Fiber Temperature Sensor

Superconducting magnets are used to manipulate particles in high energy physics. The windings of superconducting magnets must be monitored to ensure that temperature does not rise above the superconducting transition. Such a “quenching” accident caused $10M damage and shut down the large hadron collider at CERN for a year. A method for monitoring temperature that is immune to electrical noise is needed. Nitrogen vacancy (NV) or silicon vacancy (SiV) diamonds offer a way to monitor temperature optically. The NV center has spin sublevels split by D0 ≈ 2.8 GHz, while the SiV center has sublevels split by 50 GHz. These values are comparable to kT = 100 GHz at 5 K, the coil temperature, therefore the relative populations are sensitive to small changes in temperature. Fiber-optic readout of the populations ensures excellent immunity to electrical noise. The Phase I research will investigate spectroscopic techniques for measuring the sublevel population in both NV and SiV to determine temperature. In addition, the research will investigate fiberized designs that allow the probe to be integrated with superconducting coils. Successful Phase I and Phase II will lead to sales of probes and readout electro-optics for measuring temperature in cryogenic systems. Additional commercial markets include temperature monitoring for Magnetic Resonance Imaging.