For Teachers or Teacher - Student Teams

Summer, 2001

  • The first activity of each teacher or teacher-student team is to construct a pair of scintillators and use them with some basic recording device (oscilloscope, discriminator plus counter, ...) to detect cosmic rays; verify that the rates observed are in general agreement with expectations. Regardless of the success of more sophisticated activities, the counter pair would then form a basis for later investigations with students in the teacher's classroom.

  • In addition to the basic activity of building and testing their own simple detector, teachers may contribute to some of the other activities below. Teachers will vary in their prior experience. A teacher with minimal preparation may only learn something about these topics in the course of the summer; teachers with more preparation or teachers able to spend more time either during the summer, during the year, or be returning a second summer, may make substantial contributions.

  • Evaluation of detector modules and their elements.

  • 1. Study of detector elements: scintillators and their light collection and its uniformity; photomultipliers and low light yield (down to one photoelectron) techniques; discriminators, oscilloscopes, and counters.

    2. Evaluation of detector performance: bench (or roof-top?) tests. Study uniformity of single-particle response; multiparticle performance (how should pulses be shaped? what about use of sampling techniques? 8-bit digital scope PC modules?) Computer simulation of response based on bench tests? Performance variation with temperature. Comparison of expected with observed variations of rates with atmospheric pressure.

    3. Study of timing techniques: separation of events in large detectors and use of time information to estimate the number of particles in a shower and particle direction. Can interpolation techniques be used to improve timing? Can fast transient recorders be used?

    4. Estimation of particle count from pulse height? Can logarithmic converters be used?

    5. Use of large-area scintillators, and perhaps 5-inch PMT's?

  • Geodesy, GPS techniques

  • Precision of space and time GPS measurements should be estimated, Drift errors for the GPS measurements should be measured, and their sources estimated. The effect of the ephemeris corrections should be calculated. Position as measured on the U.S. Geologic Survey (7.5') quadrangle map should be compared with the GPS measurements.

  • Simulation codes

  • There is a standard Kaskade simulation code which can be installed and used to study cosmic ray shower characteristics. The overburden seen by detectors inside a building can be simulated and behavior compared for detectors inside and outside a building. What is the energy range of the parents of the ground-level muons? How are correlated signals to be interpreted? Two showers coincident by accident or proof of an extended shower?

  • Electronics

  • In order to compare results between different high schools (detector installations) there must be time stamping of each event. Precision of time-stamping can range from milliseconds with simple PC clocks to of order 10's of nanoseconds with the full GPS precision. Should shift registers and transient recorder techniques be used? Relatively simple PC-based digital oscilloscope functions are available and may be a satisfactory solution, but the problems of how to encode the epoch and the subdivision of the 1 sec. signals. Would wireless techniques be useful for communication between off-site detectors? What shaping should be done of the signals? Are there connections to information theory which should be exploited?

  • Ideas about triggering and arrays.

  • Use of the correlated information from more than one station requires good mutual timing. For two stations with good GPS local time, network delays and dispersions may allow sufficient timing precision. Use of a pre-trigger and rolling transient recorders might allow real-time large-area triggers. Any trigger should be flexible, which means downloading the trigger or programming it, most likely. The Xilinx programmable array, of which we have some modules available, is one candidate. The trigger could be downloaded, with slow communication with the detector box via the PC parallel port. Whatever the initial decision about the method of communicating between two stations, it may be expected to evolve with the rapid technological changes which have come to seem almost standard.

    As you can see from the list above, there are a lot of ideas. And many other ideas will come up. If you have questions you can reach us at: jth@pitt.edu (Julia Thompson) or kraus@pitt.edu (David Kraus)