Intercalibration of SUMER and CDS on SOHO. II. SUMER Detectors A and B and CDS NIS

Results of an intercalibration between the extreme-ultraviolet spectrometers Coronal Diagnostic Spectrometer (CDS) and Solar Ultraviolet Measurements of Emitted Radiation (SUMER) on board the Solar and Heliospheric Observatory (SOHO) are reported. The results of the joint observing program Intercal_01 are described, and intercalibration results up to July 2000 of both SUMER detectors A and B and of the CDS Normal Incidence Spectrometer (NIS) are presented. The instruments simultaneously observed radiance of emission lines at the center of the Sun, and three lines have been chosen for intercomparison: He i 584 A, Mg x 609 A, and Mg x 624 A. Initially the same area was observed by both instruments, but, after restrictions were imposed by the scanning mechanism of SUMER in November 1996, the instruments viewed areas of different sizes. Nevertheless, the temporal correlation between the two instruments remained good through June 1998, when contact with the SOHO spacecraft was lost. Until then the CDS instrument measured (33 ? 5)% and (38 ? 7)% (?1varsigma) higher intensity than SUMER in the He i 584-A line on average for detectors A and B, respectively. Data from SUMER detector B agreed well for Mg x 609 A and Mg x 624 A with the CDS intensities, showing offsets of (2 ? 10)% and (9 ? 15)%, much less than the data of detector A with offsets of (7 ? 8)% and (16 ? 7)% for the two lines, respectively, relative to CDS. Finally, the intercalibration measurements after the loss and recovery of the SOHO spacecraft are analyzed. The data for observations from November 1998 to July 2000 are compared, and it is shown that, although the responses of the instruments have changed, the CDS and the SUMER still perform well, and their temporal correlation is good.     

Intercalibration of SUMER and CDS on SOHO. III. SUMER and CDS-GIS. Solar and Heliospheric Observatory

Simultaneous observation of the same solar sources with different instruments is one way to test prelaunch radiometric calibrations and to detect changes in responsivity with time of extreme-ultraviolet instruments in space. Here we present the results of intercalibration of the SUMER (Solar Ultraviolet Measurements of Emitted Radiation) spectrometer (detectors A and B) and the GIS (Grazing Incidence Spectrometer), one of two spectrometers that compose the CDS (Coronal Diagnostic Spectrometer) on the Solar and Heliospheric Observatory (SOHO). The two instruments observed simultaneously radiances of emission lines at or near the center of the solar disk. The emission line chosen for intercomparison was Ne VIII at 770 A. However, such an intercomparison of the SUMER and CDS-GIS measurements means comparing two data sets with large differences in resolution and field of view. The latter difference, especially, introduces differences in the measured intensities caused by the solar variability that is relatively strong in the 770-A line. Using a statistical approach to overcome this problem, we found that the ratio of the GIS to the SUMER average radiances amounted to 2.6 +/- 0.9 before the SOHO's loss of attitude and to 2.1 +/- 0.7 afterward. These findings confirm earlier estimates of the GIS's responsivity being too low, and an update of the GIS calibration is recommended. Despite the large differences in resolution and field of view of the two instruments, the shapes of their normalized and rescaled histograms of the radiances agree well and therefore represent characteristic features of the Ne VIII line.     

Radiometric calibration of the vacuum-ultraviolet spectrograph SUMER on the SOHO spacecraft with the B detector

The Solar Ultraviolet Measurement of Emitted Radiation (SUMER) vacuum-ultraviolet spectrograph was calibrated in the laboratory before the integration of the instrument on the Solar and Heliospheric Observatory (SOHO) spacecraft in 1995. During the scientific operation of the SOHO it has been possible to track the radiometric calibration of the SUMER spectrograph since March 1996 by a strategy that employs various methods to update the calibration status and improve the coverage of the spectral calibration curve. The results for the A Detector were published previously [Appl. Opt. 36, 6416 (1997)]. During three years of operation in space, the B detector was used for two and one-half years. We describe the characteristics of the B detector and present results of the tracking and refinement of the spectral calibration curves with it. Observations of the spectra of the stars alpha and rho Leonis permit an extrapolation of the calibration curves in the range from 125 to 149.0 nm. Using a solar coronal spectrum observed above the solar disk, we can extrapolate the calibration curves by measuring emission line pairs with well-known intensity ratios. The sensitivity ratio of the two photocathode areas can be obtained by registration of many emission lines in the entire spectral range on both KBr-coated and bare parts of the detector's active surface. The results are found to be consistent with the published calibration performed in the laboratory in the wavelength range from 53 to 124 nm. We can extrapolate the calibration outside this range to 147 nm with a relative uncertainty of ?30% (1varsigma) for wavelengths longer than 125 nm and to 46.5 nm with 50% uncertainty for the short-wavelength range below 53 nm.     

