This is my new Pentax Asahi Takumar 1:1.4/50mm lens… but it also happens to be radioactive! It contains Thorium 232.
I journey to Fredericksburg VA to find uranium glassware to buy!
Background 38 CPM
Total 19,262 CPM *
Beta+Gamma 14,116 CPM *
Gamma 1,392 cpm *
* values shown minus background (e.g. 19300 CPM total becomes 19,262 CPM after 38 CPM removed)
This is how we figure it out:
Alpha = Total – Beta+Gamma
Beta = Beta+Gamma – Gamma
Gamma = Gamma
We can replace the words for real values from above:
Alpha = (19262 CPM) – (14116 CPM) = 5146 CPM
Beta = (14116 CPM) – (1392 CPM) = 12724 CPM
Gamma = (1392 CPM) = 1392 CPM
The results sum back to the total, which helps us check our work:
Alpha + Beta + Gamma = 5146 CPM + 12724 CPM + 1392 CPM = 19262 CPM
Here’s that bit about the copper lol I added it for fun, but it is correct.
Sheilding HVL of Copper: 10.2 mm
Thickness of Sample: ~4mm
Most Common Energy of Gamma: 214Bi 609.31 keV at 44.8%
e^-log(2)4mm/10.2mm = 0.76199, where d/dx e^-((ln(2)/10.2mm)*x) = (4^((-2+x)/x) log(2))/x^2
Lets learn about lasers!
Lasing Medium / Gain Medium – The material which forms the laser light.
Pump – The energy source needed to induce the population inversion.
Population Inversion – The act of causing the electrons in the lasing medium to jump to higher energy states.
Meta-Stable – A short period of stability.
Stimulated Emission – When an electron drops to a ground state and emits a photon as a result of another photon passing by it. Both photons are coherent.
Spontaneous Emission – When an electron drops to a ground state and emits a photon after a short time in a meta stable state.
The lasers in the video are DPSS Lasers (Diode Pumped Solid State)
An Infrared Aluminum Gallium Arsenide diode laser emits 808nm photons. These pump a Neodymium-Doped Yttrium Orthovanadate or Neodymium-Doped YAG crystal which emits 1064nm laser light. This light is Freq doubled using Potassium Titanyl Phosphate crystal to become 532nm, a beautiful green color
How to calculate the current activity of a source given the activity at one point, the time which has elapsed, and the decay constant.
Activity_now = Activity_then * e^-((ln2/halflife)*elapsed_time)
Now, enter into your calculator for activity of 1000Bq, halflife of 20min, and elapsed time of 40min:
1000 * e ^ – ( ( ln(2) / 20 ) * 40 ) )