. FRC 2 nd Str. IRC SRC U U IRC Upgrade plans of the Injector 28GHz SC-ECRIS RFQ (4-rod) 36.6 MHz Rebuncher 36.6 MHz DTL1 ~ 3 (QWR) 36.6 MHz Beam dynamics using TRACK LEBT MEBT RILAC SOL TQ Prebuncher MHz 0 3 m SOL DQ DQ to 100 kev/u 680 kev/u TQ TQ Neut. Factor????????? spiral???? 30 kw 30 kw 30 kw 30 kw Space Charge Forces