The Electron Capture ^{163}Ho Experiment ECHo

The determination of the absolute scale of the neutrino masses is one of the most challenging present questions in particle physics. The most stringent limit, \(m(\bar{\nu }_{\mathrm {e}})< 2\)  eV, was achieved for the electron anti-neutrino mass. Different approaches are followed to reach a sensitivity on neutrino masses in the sub-eV range. Among them, experiments exploring the beta decay or electron capture of suitable nuclides can provide information on the electron neutrino mass value. We present the electron capture \(^{163}\) Ho experiment ECHo, which aims to investigate the electron neutrino mass in the sub-eV range by means of the analysis of the calorimetrically measured energy spectrum following electron capture in \(^{163}\) Ho. A high precision and high statistics spectrum will be measured with arrays of metallic magnetic calorimeters. We discuss some of the essential aspects of ECHo to reach the proposed sensitivity: detector optimization and performance, multiplexed readout, \(^{163}\) Ho source production and purification, as well as a precise theoretical and experimental parameterization of the calorimetric EC spectrum including in particular the value of \(Q_{\mathrm {EC}}\) . We present preliminary results obtained with a first prototype of single channel detectors as well as a first 64-pixel chip with integrated micro-wave SQUID multiplexer, which will already allow to investigate \(m(\nu _{\mathrm {e}})\) in the eV range.     

Recent Results in the Mie Theory

Abstract

The Hart-Montroll (HM) method of analytical summing of the Mie series is reconsidered. The HM scattering amplitude is corrected for the low values of the diffraction parameter kR. The question of unitarity violation is discussed and solved. It is stressed that non-Rayleigh polarization may be obtained only by developing the approximation beyond that of HM.     

Preliminary Results of the MARE Experiment

The microcalorimeter array for a rhenium experiment (MARE) project aims at the direct and calorimetric measurement of the electron neutrino mass with sub-eV sensitivity. The design is based on large arrays of thermal detectors to study the beta decay of \(^{187}\) Re and the electron capture of \(^{163}\) Ho. One of the activities of the project, MARE 1 in Milan, has started in Milan using one array of 6  \(\times \)  6 silicon implanted thermistors equipped with AgReO \(_4\) absorbers. The purposes of MARE 1 in Milan are to achieve a sensitivity on the neutrino mass of a few eV and to investigate the systematics of \(^{187}\) Re neutrino mass measurements, focusing on those caused by the beta environmental fine structure and the beta spectrum theoretical shape. In parallel, the MARE collaboration is performing an R&D work for producing absorbers embedded with radioactive metal \(^{163}\) Ho. We report here the status of MARE using Re as beta source and the preliminary results obtained with \(^{163}\) Ho.     

Results and Prospects for the Cryogenic Dark Matter Search (CDMS) Experiment

The Cryogenic Dark Matter Search (CDMS) experiment, located at the Soudan underground mine, operated 30 low-temperature Ge and Si detectors for several years to search for Weakly Interacting Massive dark matter Particles (WIMPs). Due to their excellent background discrimination power and low energy threshold, our detectors have provided world-leading sensitivity for WIMP-nucleon interactions for most of the past decade over a large WIMP mass range. The final exposure of our CDMS?II detectors yielded two candidate events, with an expected background of 0.9 ± 0.2 events, and this result was published in March 2010 in Science. A reanalysis of 8 Ge detectors with a lowered, 2 keV recoil energy threshold, provided increased sensitivity to interactions from WIMPs with masses below ?10 GeV/c² and excluded possible low-mass WIMP signals from the DAMA/LIBRA and CoGeNT experiments. The CDMS collaboration is moving forward with the SuperCDMS experiments at Soudan and SNOLAB with the goal of probing the zeptobarn scale and beyond over the next decade. To achieve this goal, a new generation of larger mass detectors with interleaved geometry for the phonon and ionization readout has been developed.     