Polarization sensitivity of the SUMER instrument on SOHO

The Solar Ultraviolet Measurements of Emitted Radiation (SUMER) instrument on the Solar and Heliospheric Observatory (SOHO) satellite is sensitive to the state of linear polarization of the incident radiation primarily owing to two optical elements, the holographic grating and the wavelength scan mirror. The large angle of incidence of light striking the scan mirror, which varies from roughly 73.3 degrees to 81.6 degrees (with respect to the mirror normal), causes the mirror to act as a linear polarizer. Similarly, the spectrometer grating operates at incidence angles between 16.7 degrees and 35.0 degrees , adding to the polarization effect at some wavelengths. Measurement and characterization of this polarization sensitivity as a function of wavelength were performed with the engineering model optics (scan mirror and grating) and synchrotron radiation, which is nearly 100% linearly polarized, from the Super Anneau de Collisions d'Orsay (SUPERACO) positron storage ring in Orsay. The polarization sensitivity or modulation factor of the SUMER instrument was found to be between 0.4 and 0.6, depending on the wavelength and the angle of incidence of light striking the scan mirror; this agrees with the calculated polarization properties based on the measured optical constants for the silicon carbide mirror and grating.     

Radiometric calibration of the telescope and ultraviolet spectrometer SUMER on SOHO

The prelaunch spectral-sensitivity calibration of the solar spectrometer SUMER (Solar Ultraviolet Measurements of Emitted Radiation) is described. SUMER is part of the payload of the Solar and Heliospheric Observatory (SOHO), which begins its scientific mission in 1996. The instrument consists of a telescope and a spectrometer capable of taking spatially and spectrally highly resolved images of the Sun in a spectral range from 50 to 161 nm. The pointing capabilities, the dynamic range, and the sensitivity of the instrument allow measurements both on the solar disk and above the limb as great as two solar radii. To determine plasma temperatures and densities in the solar atmosphere, the instrument needs an absolute spectral-sensitivity calibration. Here we describe the prelaunch calibration of the full instrument, which utilizes a radiometric transfer-standard source. The transfer standard was based on a high-current hollow-cathode discharge source. It had been calibrated in the laboratory for vacuum UV radiometry of the Physikalisch-Technische Bundesanstalt by use of the calculable spectral photon flux of the Berlin electron storage ring for synchrotron radiation (BESSY)-a primary radiometric source standard.     

Radiometric calibration of SUMER: refinement of the laboratory results under operational conditions on SOHO

The radiometric calibration of the solar telescope and spectrometer SUMER was carried out in the laboratory before delivery of the instrument for integration into the SOHO (Solar and Heliospheric Observatory) spacecraft. Although this effort led to a reasonable coverage of the wavelength range from 53.70 to 146.96 nm, uncalibrated portions of the sensitivity curves remained before SUMER became operational in early 1996. Thereafter it was possible to perform extrapolations and interpolations of the calibration curves of detector A to shorter, longer, and intermediate wavelengths by using emission line pairs with known intensity ratios. The spectra of the stars alpha and rho Leonis were also observed on the KBr (potassium bromide) photocathode and the bare microchannel plate (MCP) in the range from 120 to 158 nm. In addition, the sensitivity ratios of the KBr photocathode to the bare MCP were determined for many solar lines as well as the H i Lyman and the thermal continua. The results have been found to be consistent with published laboratory data. The uncertainty is +/-15% (1 varsigma) in the wavelength range from 54 to 125 nm.     

