Biopolymer mass spectrometer with cryogenic particle detectors

Neutrino mass and low-temperature calorimetry

“…These range from a search for neutrinoless double beta decay [43], which would test the "Standard Model" of electroweak interactions, to biological applications in which the cryogenic detector provides great gain of detection efficiency in mass spectrometry of DNA fragments. [44] One can turn the calorimeter problem around: knowing the energy deposited by a particle and the temperature rise, the heat capacity can be determined. This has been used to obtain the heat capacity of silicon at low temperatures.…”

MS Detectors

“…In contrast to EM or MCP ionization detectors, which are markedly less efficient at generating secondary electrons from larger, complex, biomolecular ions, cryodetectors exhibit no falloff in response at high mass. The recent interest in using cryodetectors for MS has been strongly motivated by the desire to improve measurement detection, sensitivity, and uniformity of response for very large biomolecules (2,3,24).…”

“…The detector is composed of a 16-element STJ array that operates at 0.3 K. The STJ array allows individual STJs to remain small (~100 µm 2 ) to enable single-ion detection on any array element (the total detector area is ~1 mm 2 ). The detector cryostat is based on closed-circuit, regenerative 3 He cryosorption technology, which is controlled automatically and can operate for 20 h between regeneration cycles. It can detect 1 fmol of IgG (150 kDa); differentiate charge-state information from ion-energy measurements ( Figure 3); and measure megadalton-sized, singly charged ions of immunoglobulin M as well as von Willebrand factor proteins and their multimers (28).…”

“…Thus, it has remained an area of rather understated importance, despite the fundamental need to better "see" ions. Only a few groups have recognized the demand for new MS detectors, and only one lone special journal issue on MS detectors has appeared (1)(2)(3)(4). Some initially promising developments, including work on electro-optical arrays, never quite took hold in the MS community (5,6).…”

Identification of microorganisms using superconducting tunnel junctions and time-of-flight mass spectrometry

“…The suitability of mass spectrometry has already been demonstrated. [l] In this paper, we describe ongoing efforts to identify microorganisms using timeof-flight mass spectrometry and superconducting tunnel junction detectors, The use of cryogenic detectors for mass spectrometry is relatively new [2][3][4] but they have a number of properties which merit exploration. First, the sensitivity of cryogenic detectors is expected to be independent of ion mass, unlike detectors based on secondary electron emission whose sensitivity decreases for heavier, slower ions.…”