Pool Boiling in Microgravity: Recent Results and Perspectives for the Project DEPA-SJ10

Two research projects on pool boiling in microgravity have been conducted aboard the Chinese recoverable satellites. Ground-based experiments have also been performed both in normal gravity and in short-term microgravity in the Drop Tower Beijing. Steady boiling of R113 on thin platinum wires was studied with a temperature-controlled heating method, while quasi-steady boiling of FC-72 on a plane plate was investigated with an exponentially increasing heating voltage. In the first case, slight enhancement of heat transfer is observed in microgravity, while diminution is evident for high heat flux in the second one. Lateral motions of bubbles on the heaters are observed before their departure in microgravity. The surface oscillation of the merged bubbles due to lateral coalescence between adjacent bubbles drives it to detach from the heaters. The Marangoni effect on the bubble behavior is also discussed. The perspectives for a new project DEPA-SJ10, which has been planned to be flown aboard the Chinese recoverable satellite SJ-10 in the future, are also presented.     

A Survey of Recent Results for a Class of Facilities Location Problems

With advances in computer technology and the state of the art in integer programming, many previously intractable problems are now being solved. This survey attempts to determine the extent to which new developments have been applied to certain facilities location problems. Some promising new techniques are highlighted.     

Recent Results of a New Microwave SQUID Multiplexer

We present recent results of a prototype microwave SQUID multiplexer containing four SQUIDs coupled to GHz frequency resonant circuits and fed with a single microwave readout line. The system is operating at a readout frequency range of 8–10 GHz. All four SQUIDs share a common DC bias and modulation lines. A new modulation scheme is tested to eliminate the need for individual flux biasing of the SQUIDs, which extends the dynamic range of the readout. In this scheme a common modulation signal is imposed on each SQUID and the received signal is demodulated at one and two times the modulation frequency to maintain sensitivity at any flux state. We also demonstrated a microwave RF bias scheme eliminating the necessity of the DC current bias to the SQUID. Our preliminary performance tests at 4.2 K show that the input noise of the device is ∼5 pA/ .      

Magnetic Dynamics in Condensed Oxygen: Recent Experimental Results

The spin dynamics in the condensed phases of ambient–pressure molecular oxygen (liquid, plastic–crystalline (–), magnetically disordered (–) and fully ordered –O ₂ ) iS investigated by means of the concurrent use of neutron scattering and muon–spin relaxation. Above the transition the magnetic dynamics is governed by fast paramagnetic fluctuations whose spectrum is determined from the S(Q,) dynamic structure factors accessible from inelastic neutron scattering. Such information is shown to provide a key to understand the non–trivial temperature dependence of longitudinal relaxation rates found in muon spin relaxation measurements. Recent neutron scattering measurements performed within the magnetically ordered –phase under high–resolution conditions reveal the presence of a low–energy excitation of magnetic origin, unnoticed in a previous polarized–neutron experiment, which corresponds to the continuation to longer wavevectors of the spin–wave mode detected in antiferromagnetic resonance (AFMR) experiments carried out by optical means.     

Recent Results in the Interpretation of Interference and Lorentz Images of Vortices in Superconductors

The main ideas and approximations underlying the model developed to interpret the principal features of holographic and Fresnel images of superconducting vortices, or fluxons, are briefly reviewed and applied to the exploitation of new experimental setups, like the standard and coherent Foucault techniques. It is also shown how the model can be implemented to interpret effects due to misalignment and/or distortion of the fluxon cores. Finally, the effect of the finite specimen thickness is also taken into account by resorting to the solution of the Ginzburg-Landau equations found by Clem, and by showing that through it a better agreement can be obtained between theoretical and experimental results.     

