User:JOANNAYSX
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ALL ABOUT ME
My name is Xiaoshuai Yuan, and you also can call me Joanna. I am currently a freshman major in biochemistry. I am currently enrolled in 2008WISE187SESSIONV, I hope this will be an intreasting course. I was born in China. In the summer of 2004, I came to the United States alone to reunion with my parents and to pursue my dreams. Mandarin is my first language, but right now I have to learn English in order to communicate with others. I am a shy person at the beginning, but will gradually become warm afterwards. I am interested in a lot of things, such as read comic books, listen to pop songs, and play around with my Maltese and Yorkshire. Drawing is one of my hobbies, and I love animals. College life is tough especially to me, a foreign language speaker, but I will work hard, and do my best. You can find out more about me through space page.
MY HIGH SCHOOL
April 8, 2008
Today we learn how to test the efficiency of a cosmic ray detector. We can test the efficiency of the middle detector by comparing the coincident of the top and the middle detectors and the coincident of the all three detectors. First we need to make sure each detector are connected the right spots, and set up certain voltage for the top and the bottom detectors in order to get correct data. We control the voltage of the detector which we want to test. By changing the voltage between 5.0V and 3.5V, we get the following data.
April 10, 2008
What factors affect the detection of cosmic rays?
1. As we increase the surface area of the scintillator, more cosmic rays will be detected.
2. If we increase the distance between each detector, the time interval between detected cosmic rays will expand.
3. Changing the altitude of the detectors affects the cosmic rays detected because cosmic rays increase with altitude
4. We can test the direction of cosmic rays through changing in orientation.
5. Question about temperature and pressure which may also affect the detection of cosmic rays.
Thinking: Cosmic rays may gain energy from increasing temperature, therefore they might move faster. If that happened, more cosmic rays will detect.
Designed Experiment
Idea from:
First day in this lab, we saw Cosmic Chris received different numbers of cosmic rays when we changing his orientation. From the observation we concluded that changing in orientation affects the detection of the cosmic rays, therefore I want to design an experiment in order to test the direction of cosmic rays.
Materials list:
1. Scintillation detectors
2. Coincidence box
3. Cables
4. Voltage supply
5. Computer with Data AcQuisition (DAQ) program
6. Instrument for measuring angle
7. Detector holder
8. Compass
Procedure
A. Test the efficiency of two scintillation detectors
1. Put the detector you want to test in the middle of the other two detectors. Use identical cables connecting them to the coincidence box (make sure they are on the correct spots, so we can get coincidence of the top and the bottom detectors, and control the voltage of the middle detector). And connect it to the computer.
2. Open and set up the DAQ program, and set up the voltage of the top and bottom detectors.
3. Run the DAQ program, and keep the voltage of the middle detector between 3V and 6V. Each time increases the voltage 0.1-0.2 V, and repeat.
4. From the data we can get the efficiency of the middle detector.
Efficiency of the middle detector = the coincidence of the top and bottom detectors/ the coincidence of the all three
5. Get a noise level (in Hz) form the events of the middle detector.
Noise level= the events of the middle detector/ time interval (in second)
6. Using the data of Efficiency, Voltage, and the noise level plot an efficiency curve.
7. Repeat the steps to test another detector, until you have two efficient detectors.
8. From the Efficiency Curve identify the voltage gives the most efficient detection.
B. Detecting cosmic rays respect to different orientation
1. Using compass identify direction, set the combined two detectors along the W-E direction.
2. Connect the detectors to voltage supply, and set the voltage you identify in step 8 above, and time interval.
3. Run the DAQ program
4. Each time change the orientation of the detectors 15 ° to the North, repeat the steps until the detectors return to the original position.
5. Using the coincident of the two detectors and the angle plot a graph.
6. Lie the detectors on the ground to detect.
7. Each time, lift one side of the detectors 15 ° up, with respect to the ground, and repeat the steps until the detectors lie on the ground again.
8. Using the coincident of the two detectors and the angle respect to the ground plot a graph.
April 15, 2008
Experiment -- Rate vs. angle & compass
In today’s lab, I worked with Veronica to test the relation between the rate of the detected cosmic rays and the angle respect to the ground and to the compass direction.
Rate vs. angle
April 17, 2008
Today we were introduced Statistical Errors. Experiment errors include accuracy, precision, systematic errors, and random errors. Statistical errors are the square root of the number of the counts. We show them as error bars in our graph. After that we continued our experiment in a group as last time.
