T. M. Lanting

McGill University, Montréal, Quebec, Canada

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Publications (19)27.75 Total impact

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    ABSTRACT: We present thermal Sunyaev-Zel'dovich effect (SZE) measurements for 42 galaxy clusters observed at 150 GHz with the APEX-SZ experiment. For each cluster, we model the pressure profile and calculate the integrated Comptonization $Y$ to estimate the total thermal energy of the intracluster medium (ICM). We compare the measured $Y$ values to X-ray observables of the ICM from the literature (cluster gas mass $M_{gas}$, temperature $T_X$, and $Y_X =M_{gas}T_X$) that relate to total cluster mass. We measure power law scaling relations, including an intrinsic scatter, between the SZE and X-ray observables for both the X-ray selected and uniform REFLEX-DXL cluster sample and the full ad hoc APEX-SZ sample. We observe that the lack of uniform X-ray analysis for the full cluster sample introduces significant variability into the measured scaling relations and dominates the level of intrinsic scatter. For the REFLEX-DXL sample, we find results consistent with a self-similar model of cluster evolution dominated by gravitational effects. Comparing to predictions from numerical simulations, these scaling relations prefer models that include cooling and feedback in the ICM. Lastly, we find that the $Y-Y_X$ scaling relation has the lowest measured intrinsic scatter.
    04/2014;
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    ABSTRACT: A technological milestone for experiments employing transition edge sensor bolometers operating at sub-Kelvin temperature is the deployment of detector arrays with 100s-1000s of bolometers. One key technology for such arrays is readout multiplexing: the ability to read out many sensors simultaneously on the same set of wires. This paper describes a frequency-domain multiplexed readout system which has been developed for and deployed on the APEX-SZ and South Pole Telescope millimeter wavelength receivers. In this system, the detector array is divided into modules of seven detectors, and each bolometer within the module is biased with a unique ∼MHz sinusoidal carrier such that the individual bolometer signals are well separated in frequency space. The currents from all bolometers in a module are summed together and pre-amplified with superconducting quantum interference devices operating at 4 K. Room temperature electronics demodulate the carriers to recover the bolometer signals, which are digitized separately and stored to disk. This readout system contributes little noise relative to the detectors themselves, is remarkably insensitive to unwanted microphonic excitations, and provides a technology pathway to multiplexing larger numbers of sensors.
    The Review of scientific instruments 07/2012; 83(7):073113. · 1.52 Impact Factor
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    ABSTRACT: A technological milestone for experiments employing Transition Edge Sensor (TES) bolometers operating at sub-kelvin temperature is the deployment of detector arrays with 100s--1000s of bolometers. One key technology for such arrays is readout multiplexing: the ability to read out many sensors simultaneously on the same set of wires. This paper describes a frequency-domain multiplexed readout system which has been developed for and deployed on the APEX-SZ and South Pole Telescope millimeter wavelength receivers. In this system, the detector array is divided into modules of seven detectors, and each bolometer within the module is biased with a unique ~MHz sinusoidal carrier such that the individual bolometer signals are well separated in frequency space. The currents from all bolometers in a module are summed together and pre-amplified with Superconducting Quantum Interference Devices (SQUIDs) operating at 4 K. Room-temperature electronics demodulate the carriers to recover the bolometer signals, which are digitized separately and stored to disk. This readout system contributes little noise relative to the detectors themselves, is remarkably insensitive to unwanted microphonic excitations, and provides a technology pathway to multiplexing larger numbers of sensors.
    12/2011;
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    ABSTRACT: SPTpol will consist of an 850 element polarization sensitive bolometric camera deployed to the South Pole Telescope in late 2011. This camera is optimized for measurement of the polarization of the cosmic microwave background with arcminute resolution. These measurements will be used to constrain neutrino masses and to constrain the amplitude of gravitational waves from inflation. The camera includes two detector architectures that observe in two different frequency bands. At 150 GHz, SPTpol will use 650 feedhorn‐coupled TES polarimeters fabricated at NIST. At 90 GHz, it will use 200 absorber‐coupled polarimeters developed at Argonne National Lab. The NIST pixels will be coupled to the telescope using a monolithic array of corrugated feeds and the Argonne devices will be coupled with individually machined contoured feeds. The entire focal plane will be readout using a digital frequency‐domain multiplexer system. We provide an overview of the project, describe the detectors and discuss the design of this system.
    AIP Conference Proceedings. 12/2009; 1185(1):511-514.
