1 / 18

Activation and "Hands-On" Maintenance Criteria for Heavy-Ion Accelerators

Activation and "Hands-On" Maintenance Criteria for Heavy-Ion Accelerators. I. Stra ší k 1,2 , E. Mustafin 1 , M. Pavlovi č 3 , N. Sobolevskiy 4 , V. Chetvertkova 1,2. 1 G SI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Germany

colette-collins
Télécharger la présentation

Activation and "Hands-On" Maintenance Criteria for Heavy-Ion Accelerators

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Activation and "Hands-On" Maintenance Criteria for Heavy-Ion Accelerators I. Strašík1,2, E. Mustafin1, M. Pavlovič3, N. Sobolevskiy4,V. Chetvertkova1,2 1GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Germany 2Johann Wolfgang Goethe Universität Frankfurt am Main, Germany 3Slovak University of Technology in Bratislava, Slovakia 4Institute for Nuclear Research of the Russian Academy of Sciences, Moscow, Russia 1

  2. Motivation • The activation of accelerator structures due to beam-losses is an important issue for existing (LHC, SNS, RHIC, …) and planned (FAIR) hadron facilities. • Quantification of residual activity induced by lost particles is necessary to evaluate radiation hazard to personnel during “hands-on” maintenance. • Activation studies of the AccPhy group at GSI Darmstadt. • Irradiation experiments with heavy ions. • Monte Carlo simulations (FLUKA, SHIELD, MARS, GEANT4). • Validation of the simulation codes. • Activation of various accelerator components. • General – beam pipe, bulky targets. • Specific – slow-extraction area of the SIS100 synchrotron. • Tolerable beam-loss criteria for “hands-on” maintenanceon heavy ion accelerators. 2

  3. Experimental studies of the residual activity 2003: target materials: stainless steel, copper beam: 12C beam energies: 200, 300 and 400 MeV/u [1] A. Fertman et al, GSI-Acc-Note-2003-07-001, (2003) 2005 – 2006: target materials: stainless steel, copper beam: 238U beam energies: 120, 500 and 950 MeV/u [2] A. Fertman et al, Nucl. Instr. and Meth. in Phys. Res. B Vol. 260 (2007) [3] I. Strašík et al., Nucl. Instr. and Meth. in Phys. Res. B Vol. 266, (2008) 2009: target material: copper, alluminium beam: 40Ar beam energies: 500 MeV/u and 1 GeV/u [4] I Strašík et al., Nucl. Instr. and Meth. in Phys. Res. B Vol. 268, (2010) [5] V Chetvertkova et al., to be submitted in Nucl. Instr. and Meth. in Phys. Res. B 2010: target material: alluminium beam: 238U beam energies: 500 MeV/u and 950 MeV/u [6] V. Chetvertkova et al., to be submitted in Nucl. Instr. and Meth. in Phys. Res. B 2008: target material: stainless steel beam: 238U beam energy: 1 GeV/u [7] I. Strašík et al., Proceedings of HIAT09 Conferrence, (2009) 3

  4. Validation of the simulation codes target material: stainless steel beam: 238U beam energy: 950 MeV/u simulation codes: FLUKA, SHIELD cooling time: 3 days total activity of all isotopes ratio Experiment/FLUKA = 1.09 (u = 0.1%) ratio Experiment/SHIELD = 0.66 (u = 0.5%) individual isotopes depth profiles 52Mn AE – experimentally measured activity AS– activity calculated by simulation codes 4

  5. Criterionfor the proton accelerators of 1 W/m BEAM HALO AND SCRAPING The 7th ICFA Mini-workshop on High Intensity High Brightness Hadron Beams Wisconsin, USA, September 13-15, 1999 "One important outcome of this workshop is the agreement that an average beam loss of 1 W/m in the uncontrolled area should be a reasonable limit for hands-on maintenance." (page 3 in workshop proceedings) 1 W/m ~ 6.2 × 109 protons/m/s at 1 GeV beam: 1 GeVprotons beam-pipe material: stainless steel beam-losses: 1 W/m beam-pipe wall thickness: 2 mm beam-pipe length: 10 m beam-pipe diameter: 10 cm angle of incidence: 1 mrad irradiation time: 100 days cooling time: 4 hours simulation code: FLUKA effective dose-rate at the distance 30 cm from the beam-pipe:~1 mSv/h 5

  6. Residual activity induced by heavy ions primary beam: 1H,4He,12C,20Ne,40Ar,84Kr,132Xe,197Au,238U beam energy: 200 MeV/u – 1 GeV/u beam-pipe material: stainless steel beam-losses: 1 W/m beam-pipe wall thickness: 2 mm beam-pipe length: 10 m beam-pipe diameter: 10 cm angle of incidence:1 mrad irradiation time:100 days cooling times: 0 days, 4 hours,1 day, 1 week, 2 months, 1 year, 10 years simulation code: FLUKA, SHIELD calculated quantities: activity [Bq], effective dose-rate [mSv/h] 6

