 |
 |
I have some early results from Gismo on polar angle dependence of electrons in the LCD calorimeters. They are quite surprising (to me at least) for the Small. I find that the energy response for 10 GeV electrons is 20% different in the barrel and endcap, even for equal incident angles (eg 15 and 75 degrees). It turns out that the barrel response is sensitive to the magnetic field: it drops by 20% (to match the endcap within a few percent) when the field is turned off. There is a step when the particles move from the barrel to the endcap in the scan. The endcap response does not depend on B. I tried the exercise of making the entire calorimeter sensitive and found that the results were then independent of barrel, endcap and magnetic field. This suggests that the sampling fraction is changing with B. The Large detector shows only a small, few percent, variation in angle from the barrel through the endcap. I don't have a model for why there would be such a large effect of the field in the Small barrel. I have asked Ray Frey to fire up EGS4 for a comparison and David Wagner & Co. to check their GEANT3 simulations. It could have to do with the thin silicon. Hopefully we'll see soon if this is real or a figment of Gismo's imagination! Stay tuned... Richard -- Richard Dubois SLD, Stanford Linear Accelerator Center [log in to unmask] http://www.slac.stanford.edu/~richard/ 650-926-3824 650-926-2923 (FAX)