17 keV-photon induced damage of Bi-2212 whiskers by synchrotron μ-beam exposure

Experimental data show that the normal state resistivity of superconducting Bi2Sr2CaCu2O8+δ (Bi-2212) whiskers increases after a six-hours irradiation by a synchrotron μ-beam with 17 keV photons. We analyze this result on the basis of previously reported effects in Bi-2212 whiskers due to ageing or heating processes. A finite element model of the experimental setup clarifies that the heat load induced by the microbeam has to be excluded as a possible cause for the material changes. The knock-on the interstitial, loosely bound, O species by secondary electrons is discussed as the most likely mechanism responsible for this effect.