CosMO Mill

    As seen on the photo, the CosMO Mill consists of two CosMO detectors mounted on a wing arm. The particle rate is measured with a coincidence requirement; a signal must appear in both detectors. Starting at the 90 degree position, data is taken for one hour. Then, a step motor moves the arm by 15 degrees into the new position. This allows the continuous measurement of the dependence of cosmic particle rate on the Zenith angle at an interval of 90 to -90 degrees. Zenith angle dependence of the cosmic particle rate in the angle interval of 90 to -90 degrees.


      The CosMO Mill consists of:

      • two CosMO detectors
      • a DAQ card,
      • a wing arm with the two detectors mounted at 97 cm distance,
      • a step motor and the electronic components to steer the arm,
      • a notebook to control the angle position and for the accumulation of data with the program muonic.

      In order to measure the particle flux in the corresponding angle position and to exclude wrong signals, signals are only accepted if they fulfil the coincidence condition.

      Data Structure

        The datasets available via Cosmic@Web contain: time, air pressure, temperature, angle position, particle rate. More detailed information can be found in the description of the dataset.

        Possible Student Exercises

        • Investigate the particle rate in dependence of the zenith angle.
        • Investigate the influence of weather conditions on the rates.
        • Compare the measurements from different years.
        • Compare the mill's rates with those of the Trigger Hodoscope.
        • Compare with own measurements performed with the CosMO or Kamiokannen experiments.

        Example Diagrams

          At Cosmic@Web you will find few example diagrams using the Session-ID CosMO-Muehle.

          Frequency Distribution of the Muon Rate


          Muon Rate - Angle - Air Pressure Diagram