Combinational circuits. Dept. of Mechatronics Engg. HALF ADDER. FULL ADDER Lab 07 3.
A half life of ba lab
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John Frontczak IB HL Physics, Young 22/11/10 Half-Life of Ba ❑ 137 Lab Background: 1. Half-life is the amount of time it takes for a substance to decrease by half while undergoing decay. 2. Equation for beta decay of 137-Ba: Cs 55 137 → e −1 0 + Ba 56 137 3. Geiger-Muller Tube: It's a cylinder surrounding a wire that's kept at a high voltage. The cylinder is filled with low pressure gas, and when ionizing radiation passes through it, it can knock some of the electrons off of the gas particles. Those electrons are then accelerated towards the center wire. As they accelerate towards the central wire they pick up speed, and they are eventually able to knock other electrons off other gas particles. And those accelerate and hit other electrons and so on, and so forth, until you get large amount of electrons moving towards the central wire. That creates a current that is then detected and measured with the scalar.
Transcript of A half life of ba lab
John FrontczakIB HL Physics, Young
22/11/10
Half-Life of Ba❑137 Lab
Background:1. Half-life is the amount of time it takes for a substance to decrease by half while undergoing decay.
2. Equation for beta decay of 137-Ba: Cs55137 → e−1
0 + Ba56137
3.Geiger-Muller Tube: It's a cylinder surrounding a wire that's kept at a high voltage. The cylinder is filled with low pressure gas, and when ionizing radiation passes through it, it can knock some of the electrons off of the gas particles. Those electrons are then accelerated towards the center wire. As they accelerate towards the central wire they pick up speed, and they are eventually able to knock other electrons off other gas particles. And those accelerate and hit other electrons and so on, and so forth, until you get large amount of electrons moving towards the central wire. That creates a current that is then detected and measured with the scalar.
Photomultiplier Tube:Coupled with a scintillator, the scintillator gives off a little flash of light as radiation passes through it. The light it gives off hits the front of the photomultiplier tube, knocking an electron off of the surface of the coating in the front. The electron is then accelerated through a series of little panels in the tube (Dynodes), and when an electron hits a dynode, more than one electron get knocked off. This also causes a large amount of electrons that can be counted and collected.
4. The photomultiplier tube is able to take more samples at a faster rate than the Geiger-Muller tube, making it more likely to get more accurate data.
Analysis:Table 1: Data-
time countevents(raw) events
0:00 0 0 00:15 22007 22007 21143.40:30 43098 21091 20227.40:45 62888 19790 18926.41:00 81299 18411 17547.41:15 98564 17265 16401.41:30 114762 16198 15334.41:45 129688 14926 14062.42:00 143750 14062 13198.42:15 156521 12771 11907.42:30 169388 12867 12003.42:45 180988 11600 10736.43:00 191734 10746 9882.43:15 202475 10741 9877.43:30 212171 9696 8832.43:45 221134 8963 8099.44:00 229798 8664 7800.44:15 237944 8146 7282.44:30 245498 7554 6690.44:45 252589 7091 6227.45:00 259299 6710 5846.4
Graph 1: The number of events that occurred between 15 second intervals
4000 6000 8000 10000 12000 14000 16000 18000 20000 22000 240000:00
1:12
2:24
3:36
4:48
6:00
f(x) = 0.629798287938871 exp( − 0.000164048778003356 x )
Calculating the Equation:
At=A0 e− λt
A tA0
=e− λt
λt=−ln (A tA0
)
λ=−ln (
AtA0
)
t
Calculating λ:
λ=−ln ( 7800
16400)
165 sec
λ=0.7432165
λ=0.0045
Calculating the decay constant:
T 12
= ln 2λ T 1
2
= ln 20.0045
T 12
=153.8964072≈153.9 sec.
Final Notes:
The official (researched and agreed upon) half of Ba55137 is about 152 seconds. The value calculated in this
lab, based upon the data provided was about 154 seconds. Without further context, this value seems to be close to the official value, implying that the experiment and the data is (at least) partial valid and accurate. The two second difference however would add up to a huge difference in the calculated mass of the remain Ba after a even a day.