Radiometric Calibration Tracking of the Vacuum-Ultraviolet Spectrometer SUMER During the First Year of the SOHO Mission

Detailed radiometric calibration tracking of the vacuum-ultravioletspectrometer SUMER (from solar ultraviolet measurements of emittedradiation) was performed during the first year of the Solar andHeliospheric Observatory (SOHO) mission and will continue. Inview of the flight history of many previous solar UV instruments, thestability of calibration of the extreme-ultraviolet instruments on SOHOhas been a major concern. Results obtained during the first year ofoperation show that excellent radiometric stability has been achievedwith SUMER. These results were accomplished by stringentcleanliness and contamination-control procedures during all phases ofthe project. We describe the strategy and results of the in-flightcalibration tracking program performed with SUMER.     

Electromagnetic-field calculation for a thermal UHF detector at high temperatures. I

Scattering characteristics have been determined from semiinfinite dielectric nonuniformity in a waveguide.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 31, No. 4, pp. 727–734, October, 1976.     

A Robust Cooling Platform for NIS Junction Refrigeration and sub-Kelvin Cryogenic Systems

Recent advances in Normal metal–insulator-superconductor (NIS) tunnel junctions (Clark et al. Appl Phys Lett 86: 173508, 2005, Appl Phys Lett 84: 4, 2004) have proven these devices to be a viable technology for sub-Kelvin refrigeration. NIS junction coolers, coupled to a separate cold stage, provide a flexible platform for cooling a wide range of user-supplied payloads. Recently, a stage was cooled from 290 to 256 mK (Lowell et al. Appl Phys Lett 102: 082601 2013), but further mechanical and electrical improvements are necessary for the stage to reach its full potential. We have designed and built a new Kevlar suspended cooling platform for NIS junction refrigeration that is both lightweight and well thermally isolated; the calculated parasitic loading is \(<\!\!300\)  pW from 300 to 100 mK. The platform is structurally rigid with a measured deflection of 25  \(\upmu \) m under a 2.5 kg load and has an integrated mechanical heat switch driven by a superconducting stepper motor with thermal conductivity G \( = 4.5 \times 10^{-7}\)  W/K at 300 mK. An integrated radiation shield limits thermal loading and a modular platform accommodates enough junctions to provide nanowatts of continuous cooling power. The compact stage size of 7.6 cm \(\times \) 8.6 cm \(\times \) 4.8 cm and overall radiation shield size of 8.9 cm \(\times \) 10.0 cm \(\times \) 7.0 cm along with minimal electrical power requirements allow easy integration into a range of cryostats. We present the design, construction, and performance of this cooling platform as well as projections for coupling to arrays of NIS junctions and other future applications.     

A monolithic optical phase-shift detector on silicon

A novel monolithically integrated device used as an optical phase-shift detector is presented. It consists of a diffraction grating etched at the surface of a p-n photodiode fabricated by a process compatible with a standard silicon CMOS technology. When two coherent light beams are collimated toward the surface of the device, the detected optical power generates a current depending on the relative phase between the two incident beams. The operating principle of this detector and the results obtained by finite-difference time-domain modeling are presented. The fabrication process of the first devices is described and the experimental validation of the concept is demonstrated.     

一种基于模式识别的新型双端检测器

本文提出了一种基于最近邻线分类器的新的双端检测器（DTD）。主要的思想是充分地利用特征信息以及用模式识别方法来设计DTD。本文从模式分类的角度分析了二种主要的传统DTD（Geigel和相关DTD）并给出了新的设计方法。一种称为NNL分类器的新的非参数分类器被用来检测双端通话。NNL分类器具有低运算量和优良的性能。用NNL分类器．我们熔合了几种传统的DTD并且避免了存在于大多数传统DTD中的固定阈值带来的问题。因此NNL-DTD在各种条件下是鲁棒的。实验结果也显示出了这个方法比传统方法更有效。     

Sumas de productos de v.A.I.I.D

Resumen Obtenemos en este trabajo resultados del tipo ley fuerte, teorema central del límite, ley del logaritmo iterado etc., para la sucesión de variables aleatorias donde {X_k} _k ^x =1 es una sucesión de variables independientes e igualmente distribuidas, analizando previamente su convergencia.      

