A Simple Dynamics Experiment Based on Acoustic Emission

This paper describes a simple experiment well suited for an undergraduate course in mechanical measurements and/or dynamics, in which physical information is extracted from an acoustic emission signature. In the experiment, a ping–pong ball is dropped onto a hard table surface and the audio signal resulting from the ball–table impacts is recorded. The times between successive bounces, or “flight times”, are used to determine the height of the initial drop and the coefficient of restitution of the impact. The experiment prompts questions about modeling the dynamics of a simple impact problem, including the use of the coefficient of restitution and the importance of accounting for aerodynamic effects

An overview of solar flare results from COMPTEL

The COMPTEL experiment on the Compton Gamma Ray Observatory (CGRO) has been operating in orbit since April of 1991. During that time, COMPTEL has observed several large flares, the most notable of which were several X‐class flares which took place in June of 1991. As a solar instrument, COMPTEL has the capability to measure solar flare radiation in two parallel observing modes. In its telescope mode, COMPTEL is capable of measuring both solar flare photons (in the 0.75–30 MeV range) and solar flare neutrons (in the 20–150 MeV range) using the double scatter technique with a field‐of‐view of ∼1 steradian. This approach also permits the imaging of the incident solar radiations (both photons and neutrons). The burst mode of COMPTEL utilizes two of the lower D2 detectors as large‐area spectroscopy detectors to provide additional data in the 0.6–10 MeV range. Here we shall review both modes of COMPTEL operation and provide an overview of solar flare results which are presently available