ISOL cyclotron for the RISP Jong-Won Kim RI beam production systems team Institute for Basic Science/RISP June 26, 2015

Layout of the ISOL and In-flight systems for RI beam production IFS Injector ISOL High Energy Exp. 1 Cryogenic System Low Exp. SCL1 SCL2 Cyclotron Exp. 2 SCL3 EBIS-CB High radiation area Cyclotron

Configuration of in-flight separator beam dump degrader F1 F2 F3 F4 Dipole Quadrupole Sextupole Primary beam 238U beam energy: 200- 400 MeV/u Max. beam power: 400 kW HTS quadrupole Cryostat of quad triplet F5 Pre-separator F6 Main separator Main specifications Dispersive focal plane: F1,F3, F5, F7 F7 Max. B ~10 Tm p/p <±3% Angular accep. ±40 mrad ±50 mrad Achromatic focal plane: F2 , F4, F8 F8

Design of in-flight separator facility B1 B2 B3 IFS floors Top view F1 F5 F2 F4 F6 F3 F7 Power supply Room (B1) Counting Room (B1) F8 20 m 38 m 19.56 m 22.15 m 81 m 141 m Side view 26.5 m 1F 15 m B1 Power supply Room Counting Room 4 m 9 m B2 4 m B3 Radiation dose map 1F: Air conditioning B1: Hot cell remote handling, Counting room B2:: Beam area, Vacuum pumps, etc. B3: Radiation waste, Drain tanks, Waste water storage [μSv/hr] 16O beam, 590 MeV/u, 400 kW Power supply and Counting rooms

Design of the ISOL facility TIS EBIS Ion 132Sn1+ 132Sn33+ E 60 keV 5 keV/u ISOL Driver: 35-70 MeV, H- 1 mA cyclotron RF cooler+EBIS+A/q Pre-separator Target/Ion Source Cyclotron Pre-Separator m/m = 300 EBIS RFQ Cooler 3 mm mrad, 1 eV Post linac MR-TOF The layout still evolving UCx target: 10 kW (Dia. 5 cm, 1.3 mm 19 disks) Test stand for target ion source, front-end mass separator on HV platform

Design of the ISOL targets Fission rate 132Sn production rate 132Sn (at exp. room) RISP 10 kW 1.58×1013 /s 2.18×109 /s 1.1×107 pps 35 kW 1.15×1014 /s 1.59×1010 /s 7.9×107 pps SPES 8 kW 7.6×1012 /s ~ 109 /s Target material for 10 kW: UCx Beam: 5 cm uniform

Specification of commercial 70 MeV Cyclotrons Categories BEST IBA Sumitomo* Accel Particle Proton　 Emax, Imax 35~70MeV 1mA* 30~70MeV 750uA (Fixed) 70MeV 1mA Magnet Sectors 4 B (Hill, Vaelly) 1.6T, 0.12T 1.7T, 0.12T 1.7T, 0.5T Harmonics 2 Freq. (MHz) 56.2 30 73 Ion Source multi cusp Arc MultiCUSP Volume CUSP Operating Site INFN, Legnaro (2015) ARRONAX, France(2010) N/A Proposals in 2013

Further specification of the cyclotrons Categories BEST IBA Sumitomo* RF System No. of Dees 2 Dee Angle 35o 30o 45o Harmonics 4 Frequency (MHz) 56.2 30 73 Dee Voltage (kV) 60 to 70 50 Injection System Ion Source Type multi cusp Arc MultiCUSP/ECR Volumic CUSP H- Current 15 ~ 20 mA 5mA 10mA Inflector spiral Extraction System No. exit port/beam lines 2. / 4. 2. / 6. Carbon foil (life time/uAh) 120hours @ 1mA Carousel with 6 foils 20,000 25,000uAh @ 0.5mA 500uAh @ 1.0mA Beam emittance(x,y/mm.mrad) 6.2, 3.8 horizontal 4 pi ~15 pi / 5 pi Vacuum System < 1.5x10-7 Torr 1x10-7 mbar < Pa Control System PLC　

Two previous meetings on 70 MeV H- cyclotron 1. Workshop on compact H- cyclotron for rare isotope production (Nov. 7-8, 2013)  Freddy Poirier (ARRONAX, France)  T. Zhang (CIAE, China)  R. Johnson (Best Cyclotron)  Y. Koyabu (Sumitomo)  Benoit Nactergal (IBA) 2. Cyclotron review meeting on 70 MeV H- cyclotron subsystem specification (April 3-4, 2014) T. Zhang (CIAE, China) L. Calabretta (INFN, Italy) A. Goto (Yamagata, Japan)