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    ABSTRACT: The SPT‐SZ is, currently, the most powerful instrument for detecting galaxy clusters through the Sunyaev‐Zel’dovich (SZ) effect. The SPT‐SZ focal plane consists of over 700 background limited TES spiderweb bolometers observing in three different pass bands (90 GHz, 150 GHz, and 220 GHz) readout by a frequency domain SQUID multiplexer. Together with the 10‐m South Pole Telescope, SPT‐SZ has realized exceptional sensitivity at arcminute resolution over a one degree field of view and is the first instrument to discover new galaxy clusters through the SZ effect. We will discuss the SPT‐SZ design and deployment, present initial results from the first two seasons, and outline future survey plans.
    AIP Conference Proceedings. 12/2009; 1185(1):475-477.
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    ABSTRACT: The South Pole Telescope (SPT) is a 10 m diameter, wide-field, offset Gregorian telescope with a 966-pixel, multi-color, millimeter-wave, bolometer camera. It is located at the Amundsen-Scott South Pole station in Antarctica. The design of the SPT emphasizes careful control of spillover and scattering, to minimize noise and false signals due to ground pickup. The key initial project is a large-area survey at wavelengths of 3, 2 and 1.3 mm, to detect clusters of galaxies via the Sunyaev-Zeldovich effect and to measure the small-scale angular power spectrum of the cosmic microwave background (CMB). The data will be used to characterize the primordial matter power spectrum and to place constraints on the equation of state of dark energy. A second-generation camera will measure the polarization of the CMB, potentially leading to constraints on the neutrino mass and the energy scale of inflation.
    Publications of The Astronomical Society of The Pacific - PUBL ASTRON SOC PAC. 07/2009; 123.
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    ABSTRACT: The South Pole Telescope (SPT) is conducting a Sunyaev-Zel'dovich (SZ) effect survey over large areas of the southern sky, searching for massive galaxy clusters to high redshift. In this preliminary study, we focus on a 40 deg2 area targeted by the Blanco Cosmology Survey (BCS), which is centered roughly at right ascension 5h30m, declination –53° (J2000). Over two seasons of observations, this entire region has been mapped by the SPT at 95 GHz, 150 GHz, and 225 GHz. We report the four most significant SPT detections of SZ clusters in this field, three of which were previously unknown and, therefore, represent the first galaxy clusters discovered with an SZ survey. The SZ clusters are detected as decrements with greater than 5σ significance in the high-sensitivity 150 GHz SPT map. The SZ spectrum of these sources is confirmed by detections of decrements at the corresponding locations in the 95 GHz SPT map and nondetections at those locations in the 225 GHz SPT map. Multiband optical images from the BCS survey demonstrate significant concentrations of similarly colored galaxies at the positions of the SZ detections. Photometric redshift estimates from the BCS data indicate that two of the clusters lie at moderate redshift (z ~ 0.4) and two at high redshift (z 0.8). One of the SZ detections was previously identified as a galaxy cluster in the optical as part of the Abell supplementary southern cluster catalog and in the X-ray using data from the ROSAT All-Sky Survey (RASS). Potential RASS counterparts (not previously identified as clusters) are also found for two of the new discoveries. These first four galaxy clusters are the most significant SZ detections from a subset of the ongoing SPT survey. As such, they serve as a demonstration that SZ surveys, and the SPT in particular, can be an effective means for finding galaxy clusters.
    The Astrophysical Journal 07/2009; 701(1):32. · 6.73 Impact Factor
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    ABSTRACT: We are developing a frequency-multiplexed readout for arrays of high-resolution gamma detectors based on superconducting transition edge sensors (TESs). Each sensor is part of an LCR resonant circuit and is biased at an identifying carrier frequency. Several carrier signals are added and amplified with a single SQUID preamplifier at 4 K. Gamma absorption modulates the amplitude of the carrier, and demodulation at room temperature retrieves the initial temperature evolution of the sensor. This multiplexing system has originally been developed to read out large arrays of bolometers for cosmic microwave background studies. To accommodate the faster gamma-ray signals, its demodulator bandwidth is being extended to ~20 kHz to allow reading out up to eight TESs with a detector bandwidth of ~10 kHz. Here we characterize the system noise performance and show how this multiplexing scheme can be adapted to read out arrays of superconducting gamma-ray detectors.
