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Echternach, P. M.

Publications and source records attributed to Echternach, P. M..

16 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2012

Development of Fast, Background-Limited Transition-Edge Sensors for the Background-Limited Infrared/Sub-Millimetre Spectrograph (BLISS) for SPICA

We report experimental progress toward demonstrating background-limited arrays of membrane-isolated transition-edge sensors (TESs) for the Background Limited Infrared/Sub-mm Spectrograph (BLISS). BLISS is a space-borne instrument with grating spectrometers for wavelengths lambda = 35-435 microns and with R = lambda/(delta)lambda approx. 500. The goals for BLISS TESs are: noise equivalent power (NEP) = 5x10(exp -20) W/Hz(1/2) and response time t<30ms. We expect background-limited performance from bilayers TESs with T(sub c)=65mK and G=15fW/K. However, such TESs cannot be operated at 50mK unless stray power on the devices, or dark power PD, is less than 200aW. We describe criteria for measuring P? that requires accurate knowledge of TC. Ultimately, we fabricated superconducting thermistors from Ir (T(sub c) > or = 135mK) and Mo/Cu proximitized bilayers, where T(sub c) is the thermistor transition temperature. We measured the Ir TES arrays in our 50mK adiabatic demagnetization refrigerator test system, which can measure up to eight 1x32 arrays simultaneously using a time-division multiplexer, as well as our single-pixel test system which can measure down to 15mK. In our previous Ir array measurements our best reported performance was NEP=2.5x10(exp -19) W/Hz(1/2) and tapprox.5ms for straight-beam TESs. In fact, we expected NEPapprox.1.5x10(exp -19)W/Hz(1/2) for meander beam TESs, but did not achieve this previously due to 1/f noise. Here, we detail improvements toward measuring the expected NEP and demonstrate NEP=(1.3+0.2)x10(exp -19)W/Hz(1/2) in our single-pixel test system and NEP=(1.6+0.3)x10(exp -19)W/Hz(1/2) in our array test system.

transition-edge sensors↗
NASA NTRS2011

Ultra-Sensitive Transition-Edge Sensors for the Background Limited Infrared/Sub-mm Spectrograph (BLISS)

We report progress in fabricating ultra-sensitive superconducting transition-edge sensors (TESs) for BLISS. BLISS is a suite of grating spectrometers covering 35-433 micron with R approx. 700 cooled to 50 mK that is proposed to fly on the Japanese space telescope SPICA. The detector arrays for BLISS are TES bolometers readout with a time domain SQUID multiplexer. The required noise equivalent power (NEP) for BLISS is NEP = 10(exp -19) W/Hz(exp 1/2) with an ultimate goal of NEP= 5 x 10(exp -20) W/Hz(exp 1/2) to achieve background limited noise performance. The required and goal response times are tau = 150 ms and tau = 50ms respectively to achieve the NEP at the required and goal optical chop frequency 1-5 Hz. We measured prototype BLISS arrays and have achieved NEP = 6 x 10(exp -18) W/Hz(exp 1/2) and tau = 1.4 ms with a Ti TES (T(sub C) = 565 mK) and NEP approx. 2.5 x 10(exp -19) W/Hz(exp 1/2) and tau approximates 4.5 ms with an Ir TES (T(sub C) = 130 mK). Dark power for these tests is estimated at 1-5 fW.

transition-edge sensors (TESs)↗
NASA NTRS2008

Electron Heating and Quasiparticle Tunnelling in Superconducting Charge Qubits

We have directly measured non-equilibrium quasiparticle tunnelling in the time domain as a function of temperature and RF carrier power for a pair of charge qubits based on the single Cooper-pair box, where the readout is performed with a multiplexed quantum capacitance technique. We have extracted an effective electron temperature for each applied RF power, using the data taken at the lowest power as a reference curve. This data has been fit to a standard T? electron heating model, with a reasonable correspondence with established material parameters.

Single Cooper Pair Box↗
NASA NTRS2000

Fabrication of an Aluminum Based Hot Electron Mixer for Terahertz Applications

Aluminum based diffusion cooled hot electron bolometers (HEB) mixers, predicted to have better noise, bandwidth and to require less LO power than Nb based diffusion cooled HEBs, have been fabricated. Preliminary DC tests were performed. The bolometer elements consisted of short (0.1 to 0.3 micron), narrow (0.08 to 0. 15 micron) and thin (11 nm) aluminum wires connected to large contact pads consisting of a novel trilayer Al/Ti/Au. The patterns were defined by electron beam lithography and the metal deposition involved a double angle process, the Aluminum wires being deposited straight on and the pads being deposited at a 45 degree angle without breaking vacuum. The Al/Ti/Au trilayer was developed to provide a way of making contact between the aluminum wire and the gold antenna. The Titanium layer acts as a diffusion barrier to avoid damage of the Aluminum contact and bolometer wire and to lower the transition temperature of the pads to below that of the bolometer wire. The Au layer avoids the formation of an oxide on the Ti layer and provides good electrical contact to the IF/antenna structure. The resistance of the bolometers as a function of temperature was measured. It is clear that below the transition temperature of the wire (1.8K) but above the transition temperature of the contact pads (0.6K), the proximity effect drives most of the bolometer wire normal, causing a very broad transition. This effect should not affect the performance of the bolometers since they will be operated at a temperature below the TC of the pads. This is evident from the IV characteristics measured at 0.3K. RF characterization tests will begin shortly.

Echternach, P. M.↗
NASA NTRS1998

Low Temperature Microgravity Physics Facility

We present here a brief overview of the Microgravity Fundamental Physics discipline requirements for a Low Temperature Microgravity Physics Facility and describe the plans for the development of this facility which will be attached to the Japanese Experiment Module Exposed Facility on Board the International Space Station.

temperature↗