Issues discussed in Workshops Scope of commercial order - Cyclotron (up to two switching magnets of the extraction ports) - Cyclotron + two beam delivery lines up to wobbler - Some major spare parts - Pulsed beam option Continuous operation with one carrousel (>10 days) - How many carbon foils in one carrousel? Stability of the beam current - How to monitor the beam current and beam shape? how accurately? - Any feedback to stabilize the beam current? Time constant? - Sudden beam current jump should be avoided. Can this be avoided? Other issues - Minimum time for beam stop in case of emergency - Any plan to measure carbon foil lifetime in beam current of 0.5-1 mA

Uniform beam formation by wobbling method TRANSPORT calculation for two configurations (point to parallel focusing) Initial beam distribution wobbling pattern Dependence on the radius of gyration Uniformity and beam loss vs. radius of gyration r (cm) Uniformity Beam loss (%) 1.8 ±9.2 29 1.9 ±4.8 34 2.0 ±6.0 36 Two parameters  beam width  radius of gyration

Dependence on radius of gyration with use of octupole magnets Use of multipole magnet to reduce beam losses Use both multipole magnet and wobbling method  Flexible against beam shape variation Octupole off Octupole on Dependence on radius of gyration with use of octupole magnets Beam loss reduction 34%21% X (cm) Calculated by using GICOSY

An injection beam line for pulsed beam (option) Pulsed beam for TOF measurement Proton beam time structure Neutron beam Time 0.01-1 MHz Vmax=3 kV SIMION simulation Pattern of pulsed HV

Carbon foil extraction system Best Cyclo. IBA Number of exit ports 2 Carbon foil loading system Multiple, Automatic Carbon foil thickness 120 μg/cm2 Stripping efficiency 99.96 % Lifetime of foil at 1 mA ?  ? Extracted beam emittance at different energies T [MeV] 70 60 35 εH[π∙mm∙mrad] 3.0 3.3 6.0

Heat generation on the foil by stripped electrons  Power deposit on carbon foil P = ∆W x I ∆W: beam energy loss I: current  70 MeV 1mA with 6 mm, 1um thick target - Energy by protons : 1.7keV x 1x10-3A = 1.7 W - Energy by two electrons : 70MeV/1,836 x 2mA = 76 W After use for ~20,000 Ah

Thermal test on stripper foil using electron linac

Temperature variation on stripper foil Surface temperature on foil vs. e-beam current

H- beam losses by Vacuum dissociation and Lorenz stripping 10 MeV 20 MeV 30 MeV 70 MeV Lorentz stripping 8x10-11 2.4x10-3 Vacuum dissociation 7.6x10-3 1.1x10-2 1.3x10-2 2x10-2 Vacuum level: 1.0 x10-7 torr (N2 equivalent) From Tianju Zhang (CIAE)

Locations of beam losses in ARRONAX cyclotron 1st measurements in march 2013 (Arronax/IBA team) Exit window for beamline Radial probe Machine: Some hot spots 10 to 40 mSv/h: Extractions windows Radial probe Around alpha deflector No spot > 100mSv/h Ambient > 3 mSv No knowledge on built-up yet as 1st measurements Beamlines: Specific points along beamlines due to particles losses Faraday cups Collimators impact on maintenance and dedicated strategies Remove parts of accelerators before consequent build-up Preliminary snapshot F. Poirier (CNRS/Arronax), Nov. 2013

A plan for the proton cyclotron of RISP Budget allocated for an ISOL cyclotron at RISP : ~14 M$ By Luciano Calabretta (May 2015)

Project schedule for cyclotron installation ~54 months * Our building construction schedule is tight, so we may need a provision to delay the delivery up to one year.

Concluding remarks We want to immediately start international collaboration to design an A/q=2 cyclotron provided that cyclotron experts agree the RISP plan for ISOL cyclotron is attractive to commercial vendors. We want to have preliminary quotations from the vendors, which includes the cost, construction period, risk management and so on. plan to make the contract in 2015. If we have to take a review process in Korea to revise from 70 MeV H- to 40A MeV A/q=2, recommendation letters from international experts would be greatly appreciated.