1. Radiation at accelerator laboratories Prompt radiation from the particle beam Beam induced radiation –Neutrons –Gammas –Synchrotron radiation Radiation from activated material Activation of air –Beam –Neutrons

2. Continued… Activation of cooling water Radiation protection –Shielding –… Monitoring Safety precautions –Access restrictions –Interlocks –…

3. Regulations Radiation workers (class A) –20 mSv/a (5-year floating average) 12.5  Sv/h (1600 h/a) 50 mSv/a for one year At JYFL: general limit is 0.5  Sv/h –Rooms with free access

4. Dose Effect or limit 0.001 Sv/aLimit for dose from food (long term) 0.002 SvTypical dose from Tchernobyl in Finland during 50 years 0.004 Sv/aTypical dose level in Finland. In some areas radon may increase this much 0.005 Sv/aLimit for food (short term) 0.02 Sv/aDose limit for a radiation worker (5-year floating average) 0.05 Sv/aMaximum dose for one year (radiation worker) 1.2 SvSingle dose may give radiation illness symptoms. Long term dose: No symptoms 3 – 4 SvSingle dose: 50 % die within a few weeks, if extensive medical aid is not given 40 – 60 SvSingle dose: Nervous system and digestive organs will be damaged quickly

5. Absorbed dose –D: 1 gray =1 Gy = 1 J/kg Absorbed dose rate – : Gy/s Dose equivalent – –Quality factor Q –Other biological effects: N (=1) –H: 1 Sievert = 1 Sv Units

6. RadiationEffective quality factor X-ray- and gamma radiation1 Beta and electron radiation1 Thermal neutrons2.3 Protons and other ions, whose charge is 1e and rest mass larger than 1u and whose energy is not known 10 Fast neutrons20 Alpha particles and other particles, whose charge is larger than 1e (or unknown) and whose energy is unknown 20

7. Dose equivalent rate Effective dose equivalent – –w T weight for a specific tissue

8. Primary beam Proton beam

9. Helium

10. Chinese hamster ovary (CHO) cells Gamma dose

11. Primary beam Never apply to living organisms –Except by purpose Radiation therapy Sterilization …

12. Secondary radiation Neutrons and gammas from the beam hitting material –Dose rate decreases immediately when the beam is switched off

13. Residual radiation Beam hits the accelerator, beam tube or other devices –Protons produce most activities (p,xn) –Co-isotopes from Fe Secondary neutrons activate material through neutron capture –E.g. 63 Cu + n = 64 Cu (12.7 h) –Fe isotopes from Fe

15. “Targets” for thermal neutrons 63 Cu in natural Copper Sodium in concrete Argon in air Zinc in copper Manganese and cobalt in iron or steel Antimony in lead Trace quantities of manganese, cobalt, cesium and europium in earth and concrete Possibly tungsten-186 in natural tungsten

17. Other aspects Minimize the amount of material that can be activated –E.g. inside the accelerator Ta collimator in the spiral inflector (JYFL) Proper choice of materials –Depends on accelerated ions and their energies Cross-sections for nuclear reactions E.g. 30 Mev (or more) protons induce 22 Na from aluminum

19. Shielding As close to the source as possible Distance helps: 1/r 2 Use chicanes (corridors with corners/bends) Lower pressure in rooms where air may be activated (ventilation) Use separate water cooling circuit for water that can be activated Proper choice of materials and the order of materials –Thermalization of fast neutrons first Material choice depends on neutron energy ( 10 B, Fe, plastics,…)

20. Shielding… Assume the “worst” case for dimensioning the wall, floor and ceiling thickness/material –The whole beam is stopped Which beam? –Light ion –High energy –High intensity The allowed dose rate (  Sv/h) outside the radiating room sets limits for the radiation attenuation

21. Monitoring Already according to the Safety License you have to monitor radiation levels (dose rates) Gamma and neutron monitoring –Alarms –Feed-backs –Interlocks Personal dose monitoring (class A and B radiation workers) –4 week intervals (A) –12 week intervals (B) For work with a clear risk of dose –Plan the work well –Measure the dose on-line

22. Permissions You always need a Safety License by STUK/Radiation and Nuclear Safety Authority for your operation if it may produce radiation!