Some Results of the Educational Experiment APIS (Cervantes Mission on Board ISS)

Some results of the analysis of the pictures taken along the performance of the Análisis de Propiedades Inerciales de Sólidos, Analysis of the Inertia Properties of Solid Bodies (APIS) experiment carried out in the Cervantes mission on board ISS, are presented. APIS was an educational experiment devoted to take advantage of the unique conditions of absence of relative gravity forces of a space platform such as ISS, to show some of the characteristics of the free rotational motion of a solid body, which are impossible to carry out on earth. This field of experimental research has application to aerospace engineering science (e.g. attitude control of spacecrafts), to astrophysical sciences (e.g. state of rotation and tumbling motions of asteroids) and to engineering education. To avoid the effect of the ambient atmosphere loads on the motion, the test body is placed inside a sphere, which reduces the effect of the aerodynamic forces to just friction. The drastic reduction of the effect of the surrounding air during the short duration of the experimental sequences allows us to compare the actual motion with the known solutions for the solid body rotation in vacuum. In this paper, some selected, relevant sequences of the sphere enclosing a body with a nominal cylindrical inertia tensor, put into rotation by the astronaut, are shown; the main problems to extract the information concerning the characteristic parameters of the motion are outlined, and some of the results obtained concerning the motion of the test probe are included, which show what seems to be a curious and unexpected solution of the Euler equations for the solid body rotation in vacuum, without energy dissipation, when the angular momentum is almost perpendicular to the axisymmetry axis.     

Results of Quenching Factor Measurements of CaWO_4 at mK Temperatures for the Direct Dark Matter Search Experiment CRESST

The CRESST experiment aims at a direct detection of WIMP dark matter (DM) using scintillating CaWO \(_4\) crystals operated as phonon detectors at mK temperatures. An important feature of the experiment is the active background discrimination technique exploiting the different light outputs depending on the kind of particle interaction. The reduced light yield of nuclear recoils compared to electron recoils is quantified by quenching factors (QFs). The precise measurement of the QFs and thus the identification of the individual recoiling nucleus in the multi-target material CaWO \(_4\) is crucial for neutron background discrimination and assuming a positive DM signal would allow to a certain extent WIMP-mass spectroscopy. At the Munich tandem accelerator a dedicated neutron scattering facility has been set up to measure the QFs of CaWO \(_4\) , in particular that of tungsten, at mK temperatures. Monoenergetic neutrons (11 MeV) produced by the accelerator are scattered off a CRESST-like detector module that is operated in a dilution refrigerator. In this setup, the recoiling nucleus (O, Ca and W) is identified by time-of-flight measurement in liquid-scintillator detectors placed at fixed scattering angles. The QF of W could be determined with unprecedented accuracy at mK temperatures and under realistic measurement conditions: \(QF_W=0.0196\pm 0.0022\) (preliminary value).     

Color Perception in Microgravity Conditions: The Results of CROMOS Parabolic Flight Experiment

The aims of this research are first to verify the actual difference in color perception between conditions in Earth’s (1×g) and parabolic flight’s microgravitational conditions (μg) and to improve the methodology used for data collection, testing the CROMOS software for color sensitivity investigation. Additionally this paper seeks to establish a larger awareness of microgravity vision and its design implications in the field of aerospace engineering. The analysis of variations in color perception between microgravity and 1×g can be applied to a range of fields concerning the space habitat (Fig. 1), the design of information (such as safety notices), or in the space station the analysis of chemical and biological reactions based on chromatography (for example, when subtle color variations are used as indicators in histological cell analysis).     

Detector Development for the abBA Experiment

We have developed a new type of field-expansion spectrometer to measure the neutron beta decay correlations (a, b, B, and A). A precision measurement of these correlations places stringent requirements on charged particle detectors. The design employs large area segmented silicon detectors to detect both protons and electrons in coincidence. Other requirements include good energy resolution (< 5 keV), a thin dead layer to allow observation of 30-keV protons, fast timing resolution (~1 ns) to reconstruct electron-backscattering events, and nearly unity efficiency. We report results of testing commercially available surface-barrier silicon detectors for energy resolution and timing performance, and measurement of the dead-layer thickness of ion-implanted silicon detectors with a 3.2 MeV alpha source.     

