Experiment 1 - Time Variation of Count Rate

Home Up Experimental Setup Experiment Data analysis Discussion

To discuss the variation of rate of cosmic ray, the details can be usually covered by a whole book. For our experiment, we mainly concern the rate of extensive air shower against time variation. Prior to our experiment, much work had already been done to look for variations in other cosmic ray phenomena. For example, the muon intensity and neutron intensity have been recorded throughout the day over long periods of time and where time variations have been found.

The search for variations in the rate of arrival of extensive showers has been a field of great interest and great challenge. A variation in sidereal time is of particular interest since it has a direct bearing on the origin of the primary cosmic ray. (Stars in sky are suns. Are there any mechanisms about creation and aceleration of cosmic ray) In extensive air showers, people usually concerned particles with high primary energies. If such a variation is present, it is evident that magnitude of variation is small, of the order of 1% or less. It is extremely difficult to find experiments which give supporting and consistent results for variations. In our experiments, small showers have also been taken account for practical reasons. 

The experiment is divided into 4 parts.

Part I - Check your experimental setup

In this part, you need to verify your data acquisition kit really works. Try to capture data by disable some channels, by changing the geometry of scintillators, and take a look in what are different. You should verify whether the results match to what you had foreseen. For a first glance on your data, you are suggested to extract some basic informations from raw data, such as event rate, order of pulse width, interarrival time.

Part II - Obtain event count rate against time

In this part, you will prepare to handle a long time data acquisition. Make your decision carefully before getting started. It is the time for you to decide how long for the data capturing period, how to place your plastic scintillators.

Part III - Analyse your data

In this part, you have to check the correlation between event count rate and time. Periodicity or other special variation on count rate is our major interest. Some mathematical technique are involved in this part.

Part IV - Discuss the reasons of variation and suggest errors and improvements 

In this part, you are given a chance to explain the results obtained in part III. You are encouraged to have you own insight to develop you own answer. There may be some faults in the experiment, you may help us to figure out the errors in the experiment and state the improvements.