Packet D: Bonus 1
In February 2025, a team led by the University of Surrey discovered an oblate spheroid nucleus for one of this element’s isotopes. For 10 points each:
[10m] Name this element whose 208-isotope is molten and mixed with bismuth as a neutron moderator material. That isotope of this element has a doubly magic nucleus and ends the thorium and actinium decay series.
ANSWER: lead [or Pb; accept lead-208 or Pb-208]
[10e] Lead-bismuth mixtures are also used as coolants in the fast type of these devices. Elevated temperatures in these devices can generate steam voids, which resulted in a meltdown of its RMBK type at Chernobyl.
ANSWER: nuclear reactor [or fission reactor; accept fast breeders; prompt on nuclear power plant or fission power plant]
[10h] A drawback of using bismuth-209 is that it can spontaneously undergo this process then beta-minus decay to form alpha-emitting polonium-210. A sensitive elemental analysis technique uses energy-dispersive XRS to induce this process.
ANSWER: neutron activation [accept neutron activation analysis or NAA; accept neutron capture or neutron absorption; prompt on activation or capture or absorption]
<Oxford A/Columbia C, Chemistry> | Packet D - UBC B, Oxford A, Waterloo B, CWRU A
| Heard | PPB | E % | M % | H % |
|---|---|---|---|---|
| 69 | 17.10 | 100% | 68% | 3% |
Conversion
| Team | Opponent | Part 1 | Part 2 | Part 3 | Total | Parts |
|---|---|---|---|---|---|---|
| Iowa State | Carleton College | 10 | 10 | 0 | 20 | ME |
| Minnesota A | Washington A | 10 | 10 | 0 | 20 | ME |
| Missouri A | Claremont | 0 | 10 | 0 | 10 | E |
| Washington B | Missouri B | 10 | 10 | 0 | 20 | ME |
Summary
| Tournament | Edition | Match | Heard | PPB | E % | M % | H % |
|---|---|---|---|---|---|---|---|
| California (North) | Main Site | ✓ | 3 | 16.67 | 100% | 67% | 0% |
| California (South) | Main Site | ✓ | 4 | 17.50 | 100% | 75% | 0% |
| Florida | Main Site | ✓ | 3 | 13.33 | 100% | 33% | 0% |
| Great Lakes | Main Site | ✓ | 4 | 20.00 | 100% | 100% | 0% |
| Lower Mid-Atlantic | Main Site | ✓ | 9 | 17.78 | 100% | 78% | 0% |
| Midwest | Main Site | ✓ | 9 | 17.78 | 100% | 56% | 22% |
| Northeast | Main Site | ✓ | 6 | 18.33 | 100% | 83% | 0% |
| Overflow | Main Site | ✓ | 4 | 17.50 | 100% | 75% | 0% |
| South Central | Main Site | ✓ | 2 | 15.00 | 100% | 50% | 0% |
| Southeast | Main Site | ✓ | 7 | 15.71 | 100% | 57% | 0% |
| UK | Main Site | ✓ | 6 | 20.00 | 100% | 100% | 0% |
| Upper Mid-Atlantic | Main Site | ✓ | 8 | 15.00 | 100% | 50% | 0% |
| Upstate NY | Main Site | ✓ | 4 | 15.00 | 100% | 50% | 0% |