121453674
Quasiparticle propagation in aluminum fins and tungsten TES dynamics in the CDMS ZIP detector
Abstract With the aim of improving the rejection of surface beta contamination on the CDMS ZIP detector, we have studied the effectiveness of our phonon pulse-shape discrimination by matching a Monte Carlo calculation to data from a 350 μ m long Al fin with W TESs (Transition-Edge Sensors) at both ends. From this fit, we determined the Al film diffusivity to be D Al = 0.010 ± 0.001 m 2 / s , the quasiparticle trapping length in the Al fin to be l trap = 180 ± 10 μ m , and the Al to W TES transmission to be f Al / W = 0.002 ± 0.001 .
110998320
Determination of the Tc distribution for 1000 Transition Edge Sensors
The ZIP detectors deployed in the CDMS II experiment utilize phonon sensors comprising W Transition Edge Sensors (TESs). In order to ensure uniform collection of the athermal phonon signal the TESs are dispersed uniformly on one side of a 1 cm thick, 3 inch diameter, disk. Each quadrant contains 1036 TESs connected in parallel to one series-array SQUID amplifier. The initial superconducting transition temperatures of these TESs tend to be too high for our requirements, and substantial gradients make the operation of the detectors difficult. Hence our implementation of Fe-56 ion implantation, as reported at the previous LTD meeting, to reduce in a controlled manner the transition temperature. However, the successful implementation of this ion-implantation scheme requires accurate knowledge of the initial transition temperature of each TES in a given quadrant. We report on our approaches and techniques employed to address the issue of determining the initial Tc distribution.
119513567
The Spontaneous Magnetization of a Two-Dimensional Rectangular Ising Model
22489858
A multichamber system for analyzing the outgassing, deposition, and associated optical degradation properties of materials in a vacuum.
We report on the camera materials test chamber, a multivessel apparatus that analyzes the outgassing consequences of candidate materials for use in the vacuum cryostat of a new telescope camera. The system measures the outgassing products and rates of samples of materials at different temperatures and collects films of outgassing products to measure the effects on light transmission in six optical bands. The design of the apparatus minimizes potential measurement errors introduced by background contamination.
59269082
Higher spin gravity with matter in AdS3 and its CFT dual
A bstractWe study Vasiliev’s system of higher spin gauge fields coupled to massive scalars in AdS3, and compute the tree level two and three point functions. These are compared to the large N limit of the WN minimal model, and nontrivial agreements are found. We propose a modified version of the conjecture of Gaberdiel and Gopakumar, under which the bulk theory is perturbatively dual to a subsector of the CFT that closes on the sphere.
125767438
1/16 BPS states in $\mathcal N=$ 4 super-Yang-Mills theory
We investigate the problem of counting 1/16 BPS operators in N=4 Super-Yang-Mills theory at weak coupling. We present the complete set of 1/16 BPS operators in the infinite N limit, which agrees with the counting of free BPS multi-graviton states in the gravity dual AdS5xS5. Further, we conjecture that all 1/16 BPS operators in N=4 SYM are of the multi-graviton form, and give numerical evidences for this conjecture. We discuss the implication of our conjecture and the seeming failure in reproducing the entropy of large 1/16 BPS black holes in AdS5.
27784575
Numerical Simulation of High Power Microwave Sources
Electromagnetic fully relativistic particle-in-cell codes are a powerful tool for modeling and designing components of high power microwave sources and accelerator systems. This paper reviews the principles and properties of numerical simulation codes as applied to problems of microwave generation. The important aspects which can be treated with such codes are, improved representation of microwave circuits in complicated geometries, proper treatment of nonlinear particle wave interaction in the body of a device, inclusion of self-consistent self-field effects, and treatment of surface properties such as emission, secondary particles, and surface breakdown. Examples of application of two- and three-dimensional codes to specific devices such as gyrotrons, magnetrons, and klystrons is presented. The information obtained from large numerical simulation codes provides both detailed insight hNto source physics as well as the basis for improved design technology.