Radiation Hardness of Superconducting Magnetic Field Detectors Made by Heavy-Ion Lithography

Radiation hardness of a magnetic field detector, based on YBCO superconductor strips locally nanostructured by means of high-energy heavy-ion lithography, was tested under 3.5 MeV proton as well as under fast neutron beams. No change was detectable within the experimental errors in the sensor calibration curves up to a proton fluence of 4.3 ldr 10¹⁴ cm^-2. On line response of the device, under proton flux of about 3ldr10¹⁰ cm^-2s^-1, showed a temporary increase of the nanostructured zone resistance that vanishes after the beam switching off. Irradiation with fast neutrons at a fluence of 4.14ldr10¹³ cm^-2 slightly changed the critical temperature of the as-grown regions but, remarkably, the nanostructured areas, sensitive to magnetic field, held the same performances.

I. Introduction

The development of long-term radiation-hard sensors is at present time requested for applications in space or in large facilities such as accelerators or fusion machines. A sensor operating in such hostile environments is usually exposed to radiation spectra that in space environment are mainly constituted by protons with different energies [1] and in accelerators as Large Hadron Collider (LHC) by different hadrons [2]. Due to the complexity of such spectra, radiation level predicted for the electronic devices working in these hostile ambients are often expressed in terms of total absorbed dose in Si (to consider the effect of the ionising radiation), of 1-MeV equivalent neutrons/cm² fluence in Si (to take into account displacement damage) and of number of hadrons/cm² with energy above 20 MeV (to study the Single Event Errors) [2]. For each of these damage mechanisms the required radiation hardness threshold depends on the working conditions [1], [3], [4].