Activation by Heavy-Ion Beams HICforFAIR Workshop Beam physics for FAIR 2012 Activation by Heavy-Ion Beams Vera Chetvertkova GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Germany J. W. Goethe Universität Frankfurt am Main, IAP, Germany v.chetvertkova@gsi.de

Introduction Activation of the accelerator components caused by the beam losses Increased dose rates in the vicinity of the irradiated materials Restrictions on the hands-on maintenance of the machine necessity of designing the accelerator shielding to avoid personnel exposure Activation – one of the main intensity limiting factors for high energy and high intensity hadron accelerators Vera Chetvertkova “Activation by Heavy Ion Beams

Introduction Activation gets higher with increasing energies and intensities Necessity of quantifying the residual activity induced by beam particles per unit thickness Activation studies at GSI: stainless steel and copper targets irradiated by U beams at 500 MeV/A and 950 MeV/A [1], [2] copper targets irradiated by Ar beams at 500 MeV/A and 1 GeV/A [3]. [1] Fertman et al., , Nucl. Instr. Meth. Phys. Res. B, 260 (2007) 579. [2] Strasik et al., Nucl. Instr. Meth. Phys. Res. B, 266 (2008) 3443. [3] Strasik et al., Nucl. Instr. Meth. Phys. Res. B 268 (2010) 573 Vera Chetvertkova “Activation by Heavy Ion Beams

Introduction Proton beam-loss criterion “An average beam loss of 1 W/m in the uncontrolled area should be a reasonable limit for hands-on maintenance.“ [4] 1 W/m ≈ 6.24 × 109 protons/s/m at 1 GeV; Irradiation time: 100 days Dose rate < 1 mSv/h; 4 hours after the end of operation 30 cm away from the component surface [4] Beam Halo and Scraping The 7th ICFA Mini-workshop on High Intensity High Brightness Hadron Beams Wisconsin, USA, September 13-15, 1999 Vera Chetvertkova “Activation by Heavy Ion Beams

Introduction Beam pipe Bulky target Primary beams: 1H, 4He, 12C, 20Ne, 40Ar, 84Kr, 132Xe, 197Au, 238U Beam energy: 200 MeV/u – 1 GeV/u Beam losses: 1 W/m irradiation time: 100 days cooling times: 0 days, 4 hours, 1 day, 1 week,2 months, 1 year, 10 years simulation codes: FLUKA (2008) Beam pipe Bulky target Beam-pipe material: stainless steel Wall thickness: 2 mm Length: 10 m, diameter: 10 cm Beam angle of incidence: 1 mrad Bulky target material: copper, stainless steel Diameter: 20 cm, length: 60 cm [I. Strasik, E. Mustafin, M. Pavlovic, Residual activity induced by heavy ions and beam-loss criteria for heavy-ion accelerators, Physical Review Special Topics – Accelerators and Beams 13, 071004 (2010)] [I. Strasik et al., Activation and beam-loss criteria for “hands-on” maintenance on heavy ion accelerators, in Proc. of SATIF10, Geneva, Switzerland, 2-4 June 2010, p.129]

Introduction simulation code: FLUKA (2008) beam energy: 500 MeV/u Isotope inventory in the target The time-evolution of the activity can be described by means of a generic curve. cooling time: 1 day [I. Strasik, E. Mustafin, M. Pavlovic, Residual activity induced by heavy ions and beam-loss criteria for heavy-ion accelerators, Physical Review Special Topics – Accelerators and Beams 13, 071004 (2010)] [I. Strasik et al., Activation and beam-loss criteria for “hands-on” maintenance on heavy ion accelerators, in Proc. of SATIF10, Geneva, Switzerland, 2-4 June 2010, p.129]

Introduction Bulky target scenario simulation code: FLUKA 2008 Ap(1GeV) – normalized activity induced by 1 GeV proton beam Ai(E) - normalized activity induced by the beam of interest at given energy [I. Strasik, E. Mustafin, M. Pavlovic, Residual activity induced by heavy ions and beam-loss criteria for heavy-ion accelerators, Physical Review Special Topics – Accelerators and Beams 13, 071004 (2010)] [I. Strasik et al., Activation and beam-loss criteria for “hands-on” maintenance on heavy ion accelerators, in Proc. of SATIF10, Geneva, Switzerland, 2-4 June 2010, p.129]

Calculated using MC transport codes: Introduction Calculated using MC transport codes: FLUKA SHIELD Verification at different projectile-target combinations is needed Goal of the work Obtain new information on interactions of heavy ions for verification of Monte Carlo transport codes

Contents Experimental technique Preliminary simulations Types of targets Irradiation and Measurements Analysis of the Gamma-spectra Uncertainty Assessment Experimental results and comparison with the simulations Activation of aluminum Activation of copper Discussion: Activation studies for accelerator applications Conclusion

Experimental technique Activation experiment Scheme of the experiment Beam Target Experimental Cave HPGe detector g Measurement Room

Experimental technique: Preliminary simulations Simulations of the interaction of certain ions with chosen material Finding the stopping range Choosing the target geometry Finding the nuclide production rates Choosing the irradiation condition Choosing the measurement times

