1. Typical Decay scheme II http://www.nucleide.org/DDEP_WG/Nuclides/Na-22_tables.pdf Nuclei can decrease their proton number by one in three ways, positron emission (the most common) Electron capture (much more rarely; see next slide), or proton emission (very rare). Decay rates expressed in terms of Becquerrel (1/sec) or Curies (37 GBq)

2. Absorption length for gammas (in lead and aluminum) From E. Segre, “Nuclei and Particles” 2 nd ed. (1977)

3. Examples 1.The LENS neutron source at IU creates roughly 4e4 neutrons per pC of proton charge (incident at 13MeV) through the reaction: 9 Be(p,n) 9 B in a 1mm thick target. Estimate the cross section for this reaction (Note: Fro Be  =1.85 g/cm 3 and W=9.01g/mole). 2. A foil of natural In that is 1.0 mm thick is placed in a thermal neutron beam (v=2200 m/s) of flux 10 7 n/cm 2.s. In has a molecular weight of 114.8 g/mole, and a density of 7.31 g/cm 3. 116 In is a beta emitter and we will assume that it is only produced in a state that decays with a 54 min half life. a). What is the flux of neutrons on the back side of the foil? b). If the foil is in the beam for 1.0 min, what is the activity due to 116 In? c). What is the 116 In activity if the foil is in the beam for 10 hours? The information at the website on the following slide may be useful.

4. Cross Sections http://www.ncnr.nist.gov/resources/n-lengths/

5. Alpha Decay http://en.wikipedia.org/wiki/File:Alpha1spec.png T&R Fig. 12.11

6. Lecture 23 Potential Barrier: Alpha decay The deeper the “bound” state is below the top of the barrier, the lower will be the kinetic energy of the alpha particle once it gets out, and the slower will be the rate of tunneling (and hence the longer the half-life). Figures from Rohlf “Modern Physics from  to Z o ”.

7. Radiation Shielding Different types of radiation penetrate through matter with different ranges. Alpha particles are very easily stopped (doubly charged and relatively slow), beta particles are relatively easy to stop, gamma rays need very heavy shielding, and neutrons are the hardest to shield against. https://reich-chemistry.wikispaces.com/b.sulser+and+k.nagle+powerpoint+presentation neutron

8. Radiation Dose Dose: 1 Gray = 1 J/kg of whatever radiation (energy deposited per unit mass), supplants the RAD (Radiation absorbed dose) Roentgen (older unit, radiation needed to produce a certain charge per unit mass (1 esu /cm 3 of dry air). This corresponds to 0.258 mC/kg. Equivalent Dose 1 Sievert: absorbed dose multiplied by factors to account for relative biological effectiveness for particular radiation type ( , n etc.; energy etc. ) and body part involved. NOTE units are the same as the Gray, but the meaning is quite different. REM (Roentgen Equivalent Man): 1 REM = 10 mSv

9. Radiation Dose http://www.ccohs.ca/oshanswers/phys_agents/ionizing.html NOTES: Prior to 1990 the weighting factor was referred to as the “Quality Factor and you will still see this term used. There is some controversy over the appropriateness of the weighting factors (especially for alphas)

10. Effects of Radiation “LD50/60” Dose that would result in death for 50% of the population so exposed within 60 days (Lethal Dose to 50% of the population) LD50/60 limit for gamma radiation is roughly 450 RAD (or 4.5Gray) for whole-body exposure Threshold lethal Dose (2 Gy, whole body exposure) Beyond these acute dose issues, future development of cancer is also a concern Doses at ~10 cSv appear to produce no increased risk of cancer Occupational limits for radiation workers are set at levels below this to be conservative (typically 50 mSv/yr for radiation workers). Typical background exposure in the US is of the order of 3.5 mSv/yr (as high as 8 mSv/yr in Colorado mountains).

11. Sources of Background Radiation Cosmic Rays Naturally occurring radioactive nuclei 40 K this is the most abundant radio-nuclide in your body 14 C (e.g. about 50 times/sec one C atom in the DNA of one of your cells is converted to N by beta decay). 222 R, a decay product from 238 U, and a common concern in buildings Medical tests Man-made nuclides (fallout, waste, release etc.).

12. Sources of Background Radiation http://web.princeton.edu/sites/ehs/osradtraining/backgroundradiation/background.htm

13. Effects of Radiation Recall: 1 rem is roughly 10mGy for gammas Typical background radiation is 350 mrem/yr, airline travel gives roughly 0.4-1 mrem/hr (4-10  Sv/hr) http://www.physics.isu.edu/radinf/risk.htm See also: http://trshare.triumf.ca/~safety/EHS/rpt/rpt_4/node20.html

14. Radiation Dose Different types of radiation at a given energy have different “Relative Biological Effectiveness”, and different parts of the body have different susceptibilities to radiation, so you have to be a bit careful about how you quote numbers. Today medical physicists discuss dose in Gray to specific organs, rather than Sieverts etc..

15. Relative Biological Effectiveness http://www.ccohs.ca/oshanswers/phys_agents/ionizing.html NOTES: Different parts of the body have different susceptibilities to radiation (in terms of their likelihood of developing cancer after a given exposure) This is taken into account in planning radiation treatments for cancer.

