Beam Diagnostics for RIBF in RIKEN T. Watanabe, M. Fujimaki, N. Fukunishi, M. Kase, M. Komiyama, N. Sakamoto, H. Watanabe, K. Yamada and O. Kamigaito RIKEN Nishina Center R. Koyama Sumitomo Heavy Industries Accelerator Service Cyclotrons 2010 8 September 2010 Ning-Wo-Zhuang Hotel, Lanzhou, China RIBF: Radio Isotope Beam Factory
Beam What is the purpose of beam diagnostics? These systems are our sense organ showing (1) what properties a beam has; (2) how it behaves in a machine. Why do we need diagnostics? Why If we don t use beam diagnostics, (1) one would blindly grope around in the dark; (2) improvements are hardly achievable. Accelerator is just as good as its diagnostics!
Purpose and importance of beam diagnostics Accelerator complex of RIBF Monitors used in beam transport line Monitors used in cyclotron Newly developed monitors Summary
Beam line FC PF PS Length (m) RRC- frc 9 12 3 81 frc- IRC 10 25 4 119 IRC-SRC 6 13 3 64 FC: Faraday cup PF : Profile monitor PS : Plastic scintillator TUM2CIO01 Osamu Kamigaito 1 Linac + 4 Cyclotrons+ BigRIPS (Superconducting RI Separator) Succeeded in accelerating a U beam to 345 MeV/u in 2007 Discovery of a new RI, a neutron-rich Pd 125, in same year Search for new isotopes in-flight fission of the 345 MeV/u U beam Discovery of new 45 neutron rich RIs in 2008
Accelerator complex of RIBF Monitors used in beam transport line
Difficulty of suppressing of high energy secondary electrons Suppressor Electrode Beam current (ena) 8-times stronger! Faraday Cup Transmission efficiency -> 50 Faraday cups TUM2CIO01 : Osamu Kamigaito Applied Suppressor Voltage (V)
Faraday cup used in 2007 Faraday cup used in 2008 To solve this technical issue, -1 kv -30 V -800 V -1 kv
Beam profile monitor 48 Ca beam on IRC-injection line 3 wiresscanner type
Black diagram RF Beam Beam L, L, τ tof tof Plastic Plastic scintillato scintillato r PMT r PMT PMT PMT PA PA HV HV PA PA CFD CFD FA FA Ch.1 Ch.1 PMT PMT : : TDC TDC : : CFD CFD FA FA TDC TDC Ch.2 Ch.2 FA FA Core Core 2 2 Duo Duo 2.53 2.53 GHz GHz Windows Windows 7 7 LabVIEW LabVIEW Compact Compact PCI PCI Ch.3 Ch.3 VME/NIM VME/NIM Photomultiplier Photomultiplier tube tube Time-to-digital Time-to-digital conversion conversion Control Control room room Ethernet CFD CFD USB USB 2.0 2.0 Longitudinal beam width 50 % 90 %
Monitors used in beam transport line Monitors used in cyclotron
Radial probe : Measurement of (1) beam intensity; (2) turn pattern Radial probe Phase pickup : Good isochronous magnetic fields Radial probe
238 U 86+ @ IRC-MDP2 Measured Result Δp/p=0.20% Simulation Δp/p=0.22%
Monitors used in cyclotron Newly developed monitors
Beam Chopper for noise meas. Block diagram of phase measurements by using Lock in amplifier 25-RF cavities beam 11-PPs in BT line Coaxial Switch SIG SIG RF monitoring Beam monitoring Tuning of Isochronism LIA (SR844) REF REF MOPCP094 Ryo Koyama M. O. D. C. F. M. D. C. F. M. D. C. to RF amplifiers circulating beam SIG PPs in 5-cyclotrons GPIB/LAN REF GPIB-chain F. M. D. C. M.O.: master oscillator D.C.: directional coupler F.M.: frequency multiplier Combiner Combiner Coaxial Switch LAN Network Control PC (LabVIEW)
Good isochronous magnetic fields Correlation between observed beam phases and acceleration RF
RF cavity: Max. 0.6 MW Main magnetic field: Max. 1.7 T RIKEN Ring Cyclotron Radiation dose (1 year): 3.0 Sv for gamma radiation 25.5 Sv for neutrons Ar Beam Beam: 40 Ar +15 (63 MeV/u) Faraday Cup Ar Beam HTc SQUID Monitor 10.0 ea
Reduction of ; Running costs Frequency maintenance SQUID Gradiometer of Vacuum Pumping Port Cold Head & Heater Cu Cold Finger HTS Current Sensor Vibration-Isolating Rubber Low-vibration Pulse-tube Refrigerator Signal Cable Ports SQUID Temperature Sensor Heater HTS SQUID 11W @77K HTS & Permalloy Magnetic Shield Beam line 1300 SQUID temperature Δ T < 5 mk 18h (PID control) Environmental magnetic noise can be reduced 1/1,000,000 1 st Permalloy Shield Base line Faley M I et al. 2001 IEEE Trans. Appl. Supercond. 11 1383
Beam: 40 Ar +15 (63 MeV/u) Discharge of ECR ion source Close up 400 ms Amplitudes of ripples in modulated beam (b) (b) 100 Hz 0 hour (beam off) 0.7 h (c) 100 Hz 3.8 h Measurements and analyses In real time Without interrupting beam user s experiments
Beam
Thank you for your kind attention Cyclotrons 10 banquet! This evening!! Tamaki Watanabe
Irradiation of beam Superconductor: Bi(Pb) 2 -Sr 2 -Ca 2 -Cu 3 -O x (Bi2223) Substrate: 99.9% MgO ceramic Shielding current is produced by Meissner effect Designed to have a bridge circuit Current is concentrated in bridge circuit SQUID can detect Φ with high S/N ratio Concentrated Cryogenic Current Comparator Bl = μ( I + I a s I = I I S 1 1 I 2 I S ) 0 2 = -I s (Ampere s low)
horizontal IRC-injected beam SRC-injected beam horizontal Beam Width (mm) Vertical Beam Width (mm) Vertical Utilizing the data of beam widths obtained by beam profile monitors, we estimated beam emittances based on the first order ion optics. Emittance (IRC-injected beam) = 2.2 ~ 2.3 π mm mrad (unnormalized, within 4σ region) Emittance (SRC-injected beam) = ~1.7 π mm mrad (unnormalized, within 4σ region) No notable emittance growth was observed. Corresponding normalized-rms emittance is 0.19 π mm mrad.
Turn pattern of IRC-MDP1 (07/05/22) positive current (ion dominated) Extraction Injection differential electrode Beam integral electrode Modification of SRC-MDP Zero current negative current (electron dominated) original differential electrode integral electrode differential electrode (W ribbon) 50 integral electrode differential electrode (W ribbon) Front View Top View Beam
Turn pattern of IRC-MDP1 (07/05/22) positive current (ion dominated) Extraction Zero current Injection differential electrode Beam integral electrode Modification of SRC-MDP negative current (electron dominated) differential electrode (W ribbon) original differential electrode integral electrode differential electrode (W ribbon) 50 integral electrode differential electrode (W ribbon) Front View Top View Beam