Induced-activity experiment: Vera Chetvertkova Moscow State University Department: Nuclear Physics Master thesis: “Photodisintegration of Bi209” Induced-activity experiment: Beam: Bremsstrahlung Target: thin foil Gamma-spectroscopy: Types of radio-nuclides Amount of radio-nuclides Yields of the photonuclear reactions

Monte Carlo transport codes by Activation Experiments” PhD thesis: “Verification of Monte Carlo transport codes by Activation Experiments”

Introduction Beam losses Activation of the accelerator components 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 3

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

Introduction: The Heavy-Ion Beam Loss Criteria 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] 5

Introduction: The Heavy-Ion Beam Loss Criteria simulation code: FLUKA (2008) beam energy: 500 MeV/u cooling time: 1 day The time-evolution of the activity can be described by means of a generic curve. Isotope inventory in the target [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] 6

Introduction: The Heavy-Ion Beam Loss Criteria 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] 7

Introduction Calculated using MC transport codes: Goal of the work 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 8

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 Conclusion 9

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 10

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 11

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) 12

Experimental technique: Irradiation & Measurements GSI: SIS18: Cave HHD Projectiles: N, Ar, U Energies: 85-935 AMeV Intensities: ≤ 4∙1010 ions/sec Spectra acquisitions: started several hours to several months after the end of irradiation Measurements of the beam cross-section: profile-meter the beam intensity: current transformer 13

EXPERIMENTAL RESULTS AND COMPARISON WITH THE SIMULATIONS: Activation of Aluminum 430 AMeV, 500 AMeV 14N 500 AMeV 238U 85 AMeV - 935 AMeV 27Al Foil, thick target 14

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 0.0358 ± 0.0018 0.0396 ± 0.0009 0.0224 ± 0.0007 0.0407 ±0.0008 22Na 0.0735 ± 0.0037 0.0690 ± 0.0010 0.0855 ± 0.0017 0.1592 ±0.0032 15

Single-foil experiment EXPERIMENTAL RESULTS AND COMPARISON WITH THE SIMULATIONS: Activation of Aluminum 85  935 MeV/A Uranium beams Single-foil experiment 16

EXPERIMENTAL RESULTS AND COMPARISON WITH THE SIMULATIONS: Activation of Aluminum 500 MeV/A Uranium beam 17

EXPERIMENTAL RESULTS AND COMPARISON WITH THE SIMULATIONS: Activation of Copper 500 AMeV 14N 500 AMeV natCu thick target 18

EXPERIMENTAL RESULTS AND COMPARISON WITH THE SIMULATIONS: Activation of Copper 500 MeV/A Nitrogen beam 19

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 AMeV To calculate activation at long irradiation times (20 years) 20

Activation studies for accelerator applications 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 21

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 (2008) beam energy: 500 MeV/u Irradiation time: 100 days simulation code: FLUKA (2011) beam energy: 50 MeV/u Irradiation time: 20 years copper 22

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. 23

Activation studies for accelerator applications 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 24

Activation studies for accelerator applications Code: FLUKA 2011.2 Irradiation time: 100 days Irradiation time: 20 years 25

Activation studies for accelerator applications Maximum dose rate at the distance 30 cm from the target surface, irradiated by 1 GeV protons Code: FLUKA 2011.2 Irradiation time: 100 days Irradiation time: 20 years 26

Conclusion New experimental data on activation of Comparison of the obtained data with simulations average discrepancies: ~5% FLUKA, ~30% MARS, ~50% SHIELD 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. 27