Pool Boiling with Non-condensable Gas in Microgravity: Results of a Sounding Rocket Experiment

Pool boiling experiments in microgravity have been performed in the Sounding Rocket Maser 11. A heated plate of 1cm ² was located at the bottom of a small cylindrical tank partly filled with a refrigerant Novec HFE7000 pressurized with Nitrogen. Experiments were performed at different reservoir pressures and wall heat fluxes. The wall heat flux and wall temperature were simultaneously measured during the experiment and the behavior of the bubbles on the heater was filmed with a video camera through the transparent wall of the reservoir. The presence of Nitrogen dissolved inside the liquid led to a strong Marangoni convection around the bubble. The effect of Marangoni convection and evaporation on the wall heat transfer is analyzed in function of the relative values of the wall temperature and saturation temperature.     

A Message from Recent Engineering Graduates in the Workplace: Results of a Survey on Technical Communication Skills

Survey results reveal the impact of engineers' communication skills in adjusting to jobs and achieving career goals. A direct correlation emerges between the amount of technical communication (TC) instruction and career advancement. Former students then spell out recommendations for providing relevant TC instruction within the engineering curriculum.     

Development and Evaluation of a Seismic Monitoring System for Building Interiors—Part I: Experiment Design and Results

The advent of high-speed, lightweight, and durable sensor technologies opens new possibilities for field monitoring applications. In particular, under natural or man-made loading conditions, applying these new technologies to the monitoring of building interiors may substantially help rescue and reconnaissance crews during postevent evaluations. To test such a methodology, in this paper, we develop a specialized network of conventional analog and digital (camera) sensors and use them in monitoring nonstructural components subjected to vibration loading within a demonstration building structure. A full-scale vibration experiment is conducted with a research team from the University of California, Los Angeles, on a vacant structure damaged during the 1994 Northridge Earthquake. The building of interest is a four-story office building located in Sherman Oaks, CA. The investigation has two primary objectives: (1) to characterize the seismic response of an important class of equipment and building contents and (2) to study the applicability of tracking the response of these equipment and contents using arrays of image-based monitoring systems. In this paper, we describe the experimental field setup, including the analog and camera sensor systems and the networking hardware used to collect data, present the testing matrix, and sample the processed analog data results. We summarize the difficulties encountered in the field implementation of these types of monitoring systems while highlighting their potential benefits. In a companion paper, we present the analysis methodology applied to the image sequences collected and summarize needs for future work if such systems are to be robustly employed in the field.     

检测方法偏离标准要求对陶瓷砖强度试验结果的影响

少数检测人员在陶瓷砖强度试验中未严格按照标准要求进行试验,主要表现在3个方面：试验时试样的前处理未干燥至恒重;试验时试样的放置不正确;断裂面厚度测量不正确。通过和标准测试方法的比对研究,分析讨论了这些不正确的做法对陶瓷砖强度试验结果的影响。上述研究有助于检测人员更好地找到产品质量检测数据不准确的原因,从而采用正确的试验方法,更好地认识和改进产品的质量。     

Drop Tower Experiment to Study the Capillary Flow in Symmetrical and Asymmetrical Channels: Experimental Set-up and Preliminary Results

Owing to the development of the space exploration activities, the in-orbit management of fluids such as the transportation of propellant liquid in microgravity becomes the important direction of microgravity fluid research, and one of main problems is the stability behaviors of free surface flow in capillary channel of PMD. In the present study, an experiment set-up of the fluid transport with two different capillary channels has been developed on the Beijing Drop Tower platform. Both symmetrical and asymmetrical flow channels, with the same cross-sectional areas and lengths and different cross-sectional geometries were used and HFE-7500 is chosen as test liquid. 10 times of the drop-down experiments were performed for investigation of the capillary flow characters in different volumetric flow rates, and the three main patterns of capillary flows: subcritical flow, critical flow and supercritical flow were found in experiments, these patterns are distinguished by the movement of the point of lowest surface over time. Meanwhile, the critical flow rates at which free surface becomes instable observed in our experiments are (1) 2.7 ±0.2ml/s for the critical flow rate of asymmetrical channel; and (2) 2.2 ±0.2ml/s for symmetrical channel flow, respectively.