The π0 → γγ decay rate is dominated by the chiral anomaly with 4.1± 1.0 % isospin breaking chiral corrections(proportional to the mass difference of the up and down quarks). A new measurement at Jefferson Lab using the Primakoff effect(PrimEx) is presented with a total error of 3.0%. Great care was taken to reduce systematic errors; this was checked with pair production and Compton scattering m...

We describe a IJirect Linear Algebraic I)econvolution (DI,AI)) approach to imaging of data from Compton ~-ray telescopes. lrnposition of the additional physical constraint, that all components of the model bc non-negative, has been found to have a powerful effect in stabilizing the results, giving spatial resolution at or near the instrumental limit. A companion paper (Dixon et al. 1993) presen...

A tightly focused laser beam (laser wire) is used for measurement of transverse electron beam sizes in storage rings and linear colliders. It is assumed that the laser beam does nothing with the electron beam except Compton scatter-ings which happen with a rather small probability. In reality , electrons crossing the laser beam get kicks (with 100% probability) proportional to the square of the...