  7. Isotope inventory and their relative activities simulation code: FLUKA beam energy: 500 MeV/u cooling time: 1 day Isotope inventory and their relative activities do not depend on the projectile species. 7

  8. Time evolution of the induced activity simulation code: FLUKA beam energy: 500 MeV/u At – total activity at given time (t) Aeoi – total activity immediately after irradiation (eoi) GC – generic curve The time-evolution of the activity can be described by means of a generic curve. 8

  9. Dependence of the activity on beam parameters Activity induced in the beam pipe by 1 W/m of primary beam-losses calculated with FLUKA. • Activity is decreasing with increasing primary-ion mass. • Activity is decreasing with decreasing primary-ion energy. 9

  10. Probability of the nuclear interaction • Material stainless steel • Range SRIM • Mean free path [1] S. Kox et.al., Physics Letters B Vol. 159. 10

  11. “Hands-on” maintenance criteria for heavy ions • Inventory of the isotopes does not depend on the projectile species. • Time evolution of the activity correlates to the generic curve. • The activity induced by 1 W/m of beam losses is decreasing with increasing ion mass and with decreasing energy. SHIELD FLUKA Ap(1GeV) –normalized activity induced by 1 GeV proton beam (reference) Ai(E) – normalized activity induced by the beam of interest at given energy the normalized activity [Bq/W/m] 11

  12. Activation of bulky accelerator-structures • Besides the beam pipe, accelerators contain also bulky structures like a magnet yoke or a coil. • Activation of the bulky target (cylinder) diameter:20 cm, length:60 cm material:copper, stainless steel irradiation time:3 months primary beams:1H,4He,12C,20Ne,40Ar,84Kr,132Xe,197Au,238U beam energies: 200 MeV/u – 1 GeV/u irradiation time:3 months cooling times: 0 days, 4 hours, 1 day, 1 week, 2 months, 1 year, 10 years simulation code: FLUKA, SHIELD calculated quantities: activity [Bq] • The calculated activities were normalized to the unit beam-power of 1 W delivered continuously to the target. 12

  13. Isotope inventory induced in various materials simulation code: FLUKA beam energy: 500 MeV/u cooling time: 1 day Isotope inventory induced in the bulky targets and their relative activities depend on the target material. 13

  14. “Hands-on” maintenance criteria for the bulky targets simulation code: FLUKA Ap(1GeV) –normalized activity induced by 1 GeV proton beam Ai(E) - normalized activity induced by the beam of interest at given energy 14

  15. Dependence of the criteria on the target parameters • Induced activity depends on the robustness of the target. • The criteria for heavy ions are less strict for the beam pipe than for the bulky target. Ap(1GeV) –the normalized activity induced by 1 GeV proton beam Ai(1GeV/u)–the normalized activity induced by the beam of interest at energy 1GeV/u • Heavy-ion reactions involves projectile break-up and emission of secondary nucleons from the projectile. [1] M. Maiti et al., Nucl. Instr. and Meth. in Phys. Res. A 556. [2] U. Brosa and W. Krone, Physics Letters B 105. • The break-up nucleons with high final energy do not undergo much interaction with the target nuclei and fly away at very forward angles. [3] A. Bonaccorso and D.M. Brink, Physical Review C 57. • This allows them to escape from the thin-wall beam-pipe which lowers the activation level. 15

  16. Angular distribution of the escaping nucleons • Angular distribution of nucleons escaping from the beam pipe for wall thickness of 2 mm and 20 mm calculated with FLUKA. • The angles are given with respect to the beam-pipe longitudinal central axis. Contribution to the escaped particles to the beam-pipe activation is missing and the induced activity islower than in case of the bulky target. 16

  17. Conclusions • Tolerable beam-loss criteriafor “hands-on” maintenance onheavy-ion accelerators were specified for the beam-pipe and the bulky-target geometry. • The tolerable beam losses for heavy ion accelerators were specified by scaling the existingvalue of 1 W/m for protons. • The criteria for uranium beam are 12 W/m at 1 GeV/u in case of the beam-pipe geometry. • The criteria for the bulky accelerator structures are more strict – 5 W/m at 1 GeV/uuranium beam. • The criteria calculated by FLUKA and SHIELD are in good agreement except the beam energy 200 MeV/u. • The thin-wall beam-pipe exhibits significant leakage of the heavy-ion projectiles’ break-up nucleons from the wall, which decreases the induced activity. 17

  18. Thank you for your attention

More Related