Conditions for observing the thermo-electro-photo cooling effect

The feasibility of a thermo-electro-photo device for simultaneous refrigeration and photoemission is investigated. The refrigeration is a result of phonon absorption by electrons moving up against an energy barrier at one junction and the photoemission occurs because of energy dissipation through electron-hole radiative recombination at the other. The result of the feasibility study shows that the phonon-electron-photon transition may be observed if the thermoelectric coefficient-of-performance at the cold junction and the internal quantum efficiency of light emission at the hot junction are larger than 3 and 0.25, respectively. To facilitate the energy match between the two junctions, a staircase energy band structure is proposed.     

Time Dependence of Partial Integrated Charge Fluctuations in STJs

Multiple tunneling of quasiparticles in a superconducting tunnel junction (STJ) detector increases the fluctuations in the measured charge. To optimize the energy resolution of an STJ detector, it is necessary to know the time dependence of the integrated charge and its noise. In this work, the theory of branching cascade processes was applied to the process of quasiparticle multitunneling. The duality nature of quasiparticles and the coupling of the quasiparticle and the phonon subsystems were taken into account. The formulae for time dependences of the mean value and the relative variance of the integrated charge were derived. Influence of a shaping amplifier on the relative variance of an STJ detector was also considered.     

High-speed GC and GC/MS with a series-coupled column ensemble using stop-flow operation

A pneumatically actuated valve is used to connect the junction point of a series-coupled column ensemble to a ballast chamber containing carrier gas at the ensemble inlet pressure in order to periodically stop the carrier gas flow in the first column. When the valve is opened, mixture components, which have migrated across the column junction, are accelerated toward a time-of-flight mass spectrometer that is used as an ensemble detector. Mixture components, which are still in the first column, are frozen in position. This allows for the insertion of time windows into the ensemble chromatogram that can aid in the separation of some overlapping component peaks. The capillary column ensemble (0.18-mm i.d. x 0.18-microm film thickness) consists of a 7.0-m length of polar, (trifluoropropyl)methyl polysiloxane column followed by a 7.0-m length of nonpolar dimethyl polysiloxane column. A flame ionization detector located at the column junction point is used to monitor a portion of the effluent from the first column in order to determine the valve timing sequence needed to enhance the separation of component pairs that are separated by the first column but coelute from the column ensemble. When one of the components of a targeted pair has crossed the junction but the other component is still in the first column, the valve is opened, typically for 1-5 s. The stop-flow system is used to enhance the separation of a mixture containing some common essential oil components and a mixture containing some common pesticides.     

Hot-electron microcalorimeters for x-ray and phonon detection

We propose a novel hot-electron microcalorimeter for measurements of x-rays or phonons produced by the interaction of a high energy particle with the underlying substrate. This type of detector uses a normal metal film to absorb the incoming excitation which subsequently heats the electrons above the lattice temperature. The temperature of the electrons is measured from the current — voltage characteristics of a superconductor-insulator-normal metal tunnel junction, where part of the absorber forms the normal electrode. We present simple calculations of the energy sensitivity of the junction and of the ultimate performance of x-ray and phonon detectors. We also present preliminary measurements of prototype devices which were used to test the basic detector physics.     

Analysis of megadalton ions using cryodetection MALDI time-of-flight mass spectrometry

Presented are initial results from the first commercially available matrix-assisted laser desorption/ionization time-of-flight mass spectrometer specifically designed for the sensitive detection of very high mass ions (macromizer, Comet AG). This new instrument utilizes a 16-element superconducting tunnel junction detector coupled with a fully adjustable gimbal-mounted ion source/focusing region that allows unparalleled sensitivity for detection of singly charged high molecular weight ions. Using this new technology, the singly charged ions in the megadalton region are detected from immunoglobulin M and von Willebrand factor proteins. This detector technology also measures the kinetic energy of the particles impacting the detector, which can be correlated to the charge of the particles. Immunoglobulin G and streptavidin were used to demonstrate the ability of the macromizer instrument to detect high-mass ions and to discern the charge state of the ions.     

A combined photon-hadron hodoscope calorimeter

The energy and spatial resolution and other characteristics of a combined detector permitting simultaneous detection of a large number of photons and hadrons has been studied in a 200 GeV/c hadron beam at the CERN SPS. The detector consists of the GAMS-4000 spectrometer (4096 lead-glass cells) and a modular hadron calorimeter MHC-200 located behind it (240 total-absorption sandwich counters). A new method for adding the signals from the two calorimeters, which takes into account the difference in the development of hadron showers in photon and hadron calorimeters, has been developed. It permits substantial improvement of the energy resolution of the combined detector. The hadron coordinates are defined with a precision of several millimeters and the energy resolution is typical for steel-scintillator sandwiches with a wavelength-shifter readout. The effect of the gap between the photon and the hadron calorimeters has also been studied.     