April 22, 2008
Today I worked with Veronica continuing our group work. We measured two more angles, and added them to our graph as following.
And then we measured the rate vs. compass. We set North position as 0 degree.
top views
April 24, 2008
Today is our last day to do the group experiment. Veronica and I improved our last experiment, rate vs. compass, by setting up the detectors at 45 degrees with respect to the ground. Therefore, most of the cosmic rays we detected came from one direction instead of two directions, and we also increased the time interval in order to increase the efficiency. We measured the counts at eight different angles, set north direction to 0 degree, and 45 degrees apart from each other. According to the date, we made the following graph.
From the above graph, we could see that the rate at 270 degrees (west direction) was the lowest. We concluded the observation was due to the buildings on west side which blocked some cosmic rays.
April 29, 2008
Today is our last day in the Mariachi Lab. We did our presentations as groups.
Final Report
Day one (February 5, 2008)
Today, we did some work on computer by ourselves in the radio signals lab. We can hear the music or sound from radio stations because there are antennas connect with recivers, and then through computers and the sound card. So we can hear the sound. We learnd to record 10 seconds audio. By using the computer system, we are able to find AM stations. After that, it is easy to record the sound by pushing the button. Through this exercise, we are more familiar with radio signals.
Day two (February 7, 2008)
We were introduced MATLAB program, and use it to do signal generation exercises. By type in "help", we can get information from the program. We also can make a colorful graph to show the number of periods in a period of time.
Day three (February 12, 2008)
First, we reviewed the generation of the basic signals we learned from last class. After that, we learned listening to the sound by typy different function. By changing the period, we can make the sound longer or shorter; by changing the amplitude, we can make the sound louder or lower. Finally, we learned to generate Gaussian Noise. After we added the noise to the sound, the sound became static.
Day four (February 14, 2008)
Today we work on "WAVE File Saving and Loading" by using MatLab. First we read a wave file by type in
[y, c]= wavread ('1.wav')
The frequency is c= 8000Hz
t= 0: 1/8000: 2
Wavwrite (y,4000. '2.wav') The sound is longer.
[y,c]= wavread ('2.wav')
The frequency is c=4000Hz
wavwrite (y, 16000,'2.wav')
[y,c]=wavread('3.wav')
wavwrite(sin(2*pi*830*t), 16000,'3.wav')
[y,c]=wavread('3.wav') The sound is higher and shorter.
We put g= wavread ('2.wav'), and k= wavread("3.wav')
And then we listen to sound (g+k,8000)
For the small project we read our file we recorded before
[a,b]=wavread ('joanna. if. wav')
The frequency b=48000Hz
,
Day five (February 19, 2008)
Today we use "GUI to study the time and frequency representations of sound signals." In order to execute the GUI, we type in "inclassexercise" as commands in MatLab command window. After that we load our wave file. We are able to generate three different kinds of signals: pure sinusoids, pure moises and mixture of sinusoids and noises. We also can plot the functions. Noise becomes lower as we make the noise level lower, and the noise becomes louder as we make the noise the noise level higher.
Final project (February 21&26, 2008)
Date Processing Project
Background information about "power in decibel (dB)" "The decibel (dB) is a logarithmic unit of measurement that expresses the magnitude of a physical quantity (usually power or intensity) relative to a specified or implied reference level.
The equation is: PdB= 10x log(P/Po)
By changing the equation, we can get
P= 10^(PdB/10)
We choose file To7121507.dat from folder 'C:/wse/project' of our computer. We use it plot four different graphs
As we can see the second graph (not in dB) has more peaks than the first graph.
For the second task, we "compare the signal power with a threshould which is 10^(0.6) time bigger than the estimated noise at same time instant in column H.
"If the signal power is greater than the threshold at the thime instant, mark the detection indicator as 1, otherwise mark the ditection indicator as 0." According to it, we plot the ditection indicators with time. So we get the following chart.
The third task, we put command "IF(AND(H1=0,H2=1),1,0)" to count the number of event in this five minutes. There are total 125 events in this five minutes.
After, we use two steps to modify our indicators with a 101-111 rule. First, we use command IF(AND(H1=1,H2=0,H3=1),1,0) in column J, and then we use SUM(H1,J1) in column K to add columns H and J together. Plot it with time we get