基于自制小波的EBPSK信号检测器

针对全新的高速高效调制方案——扩展的二元相移键控(EBPSK)调制的微小调制差别检测难题,在研究EBPSK调制波形及简单的冲击幅度检测的基础上,提出了一种基于自制小波的EBPSK检测器,其中自制小波是基于通过冲击滤波器后产生的冲击波形包络来构造的.通过仿真实验进行了与一些经典的小波检测器的比较,结果表明在加性高斯白噪声(AWGN)信道下,基于自制小波的EBPSK检测器性能更佳,在较低的信噪比条件下,仍能较好地检测出信号的位置和尺度,且算法实现复杂度较低.     

A silicon composite thermal and ionization X-ray detector

We have made a combination calorimetric and ionization X-ray detector by attaching a silicon p-i-n diode to a monolithic silicon microcalorimeter. Applying a bias to the diode enhanced the thermal signal, and with a reverse bias of 25 V we achieved a detection threshold of 8 eV, based upon energy scaling of the standard deviation of the baseline noise. We were able to measure a charge signal in the absence of applied bias on the diode, demonstrating that the junction potential is sufficient to drift the ionized charges to the contacts. A fraction of the electron-hole pairs created became trapped, manifested by excess broadening in the measured thermal signal and by using the variation of the thermal signal magnitude with reverse bias to fit for the fraction of charge that is trapped. The ability to collect charge without an applied bias is necessary to produce high resolution combination thermal and ionization detectors.     

A compact and gridless channel plate start detector

A small gridless time detector consisting of an electron emitting foil and two channel plates with central holes and without any grid or wire, i.e. with 100% transmission, is described. For α-particles a time resolution of 90 ps and an efficiency up to a maximum of about 50% have been obtained. The efficiency for heavily ionizing particles like evaporation residues or fission fragments is 100% and with an elastically scattered 26 MeV/amu ³²S beam an overall time resolution of 60 ps was achieved.     

A new type of position sensitive detector

A new type of position sensitive monitor is under development in order to meet the demands of beam control in the field of modern accelerators. Tests on the first prototype revealed the possibility of realizing a simple and reliable profile monitor for a wide range of beam energy and intensity.     

A fast response and gamma-insensitive neutron detector based on parallel-plate avalanche counter

The use of the parallel-plate avalanche counter for slow-neutron counting is described. The choice of a suitable neutron converter is discussed on the basis of Monte Carlo simulation, and some experimental results are shown. Excellent gamma-insensitivity, high rate capability, possibility of construction in large sensitive area and low production cost are among the promising features of this neutron detector.     

Copolymerization of vinyl monomers on the surface of CDS and photoconductivity properties of resulting composites

The reaction behaviour of CdS encapsulated copolymer (styrene-acrylonitrile copolymers; C-St · AN-CdS and styrene-methacryl acid copolymers; C-St · MAA-CdS) composites, their photoconductivity, and the mechanism of their photosensitivity were investigated. The results indicated that the reactivity ratios of the monomers for the encapsulated copolymer are considerably different from those of the homopolymer during encapsulation. The photoconductivities of C-St · AN-CdS showed a marked increase over that of CdS alone in the some range of the AN composition ratio. On the other hand, the photoconductivity of C-St·MAA-CdS was very low and showed a decrease. The dark current-voltage characteristic of CdS encapsulated in copolymer observed Ohm's law at the test voltage for the composites of low photoconductivity, while space-charge limited current (SCLC) for C-St·AN-CdS and also for CdS alone was observed. The voltage index of the SCLC was about 2 for CdS alone, larger than 2 for the CdS encapsulated in polystyrene (C-St-CdS), and showed a tendency to increase to a larger value for the CdS encapsulated in the St-AN copolymers. These characteristics were explained with the distribution state of the energy levels of the traps and also with the increase of the characteristic temperature. Similar results were also observed for the light intensity index derived from the dependence of the photocurrent upon irradiation intensity. The decay characteristic of the photocurrent was delayed for C-St-CdS and that for C-St·AN-CdS was earlier compared with that for CdS alone.