Comparative studies on the CO2- signal in tooth enamel and carbonates

When a swift ion is slowed down through a plastic detector it creates a latent track. In nuclear track detectors, this latent track can be specifically etched by an appropriate chemical solution. This enlargement process is due to a higher etch velocity (VT) along the ion's path than in the non-damaged part of the detector. The etched track velocity is definitely linked to the damage created by the incoming ion in the detector material. A relationship between the physical parameters of the energy deposition and the variation in this etched track velocity with the ion energy cannot easily be explained. We present here our study on the chemical damage created by several ions in a cellulose nitrate type detector and our first attempt to simulate them by the use of the hit theory.     

Real‐time ballistocardiographic artifact reduction using the k‐teager energy operator detector and multi‐channel referenced adaptive noise cancelling

The simultaneous electroencephalogram (EEG) and functional magnetic resonance imaging (fMRI) recording technique has recently received considerable attention and has been used in many studies on cognition and neurological disease. EEG‐fMRI simultaneous recording has the advantage of enabling the monitoring of brain activity with both high temporal resolution and high spatial resolution in real time. The successful removal of the ballistocardiographic (BCG) artifact from the EEG signal recorded during an MRI is an important prerequisite for real‐time EEG‐fMRI joint analysis. We have developed a new framework dedicated to BCG artifact removal in real‐time. This framework includes a new real‐time R‐peak detection method combining a k‐Teager energy operator, a thresholding detector, and a correlation detector, as well as a real‐time BCG artifact reduction procedure combining average artifact template subtraction and a new multi‐channel referenced adaptive noise cancelling method. Our results demonstrate that this new framework is efficient in the real‐time removal of the BCG artifact. The multi‐channel adaptive noise cancellation (mANC) method performs better than the traditional ANC method in eliminating the BCG residual artifact. In addition, the computational speed of the mANC method fulfills the requirements of real‐time EEG‐fMRI analysis. © 2016 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 26, 209–215, 2016     

Light detector development for CRESST II

CRESST-II detector modules rely on the ability to actively discriminate electron recoils from nuclear recoils via simultaneous measurement of phonons and scintillation light. The scintillation light produced in each target crystal is detected via an associated calorimeter consisting of a thin silicon wafer read out by a tungsten phase transition thermometer deposited on its surface. About 1% of the energy deposited in CaWO₄ is detected as scintillation light; therefore, the sensitivity of the light detector is crucial for the discrimination of electron recoils from nuclear recoils at energies relevant for WIMP searches. We report the detector performance obtained using a thermometer geometry characterized by phonon collectors and a thin film thermal coupling to the heat sink (Fig. 1). This concept allows a high sensitivity by decoupling the area required for the collection of non-thermal phonons and the heat capacity of the sensor. With a 30×30×0.45 mm³ light detector, energy thresholds below 5 keV referred to energy deposition in CaWO₄ have been obtained. Results achieved will be presented and an overview on further possibilities of development will be given.     

New Developments in Superconducting Tunnel Junction X-Ray Spectrometers for Synchrotron Science

We are developing Ta-based superconducting tunnel junction (STJ) X-ray detectors for high-resolution soft X-ray spectroscopy at the synchrotron. For scaling to large detector arrays, we have also built a compact, low-cost, remote-controllable preamplifier with <3?eV electronic noise. Current Ta-STJs attain an energy resolution between 6.5 and 9?eV FWHM for energies up to ～2?keV, and can be operated at rates up to ～5,000 counts/s as long as the signals decay with a single exponential time constant.     

A New Range Finder Based on a Four-Port Junction

The design and performance of a prototype range finder based on a four-port junction are presented. The four-port junction is used as a precision phase detector. The system proposed presents advantages such as compact size, low cost, low consumption, and low computational time. The principle of operation, the sensor and the results are described in this paper.      

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

We continue our development of a phonon-mediated distributed-TES X-ray detector. X-rays are absorbed in a large silicon or germanium crystal, and the energy is read out by four distributed TESs. This design takes advantage of existing TES technology while overcoming the difficulties of designing spatially large arrays. In this paper, we discuss three detector designs. First, a silicon detector with 220 μm deep trenches through a 350 μm crystal. Second, a germanium detector with 275 μm deep trenches through a 550 μm crystal. Finally another silicon detector with 330 μm deep trenches through a 350 μm crystal. We discuss energy loss mechanisms in the detector and propose a reason for the energy resolution that we observe.      

