Paul L. Brink

Nonlinear optimal filter technique for analyzing energy depositions in TES sensors driven into saturation

We present a detailed thermal and electrical model of superconducting transition edge sensors (TESs) connected to quasiparticle (qp) traps, such as the W TESs connected to Al qp traps used for CDMS (Cryogenic Dark Matter Search) Ge and Si detectors. We show that this improved model, together with a straightforward time-domain optimal filter, can be used to analyze pulses well into the nonlinear saturation region and reconstruct absorbed energies with optimal energy resolution.

Phonon-mediated superconducting transition-edge sensor x-ray detectors for use in astronomy

In this paper we present preliminary work on a spatial, arrival time and energy resolving x-ray detector for the study of magnetic reconnection in the solar corona. Our detectors are cryogenic phonon-mediated superconducting Transition-Edge Sensors (TESs). X-rays are incident on a silicon substrate; the generated phonons propagate to the opposite side of the substrate and are absorbed in the tungsten TES electron system. Through a novel spatial distribution of four TESs we aim to achieve simultaneous measurement resolutions of ~10 μm, sub μs, and ~4 eV and with count rates of ~1 kHz. This four TES system is described and preliminary data obtained with a prototype two-channel detector is presented.

Confocal sputtering of conformal α-β phase W films on etched Al features

The authors report on thin-film processing improvements in the fabrication of superconducting quasiparticle-trap-assisted electrothermal-feedback transition-edge sensors used in the design of cryogenic dark matter search detectors. The work was performed as part of a detector upgrade project that included optimization of a new confocal sputtering system and development of etch recipes compatible with patterning 40u2009nm-thick, α-β mixed-phase W films deposited on 300–600u2009nm-thick, patterned Al. The authors found that their standard exothermic Al wet etch recipes provided inadequate W/Al interfaces and led to poor device performance. The authors developed a modified Al wet-etch recipe that effectively mitigates geometrical step-coverage limitations while maintaining their existing device design. Data presented here include scanning electron microscope and focused ion beam images of films and device interfaces obtained with the new Al etch method. The authors also introduce a method for quantitatively measurin...

Development of superconducting transition edge sensors for time- and energy-resolved single-photon counters with application to imaging astronomy

Transition Edge Sensor (TES) quantum microcalorimeters can provide intrinsic arrival time and energy resolved measurements of individual photons over a large energy range centered on the optical band. Our TESs consist of thin-film superconduting tungsten pixels on a silicon substrate. The pixels are voltage-biased to remain in the sharp superconducting transition region through negative electrothermal feedback. We report progress on our first imaging TES array of 32 pixels. We describe the experimental apparatus, summarize recent progress, characterize detector performance and outline the future path of TES development.

SuperCDMS SNOLAB Low-Mass Detectors: Ultra-Sensitive Phonon Calorimeters for a Sub-GeV Dark Matter Search

We present the technical design for the SuperCDMS high-voltage, low-mass dark matter detectors, designed to be sensitive to dark matter down to 300 MeV/

Distributed transition-edge sensors for linearized position response in a phonon-mediated X-ray imaging spectrometer

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Phonon-Mediated Distributed Transition-Edge-Sensor X-Ray Detector with Deep Trenches

in mass and resolve individual electron-hole pairs from low-energy scattering events in high-purity Ge and Si crystals. In this paper we discuss some of the studies and technological improvements which have allowed us to design such a sensitive detector, including advances in phonon sensor design and detector simulation. With this design we expect to achieve better than 10 eV (5 eV) phonon energy resolution in our Ge (Si) detectors, and recoil energy resolution below 1eV by exploiting Luke-Neganov phonon generation of charges accelerated in high fields.