Development of Superconducting Strip Line Detectors (SSLDs) for Time-of-Flight Mass Spectrometers (TOF-MS)

We have succeeded in obtaining mass spectra of peptides or proteins with superconducting stripline detectors (SSLDs) which have a meander structure similar to so called superconducting single photon detectors (SSPDs). Encouraged by the previous results on the NbN-SSLD for time-of-flight mass spectrometry (TOF-MS), we fabricated other SSLDs from Nb or YBCO thin films. Because of a small London penetration depth, the Nb-based SSLD is expected to have a fast response time. Another promising superconducting material is YBCO which has a critical temperature around 90 K. Operation at higher temperatures will make a noticeable impact on the practical application to MS. The optimum SSLD design for MS should be totally different from that of SSPD in order to realize both of a meaningful sensitive area for high detection efficiency and a reasonably-fast response time for high mass resolution. We made SSLDs with a variety of stripline structures from different materials. One of the key factors for the SSLD design is kinetic inductance. In this study, TOF-MS spectra of biomolecules are presented, and the relationship between SSLD geometry and their performance is discussed.