Experimental technique: Types of targets Complementary experiments for checking the position of the stopping range Truncated cylinder (covered with organic material) Aluminum irradiated with Uranium beam 500 MeV/u 950 MeV/u Fast estimation of the stopping range of the projectiles (~ 0.5 mm precision)

Experimental technique: Types of targets Single-foil target Studying the isotope inventory, esp. short lived nuclides (Manual handling is possible shortly after the end of the irradiation)

Experimental technique: Types of targets Thick target Studying the isotope inventory, The depth distribution, The stopping range of certain ions (e.g. uranium) Activation foils

Experimental technique: Irradiation GSI: SIS18: Cave HHD Extracted beam Projectiles: N, Ar, U Energies: 120-950 MeV/A Intensities: ≤ 4∙1010 ions/sec Measurements of the beam cross-section: profile-meter Measurements of the beam intensity: current transformer

Experimental technique: Measurements Gamma-spectroscopy: HPGe detector Calibration: 22Na, 60Co, 137Cs, 152Eu Spectra acquisitions: started several hours to several months after the end of irradiation U (500 MeV/A) + Al

Experimental technique: Analysis of the γ-spectra

Experimental technique: Uncertainty Assessment Peak net area Half-life and gamma emission probability [http://ie.lbl.gov/toi/index.htm]. Absolute efficiency of the detector uncertainty of the calibration source (< 2 %), uncertainty of the peak net area (< 2%) uncertainty of fitting the curve (1% - 7%). Thickness of the activation foil (< 0.5%) Total intensity of the beam on the target uncertainty of current transformer (~ 3%) Depth uncertainty and resolution uncertainty of the foil position in the target (~ 0.05 mm). Uncertainty of the foil thickness (< 0.5%)

EXPERIMENTAL RESULTS AND COMPARISON WITH THE SIMULATIONS: Activation of Aluminum 430 MeV/u, 500 MeV/u 14N 500 MeV/u 238U 120 MeV/u 200 MeV/u,300 MeV/u 400MeV/u, 500 MeV/u 600 MeV/u, 700 MeV/u 800 MeV/u, 950 MeV/u 27Al Foil, thick target

EXPERIMENTAL RESULTS AND COMPARISON WITH THE SIMULATIONS: Activation of Aluminum 500 MeV/A Nitrogen beam Nuclide Experiment, Nucl/ion FLUKA, Nucl/ion 7Be 0.00431 0.00515 22Na 0.00774 0.00727 24Na 0.00743 0.00636

Single-foil experiment EXPERIMENTAL RESULTS AND COMPARISON WITH THE SIMULATIONS: Activation of Aluminum 430 MeV/A Argon beam Single-foil experiment 7Be, nuclide/ion/mm 22Na, nuclide/ion/mm 24Na, nuclide/ion/mm Experiment 2.08·10-4 ± 1.29·10-5 1.62·10-4 ± 8.86·10-6 1.11·10-4 ± 5.63·10-6 FLUKA 2.01·10-4 ± 1.13·10-5 1.62·10-4 ± 1.58·10-5 1.10·10-4 ± 1.13·10-5

EXPERIMENTAL RESULTS AND COMPARISON WITH THE SIMULATIONS: Activation of Aluminum 500 MeV/A Argon beam Experiment, Nucl/ion FLUKA, Nucl/ion MARS, Nucl/ion SHIELD, Nucl/ion 7Be 0.00359 0.00335 0.00380 0.00407 22Na 0.00735 0.00670 0.00882 0.01592

Single-foil experiment EXPERIMENTAL RESULTS AND COMPARISON WITH THE SIMULATIONS: Activation of Aluminum 120  950 MeV/A Uranium beams Single-foil experiment

EXPERIMENTAL RESULTS AND COMPARISON WITH THE SIMULATIONS: Activation of Aluminum 500 MeV/A Uranium beam 237U 7Be

EXPERIMENTAL RESULTS AND COMPARISON WITH THE SIMULATIONS: Activation of Aluminum 500 MeV/A Uranium beam Experiment, Nucl/ion FLUKA, Nucl/ion SHIELD Nucl/ion 7Be 0.0145 0.0164 0.0214 22Na 0.0369 0.0336 0.1017 227Th 1.297·10-4 4.656·10-4 3.007·10-4 230Pa 1.771·10-4 3.241·10-4 4.779·10-4 233Pa 8.365·10-4 0.00201 0.0017 237U 0.01604 0.00899 0.0066 Experiment FLUKA 83Rb 16.625·10-4 8.946·10-4 99Mo 2.690·10-4 2.512·10-4 127Xe 1.317·10-3 1.291·10-3 141Ce 13.440·10-4 4.193·10-4 149Gd 4.741·10-4 5.124·10-4 169Yb 12.071·10-4 9.464·10-4 185Os 3.535·10-4 9.227·10-4 188Pt 2.152·10-4 5.716·10-4 202Tl 2.479·10-5 2.092·10-5 205Bi 2.044·10-4 9.311·10-4 206Po 1.969·10-4 10.407·10-4  The experimental and calculated number of nuclides is quoted 7 days after the end of irradiation