The analysis of the transmission-type optical smoke detector threshold sensitivity to the high rate temperature variations

Reliability of the transmission-type optical smoke detectors is limited by the high sensitivity of optical components to parasitic effects, especially to contamination and temperature. Influences of the high rate temperature variations cannot be eliminated by filtering, as their spectral range partially overlaps with the spectral range of a smoke absorption index. Hence, sensitivity to these effects has to be eliminated through the mutual cancellation of the corresponding components of the output signal. First determining the temperature dependence of the light source and the receiver in the generalized block diagram of the transmission-type optical smoke detector, transfer functions are derived, specifying the detector output signal as a function of the temperature variations of the blocks considered. Using the second-order thermal model for the thermal system of the optoelectronic diodes, an expression is given for the steady-state solution of the difference of the source and the receiver diode junction temperatures, when the ambient temperature is a ramp function of time. On the basis of the thermal system analysis, a block diagram is shown to be equivalent to RC low-pass (LP) filters that model the pn junction temperature dependence on ambient temperature. For the completed block diagram, with the help of the expressions derived, an analysis is performed to establish how to eliminate the detector threshold sensitivity to ambient temperature variations, or to adjust it to realize a multicriteria fire detector.     

Development of superconducting absorbers for CRESST light detectors

An important aspect of dark matter search experiments is the active background reduction by identification of the type of particle interacting in the detector. In CRESST this is achieved by a simultaneous detection of heat and light produced by an interaction in a scintillating crystal. The overall light collection efficiency is a crucial parameter in order to achieve enough sensitivity to measure the small fraction of the deposited energy that is emitted as scintillation light. For this purpose, a thin superconducting lead film deposited on sapphire substrates has been tested as an alternative light absorber to a silicon absorber. The first results already show a better light absorption of the lead film. Other superconducting films are also being analyzed.     

A new multidetector system with magnetic spectrograph for study of cosmic ray extensive air shower components

An array of detectors for simultaneous observation of different components of cosmic ray extensive air showers (EAS) is described. The detector array, comprising plastic scintillation counters as electron detectors, magnetic spectrograph units and a muon flash tube chamber as muon detectors and a large volume multiplate cloud chamber as hadron detector has been set up and is now being operated at NBU campus. The array of detectors is sensitive to air showers initiated by cosmic primaries of energy in the range 10¹⁴–10¹⁵ eV.     

Large-scale gadolinium-doped water Cherenkov detector for nonproliferation

Fission events from Special Nuclear Material (SNM), such as highly enriched uranium or plutonium, can produce simultaneous emission of multiple neutrons and high-energy gamma-rays. The observation of time correlations between any of these particles is a significant indicator of the presence of fissionable material. Cosmogenic processes can also mimic these types of correlated signals. However, if the background is sufficiently low and fully characterized, significant changes in the correlated event rate in the presence of a target of interest constitutes a robust signature of the presence of SNM. Since fission emissions are isotropic, adequate sensitivity to these multiplicities requires a high efficiency detector with a large solid angle with respect to the target. Water Cherenkov detectors are a cost-effective choice when large solid angle coverage is required. In order to characterize the neutron detection performance of large-scale water Cherenkov detectors, we have designed and built a 3.5 kL water Cherenkov-based gamma-ray and neutron detector, and modeled the detector response in Geant4 [1]. We report the position-dependent neutron detection efficiency and energy response of the detector, as well as the basic characteristics of the simulation.     

A 4π double obelisk of position sensitive PPACs for new vistas in photofission experiments

An arrangement of two-dimensional position sensitive PPACs (parallel plate avalanche counters) covering a large solid angle (> 50% of 4π) for use in a new type of photofission experiments is described. For the first time simultaneous measurements of both the photofission fragment angular and mass distributions are enabled by this device. The mass information is obtained by the double time of flight technique (with modest accuracy) whereas an excellent angular resolution of < 1° is achieved. The detector performances are outlined. First applications in high intensity bremsstrahlung and tagged photon experiments are discussed.     

Recent developments in detector research

Recently developed methods of cryogenic particle detection and potential applications will be introduced. The main part of this article focuses on our experimental results on two different approaches of detecting nuclear radiation with superconducting tunnel junctions. The best energy resolution is obtained when the junction itself serves as absorber. Using Sn/SnO_x/Sn tunnel junctions we obtained an energy resolution of about 90 eV for 6 keV X-rays up to now. The processes limiting the resolution of the present devices will be discussed. Larger absorber masses and position resolution are realized by an entirely new type of particle detector based on the detection of nonthermal phonons which are generated by the absorption of radiation within a single-crystalline absorber of dielectric material. We report on experimental tests of a detector composed of a silicon single crystal (size: 10 × 20 × 3 mm³) and of an array of superconducting Al/Al₂O₃/Al tunnel junctions evaporated onto the surface of the crystal, serving as phonon detectors. Pulse height analysis and the investigation of time differences between pulse onsets in different junctions are shown to yield information about the absorption point of -particles.