I've been looking lately at using an already constructed superconducting magnet instead of building my own for the upcoming experiment, (an Experimental Search for the Bremsstrahlung Radiation Predicted by the Hole Theory of Superconductivity). The issue at hand is that the bore isn't large enough to accept the originally planned 3.8 cm radius spherical Pb sample. I took a look this morning at what reducing the sample size would do to the energy of the predicted radiation in electron volts as well as what the dependency of the radiation flux would be with respect to sample size. The two formula for the energy and the flux (pictures 1 and 2) are:
See the aforementioned proposal as well as reference 2 for more details.
Plotting each of these versus R, the radius of the sample gave the following plots, (pictures 3 and 4). If the radius is reduced all the way down to 2 cm, the fall off in energy isn't unacceptable. It still lands in the ballpark of 160 keV which should light up the NaI detector just fine. Where I run into trouble is in the flux. Because of the R squared dependency it goes down by a factor of three.
1. Experimental proposal and such
2. Paper on radiation predicted by the hole theory of superconductivity
Hirsch J. (2003). Charge expulsion and electric field in superconductors, Physical Review B, 68 (18) DOI: 10.1103/PhysRevB.68.184502