    IEEE Transactions on Applied Superconductivity 07/2007; · 1.20 Impact Factor
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    ABSTRACT: The apex-sz instrument is designed for the discovery and study of galaxy clusters at mm-wavelengths using the Sunyaev Zel’dovich effect. The receiver consists of 320 superconducting transition edge sensor (TES) bolometers cooled to 250 mK with the combination of a three stage He sorption fridge and mechanical pulse tube cooler. The detectors are instrumented with a frequency domain multiplexing readout system. The receiver is mounted on the 12 m apex telescope located at 5100 m on the Atacama plateau in Chile. For the first light engineering deployment of December 2005, the receiver was configured with a 55 element wedge of the bolometers and operating in the 150 GHz atmospheric window. During the engineering run we achieved significant milestones in our instrumentation development efforts, including celestial observations with a monolithically fabricated TES bolometer array cooled with a mechanical cooler and successful implementation of a SQUID-based MHz AC-biased readout. These technology demonstrations point the way toward future large TES bolometer array instruments. Here we describe the results of this deployment and future plans for the apex-sz instrument.
    New Astronomy Reviews 12/2006; 50(11-12):960-968. · 1.82 Impact Factor
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    ABSTRACT: We have demonstrated frequency-domain readout multiplexing of eight channels for superconducting transition-edge sensor bolometer arrays. The multiplexed readout noise is 6.5pA/√Hz, well below the bolometer dark noise of 15–20pA/√Hz. We measure an upper limit on crosstalk of 0.004 between channels adjacent in frequency which meets our design requirement of 0.01. We have observed vibration insensitivity in our frequency-domain multiplexed transition-edge sensors, making this system very attractive for telescope and satellite observations. We also discuss extensions to our multiplexed readout. In particular, we are developing a SQUID flux-locked loop that is entirely cold and collaborating on digital multiplexer technology in order to scale up the number of multiplexed channels.
    Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 01/2006; 559(2):793-795. · 1.14 Impact Factor
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    ABSTRACT: We describe our frequency-domain readout multiplexer for transition-edge sensor (TES) bolometers and present measurements of an eight-channel multiplexer. Each sensor is biased with a sinusoidal bias at a distinct frequency. As the sensor absorbs power, it amplitude-modulates its sinusoidal bias. Sensor currents are summed and measured with a single superconducting quantum interference device (SQUID) array. The SQUID array consists of 100 dc-SQUID's in series and is operated with shunt feedback electronics which have a slew rate of 1.210<sup>7</sup> Φ<sub>0</sub>/s. A tuned filter consisting of an inductor and capacitor are placed in series with each sensor to both limit the bandwidth of the Nyquist noise from each sensor and to allow us to bias all multiplexed sensors with a common wire. We place an upper limit on crosstalk between adjacent channels of 0.004, well below our design requirements. Demodulated noise spectra from multiplexed sensors show the expected white noise levels at frequencies above 200 mHz.
    IEEE Transactions on Applied Superconductivity 07/2005; · 1.20 Impact Factor
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    ABSTRACT: We demonstrate an eight-channel frequency-domain readout multiplexer for superconducting transition-edge sensors (TESs). Each sensor is biased with a sinusoidal voltage at a unique frequency. The sensor currents are summed and measured with a single superconducting quantum interference device (SQUID) array. The 100-element SQUID array is operated with shunt feedback electronics that have a slew rate of 1.2×10<sup>7</sup> Φ<sub>0</sub>/ s at 1 MHz . The multiplexer readout noise is 6.5 pA / √ Hz , which is well below the expected sensor noise of 15 pA / √ Hz . We measure an upper limit on adjacent channel crosstalk of 0.004, which meets our design requirements. The demodulated noise spectra of multiplexed TESs are white at frequencies down to 200 mHz .
    Applied Physics Letters 04/2005; · 3.79 Impact Factor
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    ABSTRACT: Fabrication of arrays of a thousand or more sensors is becoming practical. However, readout of these arrays remains a major instrumental challenge. We address this challenge using frequency-domain multiplexing of signals from an array of superconducting transition-edge sensors (TES). Each TES sensor is connected in series with an LC tuned circuit and biased with an alternating current at a selected frequency, ranging from 380kHz to 1MHz.The signal from each sensor amplitude-modulates its respective bias current. The LC filter reduces the bandwidth of the Johnson noise from the remaining sensors. The signals are combined at a current summing node and measured with a single superconducting quantum interference device (SQUID) array (100 elements). We have developed a custom SQUID controller with a measured slew rate of 107Φ0/s at 1MHz.We designed and fabricated photolithographed LC filters. With these filters we have demonstrated multiplexing with two TES sensors and are preparing to scale up to 32 sensors.
    Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 01/2004; 520(1):548-550. · 1.14 Impact Factor
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    ABSTRACT: Cryogenic sensors composed of transition-biased superconducting films have demonstrated remarkable sensitivity at γ-ray, x-ray, optical, and far-infrared to millimeter wavelengths. However, for these sensors to find widespread application in astronomy and materials analysis, technologies for building and reading out large arrays are required. We are currently developing a frequency-domain multiplexing scheme for the read-out of large numbers of microcalorimeters using a much smaller number of amplifiers. In this scheme, each sensor is biased at an identifying frequency and operated in a series LC circuit to suppress out-of-band noise. Here, we present results demonstrating the undegraded operation of two γ-ray sensors multiplexed using this technique. In addition, we provide a series of design rules which relate the minimum bias frequency and the values of the reactive elements in the system to a small number of sensor properties. Finally, we discuss the ultimate limits on the number of sensors that can be measured with a single amplifier.
    IEEE Transactions on Applied Superconductivity 07/2003; · 1.20 Impact Factor
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    ABSTRACT: We describe the development of a frequency-domain multiplexer (MUX) to read out arrays of superconducting transition-edge sensors (TES). Fabrication of large-format arrays of these sensors is becoming practical; however, reading out each sensor in the array is a major instrumental challenge. Frequency-domain multiplexing can greatly simplify the instrumentation of large arrays by reducing the number of SQUID's (superconducting quantum interference devices) and wires to the low temperature stages. Each sensor is AC biased at a different frequency, ranging from 380 kHz to 1 MHz. Each sensor signal amplitude-modulates its respective AC bias frequency. An LC filter associated with each sensor suppresses Johnson noise from the other sensors. The signals are combined at a current summing node and measured by a single SQUID. The individual signals from each sensor are then lock-in detected by room temperature electronics. Test chips with fully lithographed LC filters for up to 32 channels have been designed and fabricated. The capacitance and inductance values have been measured and are close to the design goals. We discuss the basic principles of frequency-domain multiplexing, the design and testing of the test chips, and the implementation of a practical system.
    IEEE Transactions on Applied Superconductivity 07/2003; · 1.20 Impact Factor
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    ABSTRACT: We describe the development of a frequency-domain multiplexer (MUX) to read out arrays of superconducting transition-edge sensors (TES). Fabrication of large-format arrays of these sensors is becoming practical; however, reading out each sensor in the array is a major instrumental challenge that is possibly solved by frequency-domain multiplexing. Each sensor is AC biased at a different frequency, ranging from 380 kHz to 1 MHz. The sensor signal amplitude-modulates its respective AC bias frequency. An LC filter associated with each sensor suppresses Johnson noise from the other sensors. The signals are combined at a current summing node and measured by a single superconducting quantum interference device (SQUID). The individual signals from each sensor are then lock-in detected by room temperature electronics. Test chips with fully lithographed LC filters for up to 32 channels have been designed and fabricated. The capacitance and inductance values have been measured and are close to the design goals. We discuss the basic principles of frequency-domain multiplexing, the design and testing of the test chips, and the implementation of a practical system.
    Proc SPIE 02/2003;
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    ABSTRACT: The APEX-SZ experiment is a sky survey designed to discover galaxy clusters via the Sunyaev–Zel’dovich effect at millimeter wavelengths. We describe the components of the instrument, including the 12 m Atacama Pathfinder Experiment telescope, optics, Transition-edge sensor bolometer array and SQUID readout. APEX-SZ will begin observations in 2004.
    New Astronomy Reviews 01/2003; · 1.82 Impact Factor
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    ABSTRACT: We present the multiplexed readout of two gamma-ray microcalorimeters made from transition-edge sensors. We use a frequency-domain multiplexing scheme in which each sensor is biased at an identifying frequency. We show that the energy resolution of the sensors is unaffected by multiplexing, and that crosstalk between the sensors is negligible. Our results indicate the feasibility of multiplexing 30 sensors or more to one readout line. © 2002 American Institute of Physics.
    Applied Physics Letters 06/2002; 81(1):159-161. · 3.79 Impact Factor
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    ABSTRACT: We will report on the APEX-SZ bolometer camera which houses a 320 element Transition-Edge Sensor (TES) bolometer array designed to survey for galaxy clusters using the 12-meter diameter APEX telescope sited in Chile. Design and fabrication of the TES bolometer array will be discussed, as well as its integration with a frequency-domain SQUID multiplexed readout system. The full configuration of the APEX-SZ camera was deployed in April 2007. A preliminary galaxy cluster map from this deployment will be presented.
    Journal of Low Temperature Physics 151(3):697-702. · 1.18 Impact Factor