Cosmic Ray, Statistics and
Stochastic Processes Topical Group

WWSL Experiments
Data of Previous Experiments
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Introduction

  Experimental Module at the WWSL Oregon site (University of Oregon)   Experimental Module A at the WWSL Moscow site (Moscow Bauman State Technical University)   Experimental Module B at the WWSL Moscow site (Moscow Bauman State Technical University)  

     The photographs above show WWSL's Cosmic Ray Experimental Modules at the Florida site, top, at the Oregon site, bottom left, and at the Moscow site, bottom center and right. Click pictures to enlarge.

     Oregon and Moscow setups, see layout, consist of two scintillating detectors telescope. The signals from the detectors are read out to a coincidence unit. The unit selects events due to cosmic ray particles passing through both detectors. The output signals from coincidence units are collected by a data acquisition system and a computer. For study of penetration properties and composition of cosmic ray, an absorber of variable thickness (a set of lead or tungsten plates) is sandwiched between detectors.

    The telescope of Florida Cosmic ray lab module, see Florida telescope layout, consists of two (upper and lower) 4-detector sections. The lower detector section simultaneously serves as a carrier for the lower absorber lead (Pb) blocks. The upper absorbers carrier (table between lover absorbers and upper detector section) is motorized. Thus, this device serves as a 4-channel telescope, with all 4 channels registering the flux of the cosmic ray in parallel, but each channel has different absorber thickness.

    The sequence of the thicknesses of the lead absorber blocks for the lower carrier, in inches is: 0, 8, 4 and 0.5. For the upper carrier it is 0, 2, 1 and 3 correspondingly. Using a remote control window in the browser, students can rotate the upper carrier to different experimental positions. After the selected position of the table is established, the student takes data from the four channels simultaneously with the different thicknesses of the absorber.

    This gives the student four data points for each measurement period. Thus, the total number of experimental data points is sixteen. The advantages of the design are:

  • The amount of time needed to collect the experimental data is four times shorter. It is a very effective use of the student's time for data collection. Since all four scintillation telescopes are used, all Pb absorber bricks are in service simultaneously;
  • Since the student is able to take data for the four experimental points concurrently, he/she can immediately observe the effect of absorption of the cosmic rays (nuclear charged particles) in matter;
  • The lead absorbers have been situated to give absorber thicknesses from 0-4 inches in 0.5 inch increments, and from 4-11 inches in 1 inch increments. This is optimal because the maximum changes occur in the region from 0 to 4 inches of Pb-absorber thickness, thus the data region of greatest interest lies from 0-4 inches;
  • It is possible to use this setup to investigate additional effects of cosmic rays, such as: the study of the cosmic-ray showers in the atmosphere; study of the muon decay, etc.

     Student projects which can be pursued using these setups can be divided into two groups:
         Projects studying the properties of cosmic rays and the experimental methods and apparatus of cosmic ray and high energy physics;
         Projects studying the properties of random processes (in this case, the flux of cosmic ray particles is considered as a generator of random processes).

     The first group may contain the following projects:
  • The composition of cosmic rays near the earth's surface;
  • The angular distribution of cosmic ray flux;
  • Fluctuations in energy loss of charged particles;
  • The effect of the detector's dead time on the character of the statistical distribution of the signals.
     The second group may contain the following projects:
  • Properties of Poisson statistics;
  • The relationship between binomial, Poisson and normal distributions;
  • Fitting data to different statistical distributions;
  • The "waiting time paradox" for Poisson processes;
  • Study of correlation in stochastic processes.
     With wide choices of projects available for each experimental setup, educators can select sets of projects which best suit their students.