Question
In an early design for nuclear batteries, illuminating one of these substances made of hafnium induces the discharge of a gamma ray. For 10 points each:
[10m] Name these metastable nuclei. Mössbauer spectroscopy detects an energy shift between two of these excited states, which are named in analogy to a concept in organic chemistry.
ANSWER: nuclear isomers [accept isomer shift; reject “isotopes”]
[10e] Since the rate of gamma emission is too low, nuclear batteries today instead rely on this mode of radioactive decay, by which a nucleus emits an electron or positron.
ANSWER: beta decay [or release of a beta particle; accept beta-minus decay; accept beta-plus decay]
[10h] If gamma emission were faster, isomer batteries could dramatically improve this key metric, the limiting factor in standard betavoltaic batteries. A Ragone plot shows that this intensive property of a battery always trades off with energy density.
ANSWER: power density [or specific power; prompt on power; prompt on discharge rate]
<Chemistry>
Summary
| 2023 ACF Nationals | 04/22/2023 | Y | 20 | 11.00 | 100% | 10% | 0% |
Data
| Chicago A | Houston A | 10 | 10 | 0 | 20 |
| Chicago B | Virginia A | 0 | 10 | 0 | 10 |
| Stanford A | Claremont A | 0 | 10 | 0 | 10 |
| South Carolina A | Columbia B | 0 | 10 | 0 | 10 |
| Georgia Tech B | Cornell B | 0 | 10 | 0 | 10 |
| MIT A | Illinois A | 0 | 10 | 0 | 10 |
| Florida A | Indiana A | 0 | 10 | 0 | 10 |
| Johns Hopkins A | Imperial A | 0 | 10 | 0 | 10 |
| Vanderbilt A | Maryland A | 0 | 10 | 0 | 10 |
| Brown A | Minnesota B | 0 | 10 | 0 | 10 |
| NYU A | Northwestern A | 0 | 10 | 0 | 10 |
| Harvard A | Penn A | 0 | 10 | 0 | 10 |
| Rutgers B | Columbia A | 0 | 10 | 0 | 10 |
| Toronto A | Purdue A | 0 | 10 | 0 | 10 |
| North Carolina A | UC Berkeley A | 0 | 10 | 0 | 10 |
| Yale A | UC Berkeley B | 0 | 10 | 0 | 10 |
| McGill A | Texas A | 0 | 10 | 0 | 10 |
| Cornell A | Iowa State A | 10 | 10 | 0 | 20 |
| Georgia Tech A | Florida B | 0 | 10 | 0 | 10 |
| Chicago C | Penn State A | 0 | 10 | 0 | 10 |