The Most Tightly Bound Nuclei
The most tightly bound of the nuclei is 62Ni, a case made convincingly by M. P. Fewell in an article in the American Journal of Physics. Though the championship of nuclear binding energy is often attributed to 56Fe, it actually comes in a close third. The four most tightly bound nuclides are listed in the table below with a tabulation of the binding energy B divided by the mass number A. The curve adapted from Fewell shows those nuclides that are close to the peak.
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The most tightly bound nuclides are all even-even nuclei. The curve drawn through the cluster of nuclei above is just to show the nature of the trend with mass number. A similar kind of trend is observed with even-odd nuclides at a lower range of binding energy, and then by odd-odd nuclei at the least-bound extreme. The peaks of all three groups occur around A = 60.
The high binding energy of this group of elements around A=60, typically called "the iron group" by astrophysicists, is significant in the understanding of the synthesis of heavy elements in the stars. It is curious that the abundance of 56Fe is an order of magnitude higher than that of 62Ni. Fewell discusses this point, and indicates that the reason lies with the greater.
LISTENING
1. You are going to listen to the staff report “Mexican Plant to Host July Global Response Exercise“. Mind the proper names.
Laguna Verde nuclear power plant in Alta Lucero
"Joint Radiation Emergency Management Plan"
the IAEA´s Incident and Emergency Centre (IEC)
the Inter-Agency Committee for Response to Nuclear Accidents (IACRNA)
Cernavoda nuclear power plant in Romania
the World Health Organization (WHO)the World Meteorological Organization (WMO)
Mexico and the Mexican neighboring countries
2. Speed listening. Note only the essential details of what you hear:
9.The Olympics……………………….
10.China and the IAEA……………………..
11.A training workshop………………………..
12.Anita Nilsson said………………………………
13.IAEA´s work in Beijing………………………………………
14.Chinese authorities…………………………………………
15.Nuclear security measures……………………………………
16.Help to Member states…………………………………………
3. General information: Complete the chart with the basic ideas:
| What? | Where? | When? | Who? | How? | Why? |
4. Gap filling: Listen once again and complete the gaps in the summary of the passage below with the correct word or phrase you hear:
On the threshold of the Summer Olympic Games Chine and the IAEA are working together at strengthening _____________ and minimizing threats. For that purpose _______________ was held in Beijing. The IAEA’s role was to assist in integrating ___________into the existing Chinese security system. The spheres which are covered by the conducted advisory missions and training exercises are _____________.
The IAEA has already rendered technical assistance to different international public events among which are ____________________.
Member States of the IAEA get comprehensive help from the Office of Nuclear Security in form of ______________. This is vitally important for protecting __________________and fighting against__________.
5. Decide whether these statements are true, false or the information is not given:
1.In recent years safety record of nuclear power has caused concern and necessity to improve.
2.60 IAEA Member States and 10 international organizations will take part at the Conference in Mexico.
3.The 2-day exercise is to assess efficiency of communications between possible crisis partners.
4.During the emergency drill different emergency response bodies will show their preparation to deal with radiological accidents.
5.The similar event in Romania showed necessity in arranging such activities.
6.Emergency Conventions set rules how information exchange and assistance should be realized in the conditions of radiological emergency.
7.When the event at Laguna Verde finishes, the IAEA will publish a statement that there was nothing dangerous for the public.
6. Work in pairs or groups. Discuss the topic mentioned in the staff report “Mexican Plant to Host July Global Response Exercise“.
PRESENTATION
Make up a presentation “BINDING ENERGY”
(See appendix 4)
SECTION 5
MODES OF RADIOACTIVE DECAY
LEAD-IN