What do we know about irradiation problems in High Luminosity LHC?
by Rene Flukiger (Florida State University (US))
Tuesday, 20 March 2012 from to (Europe/Zurich)
at CERN ( 30-7-010 )
at CERN ( 30-7-010 )
In view of the High Luminosity LHC, the behaviour of the superconductor and the insulator in the quadrupoles under the effect of high energy irradiation is an important issue. The expected radiation spectrum is highly complex and comprises several irradiation sources: photons, electrons, neutrons, protons and pions, covering a wide energy range, extending up to values well above 1 GeV. However, the worldwide available energy sources cover only a part of this energy spectrum; in addition, the limited flux of most sources does not allow reaching significant fluences in a realistic time. It follows that for predicting the behaviour of the quadrupoles, the analysis must comprise both, new experiments with the available radiation sources as well as extended calculations for energies and sources being still inaccessible at the present day. The known data of Nb3Sn superconducting wires submitted to neutron irradiation at energies between 1 and 14 MeV are presented and discussed. The decrease of atomic ordering being identified as the main cause for the change of superconducting properties, an attempt is made to generalize the response to neutron to that of charged particles, e.g. protons and pions. The ongoing neutron and proton irradiation program at CERN for Nb3Sn wires is presented. Little is known about the effects of irradiating Nb3Sn wires with high energy photons and electrons. At low energies these sources seem to cause point defects only, having little effect on Jc. In contrast to the superconductor, photons and electrons are expected to cause substantially higher damage in insulating materials. It appears that a systematic research is needed for a better knowledge of their properties after high energy irradiation. A brief review of recent data is given.
|Organised by||Ezio Todesco|