User:Vliao88
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My name is Virginia Liao. I was born in New York City in June 23, 1988. My hometown is currently in Brooklyn. I am a freshmen student at Stony Brook University. I am also part of the Women in Science and Engineering (WISE) program. I am thinking about majoring in chemistry and possibly minoring in astronomy. I also attended Brooklyn Technical High School and when I was there, I loved volunteering at soup kitchens and was Vice-President of the Beta Club. My hobbies include listening to music, reading magazines and newspapers, watching TV, reading adventure books, collecting quarters of all 50 states and hanging out with my friends. My interests are movies, dancing, science, sports, and my boyfriend. I am also very addicted to asian drama series, but I know how to control myself.
My favorite color is green because it calms me down. My favority season is autumn because I like it how the leaves change colors and when they fall to the ground, I enjoy stepping on them to feel and hear the crunchiness under my shoes. I also like the cool breeze. I come from a family of five. My parents immigrated from China before I was born, and I have two siblings, a younger sister and younger brother. My native language is Cantonese, but like many chinese kids in America, my knowledge of Chinese is very limited, and if I was to go to China, I would get lost. Both my siblings and I went to the same pre-school, elementary school, junior high school, and high school (I kinda hope we don't all go to the same college as well). My younger sister is in her last year of high school, and my younger brother is in his first year of high school.
I am looking forward to working on a research project in Basic Processing of Radio Signals.
Research Log:
Session III: Cosmic Rays and Particle Detectors
03/24/07
Today was our first day at a new project. The goal of this project is to study the properties of cosmic rays and eventually create our own experiments. The reason why peopele study cosmic rays because they can affect humans and possibly provide answers to the mysteries of the universe. There are many ways of detecting the paths of such ionized particles. These include using cloud chambers, spark chambers, and scintillation counters. I think looking through the cloud chamber was the most interesting equipment, but I still don't understand how you study the cosmic rays from there. I am also wondering if the event counter on top the rack unit module is the same as the counter on Cosmic Chris. We also learned how to plug the wires into the rack unit module, counter, and oscilloscope. The signals that produced were quite interesting because one signal looked like the radio signals that I worked with in the previous project, and another signal looked like a square shaped graph. I am amazed at how fast this oscilloscope can detect and produce the signal within a fraction of a second. If a much longer cable was connected to the scintillation detector, then the plot on the oscilloscope would move slightly to the right because it takes longer for the signal to reach the equipment. I am also confused with why the scintillation detectors are used if they can not differentiate between the desired cosmic rays or some 'noise'.
03/27/07
Today we had to set up the equipment to record the number of counts and coincidences in terms of varying time and voltages. I was confused with the equipment setup at first, but the main reason why I thought the setup wasn't working was because we didn't turn the switch to 'START' and so nothing was counting even when the counter was powered on. The first part of the experiment was to record the number of coincidences for 5 trials at two different time intervals. So Priya and I recorded it at 20 seconds and 120 second intervals. There was some uncertainty here because Priya and I weren't able to start the counter and timer at the same time nor stop them at the same time. We noticed that when we increased the recording time, the data had a higher degree of precision than the recording time at 60 seconds. The error is determined by square rooting the data value. This is shown in the following plot.
Next we recorded the number of coincidences and counts for 5 different voltages at 120 seconds. We noticed that the rate of coincidences and counts increased while the voltages increased. This is shown in the following two plots.
03/29/07
Today we learned how to use the Data AcQuisition (DAQ) Program to collect data from the 3 scintillator detectors. I found the chip in the machine board that makes this program possible to be kind of odd because it needed to be programmed every time it is used because once the machinee board is powered off, it forgets the program. But anyways, Priya and I decided to time it at 120 seconds to get more accurate results and ran the program from 5 volts to 6 volts in 2 volts intervals. Then the data was pasted into excel. It was kind of cool how excel has a way to automatically import data; kind of making our lives a several seconds easier. Efficiency is then calculated by dividing the number of coincidences through scintillators 1,2, and 3 by the number of coincidences through scintillators 1 and 2, and then multiplied by 100 to get a percentage. This is done because not all the "rays" that went through scintillator 1 and 2 may have went through scintillator 3 as well. Below is the graph of our data. We noticed that the efficiency increases with higher voltages, but the efficiency did decrease slightly at 6.0 volts, which I don't have an explanation for except that less rays passed the third scintillator at 6 volts than at 5.8 volts.