17. Relative Biological Effectiveness http://en.wikipedia.org/wiki/Relative_biological_effectiveness Note that a 1.5 Gy dose of Carbon ions has the same biological effect as a 4.5Gy dose of photons (for this particular cell type).

18. Applications of Radiation Radiation and radioactive materials are used in numerous applications today, we’ll touch on only a few of these: Nuclear Medicine Diagnostics (x-rays, CAT scans, PET scans, etc.) Cancer treatment (x-rays/gamma-rays, radio-nuclides, protons, heavy ions) The key here is that rapidly reproducing cells (such as CANCER, in children/fetuses) are more susceptible to radiation damage AND CANCER cells are less able to repair the damage radiation causes (at least that is the dogma, there is some conflicting information on this). Dating of artifacts (archeologic, organic, geologic etc.) trace element analysis Nuclear power

19. Proton Radiotherapy http://en.wikipedia.org/wiki/Proton_therapy http://mpri.org/science/vstreatments.php

20. Nuclear Fission http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/fission.html KEY element (from CALM): Large, unstable, nuclei (2) Neutron activated dissociation (3) These are both necessary but not sufficient: “Chain reaction (8)” but what does that mean? One neutron induces a reaction that produces MULTIPLE neutrons out (to sustain the reaction) (6) THIS IS THE KEY ingredient.

21. Fission products http://www.euronuclear.org/info/encyclopedia/f/fissionproducts.htm http://en.wikipedia.org/wiki/Fission_products

22. Nuclear Reactors (LWR’s) http://reactor.engr.wisc.edu/power.html Boiling water reactor (BWR) Pressurized water reactor (PWR) 66% of US reactors are this type

23. Yucca Mountain http://www.ocrwm.doe.gov/ymp/about/why.shtml

24. American Nuclear Plants http://www.nrc.gov/info-finder/reactor/

25. Nuclear Waste depots http://en.wikipedia.org/wiki/Radioactive_waste

26. Nuclear Decay Chains Does not include the 4n+3 chain or Actinium series which terminates in 207 Pb (Wikipedia does not have so nice a graphic for that chain; from: http://en.wikipedia.org/wiki/Decay_chain 4n chain: Thorium series 4n+1 chain Neptunium series 4n+2 chain Radium series

27. Dates have to be calibrated to account for historic variations in the production and distribution of 14 C in the atmosphere (thank goodness for the Bristlecone pine tree). Figs from: http://www.ndt- ed.org/EducationResources/CommunityCollege/Radiography/Physics/carbondating.htm and http://en.wikipedia.org/wiki/Radiocarbon_dating About 1 part per trillion of atmospheric carbon is 14 C, thanks to this mechanism.

28. Various Dating schemes See article at: http://physics.info/half-life/ Radiocarbon Dating of a Hypothetical Organic Sample age (half-lives)age (years) 14 C (atoms) 12 C (atoms) 14 C : 12 C (ppt)* 00128128 × 10 12 1 15,73064128 × 10 12 0.5 211,46032128 × 10 12 0.25 317,19016128 × 10 12 0.125 422,9208128 × 10 12 0.0625 528,6504128 × 10 12 0.03125 634,3802128 × 10 12 0.015625 740,1101128 × 10 12 0.0078125 Note; this is really a toy example (10 14 carbon atoms is only 2 ng of sample, typically you would need much more; estimate how much more)

29. Various Dating schemes See article at: http://physics.info/half-life/ Potassium-Argon Dating of a Hypothetical Mineral Sample age (half-lives)age (10 9 years) 40 K (atoms) 40 Ar (atoms) 40 K : 40 Ar 00640– 11.2632 1 : 1 22.5216481 : 3 33.788561 : 7 45.044601 : 15 56.302621 : 31 67.561631 : 63 Potassium-Argon Dating of a Hypothetical Mineral Sample

30. Various Dating schemes See article at: http://physics.info/half-life/ Radioisotopic Dating Techniques techniquerange (years past)dateable items lead 2101–150lake and ocean sediments, glacial ice carbon 141–40,000previously living things uranium series1–400,000bone, teeth, coral, shells, eggs potassium-argon10,000–3 billionminerals, igneous rocks uranium-lead1 million–4.5 billionminerals, igneous rocks rubidium-strontium60 million–4.5 billionminerals, igneous rocks

31. Early Particle discovery:  - From E. Segre “Nuclei and Particles”, 2 nd edition Particles appear as tracks (in bubble chambers in the early days, in electronic trackers of various sorts today) that are bent by a magnetic field. By measuring curvature, track length etc. things like half-life, momentum, charge etc. can be determined.

32. Early categorization of Particles Early collider experiments started to reveal more and more particles, and people started to question whether they were truly “Fundamental”, but did allow for the prediction of “missing particles that were later found. Attempts to rationalize this “zoo” of particles led Gell-Mann (and independently Zweig) to suggest more fundamental building blocks (based largely on the observation of patterns [symmetries] in the properties of the particles; they appeared in families of 1, 8, 10, 27 etc. members]:

33. The Standard Model http://newsimg.bbc.co.uk/media/images/41136000/gif/_41136526_standard_model2_416.gif