Characterization and Analysis of Integrated Silicon Photonic Detectors for High-Speed Communications

As the digital age of rapidly expanding information systems and technology continue to grow and develop at an ever increasing rate, new fabrication media must be investigated in order to keep up with these trends. The modern age has been defined by the innovation and advancement of the semiconductor transistor specifically Silicon, however these days of exponential performance gain through gate minimization are coming to a close. One such field which shows great promise for meeting the challenges of the future is the integration of photonic and complementary metal oxide semiconductor components; leveraging the long standing fabrication history of Silicon devices. This document describes the characterization and analysis of integrated photodiodes for digital and analog applications. The photodiode is one small but necessary component for the integration of system-level photonic devices. A number of standard measurements were taken on the photodiodes to analyze their performance and potential application. Additionally, an anomalous detector behavior was investigated through both transient measurements to identify the driving mechanism of the abnormality. Through this testing the devices were found to perform with up to 30-GHz of bandwidth while maintaining dark currents below 5 nA. The non-linear behavior was observed under CW conditions and analyzed using the transient response of the photodiode. The transient response of the photodiode supported that the non-linear mechanism was photon-induced avalanche-like effect, however, further investigation is required. Additional work is described to further investigate this behavior, as well to identify potential effects on future application in system level communication designs

Can angular momentum loss cause the period change of NN Ser?

NN Ser is a non mass-transferring pre-cataclysmic variable containing a white dwarf with a mass of $\sim 0.5 M_{\odot}$ and an M dwarf secondary star with a mass of $\sim 0.2 M_{\odot}$. Based on the data detected by the high-speed CCD camera ULTRACAM, it was observed that the orbital period of NN Ser is decreasing, which may be caused by a genuine angular momentum loss or the presence of a third body. However, neither gravitational radiation and magnetic braking can ideally account for the period change of NN Ser. In this Letter, we attempt to examine a feasible mechanism which can drain the angular momentum from NN Ser. We propose that a fossil circumbinary disk (CB disk) around the binary may have been established at the end of the common envelope phase, and the tidal torques caused by the gravitational interaction between the disk and the binary can efficiently extract the orbital angular momentum from the system. We find that only if M dwarf has an ultra-high wind loss rates of $\sim 10^{-10} M_{\odot} \rm yr^{-1}$, and a large fraction ($\delta\sim 10$) of wind loss is fed into the CB disk, the loss rates of angular momentum via the CB disk can interpret the period change observed in NN Ser. Such a wind loss rate and $\delta$-value seem to be incredible. Hence it seems that the presence of a third body in a long orbit around the binary might account for the changing period of NN Ser.Comment: 4 pages, accepted for publication in A&A Letter

Astroclimatic Characterization of Vallecitos: A candidate site for the Cherenkov Telescope Array at San Pedro Martir

We conducted an 18 month long study of the weather conditions of the Vallecitos, a proposed site in Mexico to harbor the northern array of the Cherenkov Telescope Array (CTA). It is located in Sierra de San Pedro Martir (SPM) a few kilometers away from Observatorio Astron\'omico Nacional. The study is based on data collected by the ATMOSCOPE, a multi-sensor instrument measuring the weather and sky conditions, which was commissioned and built by the CTA Consortium. Additionally, we compare the weather conditions of the optical observatory at SPM to the Vallecitos regarding temperature, humidity, and wind distributions. It appears that the excellent conditions at the optical observatory benefit from the presence of microclimate established in the Vallecitos.Comment: 16 pages, 16 figures, Publication of the Astronomical Society of the Pacific, accepte

3D Gamma-ray and Neutron Mapping in Real-Time with the Localization and Mapping Platform from Unmanned Aerial Systems and Man-Portable Configurations

Nuclear Scene Data Fusion (SDF), implemented in the Localization and Mapping Platform (LAMP) fuses three-dimensional (3D), real-time volumetric reconstructions of radiation sources with contextual information (e.g. LIDAR, camera, etc.) derived from the environment around the detector system. This information, particularly when obtained in real time, may be transformative for applications, including directed search for lost or stolen sources, consequence management after the release of radioactive materials, or contamination avoidance in security-related or emergency response scenarios. 3D reconstructions enabled by SDF localize contamination or hotspots to specific areas or objects, providing higher resolution over larger areas than conventional 2D approaches, and enabling more efficient planning and response, particularly in complex 3D environments. In this work, we present the expansion of these gamma-ray mapping concepts to neutron source localization. Here we integrate LAMP with a custom $Cs_2LiLa(Br,Cl)_6:Ce$ (CLLBC) scintillator detector sensitive to both gamma-rays and neutrons, which we dub Neutron Gamma LAMP (NG-LAMP). NG-LAMP enables simultaneous neutron and gamma-ray mapping with high resolution gamma-ray spectroscopy. We demonstrate the ability to detect and localize surrogate Special Nuclear Materials (SNM) in real-time and in 3D based on neutron signatures alone, which is critical for the detection of heavily shielded SNM, when gamma-ray signatures are attenuated. In this work, we show for the first time the ability to localize, in 3D and realtime, a neutron source in the presence of a strong gamma-ray source, simultaneous and spectroscopic localization of three gamma-ray sources and a neutron source, and finally the localization of a surrogate SNM source based on neutron signatures alone, where gamma-ray data are consistent with background

Low-lying GT(+) strength in Co-64 studied via the Ni-64(d,He-2)Co-64 reaction

The Ni-64(d,He-2)Co-64 reaction was studied at the AGOR cyclotron of KVI, Groningen, with the Big-Bite Spectrometer and the EuroSuperNova detector using a 171-MeV deuteron beam. An energy resolution of about 110 keV was achieved. In addition to the J(pi) = 1(+) ground state, several other 1(+) states could be identified in Co-64 and the strengths of the corresponding Gamow-Teller transitions were determined. The obtained strength distribution was compared with theoretical predictions and former (n,p) experimental results and displayed a good agreement. Due to the good energy resolution, detailed spectroscopic information was obtained, which supplements the data base needed for network calculations for supernova scenarios

Squamous cell carcinoma of the vulva in a patient with androgen insensitivity syndrome

The first case of squamous cell carcinoma of the vulva in a patient with androgen insensitivity syndrome is described.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28491/1/0000287.pd