After this, we sat around the blackboard to talk about possible research projects. So the first step is to ask questions and build on from there. Our questions can be found here: http://www-mariachi.physics.sunysb.edu/wiki/index.php/GroupIIIExperiments.
During our break, we did some research and looked at the last session's experiments to make sure we do not repeat them. The following questions are what we are going to attempt to answer:
1) Do cosmic rays pass through all materials?
2) Does it matter where you are?
3) Does it matter where the counters are relative to each other?
4) Does the number of CRs depend on light and dark areas?
The first question is very related to the second and third question, so we plan to answer the first question that would incorporate the second and third question. So the type of materials that we plan to use is the Physics Building, a tank of water, cloths, mirror, and air (as a control). When we use the physics building, we can place a scintillator on the roof, in one of the floor levels, and the basement. We will probably use Cosmic Chris to record the counts since we're not sure if can carry around the counter. For the second material, we were thinking about placing a closed tank of water in between two scintillators at some distance above and below the tank of water. We will be using the counter and probably the DAQ program to measure the efficiency. For the cloths, we were planning to bring in bedsheets and what not. There will also be a control for data analysis. We came up with another question and that is the fourth question. We can leave the scintillators under a source of light (ie. a lamp) and place another scintillator in complete darkness.
04/10/07
Today we decided to test out our experiments to see if we could do them or not. So we first did the light and dark experiment. We placed Cosmic Chris into the bathroom and started the counter. The data is as follows:
Note : We weren't able to do all five trials laying down flat in the dark because we ran out of time.
The graph on the left is the coincidence rate in the light and dark when Cosmic Chris is laying down. The graph on the right is the coincidence rate in the light and dark when Cosmic Chris is standing up. Since the error bars in the graph would overlap each other, it is difficult to draw solid conclusions from this experiment. But if we lengthened our timing intervals, our error would be smaller and so, the error bars may not overlap each other. However, this would probably take up too much time because we won't be able to take as many trials if the time intervals were increased.
So when this Thursday comes, we will go on to the next experiment involving materials. The first material that we will use is the Physics building.
Hypothesis: I think that the number of CRs counted be: roof > ground floor > concrete > tin roof.
Equipment: Cosmic Chris, other mobile counters, scintillators that can hook up to the computer, timer
Procedure: We will place Cosmic Chris under the tin roof, under the concrete layer, and the ground floor. We will also place him in the roof as a control. We will be doing 3 trials for 3 minute intervals and Cosmic Chris will be in the laying down position. If there are more mobile counters, we can cut down the data collection time by spliting up into two groups. If not, one group can use two seperate scintillators near the computers to measure the counts under the tin roof and process the data while the other group do the other places.
Since we need to know if there are significant differences in these 4 places in the building, we won't be able to plan out the experimental plan for the other materals yet.
04/12/07
Before we started our next experiment, Mr. Marx corrected our statistical data from the previous experiment. I had calculated the average wrong and needed to correct that, which is shown in the previous entry.
Since there weren't anymore detectors like Cosmic Chris, all four of us had to do the data collection together. We couldn't go up to the roof, but we went to the next highest level, which is Level D. We brought Cosmic Chris near the window and started to count for three trials. We also timed it for 300 s (5 minutes) because based on the previous data from the light and dark experiment, we wanted to keep our error around 1%. Then we went to Level C. We had to go inside the Math/Astronomy library to be under the position we were in Level D. The following is our data:
Although we were not able to go to the other levels in the building, there certainly is a difference in the coincidence rate values between Levels D and C. The coincidence rate dropped (and there are no error bars overlapping) when we moved down the building because the cosmic rays had to go through more material. We just need to collect more data at the lower levels to confirm this.
