Laboratory Methods Flashcards
Sample variance
Simple propagation of error (for uncorrelated errors)
General propagation of error
Error on f = AB and f = A/B
Error weighted average
Error of the error weighted average
Poisson distribution
Error of the Poisson distribution for large N
Time between Poisson events
The time between Poisson events follows an exponential distribution. Specifically, if one event falls at time t = 0, the time of the next event’s arrival is distributed as
Complex impedance of a capacitor, inductor, and resistor
High-pass filter
High frequencies pass, low frequencies attenuated
Low-pass filter
Low frequencies pass, high frequencies attenuated
Diode
Allows current to flow only in one direction, from anode to cathode in the picture below. No current can flow until a minimum bias voltage is applied - typically about 0.7 V for a silicon diode. Apart from this, the voltage drop is essentially indepenent of the current. Uses: turn AC into DC, reroute current away from sensitive components (if the voltage surges, the diode starts conducting, resulting in an almost short circuit at high enough voltages)
Op-amp
(note that the op-amp has a maximum output voltage)
AND gate
OR gate
Average path length of an alpha particle
Average path of a high energy electron
Radiation collision targets
- Nuclei interact almost exclusively with atomic electrons
- Electrons can either interact with atomic electrons or atomic nuclei (although the latter is still more rare)
Minimum ionizing particle
At relativistic speeds, all particles lose roughly similar amounts of energy per unit distance (about 1 keV / cm in air). This value is the minimum energy loss, and therefore relativistic particles are referred to as “minimum ionizing particles”.
Photoelectric effect
Compton wavelength
Radioactive decay
Half-life to mean lifetime
Mean lifetime with multiple decay modes
Collisional gas lasers
Medium is gas or gaseous mixture. Transitions are due to collisions between atoms. In a He-Ne laser, there are a huge number of possible laser levels, but a specific wavelength can be selected by placing the laser in a resonant cavity.
Molecular gas lasers
Medium is again a gas, and the transitions are between vibrational energy levels. CO2 is commonly used, as it is cheap and gives a rich vibrational spectrum.