EXPERIMENTAL RESULTS AND COMPARISON WITH THE SIMULATIONS: Activation of Copper 500 MeV/u 14N 500 MeV/u natCu thick target

EXPERIMENTAL RESULTS AND COMPARISON WITH THE SIMULATIONS: Activation of Copper 500 MeV/A Nitrogen beam

EXPERIMENTAL RESULTS AND COMPARISON WITH THE SIMULATIONS: Activation of Copper 500 MeV/A Nitrogen beam Nuclide Experiment, Nucl/ion FLUKA, Nucl/ion SHIELD, Nucl/ion 7Be 0.0022 0.0045 22Na 1.862·10-4 1.897·10-4 2.803·10-4 51Cr 0.0046 0.0034 0.0024 54Mn 0.0055 0.0050 0.0018 59Fe 7.022·10-4 5.595·10-4 6.832·10-4 56Co 0.0025 0.0036 0.0088 57Co 0.0090 0.0119 0.0095 65Zn 6.660·10-4 3.706·10-4 0.0012 46Sc 8.836·10-4 6.606·10-4 58Co 0.0122 0.0133 60Co 0.0051  The experimental and calculated number of nuclides is quoted 7 days after the end of irradiation

EXPERIMENTAL RESULTS AND COMPARISON WITH THE SIMULATIONS: Activation of Copper 500 MeV/A Argon beam 59Fe 22Na

EXPERIMENTAL RESULTS AND COMPARISON WITH THE SIMULATIONS: Activation of Copper 500 MeV/A Argon beam Nuclide Experiment, Nucl/ion FLUKA, Nucl/ion SHIELD-A Nucl/ion 7Be 0.0207 0.0166 0.0266 22Na 0.0039 0.0026 0.0049 48V 0.0157 0.0132 0.0161 51Cr 0.0445 0.0293 0.0206 54Mn 0.0546 0.0470 59Fe 0.0079 0.0051 0.0060 56Co 0.0263 0.0345 0.0023 57Co 0.1006 0.1152 0.0837 65Zn 0.0075 0.0037 0.0115 46Sc 0.0080 0.0057 58Co 0.1225 0.1295 60Co 0.062 0.0515  The experimental and calculated number of nuclides is quoted 7 days after the end of irradiation

Activation studies for accelerator applications Scaling law is possible because of the same isotope inventory (generic curve) Scaling law could be violated At low energies At long irradiation times The goal: To calculate activation of a bulky target by different ions at energies below 200 MeV/A To calculate activation at long irradiation times (20 years)

Activation studies for accelerator applications The Limits of Applicability of the Heavy-Ion Beam Loss Criterion Primary beams: 1H, 4He, 12C, 20Ne, 40Ar, 84Kr, 132Xe, 197Au, 238U Beam energies: 50 MeV/u, 100 MeV/u, 200 MeV/u Irradiation time: 20 years Cooling times: 0 hours, 4 hours, 1 day, 1 week, 2 months, 1 year, 2 years, 5 years, 10 years, 20 years, 50 years Target materials: Carbon, Aluminum, Iron, Copper, Lead Target radius: 20 cm, Target thickness: 60 cm

Activation studies for accelerator applications The Limits of Applicability of the Heavy-Ion Beam Loss Criterion Bulky target scenario cooling time: 1 day simulation code: FLUKA (2011) beam energy: 50 MeV/u Irradiation time: 20 years simulation code: FLUKA (2008) beam energy: 500 MeV/u Irradiation time: 100 days copper

Activation studies for accelerator applications Time evolution of the total residual activity Energy 500 MeV/A, Duration of irradiation 100 days. Energy 50 MeV/A, Duration of irradiation 20 years.

Activation studies for accelerator applications Study of the least activated materials used in accelerator constructions Primary beams: 1H Beam energies: 1 GeV/u Irradiation times: 100 days, 20 years Target materials: C, Al, Cr, Ti, Mn, Fe, Cu, Ni, Nb, Mo, Pb Target radius: 20 cm, Target thickness: 60 cm

Activation studies for accelerator applications Total activities of the bulky targets irradiated by 1 GeV proton beam with intensity 5·1010 protons/sec Code: FLUKA 2011.2 Irradiation time: 100 days Irradiation time: 20 years

Activation studies for accelerator applications Maximum dose rate at the distance 40 cm from the surface of the target, irradiated by 1 GeV 5·1010 protons/sec. Code: FLUKA 2011.2 Irradiation time: 100 days Irradiation time: 20 years

Conclusion New experimental data on activation of Limits of applicability of the heavy-ion beam-loss criteria: energy ~ 100 MeV/A The least activated materials used in accelerator applications Carbon, Aluminum, Titanium, Manganese, Iron => Thin-foil aluminum targets 430 MeV/A argon beam; 120 – 950 MeV/A uranium beams; => Thick aluminum targets 500 MeV/A nitrogen beam; 500 MeV/A argon beam; 500 MeV/A uranium beam; => Thick copper target 500 MeV/A nitrogen beam.