04/17/07
Since Cosmic Chris needed to be recharged, we did a different experiment to see in which position most cosmic rays comes from. While Kimberley and Jessica worked on an experiment that involved increasing the height between two scintillators, Priya and I worked on an experiment that involved changing the position of two scintillators by using the octagon rack. The 3 positions that we tested was diagonal (45 degrees), vertical (90 degrees), and horizontal (180 degrees). The following are our data and results.
As the position changed from horizontal to diagonal to vertical, the coincidence rate increased. This means that the cosmic rays "generally" come from either above and below the scintillators and that placing the scintillators lying down flat (vertical position) would get us the most counts.
04/19/07
Today we continued with our original experiment, but since we had done our previous data collections near the window, we had to start over from another position each level since there would cosmic rays coming from outside the windowns that could affect our counts. At each level, we had three trials timed at 300 second intervals each. We were not able to finish with all our trials at the basement level, but we will finish up next Tuesday.
It's difficult to compare the levels if we're comparing two levels that are right above each other. For example, we can't say that level D had more counts than in level C since the data points and error bars overlap. But if we compare level D with level A, we can say that there are more counts on level D than on level A. However, before we jump into any more conclusions, we will have to take more data next Tuesday at the basement level and possible under the concrete roof to confirm our hypothesis.
04/24/07
We continued our experiment and collected our last data values. Before we did the experiment, Professor Marx and Dima showed us there was statistical error in our graph from this past Tuesday's experiment. Dima said that our data values at Level C and A were no within each other's error bars and so he thinks that we may have missed a cycle. So we went back to levels C and A to do one trial. Sure enough, we were missing one cycle. In addition, while we were counting the cycles, we did not tell each other which cycle it was up to because if we didn't do that, we may have missed another cycle. So we took Cosmic Chris to the basement level to finish our two remaining trials there and one last count in the lab.
From the data above, we can say that the number of cosmic rays that reaches the lower levels of the building is less than the number of cosmic rays at higer levels of the bulding. One possible reason for this is because the cosmic rays have to go through more levels, or more materials, and so some of them get reflected in other directions or the ones with weaker energies don't go through at all. In our graph, we did not include the data from the lab room because we did not have enough time to go into other factors of the materials that could affect the counts because the lab room is under a tin roof.
Note: I changed the graph of the scintillators at different angles in blog entry 04/17/07.
Reflections Even though learning to use excel too a lot of time, I had fun doing this project and I feel that I've learned a lot of things that might be very useful to me in the future. For example, brainstorming for ideas, statistics, and excel. One suggestion that I do have to mariachi is that there should another kind of scintillator like Cosmic Chris so that more experiments can be done in a more efficient way.
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Session II: Basic Processing of Radio Signals
2/22/07
First I took a survey and I did not know how to answer more than half the questions in there. But during the presentation, I learned what radio signals are and other equipment around here. If I heard correctly, the purpose of this research is to pick up the millisecond cosmic ray and analyze it and simulate it. My question for today is: What are cosmic rays and where they come from? and what kind of cosmic ray are we looking for?
2/27/07
I learned what radio waves are, and the functions of antennas and receivers. I also learned the three compoenents of the setup, which are: antenna, receiver, and sound card. I also learned set up the equipment to pick up radio signals. My question of the day is: does this lab have any omni-directional antennas?
3/01/07
MATLab is fun!..well kinda because remembering what all the codes are and what they do is somewhat confusing. If I could practice with it more, I think that would not be such a problem for me. What did frustrate me during the time when I was coding was when I missed one small detail like a semi-colon at the end to close it, or if there were spaces when it was not supposed to or when there was a missing comma, the program could not read it. But I did learn how to make arrays, transpose vectors, functions of ones and zeros, and graphing the arrays into a plot and stem graph. The two things that I still did not know how to do was coding in 'rand' and strings.
3/06/07
I learned how to create sinusoids and how varying the frequency or the steps can change the plot. If I increased the frequency value and decreased the step in the array, the plot would be more accurate, but hard to read, unless I redefine the stop variable in the array. I also learned how to create sounds by varying the amplitude and the frequency. If the frequency is decreased, the computer will produce a longer sound and if the frequency is increased, the sound produced will last shorter. Below are two graphs of the function y(t)= sin(2π*ft) with a frequency f=500.
