Experiment
Home Up Experimental Setup Experiment Data analysis Discussion
Preparation
In this experiment, you are required to seek for the variation about count rate against time. You should make your own plan and make use the software PCI6602Monitor.exe provided in downpage page to help you obtain informations about cosmic ray events. Of course, you can analyse raw data directly in directory C:\GPS_CR\DATA. These data files carry much more informations than the report generated by PCI6602Monitor.exe.
Here list the steps which shows you how to obtain a count rate plot in general. Once you understand the steps throughfully, you can make you custom graph and perform the experiments listed at the bottom of this page. Graphical representation is helpful for further analysis. It is advised to make event plot for all experiments listed below (The following discussion about obtaining a count rate plot is not an essential part of the experiment, you are free to skip them)
Step 1. Data acquisition
Run PCI6602Monitor.exe to generate a report. For example, you want a report named report.log, carry the informations about event rate A and B. The report will contain 1 night information (7pm to 9am next day) The sample data file is listed for reference.
report.log - First few lines
Start Time (SS MN HH DD MM YY) Elapsed Time (sec) A^B^~C A^C^~B B^C^~A A^B^C GPS
42 32 19 30 01 02 596 1945 209 1382 23 595
19 48 19 30 01 02 596 2021 245 1387 14 595
19 58 19 30 01 02 600 2009 205 1359 25 601
01 15 20 30 01 02 596 2002 206 1337 20 594
17 25 20 30 01 02 596 1921 214 1332 22 595
13 35 20 30 01 02 596 1915 234 1359 17 596
13 45 20 30 01 02 600 1959 227 1360 17 601
55 57 20 30 01 02 596 1973 212 1408 27 595
55 07 21 30 01 02 600 2030 223 1350 25 601
Notice that each bin contain ~10 mins and started at 7:32 pm. The report will ended at around 9:00am of the next day.
If you do not know how to use the software or what is the definition of fields on the report, you should visit the downpage page .
Step 2. Analyse your report
The report is a pure text file which can be modified by any text editor. It is recommended to use EXCEL packaged in your computer. The graph below show you that the report file Report.log has been already imported into EXCEL. Notice that an additional column time is inserted between column hour and elapsed time. AEXCEL built in function =TIME(C:C,B:B,A:A) would help you to combine hour, minute, and second field to time field.
To calculate the coincidence event rate A and B, you need to divide event count of A and B by GPS counts. It is because informations in the fields start time and elapsed time inside the report are referring to computer clock and they are not as accurate as timing by GPS. You should remember 1 GPS count equals to 1 accurate second. By using EXCEL, handling division between two columns is a straightforward task. For example, you place the formula =F2/J2 in column K and row 2, the number column F, row 2 divided by number column J, row 2 will be displayed.
At last, followed by Graph Wizard of EXCEL, the event rate plot can be obtained.
Experiment
Part 1 - Investigating daily variation on count rate
Step 1 - Prepare to obtain count rate for one day, choose bin size around 10~30 mins, you should remember you can merge bin in EXCEL. (Make you only plan first. During data acquistion period, run lesser process in your computer)
Step 2 - Obtain 4 count rate plots (A and B, A and C, B and C, A and B and C) You should calculate the error bars and include them inside your graph. You may need to magnify a subpart of you graph to verify variation exist or not.
Part 2 - Searching daily periodicity of event rate
Step 1 - Prepare to obtain count rate for one week, enlarge bin size if you need. In this part of experiment, choice of bin size may be helpful for you to handle Fourier analysis, you should choose the bin size such that number of bins in a day is the multiple of 24, 48, 96, ... etc.
Step 2 - Obtain 4 count rate plots similar to Part I - Step 2
Step 3 - Apply the method suggested in the part Data analysis, fit suitable sine wave curve with period one day, half a day ,one fourth a day, one eighth a day. Compare their amplitude.
Part 3* - Investigating variation on count rate for a month
Step 1 - Prepare to obtain count rate for a month. Owing to software, hardware, and other consideration, it is impractical for you to take measurement for a long time continuously. Generate one report for each day seems to be a good strategy.
Step 2 - Obtain 4 count rate plots (A and B, A and C, B and C, A and B and C) Combine your data with any methods (They are purely text files) ,choose a large bin to ignore small fluctuation. At last, try to find out any variation on your graph.
* This part is optional.
Part 4 - Obtain a custom event plot
Step 1 - Based on the physical phenomenon you interested in, decide how long of you measurement. For example, you know sun will self rotate of a period of ~27 days. You wish to check whether your count rate has such periodic variation. You may try to monitor the rate for few months.
Step 2 - Obtain your event rate plot and handle suitable analysis. The step is really up to you.
Before taking the experiment in this step, consults to you supervisor first. For example, you may not allowed to occupy your computer through a long time.