3/08/07
Today I learned how to generate sound signals and it was not very hard nor very different from making a "good" signal, except adding the syntax "randn" to it. When a good signal is mixed with a noise signal, the amplitude increases. When the coefficient of the frequency changes, the noise level increases, but the good signal remains unchanged. I also learned how to save and open a wave file. To understand what was happening when two signals were mixed together with a new frequency, Kimberly and I had to plot the individual signals and the two of them together. This allowed us to see that the individual signals had the same plot, and so when they were added together, the amplitude increased by two. This was somewhat surprising when I could only hear the sounds, but after plotting them, it made sense. The two signals plotted together is shown below.
3/13/07
Kimberley and I worked on a small project. It involved recording a signal using the WinRadio G313i receiver. The sampling frequency was determined and the signal was plotted. Then noise was added to the recorded signal and the level of additive noise was played around with. This new noise with signal was plotted and saved to a new wave file.
3/15/07
Today, Kimberley and I used a GUI system from MATlab to study the time and frequency characteristics of sound signals. We loaded a wave file and could specify its start time and stop time and change the sampling frequency. Then we pressed the SOUND button to hear the signal.
After some practice with the GUI system, we next generated 3 types of signals. First, we create pure sinusoids and varied the number of F1 each time. We noticed from the plots that the highest amplitude occured at the the frequency domain with the same number as F1. For example, when F1 is 20, the highest amplitude happened at 20 Hz. When F1 is 30, the highest amplitude happened at 30 Hz. When a 2-compoenent sinusoid was created with the same settings at before except that F2 = 50, the same relationship occured. For example, with F1 = 20 and F2 = 50, there was a peak at 20 Hz and a peak at 50 Hz. When a noise signal was generated with the same settings as the above sinusoids, there were too many peaks in the resulting graphs. This meant that you couldn't determine where the signal peaked at on the frequency domain. As we created different noises with varying noise levels, the peaks kept changing.
Next, we generated a 1-component sinusoid with noise signal. We also checked the box next to GRID ON and POP-UP FIG so that two figures popped up. The first pop-up figure basically shows the combined signals of the signals in second pop-up figure. Lastly, we loaded several wave file, such as "Blip.wav" and "Chimes.wav" to study the time and frequency characteristics of them.
03/20/07
Today was our last day in the radio signals session. Our last project was to find out the frequency hidden in a message signal generated from the carrier. First, we used WinRadio G313i receiver to record the AM signal at a certain IF bandwidth for 10 seconds. Then we made the stretched the IF bandwidth and recorded that for 10 seconds too. Then we selected another demodulation mode at LSB and recorded the signals at two different IF bandwidths for 10 seconds as well. We used GUI to load and plot the 4 recorded signals (which are shown below). When we compared the graphs, we noticed that if the IF bandwidth increases, the amplitude of the signal plot becomes smaller. In addition, if there was more than one peak in the plot, the peak with the smaller frequency domain was the frequency of the message of the signal. The other peaks were due to the imperfections of the equipment. Thus, the frequency of the AM signal was 750 Hz. Finally, we uploadeds our results and figures into our WIKI page.
Reflections:
Let's see....I feel that I have learned so much from this project. I learned how to create arrays, matrices (I was also trying to use my basic knowledge of linear algebra to test somethings out), connect the equipment together and into the computer, generate sinusoids, create sounds and sounds mixed with noise, save a file as a wave file, plot the signals, use GUI to understand the frequency characterisitcs of the sound signals, and use the WinRadio G313i receiver. Overall, I found this project to be fun and enriching. I used to despise all computer projramming related topics, but after using MATlab, it has renewed my interest in similar programming languages to MATlab. I think I might even want to take a course in MATlab here in Stony Brook if they offer it. I initially thought I would get lost in using MATlab since I had no prior experience, but with our mentor's help, coding the program became very logical. Just by typeing in 'help ...' was sometimes enough to get me through the programming.
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